阅读说明：本技术 数控车床在特定主轴转速下修复不同导程外螺纹的方法 (Method for repairing external threads with different lead lengths by numerical control lathe at specific spindle rotation speed ) 是由 刘建群 孙凤芝 刘珈利 韦相贵 张小军 刘伟芝 于 2019-10-18 设计创作，主要内容包括：本发明提供一种数控车床在特定主轴转速下修复不同导程外螺纹的方法,包括以下步骤：在参照工件上车制导程为P<Sub>0</Sub>的参照螺旋线；将刀尖定位于参照螺旋线中部任意位置；转动主轴使刀尖指向参照螺旋线,并标记主轴的角度位；卸下参照工件；在卡盘上安装待修螺纹的工件并转动主轴至所述角度位,待修螺纹的导程为P；移动刀尖指向待修螺纹任一牙底；计算车修程序设定的刀具起点与车修所需刀具起点的轴向偏移距离或周向偏差；在数控车床工作空间内消除轴向偏移距离,或调整车修所需刀具起点的角位移以消除周向偏差；运行数控程序对待修螺纹车修。该方法能够修复不同导程的外螺纹,成本低、便捷并具有普遍适用性。(The invention provides a method for repairing external threads with different lead lengths by a numerical control lathe at a specific spindle rotating speed, which comprises the following steps: at a reference workpiece by a lead P 0 The reference helix of (a); positioning the tool nose at any position in the middle of the reference spiral line; rotating the main shaft to enable the tool nose to point to the reference spiral line and marking the angle position of the main shaft; unloading the reference workpiece; installing a workpiece with a thread to be repaired on the chuck and rotating the main shaft to the angle position, wherein the lead of the thread to be repaired is P; moving the tool nose to point to any tooth bottom of the thread to be repaired; calculating the axial offset distance or circumferential deviation between the tool starting point set by the turning and repairing program and the tool starting point required by turning and repairing; eliminating axial deviation in working space of numerically controlled latheMoving distance or adjusting the angular displacement of the starting point of the cutter required by turning and repairing to eliminate circumferential deviation; and running a numerical control program to vehicle and repair the thread to be repaired. The method can repair the external threads with different leads, and has the advantages of low cost, convenience and universal applicability.)

1. A method for repairing external threads with different leads by a numerically controlled lathe at a specific spindle rotating speed is characterized by comprising the following steps:

s1, at the preset spindle speed, using the starting point S [ X ] of the cutter_S,Z_S]Machining a reference workpiece at a lead P on its outer surface₀Of a reference helix of, wherein X_SAs radial coordinate of the starting point S of the tool, Z_SIs the axial coordinate of the starting point S of the cutter;

s2, positioning the tool tip of the turning tool at the point A [ X ]_A,Z_A]Wherein X is_AIs the radial coordinate of point A, Z_AIs the axial coordinate of point A, Z_AThe tool tip is positioned at any position in the middle of the reference spiral line;

s3, rotating the main shaft to an angle position which makes the knife tip point to the reference spiral line to mark or memorize the angle position;

s4, detaching the reference workpiece from the chuck of the numerical control lathe;

s5, mounting the workpiece to be thread-trimmed on the chuck, and rotating the main shaft to the angle position, wherein the starting point of the tool set by the thread-trimming program to be trimmed is E [ X ]_E,Z_E]Wherein X is_EAs radial coordinate of point E, Z_EThe axial coordinate of the point E is taken as the lead of the thread to be repaired is P;

s6, moving the tool tip to point to any root position B [ X ] of the thread to be repaired_B,Z_B]Wherein X is_BIs the radial coordinate of point B, Z_BIs the axial coordinate of point B;

s7, calculating the cutter starting point E set by the vehicle repair program and the cutter needed by the vehicle repairThe actual axial offset distance L of the starting point E' is Z_B-Z_E-P*[Z_A-Z_S]/P₀And converting the actual axial offset distance L into an axial offset distance L ', L ' -L-FIX (L/P) ' P-P within a thread pitch range relative to the thread to be repaired<L'<P, where the function FIX (L/P) represents the integer part of the value taken for L/P; or calculating the circumferential deviation r between the tool starting point E' required by the turning and repairing and the tool starting point E set by the turning and repairing program_0C，r_0C＝360*L'/P；

S8, moving the cutter starting point E set by the turning program to the cutter starting point E 'required by the turning in the working space of the numerical control lathe to eliminate the axial offset distance L' or adjusting the angular displacement of the cutter starting point E set by the turning program to eliminate the circumferential deviation r_0C；

And S9, running the adjusted turning program, and machining the thread to be turned according to the turning tool starting point E', the lead P and the preset spindle rotating speed to finish the turning of the thread to be turned.

