CN108247162B

CN108247162B - Numerical control small Kong Jidian pole rotation control device and method

Info

Publication number: CN108247162B
Application number: CN201810225304.6A
Authority: CN
Inventors: 李学哲; 姚子巍; 李长宁
Original assignee: Suzhou University of Science and Technology
Current assignee: Suzhou University of Science and Technology
Priority date: 2018-03-19
Filing date: 2018-03-19
Publication date: 2023-05-26
Anticipated expiration: 2038-03-19
Also published as: CN108247162A

Abstract

The application discloses numerical control little Kong Jidian utmost point rotation control device and application method of device and numerical control aperture machine who disposes this kind of device, wherein electrode rotation control device includes step motor, step motor passes through swivel drive electrode tube, still includes: a rotor with a central hole, wherein the rotor is provided with a coding pattern; the rubber ring is arranged in the central hole, and the electrode tube penetrates into the rubber ring; a stator mated with the rotor; the linear array scanning camera is relatively fixed with the stator and matched with the coding pattern to be used for detecting the rotating speed of the rotor; and the driving circuit is used for supplying power to the stator so as to drive the rotor to rotate and is connected with a motor driver of the stepping motor and the linear array scanning camera. The method can effectively improve the processing quality of the small holes.

Description

Numerical control small Kong Jidian pole rotation control device and method

Technical Field

The application relates to the field of numerical control hole machines, in particular to a numerical control small Kong Jidian pole rotation control device, an application method of the device and a numerical control hole machine provided with the device.

Background

A numerical control electric machining small hole machine (hereinafter referred to as small hole machine) belongs to one type of electric spark machining machine tool, and is mainly used for machining micro holes of conductive substances such as superhard steel, hard alloy and the like by utilizing a continuously moving slender hollow copper pipe as a tool electrode (hereinafter referred to as electrode), discharging a medium (working solution) passing through a copper pipe hole and a workpiece, and performing pulse spark discharge on the workpiece to remove metal so as to achieve the purpose of perforation. The electric spark erosion processing is also the core part of the numerical control small hole machine, and has the main functions that: 1. adjusting the electrode machining feed speed according to the gap voltage to control the discharge gap size; 2. the rotary liquid feeding device (rotary head, guide) realizes the rotation of the electrode and the high-pressure liquid feeding. The electrode numerical control feeding control technology and the electric spark gap voltage acquisition technology have been improved obviously after years of development, and various problems caused by a rotating device have become main factors influencing the product quality at present.

The positioning precision of the small hole machine hole can be +/-1 mu, the precision error caused by rotary machining is more than +/-5 mu, and the shape of the machined hole is irregular, so that innovation of a rotary control technology has become a key technical problem to be solved urgently for a numerical control small hole machine.

The small hole machine rotating head has two functions of electrode rotation and high-pressure liquid feeding, and in the micro-hole (0.3-3 mm diameter) processing, the electrode rotates under the action of the rotating head, so that on one hand, the end face of the electrode is uniformly worn and is not offset by the reaction force of high-pressure and high-speed working liquid medium; on the other hand, the working fluid flowing under high pressure flows out of the hole according to the spiral track on the wall of the hole, like a hydrostatic bearing, so that the electrode tube is suspended in the hole center, and short circuit is not easy to occur, therefore, the rotation stability of the electrode is an important factor affecting the machining efficiency and quality of the hole.

The existing rotating mechanism (as shown in fig. 1) comprises a stepping motor (hereinafter referred to as a motor), a synchronous belt, a gear, a rotating shaft, a bearing, an electrode chuck and an electrode. The electromechanical machining of the small hole belongs to non-contact machining between an electrode and a workpiece, and the ideal machining state is that the electrode (30 cm long hollow tube) cannot shake when being axially fed. The rotation shaft is stressed, the electrode mass distribution is uneven, the electrode rigidity is limited, and the like, so that the electrode shakes greatly when rotating, and the guide on the guide frame is necessary to limit the shaking (the diameter of the inner hole of the guide is larger than that of the electrode), so that the limited action of the guide frame often causes serious consequences such as larger aperture, irregular shape, surface damage, upper and lower section aperture deviation, and the like. Meanwhile, as the electrode shakes too much, the gap discharge is out of control, even the short circuit between the electrode and the workpiece is caused, the processing quality and the processing efficiency are seriously affected, and the rotary liquid feeding device of the current small hole machine mainly has the following defects:

