A device and method for machining an annular groove

Abstract

The application relates to an annular groove machining device and method, and belongs to the technical field of super-fine long pipe machining, and solves the problem that it is difficult to realize high-precision machining of an annular groove on a super-fine long and thin-walled tubular piece. The machining device comprises a tool electrode, one end of the tool electrode is a discharge end, the discharge end comprises a plurality of electric spark machining points arranged circumferentially around a piece to be machined, and the same electric spark machining point comprises a working state and a non-working state; the working state of the plurality of electric spark machining points arranged circumferentially around the piece to be machined realizes machining of the annular groove on the surface to be machined. The annular groove can be machined in place at one time on the super-fine long and thin-walled tubular piece, and the machining efficiency is obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultra-long pipe machining, and in particular to a machining device and method for an annular groove. BACKGROUND

[0002] An annular groove needs to be machined on some ultra-long flight products. Since the ultra-long flight products have the characteristics of small diameter and thin wall, the size of the annular groove machined thereon is even smaller. For flight products where size control is crucial, the machining precision requirement of the annular groove puts higher requirements on the machining method.

[0003] It is difficult to meet the machining precision requirement of the annular groove by using the traditional turning machining method. This is because the clamping of the part and the application of cutting force in turning machining will inevitably affect the machining precision of the annular groove.

[0004] Therefore, in order to meet the machining needs of the annular groove on the ultra-long flight product, a new machining device and method for the annular groove need to be explored. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a machining device and method for an annular groove, to solve the problem that it is difficult to achieve high-precision machining of an annular groove on an ultra-long and thin-walled tubular part.

[0006] In one aspect, the embodiments of the present application provide a machining device for an annular groove, comprising a tool electrode, one end of the tool electrode being a discharge end, the discharge end comprising a plurality of electric spark machining points circumferentially arranged around a workpiece to be machined, and each electric spark machining point comprising a working state and a non-working state.

[0007] When the distance between the electric spark machining point and the surface to be machined is greater than a threshold value, the electric spark machining point is in the non-working state.

[0008] When the distance between the electric spark machining point and the surface to be machined is less than or equal to the threshold value, the electric spark machining point is in the working state.

[0009] The working state of the plurality of electric spark machining points circumferentially arranged around the workpiece to be machined realizes the machining of the annular groove on the surface to be machined.

[0010] The threshold value is the discharge distance between the electric spark machining point and the surface to be machined that meets the machining requirement.

[0011] Based on the further improvement of the above device, the plurality of electric spark machining points circumferentially arranged around the workpiece to be machined are circumferentially continuously and uninterruptedly distributed around the workpiece to be machined.

[0012] Further improvement based on the above device, the plurality of electric spark machining points arranged circumferentially around the workpiece form a continuous circular ring, and the inner circle end of the circular ring matches the shape of the annular groove.

[0013] Further improvement based on the above device, the circular ring-shaped discharge end of the tool electrode is a rigid structure and is sleeved on the workpiece, and during machining, the circular ring-shaped discharge end of the tool electrode performs eccentric motion around the central axis of the inner cavity of the workpiece.

[0014] Further improvement based on the above device, in the initial state, the center line of the circular ring-shaped discharge end of the tool electrode coincides with the central axis of the inner cavity of the workpiece.

[0015] Further improvement based on the above device, during the machining process in which the discharge end performs eccentric motion around the central axis of the inner cavity of the workpiece, the single-sided feed amount O1O2 satisfies:

[0016] O1O2=S1+(H1-H2)-S2

[0017] Wherein, H1 is the wall thickness of the workpiece; H2 is the wall thickness of the annular groove; S1 is the distance between the discharge end of the tool electrode and the machined surface before machining; and S2 is the machining gap.

[0018] Further improvement based on the above device, before machining, the distance S1 between the discharge end of the tool electrode and the machined surface satisfies:

[0019]

[0020] Wherein, S 11 , S 12 , S 13 , S 14 are actual allowance gap values between four selected points on the circular ring-shaped discharge end of the tool electrode and the machined surface, and the four points are uniformly distributed on the circular ring-shaped discharge end.

[0021] Further improvement based on the above device, the threshold value is 0-50 μm.

[0022] Further improvement based on the above device, further comprising a driving assembly for controlling the eccentric motion of the discharge end of the tool electrode, and a bearing assembly for clamping the workpiece;

[0023] Wherein, the driving assembly and the bearing assembly are installed on a machine tool.

[0024] On the one hand, the embodiment of the present application also provides an annular groove machining method, which comprises machining the annular groove by using the machining device.

[0025] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0026] 1、The discharge end of the tool electrode of the present application includes a plurality of electric spark machining points arranged circumferentially around the workpiece to be machined, and the same electric spark machining point includes a working state and a non-working state. When the tool electrode is electric spark machining the annular groove of the workpiece, the distance between the electric spark machining point and the machined surface is constantly changing, realizing the transition between the working state and the non-working state. The working state of the plurality of electric spark machining points arranged circumferentially around the workpiece to be machined realizes the machining of the annular groove on the machined surface. In this way, the discharge end of the tool electrode is avoided in the continuous machining state, thereby reducing the loss of the tool electrode.

[0027] 2、The plurality of electric spark machining points arranged circumferentially around the workpiece to be machined form a continuous circular ring, and the inner circular end of the circular ring matches the shape of the annular groove, and it is eccentrically moved on the outer end surface of the workpiece. In this process, the distance between the inner circular end surface of the discharge end and the machined surface is constantly changing. When the inner circular end surface of the discharge end is close to the machined surface, the end surface of the discharge end is the working end. When the inner circular end surface of the discharge end is away from the machined surface, the end surface of the discharge end changes to the non-working end, realizing the dynamic transition between the working end and the non-working end. In this way, the working end of the tool electrode is avoided in the continuous machining state, greatly reducing the loss of the working end of the tool electrode, realizing the tool electrode loss ≤1%, and further reducing the deformation of the working end surface of the tool electrode, thereby improving the machining precision of the annular groove of the super-fine long and thin-walled tubular workpiece.

[0028] 2、The discharge end of the tool electrode of the present application is eccentrically moved on the workpiece to be machined. During machining, the distance between the discharge end and the machined surface changes from large to small, and then from small to large. In the process of changing from large to small, metal debris will be generated between the discharge end and the machined surface. At this time, part of the metal debris will be discharged through the machining gap along with the working fluid. In the process of changing from small to large, the distance between the discharge end and the machined surface can be increased by nearly 200 times, significantly improving the efficiency of discharging metal debris. In this way, the accumulation of metal debris at the discharge end due to the delay in discharging the metal debris is avoided, thereby reducing the loss of the tool electrode and avoiding the risk of short circuit caused by the direct connection of the tool electrode with the workpiece through the metal debris.