2. The method for repairing external threads with different leads on a numerically controlled lathe at a specific spindle speed as set forth in claim 1, wherein the reference workpiece has a visually observable lead of not less than 2 times P for a period of time sufficient for the lathe to complete the machining₀A work piece of a length spiral.

3. The method for repairing external threads with different leads on a numerical control lathe at a specific spindle rotation speed according to claim 1, wherein the spiral line refers to a track left by the center point of the tool nose on the surface of a workpiece.

4. The method for repairing different-lead external threads on a numerically controlled lathe at a specific spindle speed according to claim 1, wherein in step S1, the center of the end of the reference workpiece away from the chuck is taken as a coordinate system zero point.

5. The method for repairing external threads with different leads on a numerically controlled lathe at a specific spindle speed as set forth in claim 1, wherein the radial coordinate of the point aX_AThe radial position of the tool nose is larger than the major diameter of the reference spiral line at the point A.

6. The method for repairing different-lead external threads on a numerically controlled lathe at a specific spindle speed according to claim 1, wherein in step S3, the spindle is manually rotated to the angular position.

7. The method for repairing external threads with different leads on a numerical control lathe at a specific spindle speed according to claim 1, wherein if the number of the workpieces to be repaired is more than two, the steps S5-S9 are repeated until the thread repairing is completed on all the workpieces.

8. The method for repairing external threads with different leads on a numerically controlled lathe at a specific spindle speed as claimed in claim 1, wherein in step S3, after the spindle is rotated to the angular position, marks are made on the headstock and the chuck of the lathe to mark the angular position or to recognize the relative position characteristics of the headstock and the chuck of the lathe.

9. The method for repairing the external thread with different lead of the numerically controlled lathe at the specific spindle speed according to claim 1, wherein in step S8, for the numerically controlled lathe without the function of the macro program, the axial offset distance L' is eliminated by translating the coordinate system or adding a tool compensation; in a numerical control lathe with a macro program function, any one of local coordinate systems G54-G59 is set and called by adopting a translation coordinate system, adding tool compensation, adjusting the position of a tool starting point set by a turning program in the turning program or angular deviation, so as to eliminate axial deviation distance L' or circumferential deviation r_0C。

10. The method for repairing an external thread with different leads on a numerical control lathe at a specific spindle speed according to claim 1, wherein in step S5, after the workpiece to be repaired is mounted on the chuck, the workpiece to be repaired is corrected so that the central axis of the thread to be repaired coincides with the central axis of the spindle of the numerical control lathe.

Technical Field

The invention relates to a method for maintaining threads, in particular to a method for repairing external threads with different lead lengths by a numerical control lathe at a specific spindle rotating speed.

Background

A large number of threads are processed and maintained by petroleum drilling technical service enterprises every year, petroleum pipe thread maintenance service is necessary for controlling equipment cost in the drilling industry, the service life of petroleum pipes can be prolonged through maintenance, and equipment investment is saved. The technical key point of the petroleum pipe thread maintenance lies in that the original spiral line of the thread is turned, but not completely removed and reprocessed.