1. because the electrode (namely the electrode tube) is long and thin and hollow, the mass distribution of the electrode is uneven, and the like, the electrode can shake when rotating, and the limited shaking of the passive limiting effect of the guide device still exists. In addition, the electrode is in contact with the guide device to generate a new moment resistance, so that large-amplitude shaking is converted into small-amplitude shaking with small frequency and disordered track, and the shape, the dimensional accuracy and the machining efficiency of the machined hole are directly affected.

2. Because the high-pressure liquid feeding part must be arranged at the right upper part in the rotating head, direct motor shaft driving cannot be adopted, and synchronous belt transmission must be used. The radial load of the synchronous belt pressing shaft force on the rotating shaft is large, and the rigidity of the rotating shaft (because the electrode must pass through the rotating shaft, the rotating shaft is non-solid), the bearing supporting force, the synchronous belt transmission disturbance and other factors can cause uneven stress and shaking when the electrode rotates, so that the shape, the dimensional precision and the machining efficiency of a machining hole are directly affected.

3. Because the moment of dragging rotation acts on the upper part of the electrode, the electrode is slender and hollow, and when the processing end (the lower part of the electrode) is disturbed by various tiny resistances, the rotating motion track of the electrode can be changed, and the shape, the dimensional precision and the processing efficiency of a processing hole are directly affected.

4. Because the electrode is in the workpiece small hole during processing, a monitoring and abnormal processing mechanism cannot be installed, and the dragging rotating stepping motor runs in a constant rotating speed mode (electromagnetic torque self-adaptive load capacity), once the electrode shakes too much or is in abnormal contact, the quality of a processed workpiece can be seriously affected, and even the whole workpiece is scrapped.

5. Because the loss of the electrode in the processing is difficult to predict, when a hole with a certain depth is processed, whether the processing of the through hole is finished cannot be accurately judged, so that the system processing efficiency is low, the through hole is not punched or the processing quality of the next hole is seriously influenced, and the through hole monitoring is always a technical problem which puzzles the full-automatic processing of the small hole machine.

The above problems have not been solved effectively for many years. Therefore, the rotary processing device of the existing small hole machine is improved, the rotary control and monitoring technology level is improved, and the problem is solved, so that the rotary processing device has important significance for the technical progress of the numerical control small hole machine.

Disclosure of Invention

The purpose of the application is as follows: in the existing small hole machining process, the electrode rotates under the action of the rotating head, and when the electrode shakes, the shaking amplitude is limited through the guide device. Because the manufacturing industry has higher and higher requirements on the precision of parts, the passive limiting method cannot meet the production requirement, innovation of a rotation control technology has become a key technical problem to be solved urgently for a numerical control small hole machine, and in this regard, the application provides a numerical control small Kong Jidian polar rotation control device with the functions of good processing stability, processing state monitoring and through hole detection.

The technical scheme of the application is as follows:

the utility model provides a numerical control is little Kong Jidian utmost point rotary control device, includes step motor, step motor passes through swivel head drive electrode tube, still includes:

a rotor with a central hole, wherein the rotor is provided with a coding pattern;

a flexible rubber ring provided in the central hole, the electrode tube being inserted into the rubber ring;

a stator mated with the rotor;

the linear array scanning camera is relatively fixed with the stator and matched with the coding pattern to be used for detecting the rotating speed of the rotor; and

and the driving circuit is used for supplying power to the stator so as to drive the rotor to rotate and is connected with a motor driver of the stepping motor and the linear array scanning camera.

The numerical control small Kong Jidian pole rotation control device further comprises the following preferable schemes on the basis of the technical scheme:

the inner diameter of the rubber ring is larger than the outer diameter of the electrode tube.

The inner diameter of the rubber ring is 10 μm larger than the outer diameter of the electrode tube.