[0029] 3、By eccentrically moving the discharge end of the tool electrode on the workpiece to be machined, the metal debris can be efficiently discharged, thereby realizing electric spark machining with a smaller machining gap. In this way, the machining current and voltage value can be reduced, the machining cost is reduced, and an annular groove with low surface roughness can be obtained.

[0030] 4、The present application utilizes the eccentric movement of the discharge end of the tool electrode around the central axis in the inner cavity of the super-long stainless steel pipe to process the breaking groove of the super-long stainless steel pipe, that is, in the process of processing, the super-long stainless steel pipe does not need to rotate, and the annular breaking groove can be processed on the outer surface, overcoming the problem of poor coaxiality during rotation of the super-long stainless steel pipe, which affects the processing precision.

[0031] 5、The tool electrode of the present application moves around the central axis in the inner cavity of the super-long stainless steel pipe once, and the processing of the breaking groove of the super-long stainless steel pipe is completed, realizing one-time processing in place, and the processing efficiency is significantly improved.

[0032] 6、Through the eccentric movement of the tool electrode around the central axis in the inner cavity of the stainless steel pipe, the single-sided feed amount of each end face of the discharge end is the same, which ensures the consistency of the breaking groove processing depth, thereby improving the processing precision of the breaking groove.

[0033] 7、By adjusting the value of the single-sided feed amount, the breaking groove of different wall thickness can be processed, and by adjusting the shape of the discharge end of the tool electrode, the size of different inclined angles α can be processed, which lays a foundation for rapid production and batch production of products.

[0034] In the present application, the above-mentioned technical solutions can be combined with each other to realize more preferred combination schemes. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the detailed description. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0036] Figure 1 It is a schematic diagram of the tool electrode structure of the present application;

[0037] Figure 2 It is a schematic diagram of the tool electrode structure of the present application; Figure 1

[0038] Figure 3 It is a schematic diagram of the tool electrode structure of the present application; Figure 1

[0039] It is a schematic diagram of the tool electrode structure of the present application; Figure 4

[0040] Figure 5 ​​Structure diagram of the tool electrode of the present application when the center line of the tool electrode deviates from the central axis of the inner cavity of the stainless steel pipe;

[0041] Figure 6 Sectional view diagram of the discharge end sleeve of the tool electrode of the present application when the discharge end sleeve is on the stainless steel pipe;

[0042] Figure 7 Trajectory diagram of the center point O2 of the discharge end of the tool electrode of the present application when the discharge end of the tool electrode moves eccentrically around the central axis of the inner cavity of the stainless steel pipe;

[0043] Figure 8 Trajectory diagram of any point O3 on the discharge end of the tool electrode of the present application when the discharge end of the tool electrode moves eccentrically around the central axis of the inner cavity of the stainless steel pipe;

[0044] Figure 9 Structure diagram of the bearing assembly of the present application and the stainless steel pipe;

[0045] Figure 10 Structure diagram of the breaking groove of the stainless steel pipe of the present application;

[0046] Figure 11 Structure diagram of the equal-height positioning block, the clamping plate and the stainless steel pipe of the present application;

[0047] Figure 12 Structure diagram of the auxiliary bearing block and the stainless steel pipe of the present application;

[0048] Figure 13 Actual object diagram of the breaking groove of the stainless steel pipe of the present application after processing.

[0049] Reference signs:

[0050] 1 - tool electrode; 101 - discharge end; 102 - working end; 103 - non-working end; 104 - conductive end; 2 - transmission rod; 3 - equal-height positioning block; 4 - auxiliary bearing block; 5 - clamping plate; 6 - stainless steel pipe; 601 - breaking groove; 7 - processing direction; 8 - eccentric movement direction; 9 - machine tool workbench; H1 - wall thickness of the stainless steel pipe; H2 - wall thickness of the breaking groove; a - breaking groove angle; S 11 , S 12 , S 13 , S 14 - Actual excess gap value between the four points selected on the circular working end of the tool electrode and the outer end surface of the stainless steel pipe; S2 - processing gap; O1 - center point of the discharge end; O2 - center point of the inner cavity of the stainless steel pipe; O3 - selected point on the discharge end. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present application will be described in detail below with reference to the drawings, wherein the drawings constitute a part of this application, and are used to explain the principles of the embodiments of the present application, but are not used to limit the scope of the present application.

[0052] The ratio of the general diameter to the length reaches 1:100-150, which belongs to the super thin long shaft. For example, the outer diameter of the stainless steel pipe used in some aviation products is 2mm, the inner diameter is 1mm, and the length is 1-1.2m. The ratio of the outer diameter to the length of the stainless steel pipe is 1:500-600, which belongs to the super thin long stainless steel pipe. Generally, the annular groove needs to be machined on the super thin long steel pipe. The annular groove is a breaking groove, which is used to separate the aviation product guiding system from the product fairing body when the product reaches the predetermined height and position.

[0053] Since the diameter of the super thin stainless steel pipe is small, the wall thickness is thin, and the wall thickness at the breaking groove position is even thinner, such as 0.3±0.05mm, the important dimension cannot be obtained by direct measurement. When the V-shaped breaking groove is machined at a certain position of the super thin long stainless steel pipe, it is difficult to ensure the wall thickness dimension at the breaking groove position by using the traditional turning machining method. This is because the centrifugal force of the workpiece rotation caused by the length is larger in the rotation process, the coaxiality of the workpiece is worse, and the cutting force generated is easy to cause the deformation of the super thin long stainless steel pipe.

[0054] If the existing electric spark machining device is used to machine the breaking groove of the super thin long stainless steel pipe, the super thin long stainless steel pipe needs to be rotated, and then the tool electrode is used to continuously advance on the surface of the super thin long stainless steel pipe for machining. However, since the super thin long stainless steel pipe is long, the centrifugal force of the workpiece rotation caused by the length is larger in the rotation process, the coaxiality of the workpiece is worse, and the wall thickness dimension at the breaking groove position is also difficult to ensure. In the process of machining, part of the total energy is released to the tool electrode, which will cause tool wear. The shape of the worn tool electrode is finally copied on the super thin long stainless steel pipe, which seriously affects the machining precision of the breaking groove.