The special pipe lathe for machining threads is widely used in the industry, and has the advantages of simple structure, strong applicability, obvious defects, high labor intensity of operators, poor working environment condition, and occupational risks of accidental injury, disability and the like. Adopt numerical control lathe to carry out the vehicle repair to the screw thread and can reduce intensity of labour, however, there is the tool setting problem all the time in numerical control lathe work, the maintenance process of screw thread, and the outstanding performance is: the installation of each thread to be repaired on the machine tool is random, namely the difference between the position and the angle of the currently installed thread compared with the position and the angle of the currently installed thread is larger, most of the data of the machining positions set in the previous program have no significance to the current machining, and the data are completely updated, so that the labor efficiency of an operator is greatly reduced, the error probability of the program is increased, and the damage risk of the workpiece thread and the maintenance equipment is increased. Meanwhile, in the process of maintaining the threads of the petroleum pipe, the petroleum pipe which is subjected to vehicle repair in each batch usually has different tooth forms and leads, so that the difficulty of tool setting is undoubtedly increased, and the thread vehicle repair efficiency is reduced.

Disclosure of Invention

In view of the above problems, there is a need for a method for repairing external threads with different lead lengths by a numerically controlled lathe at a specific spindle rotation speed, which is low in cost, convenient and universal.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for repairing external threads with different leads by a numerically controlled lathe at a specific spindle rotating speed comprises the following steps:

s1, at the preset spindle speed, using the starting point S [ X ] of the cutter_S,Z_S]Machining a reference workpiece at a lead P on its outer surface₀Of a reference helix of, wherein X_sAs radial coordinate of the starting point S of the tool, Z_sIs the axial coordinate of the starting point S of the cutter;

s2, positioning the tool tip of the turning tool at the point A [ X ]_A,Z_A]Wherein X is_AIs the radial coordinate of point A, Z_AIs the axial coordinate of point A, Z_AThe tool tip is positioned at any position in the middle of the reference spiral line;

s3, rotating the main shaft to an angle position which makes the knife tip point to the reference spiral line to mark or memorize the angle position;

s4, detaching the reference workpiece from the chuck of the numerical control lathe;

s5, mounting the workpiece to be thread-trimmed on the chuck, and rotating the main shaft to the angle position, wherein the starting point of the tool set by the thread-trimming program to be trimmed is E [ X ]_E,Z_E]Wherein X is_EAs radial coordinate of point E, Z_EThe axial coordinate of the point E is taken as the lead of the thread to be repaired is P;

s6, moving the tool tip to point to any root position B [ X ] of the thread to be repaired_B,Z_B]Wherein X is_BIs the radial coordinate of point B, Z_BIs the axial coordinate of point B;

s7, calculating the actual axial offset distance L between the cutter starting point E set by the vehicle repair program and the cutter starting point E' required by the vehicle repair as Z_B-Z_E-P*[Z_A-Z_S]/P₀And converting the actual axial offset distance L into an axial offset distance L ', L ' -L-FIX (L/P) ' P-P within a thread pitch range relative to the thread to be repaired<L'<P, where the function FIX (L/P) represents the integer part of the value taken for L/P; or calculating the circumferential deviation r between the tool starting point E' required by the turning and repairing and the tool starting point E set by the turning and repairing program_0C，r_0C＝360*L'/P；

S8, moving the cutter starting point E set by the turning program to the cutter starting point E 'required by the turning in the working space of the numerical control lathe to eliminate the axial offset distance L' or adjusting the angular displacement of the cutter starting point E set by the turning program to eliminate the circumferential deviation r_0C；

And S9, running the adjusted turning program, and machining the thread to be turned according to the turning tool starting point E', the lead P and the preset spindle rotating speed to finish the turning of the thread to be turned.

Further, the reference workpiece has a visual lead P of not less than 2 times for satisfying a turning condition₀A work piece of a length spiral.

Further, the spiral line refers to a track left by the center point of the tool nose on the surface of the workpiece.

Further, in step S1, the center of the end of the reference workpiece away from the chuck is taken as a zero point of the coordinate system.

Further, the radial coordinate X of the point A_AThe radial position of the tool nose is larger than the major diameter of the reference spiral line at the point A.

Further, in step S3, the main shaft is manually rotated to the angular position.

Further, if the number of the workpieces to be thread-repaired is more than two, the steps S5-S9 are repeated until all the workpieces are thread-repaired.

Further, in step S3, after the spindle is rotated to the angular position, marks are made on the headstock and the chuck to mark the angular position, or the relative position characteristics of the headstock and the chuck are recognized.