Of course, the rubber ring and the electrode tube can also be in direct contact fit.

And a plurality of bulges are formed on the wall of the inner hole of the rubber ring.

The rotor is of a disc-shaped structure;

the stator includes:

a first upper core coil and a second upper core coil which are radially symmetrically arranged at two opposite sides above the rotor,

a first lower core coil and a second lower core coil radially symmetrically arranged on opposite sides below the rotor, an

A permanent magnet disposed at a side of the rotor;

the first upper core coil is arranged right above the first lower core coil, and the second upper core coil is arranged right above the second lower core coil.

The stator further includes permanent magnets disposed on sides of the rotor.

The coding pattern comprises eight pattern areas which are uniformly distributed along the circumferential direction and have different patterns.

The motor driver of the stepping motor, the driving circuit and the linear array scanning camera are all connected with a numerical control system circuit of the numerical control pinhole machine.

A numerical control pinhole machine comprises a numerical control small Kong Jidian pole rotation control device with the structure.

The application method of the numerical control small Kong Jidian pole rotation control device comprises the following steps: when the machining hole is partially conducted to form a through hole, the working fluid entirely flows out from the bottom of the through hole, at this time, abrupt resistance torque reduction and rotation speed increase occur, and the coil current after stable adjustment is equivalent to the value of I when the machining is not performed, so that it can be determined that the through hole is formed.

The application has the advantages that:

1. according to the rotation processing characteristics of the small hole machine, the upper and lower rotation driving supporting structures are designed for the slender hollow electrode, and the rotation speed of the 'lower end' rotation electrode is always servo tracked to the rotation speed of the 'upper end' rotation electrode through the high-precision speed measurement and control system, so that the rotation control device is skillfully utilized to compensate load disturbance, the rotation stability of the electrode is greatly improved, the shape and the size precision of a processing hole are ensured, and the gap discharge control and the short-circuit ineffective processing time reduction are facilitated. The upper and lower rotary drives are utilized to decouple the functions, and the power driving part is realized by a rotary head; the guiding and overcoming of the tiny disturbance are completed by a rotary guiding control device, and the problem of electrode processing stability is solved skillfully by cooperative rotation between the two devices.

2. In addition, the rotation control device also has a processing abnormal condition detection function. The numerical control small hole machining quality and efficiency can be improved by utilizing the numerical control small hole machining device, and the numerical control small hole machining device has certain practical value and economic benefit.

3. The device can also recognize the moment of appearance of the 'quasi' through hole, solves the problem of through hole detection of a full-automatic small hole machine, improves the system processing efficiency, and avoids the consequences that the through hole is not punched or the hole processing quality is influenced.

4. The inner diameter of the rubber ring is slightly larger than the outer diameter of the electrode tube, the electrode tube and the rubber ring are in a non-contact state to be contacted in general, the rubber ring synchronously rotates along with the rotor, and the rotating speed of the rubber ring is always consistent with the rotating speed of the electrode tube. If the electrode tube is in normal small shaking, the electrode tube is slightly contacted with the rubber ring, the shaking energy of the electrode tube is absorbed by the buffer deformation of the rubber ring, and the rotation speed of the rubber ring and the rotation speed of the electrode tube are always consistent, so that even if the electrode tube touches the rubber ring, relative circumferential displacement does not exist between the electrode tube and the rubber ring, the electrode tube is not subjected to circumferential torsion force, and the electrode tube is enabled to resume normal rotation under the rotation guiding action of the rotor and the rubber ring.

Drawings

The application is further described with reference to the accompanying drawings and examples:

FIG. 1 is an overall schematic diagram of a numerical control pinhole machine in an embodiment of the present application;

fig. 2 is a schematic structural diagram of a numerical control small Kong Jidian pole rotation control device in an embodiment of the present application;

FIG. 3 is a schematic diagram of the structure of the encoding pattern on the rotor according to the embodiment of the present application;

fig. 4 is a schematic structural diagram of the numerical control small Kong Jidian pole rotation control device according to the embodiment of the present application after mounting a bracket;

wherein: 1-rotor, 2-rubber ring, 3-electrode tube, 4-stator, 401-first upper iron core coil, 402-second upper iron core coil, 403-first lower iron core coil, 404-second lower iron core coil, 405-permanent magnet, 5-coding pattern, 501-digital pattern, 502-analog image, 6-linear array scanning camera.