[0055] Since the wall thickness at the breaking groove position is thin, the positioning requirement and the machining precision requirement are relatively high, and the important dimension cannot be obtained by direct measurement. When the breaking groove is machined at a certain position of the super thin long stainless steel pipe, it is difficult to ensure the wall thickness dimension at the breaking groove position by using the traditional turning machining device. Even if the existing electric spark machining device is used, it is also difficult to ensure the wall thickness dimension at the breaking groove position.

[0056] In order to solve the above problems, the present application provides a machining device for an annular groove, which comprises a tool electrode. One end of the tool electrode 1 is a discharge end 101, and the discharge end 101 comprises a plurality of electric spark machining points arranged circumferentially around the workpiece to be machined. The same electric spark machining point comprises a working state and a non-working state.

[0057] When the distance between the electric spark machining point and the surface to be machined is greater than the threshold value, the electric spark machining point is in a non-working state;

[0058] When the distance between the electric spark machining point and the surface to be machined is less than or equal to the threshold value, the electric spark machining point is in a working state;

[0059] The working state of the plurality of electric spark machining points circumferentially arranged around the workpiece realizes the machining of the annular groove on the surface to be machined;

[0060] The threshold value is the discharge distance between the electric spark machining point and the surface to be machined that meets the machining requirements.

[0061] It can be understood that the discharge end 101 includes a plurality of electric spark machining points circumferentially arranged around the workpiece, and the plurality of electric spark machining points circumferentially arranged around the workpiece can be continuously and uninterruptedly distributed circumferentially around the workpiece, or can be discontinuously distributed circumferentially around the workpiece, and can realize continuous machining and forming of the annular groove on the surface to be machined.

[0062] In one possible implementation, one end of the tool electrode 1 is in the shape of a circular ring, that is, the plurality of electric spark machining points circumferentially arranged around the workpiece form a continuous circular ring, as shown in Figures 1-6 The inner circular end of the circular ring matches the shape of the annular groove, that is, the inner circular end is convex and the annular groove is concave, and the cross-sectional size of the convex is the same as the cross-sectional shape of the concave; the other end of the tool electrode 1 is a conductive end 104, which is electrically connected to an output end of a power supply device arranged on a machine tool, for introducing electric current and transmitting the electric current to the inner circular end. At this time, the inner circular end is a discharge end 101, so as to realize the machining of the annular groove on the surface to be machined by the working state of the plurality of electric spark machining points circumferentially arranged around the workpiece of the discharge end 101.

[0063] In a possible implementation, the discharge end is of a rigid structure, and the discharge end 101 is sleeved on the outer end surface of the stainless steel pipe 6; during machining, the stainless steel pipe 6 is electrically connected to another output end of the power supply device, and the tool electrode 1 moves eccentrically around the inner cavity central axis of the stainless steel pipe 6; wherein, during the eccentric movement of the tool electrode 1, the distance between the inner circular end surface of the discharge end 101 and the machined end surface of the stainless steel pipe 6 is constantly changing; when the distance between the electric spark machining point and the machined surface is greater than a threshold value, the electric spark machining point is in a non-working state, at this time, the electric spark machining point is the non-working end 103; when the distance between the electric spark machining point and the machined surface is less than or equal to the threshold value, the electric spark machining point is in a working state, at this time, the electric spark machining point is the working end 102; in this way, the working state and the non-working state of the same electric spark machining point are realized, and the working states of all the electric spark machining points together realize the machining of the breaking groove on the machined surface, that is, the position of the working end 102 constantly changes in the inner circular end surface of the discharge end 101, and the circular discharge end of the tool electrode moves eccentrically around the inner cavity central axis of the stainless steel pipe for one cycle, and all the working ends form a continuous annular discharge end around the machined part in the circumferential direction, so that the discharge end 101 of the tool electrode 1 is prevented from being in a continuous machining state, and the wear of the tool electrode 1 is reduced.

[0064] The circular discharge end 101 of the tool electrode 1 includes a plurality of working ends 102 distributed in a ring shape, and the plurality of working ends 102 are in a non-synchronous and non-continuous machining state when the discharge end moves eccentrically around the inner cavity central axis of the stainless steel pipe 6 for machining.

[0065] Specifically, after the tool electrode 1 moves eccentrically for one cycle, all the end surfaces of the discharge end 101 participate in electric spark machining, that is, all the working ends 102 form the complete discharge end 101, and the machining tracks of all the working ends 102 form the breaking groove 601 of the stainless steel pipe; along the deflection movement direction of the tool electrode 1, the working ends 102 present a “circular motion” phenomenon on the discharge end 101, that is, the positions of the working ends 102 are different at different times, so that all the working ends 102 are realized to alternately and orderly perform machining, the machining direction 7 is the circumferential direction of the outer end surface of the stainless steel pipe 6, and the plane where the circumferential direction is located is perpendicular to the inner cavity central axis of the stainless steel pipe 6.

[0066] Compared with the prior art, in the process of machining, the tool electrode 1 does not contact the surface of the stainless steel pipe 6, so that the stainless steel pipe 6 is not deformed, and in the process of machining, the stainless steel pipe 6 does not need to be moved, so that the annular breaking groove 601 can be machined on the outer surface of the stainless steel pipe 6, and the problem that the coaxiality of the stainless steel pipe 6 is poor in the process of rotation, thereby affecting the machining precision, is overcome; and the tool electrode 1 eccentrically moves around the inner cavity axis of the stainless steel pipe 6 for one cycle, so that the machining of the breaking groove 601 of the stainless steel pipe is completed, the machining is in place at one time, and the machining efficiency is significantly improved; and the discharge end 101 of the tool electrode 1 is in the form of a circular ring, which is eccentrically moved on the outer end surface of the stainless steel pipe 6, in this process, the distance between the end surface of the discharge end 101 and the machined surface of the stainless steel pipe 6 is constantly changing, the distance is closer to the working end 102, and the distance is farther to the non-working end 103, and the outer end surface of the stainless steel pipe 6 is machined by the working end 102, and along the machining direction, the position of the working end 102 constantly changes in the inner circular end surface of the discharge end 101, that is, when the inner circular end surface of the discharge end 101 is close to the outer end surface of the stainless steel pipe 6, the end surface of the discharge end 101 is the working end 102, and when the end surface is away from the outer end surface of the stainless steel pipe 6, the end surface changes to the non-working end 103, so that the dynamic change between the working end 102 and the non-working end 103 is realized, thereby avoiding the working end 102 of the tool electrode 1 in the continuous machining state, greatly reducing the wear of the working end of the tool electrode 1, realizing that the tool electrode wear is ≤1%, and further reducing the deformation of the working end surface of the tool electrode 1, thereby improving the machining precision of the breaking groove 601 of the ultra-fine long stainless steel pipe.