Further, in step S8, for the numerically controlled lathe without the macro program function, the axial offset distance L' is eliminated by translating the coordinate system or adding a tool compensation; in a numerical control lathe with a macro program function, any one of local coordinate systems G54-G59 is set and called by adopting a translation coordinate system, adding tool compensation, adjusting the position of a tool starting point set by a turning program in the turning program or angular deviation, so as to eliminate axial deviation distance L' or circumferential deviation r_0C。

Further, in step S5, after the workpiece to be thread-corrected is mounted on the chuck, the workpiece to be thread-corrected is also corrected so that the central axis of the thread to be corrected coincides with the central axis of the spindle of the numerically controlled lathe.

Due to the adoption of the technical scheme, the invention has the following beneficial effects:

1. by adopting the method, the turning repair of different lead external threads can be switched at will, the turning repair of the different lead external threads shares the same reference thread characteristic, the zero position of the main shaft encoder does not need to be searched or marked, the tool can be accurately set at one time, and the maintenance of the threads is more convenient.

2. According to the method for repairing the external threads with different leads by the numerical control lathe at the rotating speed of the specific spindle, the actual axial offset distance L is converted into the axial offset distance L 'within a thread pitch range relative to the threads to be repaired, the positions of the offset distance adjusting points E to E' can be adjusted in the smallest and most saved mode, and the thread turning and repairing efficiency is further improved.

3. The method for repairing the external threads with different lead lengths by the numerical control lathe at the specific spindle rotating speed does not need any external detection instrument, does not need any modification and refitting of the numerical control lathe, is lower in cost, is generally applicable to the numerical control lathe with the thread machining function, is suitable for various numerical control systems, is suitable for both straight threads and tapered threads, can be mixed and has general applicability.

Drawings

Fig. 1 is a flow chart of a method for repairing external threads with different lead in a numerically controlled lathe at a specific spindle rotation speed according to a preferred embodiment of the present invention.

Fig. 2 is a schematic diagram of a method for repairing external threads with different lead lengths by a numerically controlled lathe at a specific spindle rotation speed according to a preferred embodiment of the present invention, wherein a view angle of the view angle is from top to bottom to observe a horizontal plane on which a spindle of the numerically controlled lathe is located.

In the attached drawings, 1-a machine tool spindle box; 2-a chuck; 3-a reference object; 4-a workpiece to be repaired; and 5, turning and repairing the cutter.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1 and fig. 2, a preferred embodiment of the present invention provides a method for repairing external threads with different lead lengths in a numerically controlled lathe at a specific spindle rotation speed, which includes the following steps:

s1, at the preset spindle speed, using the starting point S [ X ] of the cutter_S,Z_S]With a lead P on the outer surface of a reference workpiece 3₀Of a reference helix of, wherein X_SAs radial coordinate of the starting point S of the tool, Z_SIs the axial coordinate of the tool start point S. The starting point S [ X ] of the cutting tool_S,Z_S]The coordinate values of (a) are set by the turning program.

In step S1, the center of the end of the reference object 3 away from the chuck 2 is preferably taken as the zero point of the coordinate system to facilitate the calculation of the subsequent coordinates. Preferably, the reference helix is an external thread, in order to facilitate the positioning of the turning tool 5; the reference workpiece 3 meets the requirement of turning for a period of visual lead P which is not less than 2 times₀A workpiece with a helical length for facilitating subsequent operations; the spiral line refers to a track left by the center point of the tool nose of the tool on the surface of the workpiece; the rotating speed of the main shaft is set according to actual requirements.

S2, positioning the tool tip of the turning tool 5 at the point A [ X ]_A,Z_A]Wherein X is_AIs the radial coordinate of point A, Z_AIs the axial coordinate of point A, Z_AThe tool tip is positioned at any position in the middle of the reference spiral line. Point A [ X ]_A,Z_A]The coordinate values of (2) can be directly obtained from the numerically controlled lathe. Preferably, the radial coordinate X of said point A_AThe radial position of the tool nose is larger thanThe large diameter of the reference thread at point a prevents the turning tool 5 or the reference workpiece 3 from being damaged by collision of the turning tool 5 with the reference workpiece 3.