Detailed Description

Fig. 1 shows a specific embodiment of a numerical control hole machine of the present application, which, like a conventional numerical control hole machine, also includes: electrode tube 3, stepper motor, numerical control system, high-pressure liquid feeder, etc. Wherein the stepper motor is connected with the electrode tube 3 through a rotating head (or called an electrode chuck) to drive the electrode tube 3 to rotate. The electrode tube 3 is vertically arranged, the rotating head is positioned at the upper end of the electrode tube 3, and the stepping motor drives the rotating head by means of the synchronous belt and the synchronous wheel.

The key improvement of the embodiment is that a numerical control small Kong Jidian pole rotation control device is also arranged, and the device comprises a rotor 1, a stator, a rubber ring 2 and a linear array scanning camera 6, as shown in reference to fig. 2. Wherein: the rotor 1 has a central hole of a through hole structure in which a flexible rubber ring 2 is fixedly embedded, the electrode tube 3 is inserted into the rubber ring 2, and a special code pattern 5 (for marking the rotation angle of the rotor) is formed on the rotor 1. The stator is engaged with the rotor 1, and the rotor can be rotated by energizing the coils of the stator. The linear array scanning camera 6 is fixed relative to the stator and is used for scanning the coding pattern 5 on the rotor 1 so as to detect the rotating speed of the rotor 1. The driving circuit supplies power to the stator to drive the rotor 1 to rotate, and the driving circuit is connected with a motor driver circuit of the stepping motor. The linear array scanning camera 6 is connected with the driving circuit to feed back the detected rotor rotation speed to the driving circuit.

The motor driver, the driving circuit and the linear array scanning camera 6 of the stepping motor are all connected with a numerical control system circuit of the numerical control pinhole machine, and the running states of the motor driver, the driving circuit and the linear array scanning camera are uniformly controlled by the numerical control system. It can be seen that: in the embodiment, the circuit connection among the stepping motor, the driving circuit and the linear array scanning camera 6 is realized by means of a numerical control system of the numerical control pinhole machine.

In this embodiment, the rotor 1 is of a disc-shaped structure, which is horizontally disposed at the lower end of the electrode tube 3, and is preferably located as close as possible to the workpiece to be processed.

The stator includes: first and second upper core coils 401 and 402, which are radially symmetrically disposed at opposite sides above the rotor 1, first and second lower core coils 403 and 404, which are radially symmetrically disposed at opposite sides below the rotor 1, and permanent magnets 405, which are disposed at sides of the rotor 1. The aforementioned first upper core coil 401 is arranged directly above the first lower core coil 403, and the second upper core coil 402 is arranged directly above the second lower core coil 404.

In this embodiment, the inner diameter of the rubber ring 2 is preferably slightly larger than the outer diameter of the electrode tube 3, and in general, it is most preferable that the inner diameter of the rubber ring is 10 μm larger than the outer diameter of the electrode tube, and both the inner diameter and the outer diameter refer to diameters. In this way, in general, the electrode tube 3 and the rubber ring 2 are in a non-contact state (a state similar to contact but not contact) to be brought into contact, the rubber ring 2 rotates in synchronization with the rotor, and the rotation speed of the rubber ring 2 and the rotation speed of the electrode tube 3 are always kept identical. If the electrode tube 3 is slightly swayed normally, the electrode tube 3 is slightly contacted with the rubber ring 2, the swaying energy of the electrode tube 3 is absorbed by the buffer deformation of the rubber ring, and the rotation speed of the rubber ring is always consistent with that of the electrode tube, so that even if the electrode tube touches the rubber ring, relative circumferential displacement does not exist between the electrode tube and the rubber ring, the electrode tube is not subjected to circumferential torsion force, and the electrode tube 3 is enabled to resume normal rotation under the action of rotor rotation guiding.