[0067] In the judgment basis of whether the discharge end 101 is the working end 102, whether the distance between the discharge end 101 and the machined surface of the stainless steel pipe 6 is greater than 50 μm, if not, the discharge end 101 is the working end 102, and if yes, the discharge end 101 is the non-working end 103. In this way, through the dynamic change between the working end 102 and the non-working end 103, the discharge end 101 of the tool electrode 1 is avoided in the continuous machining state, so as to reduce the wear of the tool electrode 1.

[0068] Specifically, one end of the tool electrode 1 is installed on a machine tool, the discharge end 101 of the tool electrode 1 is sleeved on the outer end surface of the stainless steel pipe 6, the center of the inner circular end of the discharge end 101 of the tool electrode 1 coincides with the central axis in the inner cavity of the stainless steel pipe 6, and there is a surplus gap between the discharge end 101 and the outer end surface of the stainless steel pipe 6, that is, the diameter size of the inner circular end of the discharge end 101 is greater than the outer diameter size of the stainless steel pipe 6, for example, the diameter of the inner circular end is 10-20mm, which is 5-10 times the outer diameter of the stainless steel pipe 6. In this way, the value of the single-sided feed amount O1O2 can be easily determined during the electric spark machining. During machining, the tool electrode 1 is driven to swing by the machine tool, at this time, the discharge end 101 of the tool electrode 1 is in an eccentric motion state around the central axis in the inner cavity of the stainless steel pipe 6.

[0069] wherein the single-sided feed amount O1O2 satisfies:

[0070] O1O2=S1+(H1-H2)-S2

[0071] wherein O1 represents the center point of the discharge end 101 of the tool electrode;

[0072] O2 represents the center point of the inner cavity of the stainless steel pipe 6;

[0073] H1 is the wall thickness of the stainless steel pipe 6;

[0074] H2 is the wall thickness of the fracture groove 601;

[0075] S2 is the machining gap, that is, the closest distance between the working end 102 and the end surface of the stainless steel pipe 601 when the tool electrode 1 is in eccentric motion;

[0076] S1 is the surplus gap between the discharge end 101 and the outer end surface of the stainless steel pipe 6.

[0077] wherein S1 satisfies:

[0078]

[0079] wherein, as shown in Figure 4 , S 11 , S 12 , S 13 , S 14 are actual surplus gap values between four points selected on the discharge end 101 of the tool electrode and the outer end surface of the stainless steel pipe 6, and the four points are uniformly distributed on the discharge end 101.

[0080] For example, S 11 , S 12 , S 13 , S 142.055mm, 2.060mm, 2.065mm, 2.050mm, and S1=2.058mm.

[0081] Wherein, the processing gap S2 is 10-50μm to meet the requirements of electric spark machining.

[0082] For example, S2=10μm, H1=0.5mm, H2=0.3mm, and S1=2.058mm, and O1O2=2.248mm.

[0083] Wherein, the automatic centering module on the machine tool can be used to measure S 11 , S 12 , S 13 , and S 14 If the four values are equal, the center of the inner circle end of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6.

[0084] Wherein, after the center of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6 by adjusting the machine tool, the four values of S 11 , S 12 , S 13 , and S 14 are measured. The closer the four values are, the more accurate the value of S1 is, and the more accurate the unilateral feed amount O1O2 is. Thus, during the eccentric motion of the tool electrode 1, the processing gap accuracy can be ensured, and the processing depth of the working end 101 can be ensured to ensure the size accuracy of the breaking groove 601.

[0085] Wherein, after the center of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6, the tool electrode 1 is in an eccentric motion state under the action of the machine tool. The detailed process is as follows.

[0086] The movement trajectories of the center point O1 of the discharge end 101 of the tool electrode 1 and the center point O2 of the inner cavity of the stainless steel pipe 6 are described as follows:

[0087] The tool electrode 1 is moved so that O1 is away from O2 by the same distance as the unilateral feed amount O1O2. At this time, the distance between O1 and O2 is O1O2.

[0088] O1 is rotated around O2 with O1O2 as the radius. At this time, the trajectory of the movement of O1 is a circle, as shown in Figure 7 The center of the circle is O2, and the radius is O1O2.

[0089] During the movement of O1, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the distance between O1 and O2 is O1O2, and then O1 moves in a circular motion around O2.

[0090] To further illustrate the motion trajectory of tool electrode 1, an arbitrary point O3 on discharge terminal 101 is selected, and the trajectory of O3 is used for illustration, as follows:

[0091] Move tool electrode 1 so that O3 moves toward O2, and the moving distance is O1O2;

[0092] When O1 rotates around O2, at this time, as Figure 8 As shown, the trajectory of O3 is a circle with the initial position of O3 as the center and O1O2 as the radius;

[0093] During the movement of O3, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the moving distance of O3 reaches O1O2. Then, O3 moves in a circle with its initial position as the center.

[0094] Thus, during the eccentric movement of the tool electrode 1, the distance between the inner circular end face of the discharge end 101 and the outer surface of the stainless steel tube 6 changes continuously. The distance between each part of the inner circular end face of the discharge end 101 and the outer end face of the stainless steel tube 6 changes from close to far away. Consequently, the discharge end 101 changes from a working state to a non-working state, that is, the dynamic transformation between the working end 102 and the non-working end 103 is realized. In this way, the working end 102 of the tool electrode 1 is avoided from being in a continuous processing state, which greatly reduces the wear and tear on the working end 102 of the tool electrode 1.

[0095] The discharge end 101 has a clearance S1 between itself and the outer end face of the stainless steel tube 601. This clearance ensures that the non-working end 103 at the discharge end 101 and the end face of the stainless steel tube 6 have a sufficiently large non-processing clearance, thereby ensuring that the pulse voltage released at the non-working end 103 cannot erode the metal on the surface of the stainless steel tube 6. Thus, when the tool electrode 1 moves eccentrically, the working end 102 and the non-working end 103 can be dynamically switched.