And S3, rotating the main shaft to an angle position, wherein the angle position enables the tool tip to point to the reference spiral line, and marking or recognizing the angle position.

In step S3, the spindle may be manually rotated to the angular position; after the spindle is rotated to the angular position, the spindle head 1 and the chuck 2 may be marked with a marker pen or the like to mark the angular position. Specifically, a mark F may be marked on the machine tool headstock 1, and a mark G may be marked on the chuck 2, the mark F being located on the same horizontal line as the mark G, as shown in fig. 2 (a); or the relative position characteristics of the spindle box 1 and the chuck 2 of the machine tool are recorded.

S4, the reference object 3 is removed from the chuck 2 of the numerically controlled lathe.

S5, installing the workpiece 4 to be thread-corrected on the chuck 2, as shown in (b) of figure 2, and rotating the main shaft to the angle position, wherein the start point of the tool set by the thread-correction program to be corrected is E [ X ]_E,Z_E]The lead of the thread to be repaired is P, wherein X_EAs radial coordinate of point E, Z_EIs the axial coordinate of point E. Point E [ X ]_E,Z_E]The coordinate values of (a) can be directly obtained from the turning program of the thread to be repaired.

In step S5, when the workpiece 4 to be repaired is mounted, the spindle is rotated to change the angular position thereof, and therefore, after the workpiece 4 to be repaired is mounted, the spindle needs to be rotated so that the mark F marked on the headstock 1 of the machine tool and the mark G marked on the chuck 2 are again located on the same horizontal line to position the spindle at the angular position. The rotation of the spindle may be performed manually.

Preferably, after the workpiece 4 to be repaired is mounted on the chuck 2, the workpiece 4 to be repaired is corrected so that the central axis of the thread to be repaired coincides with the central axis of the spindle of the numerically controlled lathe, thereby further improving the precision of thread repair.

S6, moving the tool tip to point to any bottom position B [ X ] of the thread to be repaired_B,Z_B]Wherein X is_BIs the radial coordinate of point B, Z_BIs the axial coordinate of point B, X_BAnd Z_BCan be directly obtained from the numerical control machine tool.

S7, calculating an actual offset distance L between the tool start point E set by the turning program and the tool start point E' required for turning, where L is Z_B-Z_E-L_p＝Z_B-Z_E-P*[Z_A-Z_S]/P₀And converting the actual offset distance L into an axial offset distance L ', L ' -L-FIX (L/P) ' P-P in a lead range relative to the thread to be repaired<L'<P, wherein the function FIX (L/P) represents an integer part of the value of L/P, or the circumferential deviation r of the tool starting point E' required for the calculation of the turning and the tool starting point E set by the turning and repairing program_0C＝360*L'/P。

In step S7, the formula "L ═ Z_B-Z_E-P*[Z_A-Z_S]/P₀"in" P x [ Z_A-Z_S]/P₀The processing mode is the core content realized by the method, is the key for solving the problem that the threads to be repaired in different leads share the same reference and the threads to be repaired are turned and repaired by randomly switching different leads, and means that the lead is P₀The axial distance between the point a on the reference helix and the tool starting point S is converted in advance to an equivalent angular displacement between the points AS ([ Z ]_A-Z_S]/P₀) For example, suppose [ Z_A-Z_S]/P₀11.253, which means that the turning tool starts to turn the helix from point S, and when it reaches point a, the spindle has turned 11.253 turns, and after removing the full number of turns 11, the actual spindle angle between point S and point a is 0.253 x 360, 91.08 degrees, which the lathe numerical control system usually cannot display, so that the spindle angle position F-G must be marked specifically, which corresponds to the actual position of point a. In addition, the turning of any lead thread by the numerical control system of the lathe starts from a so-called zero signal time point inside the lathe, which is a fixed main shaft angle position, so that a known point B for obtaining the thread to be corrected is measured on the angle, and the position E' of the starting point for correctly correcting the thread can be obtained by calculation no matter what the lead is. Due to the given tool bit in the thread-repairing procedureThe point E is not at the position, so that the screw thread can be turned and repaired by randomly switching different leads by adjusting the cutter starting point E set by the turning program to E' by various methods before turning and repairing.