The inner diameter of the rubber ring 2 is slightly larger than the outer diameter of the electrode tube 3, so that the rubber ring 2 and the electrode tube 3 are prevented from being in excessively tight contact and have larger static friction force, and the feeding jam of the electrode tube is easy to occur without using the axial downward feeding of the electrode tube 2; and at the same time, the lower end of the electrode tube is subjected to certain circumferential torsion force once the rotation speeds of the rubber ring 2 and the electrode tube 3 deviate slightly.

Of course, it is also possible to set the inner diameter of the rubber ring equal to the outer diameter of the electrode tube so that the rubber ring is in direct slight contact with the electrode tube.

The inner hole wall of the rubber ring 2 is formed with a plurality of tiny protrusions, and the outer wall surface of the electrode tube 3 touches the protrusions when the electrode tube is slightly swayed. The protrusions may be corrugated structures or array-type dot-like protrusion structures. These projections are on the one hand intended to increase the damping and on the other hand the torque required for the rotary guidance is small and no large friction drag torque is required. The electrode tube 3 rotates under the action of the rotating head, the rotor and the rotating head of the device synchronously rotate, and no interaction force exists between the rotor and the electrode tube under normal conditions. Most of shaking is small shaking which is not abnormal, shaking energy is absorbed through buffering of the rubber ring, and normal rotation is restored under the rotation guiding effect of the rotor; in case of abnormal contact and scraping between the electrode tube and the workpiece caused by excessive shaking of the electrode tube, the resistance torque is obviously increased, the rotating speed is rapidly reduced, the linear array scanning camera connected with the driving circuit detects the change of the rotating speed, and the driving circuit immediately stops processing and prompts alarm.

The rotor of the device is made of an aluminum alloy material, is light in weight and introduces a motive torque from the peripheral annular portion of the rotor in order to avoid the center electrode tube. The specific method comprises the following steps: generating a stable sine alternating signal by a circuit in the numerical control system, wherein one path of the signal is amplified by power and then output to the exciting coil, and the alternating power signal generates alternating magnetic flux in the iron core and eddy current on the rotor; the other signal is output to the regulating coil after program controlled amplification and regulation and power amplification, and alternating magnetic flux and eddy current are generated in the iron core and the rotor. Alternating magnetic flux and eddy current respectively generated by the exciting coil and the adjusting coil interact on the rotor to form electromagnetic rotation moment to push the rotor to rotate. When the magnetic flux generated by the permanent magnet is cut by the rotating rotor, the magnetic flux interacts with the induced current generated in the rotor to form braking torque, so that the rotating speed of the rotor is in direct proportion to the power of the electric signal. The rotating speed is adjusted by changing the coil current through the D/A output, and the rotating speed is higher when the current is larger. The symmetrical iron core coil groups are adopted to ensure radial load balance of the rotating shaft, and meanwhile, the output power is improved by the symmetrical iron core coils.

Because of the specificity of small hole processing, the processing state can be monitored only through the rotating speed of the rotor, so the device utilizes the linear array scanning camera to identify the coding pattern 5, and realizes non-contact and high-precision angular displacement measurement. The specific method comprises the following steps: referring to fig. 3, two laser direct writing lithography patterns are provided on the peripheral annular band of the rotor 1, one is a linear digital pattern 501, representing the current measurement zone, the rotor is divided into 8 zones (the central angle is 45 degrees fan-shaped into one zone), in order to make the linear array sensor identify the current measurement zone, three annular lines with different radii are used for encoding, 8 encoding patterns can be combined, wherein the outer annular line represents the highest position, the middle annular line represents the next highest position, and the inner annular line represents the lowest position, for example: all no patterns represent 0 region, three lines all represent 7 region, and so on; the other is a radial angle corresponding simulation pattern 502 (let the pattern be the longest in radial direction as L), in each partition (for drawing convenience, a simulation pattern is drawn in only one of the partitions in fig. 3), a mapping relationship between the angle and the radial length of the arc is established by using a simulation pattern method, i.e. every 0.45 degree, the radial length thereof increases by L/100 length units, and when the angle increases to 45 degrees, the radial length thereof increases to L. When a linear array scanning camera 6 (CCD) collects radial linear array image information, three annular line points on the inner side determine the current measurement area, the radial length of the outer side analog graph corresponds to the angle value in the area, absolute angle information can be accurately obtained through the angle values in the measurement area and the area, and the angular speed or the rotating speed can be calculated through the internal angle change in unit time. The resistance torque on the electrode tube is relatively small in normal processing, once the electrode tube is in abnormal contact with a workpiece, the resistance torque is obviously increased, and the rotating speed is rapidly reduced, so that corresponding control strategies can be timely and effectively adopted as long as the information is rapidly captured.