[0096] The conductive end of the tool electrode 1 is electrically connected with one output end of a power supply device arranged on the machine tool, and the stainless steel pipe 6 is electrically connected with another output end of the power supply device, wherein the power supply device comprises a pulse power supply, and the two output ends of the pulse power supply are respectively connected with the positive and negative poles of the pulse power supply to output pulse voltage.

[0097] Exemplarily, in the process of machining, the electrical parameters satisfy:

[0098] The pulse width is 30-60μs, the pulse interval is 20-30μs, the average machining current is 0.8-2A, and the average machining voltage is 30-60V.

[0099] Specifically, the driving assembly comprises a transmission rod 2, one end of the transmission rod 2 is connected with the tool electrode 1, and the other end of the transmission rod 2 is installed on the machine tool, and the transmission rod 2 can be controlled to swing through the machine tool, so as to drive the discharge end 101 of the tool electrode 1 to make eccentric motion around the central axis of the inner cavity of the stainless steel pipe 6.

[0100] Specifically, the transmission rod 2 swings clockwise in the swing plane YZ, and the swing plane YZ is parallel to the plane where the discharge end 101 is located, so as to realize the eccentric motion of the discharge end of the tool electrode 1 around the central axis of the inner cavity of the stainless steel pipe 6. In the process of machining, the stainless steel pipe 6 remains stationary.

[0101] Exemplarily, in the process of machining, the non-electrical parameters satisfy:

[0102] The swing speed of the driving assembly is 0.4-0.6rpm, the machining gap is 10-50μm, the machining speed is 0.02-0.045g / min, and the single-sided feed amount is 2.214-2.2.316mm.

[0103] Specifically, as shown in Figure 9 the bearing assembly comprises two equal-height positioning blocks 3 and two auxiliary supporting blocks 4 installed on the machine tool, so as to place the stainless steel pipe 6 on the two equal-height positioning blocks 3 and the two auxiliary supporting blocks 4 to clamp the stainless steel pipe 6.

[0104] Specifically, two equal-height positioning blocks 3 are arranged, and the two equal-height positioning blocks 3 are respectively located on the two sides of the to-be-machined position of the stainless steel pipe 6, so as to ensure the stability of the to-be-machined position of the stainless steel pipe 6 in the process of machining. Exemplarily, the distance between the two equal-height positioning blocks 3 is 30mm.

[0105] Specifically, two auxiliary supporting blocks 4 are arranged, and the two equal-height positioning blocks 3 are located between the two auxiliary supporting blocks 4, so as to support and position the two ends of the stainless steel pipe 6 through the two auxiliary supporting blocks 4, and further ensure the stability of the stainless steel pipe 6 in the process of machining.

[0106] wherein, as Figures 10-12As shown, the upper end faces of the above-mentioned equal-height positioning blocks 3 and auxiliary bearing blocks 4 are flush, and the upper end faces of the equal-height positioning blocks 3 and auxiliary bearing blocks 4 are provided with V-shaped grooves, and the stainless steel pipe 6 is placed in the V-shaped grooves to limit the stainless steel pipe 6.

[0107] Further, the equal-height positioning blocks 3 are further provided with clamping plates 5, the clamping plates 5 cover the V-shaped grooves and are clamped on the equal-height positioning blocks 3 to limit the stainless steel pipe 6 and further improve the stability of the stainless steel pipe 6. For example, the angle of the V-shaped groove is 60°-90°, and the depth is 5-10 mm.

[0108] Wherein, before placing the stainless steel pipe 6 on the equal-height positioning blocks 3, first, the tool electrode 1 needs to be centered, then the stainless steel pipe 6 is inserted into the discharge end 101 of the tool electrode 1, and finally the stainless steel pipe 6 is clamped by the equal-height positioning blocks 3, auxiliary bearing blocks 4 and clamping plates 5, and the stainless steel pipe 6 is centered by the equal-height positioning blocks 3 and auxiliary bearing blocks 4.

[0109] Specifically, after the tool electrode 1 is centered, the positions of the equal-height positioning blocks 3 and auxiliary bearing blocks 4 on the machine tool are adjusted by the machine tool XYZ axis to center the stainless steel pipe 6, so as to ensure that the center line of the inner cavity of the stainless steel pipe 6 coincides with the center line of the discharge end 101 of the tool electrode 1, so as to determine the value of the single-sided feed amount O1O2 and further improve the machining precision.

[0110] Wherein, the centering process of the stainless steel pipe 6 is as follows.

[0111] First, two equal-height positioning blocks 3 and two auxiliary support blocks 4 are fixed on the workbench 9 of the machine tool, and then the side surface is centered with the machine tool X axis by using a dial indicator, and the parallelism error is ≤0.01mm.

[0112] Wherein, one end of the transmission rod 2 is connected with the tool electrode 1, and is parallel to the center line of the discharge end 101 of the tool electrode 1; during the machining process, the other end of the transmission rod 2 is installed on the machine tool, so as to drive the transmission rod 2 to swing through the machine tool, and then drive the tool electrode 1 to move through the transmission rod 2, so as to realize the eccentric motion of the discharge end 101 of the tool electrode 1 around the inner cavity center axis of the stainless steel pipe 6.

[0113] In this way, the discharge end 101 of the tool electrode 1 eccentrically moves around the inner cavity center axis of the stainless steel pipe 6 for one revolution, and the machining of the stainless steel pipe breaking groove 601 is completed, realizing one-time machining in place and significantly improving the machining efficiency.

[0114] In addition, the present application also provides a machining method of an annular groove, which comprises using the above-mentioned machining device to electric discharge machine the annular groove of the workpiece to be machined, so as to solve the problem that it is difficult to machine the annular groove on the super-thin long and thin-walled tubular workpiece with high precision.

[0115] Specifically, the method comprises using the working state of the plurality of electric spark machining point positions of the tool electrode arranged circumferentially around the workpiece to realize the machining of the annular groove on the machined surface.

[0116] Wherein, the same electric spark machining point position comprises a working state and a non-working state, when the distance between the electric spark machining point position and the machined surface is greater than the threshold value, the electric spark machining point position is in the non-working state;

[0117] When the distance between the electric spark machining point position and the machined surface is less than or equal to the threshold value, the electric spark machining point position is in the working state;

[0118] Wherein, the threshold value is the discharge distance between the electric spark machining point position and the machined surface that meets the machining requirement.