The thread turning becomes a more difficult problem in the application of the numerical control lathe, mainly because after each thread to be turned is installed on the numerical control lathe, the actual starting point of the thread is in different angles (relative to the angle of a 'spindle zero position signal') and has randomness, and the actual starting point is not easy to obtain conveniently and economically, the actual starting point can be found conveniently and economically, the starting point cannot be turned and turned if the actual starting point cannot be found accurately within 360 degrees of the circumference of the spindle, so technicians apply various advanced technologies and various methods to find the actual starting point, for example, the methods of using a CCD camera, magnetic induction, laser ranging, infrared rays, self-made measuring tools, numerical control machine tool reconstruction and the like, and the thread turning cost is high and the method is complex. The method has the remarkable difference from other prior art in the thought that: taking a shortcut, and using comparison to 'bypass' to measure unknown, specifically determining an angular position of a main shaft (namely an angular position marked by F-G), comparing the angular position with a point B on each thread to be repaired at the position to obtain a deviation, and then eliminating the deviation to realize random switching of different leads to finish the thread.

Furthermore, the actual axial offset L can be converted into an axial offset L ' within a pitch range from the thread to be repaired by the formula "L ' ═ L-FIX (L/P) × P", which is effective to process the whole number of turns 11 in the above example "11.253 turns" to obtain-P ' < L ' < P, thereby adjusting the positions of the points E to E ' with the smallest and most economical offset to further improve the efficiency of the repair.

S8, moving the cutter starting point E set by the turning program to the cutter starting point E 'required by the turning in the working space of the numerical control lathe to eliminate the axial offset distance L' or adjusting the angular displacement of the cutter starting point E set by the turning program to eliminate the circumferential deviation r_0C。

In step S8, the numerical control lathe without the function of the macro program is passedThe coordinate system is translated or a tool complement is added to eliminate the axial offset distance L'. For the machine tool having the macro program function, various methods can be used, for example, a translation coordinate system, an additional tool compensation, an adjustment of a thread start point position or an angular deviation in the truing program, a setting and calling of any one of the local coordinate systems G54 to G59, and the like, to move a tool start point set by the truing program or to adjust an angular displacement of the tool start point set by the truing program. By eliminating axial offset distance L' or circumferential deviation r_0CIn any mode, the tool tip track of the turning and repairing tool 5 is ensured to be coincident with the thread track to be repaired.

And S9, running the adjusted turning program, and machining the thread to be turned at the starting point E' of the tool required for turning, the lead P and the preset spindle rotating speed to finish the turning of the thread to be turned. In step S9, the spindle rotation speed in the thread trimming process to be trimmed is the same as the spindle rotation speed in step S1.

If the number of the workpieces to be repaired is more than two, the steps S5-S9 are only needed to be executed repeatedly until the thread is repaired on all the workpieces.

The technical principle of the method for repairing the external threads with different lead lengths by the numerical control lathe at the rotating speed of the specific spindle is as follows: within the machine space, a specific lead is P₀The thread spiral track is determined by a cutter starting point S and a main shaft rotating speed, under a certain main shaft rotating speed, any point A on the spiral track has a fixed axial position relation and a fixed circumferential position relation with the point S, a point B with the same phase angle as the point A is found on the thread to be repaired with the lead P according to the position relation as reference, the cutter starting point E 'required for repairing the thread to be repaired is calculated according to the position relation, the deviation between the E' and the cutter starting point E set by a repairing program is converted according to the lead P, and the deviation is eliminated, so that the repairing cutter can be used for repairing the thread to be repaired according to the thread track with the lead P. Based on the principle, the position of the cutter starting point E or the angular displacement set by the lathe repairing program can be adjusted by any method in the space of the machine tool, and the aim of overlapping the cutter point track of the lathe repairing cutter with the thread track to be repaired is fulfilled.