It can be seen that the code pattern 5 includes eight pattern areas uniformly distributed in the circumferential direction and having different patterns, each of which is composed of the above-described linear digital pattern and analog pattern.

The rotating head drags the electrode to rotate in a constant rotating speed mode, and the electrode shakes in the rotating process due to various reasons, so that the whole electrode keeps a synchronous rotating state, an upper-lower two-point driving mode is needed to be adopted for the slender electrode, namely, a rotation control device is arranged on the guide frame. The shaking energy caused by various reasons (such as uneven electrode quality) is usually small, and the synchronous rotation state (the rotation speed of the lower rotor auxiliary electrode always tracks the rotation speed of the upper rotating head dragging electrode tube) can be ensured by the active compensation of the rotation control device, and the method is as follows: the device adopts a two-phase stepping motor, the rotating speed of the motor can be controlled by pulse frequency, and the rotating speed calculation formula (1) is as follows:

wherein: x: a driver subdivision multiple; θ, intrinsic step angle.

According to the processing rotation speed V, inputting the pulse corresponding to the fixed frequency f to a stepping motor driver, and dragging the electrode tube by the driver and the stepping motor to rotate at the constant rotation speed V; meanwhile, the lower part of the electrode tube assists the servo tracking rotating speed V in the rotating control device, so that the rotating posture of the electrode tube is kept consistent with the upper part, and the stress between the upper part and the lower part is eliminated. Thus, two rotary driving supporting points are respectively arranged on the upper part and the lower part of the slender hollow electrode, thereby ensuring the linearity of the rotation of the electrode, compensating various load disturbance and ensuring the rotation stability of the electrode.

The processing rotation speed of the electrode tube is not high (20-120 rpm), the rotating head works in a constant rotation speed mode during processing, but in order to ensure the cooperative tracking stability of the rotation control device during starting or gear shifting, the stepping motor is required to regulate the speed according to a set lifting and decelerating curve.

The disturbance caused by the processing end mainly comprises the following steps: when the electrode descends to contact with the electrode, the action of contact force and discharge force causes abnormal rotating speed, and the electrode is detected by the rotation control device and is quickly retracted, so that the damage of a workpiece hole is avoided. Then normal processing is started by descending at a low speed; during normal machining, along with the increase of the machining depth, the pressure of the working solution on the wall of the electrode tube is gradually increased, and at the moment, the numerical control system continuously adjusts the coil current according to the change of the rotating speed so as to keep the constant rotating speed V of the rotor; disturbance caused by discharge power and reaction force of working fluid during normal machining can be counteracted by the action of the rotation control device; when the electrode tube head breaks or other reasons cause the rotating electrode to be in abnormal contact with the workpiece, the resistance torque is obviously increased, the rotating speed is rapidly reduced, and at the moment, the numerical control system can immediately turn off the rotating and high-frequency power supply and rapidly back the electrode, so that the serious consequence of scrapping the workpiece is avoided.