[0119] Wherein, the discharge end 101 comprises a plurality of electric spark machining point positions arranged circumferentially around the workpiece, the plurality of electric spark machining point positions arranged circumferentially around the workpiece can be continuously and uninterruptedly distributed circumferentially around the workpiece, or can be discontinuously distributed circumferentially around the workpiece, which can realize the continuous machining and forming of the annular groove on the machined surface.

[0120] In a possible implementation, one end of the tool electrode 1 is in the shape of a circular ring, that is, the plurality of electric spark machining point positions arranged circumferentially around the workpiece form a continuous circular ring, the inner circular end of the circular ring is matched with the shape of the breaking groove 601, that is, the inner circular end is in the shape of a protrusion, and the breaking groove 601 is in the shape of a groove, the cross-sectional size of the protrusion is the same as the cross-sectional shape of the groove; the other end of the tool electrode 1 is a conductive end 104, which is electrically connected with an output end of a power supply device arranged on the machine tool, for introducing electric current and transmitting the electric current to the inner circular end, at this time, the inner circular end is a discharge end 101, so as to realize the machining of the annular groove on the machined surface by the working state of the plurality of electric spark machining point positions of the discharge end 101 arranged circumferentially around the workpiece.

[0121] In a possible implementation, the discharge end 101 is rigid, and the discharge end 101 is sleeved on the outer end surface of the stainless steel pipe 6; during machining, the stainless steel pipe 6 is electrically connected to another output end of the power supply device, and the tool electrode 1 moves eccentrically around the inner cavity central axis of the stainless steel pipe 6; wherein, during the eccentric movement of the tool electrode 1, the distance between the inner circular end surface of the discharge end 101 and the machined end surface of the stainless steel pipe 6 is constantly changing; when the distance between the electric spark machining point and the machined surface is greater than a threshold value, the electric spark machining point is in a non-working state, at this time, the electric spark machining point is the non-working end 103; when the distance between the electric spark machining point and the machined surface is less than or equal to the threshold value, the electric spark machining point is in a working state, at this time, the electric spark machining point is the working end 102; in this way, the working state and the non-working state of the same electric spark machining point are realized, and the working states of all the electric spark machining points collectively realize the machining of the breaking groove on the machined surface, that is, the position of the working end 102 constantly changes in the inner circular end surface of the discharge end 101, and the circular discharge end of the tool electrode moves eccentrically around the inner cavity central axis of the stainless steel pipe for one revolution, and all the working ends form a continuous annular discharge end around the machined part in the circumferential direction, so that the discharge end 101 of the tool electrode 1 is prevented from being in a continuous machining state, and the wear of the tool electrode 1 is reduced.

[0122] The circular discharge end 101 of the tool electrode 1 includes a plurality of working ends 102 distributed in a ring shape, and the plurality of working ends 102 are in a non-synchronous and non-continuous machining state when the discharge end moves eccentrically around the inner cavity central axis of the stainless steel pipe 6 for machining; and the machining tracks of the plurality of working ends collectively form an annular groove of the machined part.

[0123] Specifically, after the tool electrode 1 moves eccentrically for one revolution, all the end surfaces of the discharge end 101 participate in electric spark machining, that is, all the working ends 102 form the complete discharge end 101, and the machining tracks of all the working ends 102 form the breaking groove 601 of the stainless steel pipe; along the deflection movement direction of the tool electrode 1, the working ends 102 exhibit a “circular motion” phenomenon on the discharge end 101, that is, the positions of the working ends 102 are different at different times, so that all the working ends 102 are realized to alternately and orderly perform machining, the machining direction 7 is the circumferential direction of the outer end surface of the stainless steel pipe 6, and the plane in which the circumferential direction is located is perpendicular to the inner cavity central axis of the stainless steel pipe 6.

[0124] The judgment criterion for whether the discharge end 101 is the working end 102 is whether the distance between the discharge end 101 and the machined surface of the stainless steel pipe 6 is greater than 50 μm, if not, the discharge end 101 is the working end 102, and if yes, the discharge end 101 is the non-working end 103.

[0125] Specifically, the tool electrode 1 is installed on a machine tool, and during machining, the machine tool drives the tool electrode 1 to make eccentric motion, so that the discharge end 101 of the tool electrode performs electric spark machining around the end face of the stainless steel pipe 6, and the machining direction 7 is the circumferential direction of the outer end face of the stainless steel pipe 6, and the center line of the circumferential direction coincides with the central axis in the inner cavity of the stainless steel pipe 6.

[0126] Specifically, before the tool electrode 1 makes eccentric motion, the center of the inner circular end of the discharge end 101 of the tool electrode 1 needs to be adjusted to coincide with the central axis of the stainless steel pipe 6, and there is a clearance gap between the discharge end 101 and the outer end face of the stainless steel pipe 6, that is, the diameter of the inner circular end of the discharge end 101 is larger than the outer diameter of the stainless steel pipe 6. For example, the diameter of the inner circular end is 10-20mm, which is 5-10 times the outer diameter of the stainless steel pipe 6. In this way, during electric spark machining, the values of the single-sided feed amounts O1O2 can be easily determined.

[0127] Wherein, the single-sided feed amount O1O2 satisfies:

[0128] O1O2=S1+(H1-H2)-S2

[0129] Wherein, O1 represents the center point of the discharge end 101 of the tool electrode 1;

[0130] O2 represents the center point of the inner cavity of the stainless steel pipe 6;

[0131] H1 is the wall thickness of the stainless steel pipe 6;

[0132] H2 is the wall thickness of the fracture groove 601;

[0133] S1 is the clearance gap between the discharge end 101 and the outer end face of the stainless steel pipe 6;

[0134] S2 is the machining gap, that is, the closest distance between the working end 102 and the end face of the stainless steel pipe 601 when the tool electrode 1 makes eccentric motion.

[0135] Wherein, S1 satisfies:

[0136]

[0137] Wherein, S 11 , S 12 , S 13 , S 14 are actual clearance gap values between four points selected on the discharge end 101 of the tool electrode 1 and the outer end face of the stainless steel pipe 6. The four points are uniformly distributed on the discharge end 101.

[0138] For example, S 11 , S 12 , S 13 , S 142.055mm, 2.060mm, 2.065mm, 2.050mm, and S1=2.058mm.

[0139] Wherein, the processing gap S2 is 10-50μm to meet the requirements of electric spark machining.

[0140] For example, S2=10μm, H1=0.5mm, H2=0.3mm, and S1=2.058mm, and O1O2=2.248mm.