To facilitate understanding, the following is a specific example provided by an embodiment of the present invention:

preparation work:

1. fanuc numerical control system adopted by machine tool for turning and repairing

2. The thread turning tool uses a No. 15 cutter compensation tool, the thread turning tool calls the No. 15 cutter compensation in the machining program, and the cutter compensation number is specially used for the program;

3. preparing a reference workpiece 3, wherein the diameter is not particularly required, and an oil casing pipe with the diameter of phi 139.7mm and the length of not less than 200mm is used in the embodiment; it will be appreciated that in other embodiments, other sizes of workpieces may be used as reference workpieces.

4. Taking the center of the right end (namely, the end far away from the chuck 2) of the reference workpiece 3 as a zero point of a coordinate system, turning a visually-visible conionless spiral line with the lead of 6.35mm on the outer surface of the reference workpiece 3 at 150 revolutions per minute as a reference spiral line, wherein the length of the reference spiral line is not less than 100mm, and the coordinate of the starting point S of the cutter is (139, 12.7);

5. stopping the main shaft, moving a tool nose to A (141, -50.8), rotating the main shaft until the tool nose points to a reference spiral line, marking the current chuck angle position (marking F-G by a marking pen or identifying the chuck angle position characteristics), and detaching the reference workpiece 3;

6. before all instructions of the original program, the following instructions are written (taking a thread to be repaired with a thread lead of 5.08 as an example):

#501 equals 5.08; (lead of thread to be repaired)

#505 is 10.16; (tool starting point Z coordinate set by the vehicle repair program)

#515 ═ -12.345; (record No. 15 cutter repair value, here-12.345 is only an example, and the actual operation should be changed to actual value)

M98P 6350; (Call subroutine 6350)

7. The following code is written into the new program 6350 (available for use in a 6.35 lead procedure call, without modification when used)

O6350；

#502 ═ 6.35; (refer to thread lead)

#503 is 12.7; (refer to the thread cutter origin Z coordinate)

#504 ═ 50.8; (refer to thread A Point Z coordinate Z_A)

#2115 ═ 515; (restore No. 15 knife repair original value)

#1 ═ 5042; (reading the axial coordinate Z of the current tool setting position_BThe value of system parameter #5042 is passed to parameter #1)

#1- #505- #501 [ #504- #503]/# 502; (calculating the actual offset distance L of the thread to be repaired)

#2 #1- #501 FIX [ #1/#501 ]; (calculating the offset distance L' in a lead range with respect to the thread to be repaired.)

#2115 ═ 2115+ # 2; (use 15 tool compensation to eliminate the deviation of the thread to be repaired relative to the reference thread)

G0U 10; (cutter X moves 5mm in the forward direction and is far away from the position for cutter setting)

W200; (cutter Z moves 200mm forward, far from the thread to be repaired)

M99; (returning to original program, start threading by 5.08 lead)

The operation steps when the thread to be repaired is lathed are as follows:

1. installing and correcting a workpiece 4 to be repaired, wherein the lead of the thread to be repaired is 5.08;

2. rotating the chuck 2 to the mark F-G position;

3. moving the turning tool 5 until the center of the tool tip points to any thread root B and stopping at the position;

4. and operating a thread machining program.

The method for repairing the external threads with different lead lengths by the numerical control lathe at the rotating speed of the specific spindle can realize the random switching of the lathe repair of the threads with different lead lengths, and the same reference thread characteristic is shared, so that the thread repair process is simplified; the method is adopted to repair the thread without any external detection instrument or any modification and refitting of the numerical control machine tool, and the cost is low; the method is adopted to repair the thread, the cutter can be accurately set at one time, the zero position of the main shaft encoder does not need to be searched or marked, the starting point position of the cutter is adjusted in the space of a machine tool, the original program is not changed, and the maintenance is more convenient; the method is generally applicable to numerical control lathes with thread machining functions, is suitable for various numerical control systems, and has general applicability; for a numerical control system with a macroprogram function, manual recording, data input and calculation are not needed, and the use is more convenient; the method is suitable for both straight threads and tapered threads, can be mixed, is not influenced by the tapered threads, and has better universality.

The above description is intended to describe in detail the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the claims of the present invention, and all equivalent changes and modifications made within the technical spirit of the present invention should fall within the scope of the claims of the present invention.