When a small hole machine is used for deep hole machining, the machining depth is usually set by a compensation method, but the machining depth cannot be accurately calculated due to the fact that the electrode tube loss is influenced by factors such as machining materials, through holes are frequently not punched (blind holes) in actual machining, in order to avoid the phenomenon, an operator must enlarge depth compensation, after a plurality of holes are punched, the numerical control system coordinates do not reach the set depth, and the situation of continuously 'blank punching' for a certain depth is caused. Because the numerical control small hole machine is mainly used for machining batch holes, the machining efficiency is seriously affected under the condition. The device is used for a through hole detection method as follows: when the processing is not performed, the coil current (namely the current of the stator coil) of the rotation control device is I, the coil (stator coil) current gradually becomes larger along with the increase of the hole depth, when the processing hole is partially conducted to form a quasi-through hole, liquid (namely working liquid) completely flows out from the bottom of the hole, the abrupt resistance torque becomes smaller and the rotation speed becomes larger at the moment, the coil current after the adjustment and stabilization is equivalent to the value of I when the processing is not performed, the quasi-through hole can be judged to be formed, a numerical control system timely sends out an auxiliary liquid feeding electromagnetic valve opening command, and the working liquid is supplied to the processing hole by an external liquid feeding pipe, so that the processing quality from the quasi-through hole processing to the through hole stage is ensured.

Of course, the foregoing embodiments are merely illustrative of the technical concept and features of the present application, and are intended to enable people to understand the content of the present application and implement the same, not to limit the protection scope of the present application. All equivalent changes or modifications made according to the spirit of the main technical solutions of the present application should be covered in the protection scope of the present application.

Claims

1. The utility model provides a numerical control is little Kong Jidian utmost point rotary control device, includes step motor, step motor passes through swivel drive electrode tube (3), its characterized in that still includes:

a rotor (1) with a central hole, wherein a coding pattern (5) is manufactured on the rotor (1);

a flexible rubber ring (2) arranged in the central hole, wherein the electrode tube (3) penetrates into the rubber ring (2);

a stator cooperating with the rotor (1);

a linear array scanning camera (6) which is relatively fixed with the stator and is matched with the coding pattern (5) for detecting the rotating speed of the rotor (1); and

the driving circuit is used for supplying power to the stator so as to drive the rotor (1) to rotate and is connected with a motor driver of the stepping motor and the linear array scanning camera (6);

the rotor (1) is of a disc-shaped structure;

the stator includes:

a first upper core coil (401) and a second upper core coil (402) which are radially symmetrically arranged on two opposite sides above the rotor (1),

a first lower core coil (403) and a second lower core coil (404) which are radially symmetrically arranged on opposite sides below the rotor (1), and

a permanent magnet (405) arranged on the side of the rotor (1);

the first upper core coil (401) is arranged directly above the first lower core coil (403), and the second upper core coil (402) is arranged directly above the second lower core coil (404);

the motor driver of the stepping motor, the driving circuit and the linear array scanning camera (6) are all connected with a numerical control system circuit of the numerical control pinhole machine.

2. The numerical control small Kong Jidian pole rotation control device according to claim 1, wherein the inner diameter of the rubber ring (2) is larger than the outer diameter of the electrode tube (3).

3. The numerical control small Kong Jidian pole rotation control device according to claim 2, wherein the inner diameter of the rubber ring (2) is 10 μm larger than the outer diameter of the electrode tube (3).

4. A numerical control small Kong Jidian pole rotation control device according to claim 1, characterized in that the rubber ring (2) is in contact fit with the electrode tube (3).

5. The numerical control small Kong Jidian pole rotation control device according to claim 2, 3 or 4, wherein a plurality of protrusions are formed on the inner hole wall of the rubber ring (2).

6. The numerical control small Kong Jidian pole rotation control device according to claim 1, wherein the code pattern (5) includes eight pattern areas uniformly distributed in the circumferential direction and having different patterns.

7. A numerical control small hole machine, characterized by comprising the numerical control small Kong Jidian pole rotation control device according to any one of claims 1 to 6.

8. A method of using the numerical control small Kong Jidian pole rotation control device according to any one of claims 1 to 6, wherein the coil current of the stator is set to I when the machining is not performed, the coil current is gradually increased with an increase in the hole depth, and when the machining hole is partially conducted to form the through hole, the working fluid is entirely discharged from the bottom of the through hole, and the abrupt resistance torque reduction and the rotation speed increase occur at this time, and the coil current after the adjustment is stabilized is equivalent to the value of I when the machining is not performed, so that it can be determined that the through hole has been formed.