[0141] Wherein, the automatic centering module on the machine tool can be used to measure S 11 , S 12 , S 13 , S 14 If the four values are equal, the center of the inner circle end of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6.

[0142] Wherein, after the center of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6 by adjusting the machine tool, the four values of S 11 , S 12 , S 13 , S 14 The closer the four values are, the more accurate the value of S1 is, and the more accurate the single-sided feed amount O1O2 is. Thus, during the eccentric motion of the tool electrode 1, the processing gap accuracy can be ensured, and the processing depth of the working end 102 is ensured to ensure the size accuracy of the broken groove 601.

[0143] Specifically, after the center of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6, the machine tool drives the tool electrode 1 to move eccentrically, and the detailed process is as follows.

[0144] The movement trajectories of the center point O1 of the discharge end 101 of the tool electrode 1 and the center point O2 of the inner cavity of the stainless steel pipe 6 are described as follows.

[0145] The tool electrode 1 is moved so that O1 is away from O2 by the same distance as the single-sided feed amount O1O2, and the distance between O1 and O2 is O1O2 at this time.

[0146] O1 is rotated around O2 with O1O2 as the radius, and at this time, the trajectory of O1 is a circle with O2 as the center and O1O2 as the radius.

[0147] During the movement of O1, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the distance between O1 and O2 is O1O2, and then O1 moves in a circular motion around O2.

[0148] To further illustrate the motion trajectory of tool electrode 1, an arbitrary point O3 on discharge terminal 101 is selected, and the trajectory of O3 is used for illustration, as follows:

[0149] Move tool electrode 1 so that O3 moves toward O2, and the moving distance is O1O2;

[0150] When O1 rotates around O2, the trajectory of O3 is a circle with the initial position of O3 as the center and O1O2 as the radius.

[0151] During the movement of O3, when the closest distance between the end face of the discharge end 101 and the surface of the stainless steel tube 6 reaches 10μm, the power supply device is turned on to deliver a pulse voltage to the tool electrode 1 and the stainless steel tube 6, and the metal on the surface of the stainless steel tube 6 is etched at a processing speed of 0.04g / min until the moving distance of O3 reaches O1O2. Then, O3 moves in a circle with its initial position as the center.

[0152] Thus, during the eccentric movement of the tool electrode 1, the distance between the inner circular end face of the discharge end 101 and the outer surface of the stainless steel tube 6 changes continuously. The distance between each part of the inner circular end face of the discharge end 101 and the outer end face of the stainless steel tube 6 changes from close to far away. Consequently, the discharge end 101 changes from the working state to the non-working state, that is, the dynamic transformation between the working end 102 and the non-working end 103 is realized.

[0153] The discharge end 101 has a clearance between itself and the outer end face of the stainless steel tube 601 to ensure that the non-working end 103 at the discharge end 101 and the end face of the stainless steel tube 6 have a sufficiently large non-processing clearance, thereby ensuring that the pulse voltage released at the non-working end 103 cannot erode the metal on the surface of the stainless steel tube 6. Thus, when the tool electrode 1 moves eccentrically, the working end 102 and the non-working end 103 can be dynamically switched.

[0154] The conductive end 104 of the tool electrode 1 is electrically connected to one output end of the power supply device installed on the machine tool, and the stainless steel tube 6 is electrically connected to the other output end of the power supply device. The power supply device includes a pulse power supply, and its two output ends are respectively connected to the positive and negative terminals of the pulse power supply to output pulse voltage.

[0155] During the machining, the discharge end 101 of the tool electrode 1 and the stainless steel pipe 6 are immersed in a liquid medium with certain insulation, for example, kerosene, mineral oil or deionized water; when the pulse voltage is applied to the discharge end 101 and the stainless steel pipe 6, the liquid medium at the nearest point between the discharge end 101 and the stainless steel pipe 6 at that time is broken down to form a discharge channel, and due to the small cross-sectional area of the channel, the discharge time is extremely short, so that the energy is highly concentrated (10 6 W / cm 2 The instantaneous high temperature generated in the discharge area is sufficient to melt and even evaporate the metal on the surface of the stainless steel pipe 6, so as to form a small pit; after a very short interval time, the second pulse breaks down the discharge at another nearest point between the two electrodes, and so on, the tool electrode 1 continuously feeds the stainless steel pipe 6, and its shape is finally copied on the stainless steel pipe 6 to form the required machined surface; during the machining, although a small part of the total energy is also released to the tool electrode 1, causing the tool electrode 1 to be worn, but by the eccentric movement of the discharge end 101 of the tool electrode 1 around the central axis of the inner cavity of the stainless steel pipe 6, the working end 102 at the discharge end 101 is constantly changing position, so as to reduce the wear of the tool electrode 1 by avoiding continuous machining of the working end 102, and further, the working end 102 of the discharge end 101 maintains a relatively complete shape at each moment of machining, improving the machining precision.

[0156] For example, during the machining, the electrical parameters satisfy:

[0157] The pulse width is 30-60 μs, the pulse interval is 20-30 μs, the average machining current is 0.8-2 A, and the average machining voltage is 30-60 V.

[0158] Specifically, during the machining, the tool electrode 1 is controlled to move eccentrically by the machine tool, and the stainless steel pipe 6 remains stationary.

[0159] Specifically, during the machining, the tool electrode 1 is controlled to move eccentrically by the machine tool, and the stainless steel pipe 6 remains stationary.

[0160] Specifically, the transmission rod 2 swings clockwise in the swing plane YZ, which is parallel to the plane where the discharge end 101 is located, so as to realize the eccentric movement of the tool electrode 1 around the central axis of the inner cavity of the stainless steel pipe 6.

[0161] For example, during the machining, the non-electrical parameters satisfy:

[0162] The swing speed of the transmission rod 2 is 0.4-0.6 rpm, the machining gap is 10-50 μm, the machining speed is 0.02-0.045 g / min, and the single-side feeding amount is 2.214-2.2.316 mm.

[0163] Specifically, the stainless steel pipe 6 is placed on the equal-height positioning block 3 and the auxiliary bearing block 4 to clamp the stainless steel pipe 6.

[0164] The two equal-height positioning blocks 3 clamp the two sides of the to-be-machined position of the stainless steel pipe 6 to ensure the stability of the to-be-machined position of the stainless steel pipe 6 during machining. For example, the distance between the two equal-height positioning blocks 3 is 30 mm.

[0165] The two equal-height positioning blocks 3 are placed between the two auxiliary bearing blocks 4, and the two auxiliary bearing blocks 4 support and position the two ends of the stainless steel pipe 6 to further ensure the stability of the stainless steel pipe 6 during machining.

[0166] The upper end faces of the equal-height positioning block 3 and the auxiliary bearing block 4 are flush, and the upper end faces of the equal-height positioning block 3 and the auxiliary bearing block 4 are provided with V-shaped grooves, and the stainless steel pipe 6 is placed in the V-shaped grooves to limit the stainless steel pipe 6.

[0167] Further, the clamping plate 5 is covered on the V-shaped groove and clamped on the equal-height positioning block 3 to limit the stainless steel pipe 6 and further improve the stability of the stainless steel pipe 6. For example, the angle of the V-shaped groove is 60°-90°, and the depth is 5-10 mm.

[0168] Before placing the stainless steel pipe 6 on the equal-height positioning block 3, the tool electrode 1 needs to be first aligned by the machine tool, then the stainless steel pipe 6 is inserted into the discharge end 101 of the tool electrode 1, and finally the stainless steel pipe 6 is clamped by the equal-height positioning block 3, the auxiliary bearing block 4 and the clamping plate 5, and the stainless steel pipe 6 is aligned by the equal-height positioning block 3 and the auxiliary bearing block 4.

[0169] Specifically, after the tool electrode 1 is aligned, the positions of the equal-height positioning block 3 and the auxiliary bearing block 4 on the machine tool are adjusted by the machine tool XYZ axis to align the stainless steel pipe 6, so that the center line of the inner cavity of the stainless steel pipe 6 coincides with the center line of the discharge end 101 of the tool electrode 1, so as to determine the value of the single-side feeding amount O1O2 and further improve the machining precision.

[0170] The alignment process of the stainless steel pipe 6 is as follows.

[0171] First, first fix two equal height positioning block 3 and two auxiliary support block 4 on the worktable 9 of the machine tool, then use the dial indicator to find the parallelism of the side surface and the machine tool X axis, the parallelism error is less than or equal to 0.01mm.

[0172] Before placing the stainless steel pipe 6 on the equal height positioning block 3, first pass the stainless steel pipe 6 into the discharge end 101 of the tool electrode 1, then place the stainless steel pipe 6 on the equal height positioning block 3 and the auxiliary support block 4, in this way, realize the alignment of the stainless steel pipe 6 through the equal height positioning block 3 and the auxiliary support block 4.

[0173] Wherein, one end of the transmission rod 2 is connected with the tool electrode 1, and is parallel to the center line of the discharge end 101 of the tool electrode 1; in the process of machining, the other end of the transmission rod 2 is installed on the machine tool, so as to drive the transmission rod 2 to swing through the machine tool, and then drive the tool electrode 1 to move through the transmission rod 2, realize the eccentric motion of the discharge end 101 of the tool electrode 1 around the inner cavity central axis of the stainless steel pipe 6.

[0174] In this way, the discharge end 101 of the tool electrode 1 eccentrically moves around the inner cavity central axis of the stainless steel pipe 6 for one circle, and the machining of the stainless steel pipe breaking groove 601 is completed, realizing one-time machining in place, and the machining efficiency is significantly improved.

[0175] Compared with the prior art, the discharge end 101 of the tool electrode 1 of the present application comprises a plurality of electric spark machining points arranged circumferentially around the workpiece, and each electric spark machining point comprises a working state and a non-working state. When the tool electrode is electric spark machining the annular groove of the workpiece, the distance between the electric spark machining point and the machining surface changes constantly, realizing the transition between the working state and the non-working state. The working state of the plurality of electric spark machining points arranged circumferentially around the workpiece realizes the machining of the annular groove on the machining surface. In this way, the discharge end 101 of the tool electrode 1 is avoided from being in a continuous machining state, and the wear of the tool electrode 1 is reduced.

[0176] The plurality of electric spark machining points arranged circumferentially around the workpiece form a continuous circular ring, the inner circle end of the circular ring matches the shape of the annular groove, and the circular ring moves eccentrically on the outer end surface of the stainless steel pipe. In this process, the distance between the inner circle end surface of the discharge end 101 and the machining surface changes constantly. When the inner circle end surface of the discharge end 101 is close to the machining surface, the end surface of the discharge end 101 is the working end 102, and when the end surface is away from the machining surface, the end surface changes to the non-working end 103, realizing the dynamic transition between the working end 102 and the non-working end 103. In this way, the working end 102 of the tool electrode 1 is avoided from being in a continuous machining state, the wear of the working end 102 of the tool electrode 1 is greatly reduced, the wear of the tool electrode 1 is less than or equal to 1%, and the deformation of the working end surface of the tool electrode 1 is reduced, thereby improving the machining precision of the stainless steel pipe breaking groove 601.

[0177] The discharge end 101 of the tool electrode 1 of the application is eccentrically sleeved on the super-fine long stainless steel pipe 6, and during machining, the distance between the discharge end 101 and the super-fine long stainless steel pipe 6 changes from large to small and then from small to large. During the change from large to small, metal scraps are generated between the discharge end 101 and the stainless steel pipe 6, and at this time, part of the metal scraps are discharged through the machining gap along with the working liquid. During the change from small to large, the distance between the discharge end 101 and the stainless steel pipe 6 can be increased by nearly 200 times, which significantly improves the efficiency of discharging the metal scraps, thereby avoiding the accumulation of the metal scraps at the discharge end 101 due to the delayed discharge of the metal scraps, reducing the wear of the tool electrode 1, and avoiding the risk of short circuit caused by the direct connection of the tool electrode 1 with the stainless steel pipe 6 through the metal scraps.

[0178] By eccentrically sleeving the discharge end 101 of the tool electrode 1 on the super-fine long stainless steel pipe 6, the metal scraps can be efficiently discharged, and thus the EDM machining can be performed with a smaller machining gap. In this way, the machining current and voltage value can be reduced, the machining cost can be reduced, and a broken groove 601 with a lower surface roughness can be obtained.

[0179] By adjusting the value of the single-sided feed amount, the broken groove 601 with different wall thicknesses can be machined, and by adjusting the shape of the discharge end 101 of the tool electrode 1, the broken groove 601 with different inclined angles can be machined, which lays a foundation for rapid production and batch production of products.

[0180] The discharge end 101 of the tool electrode 1 of the application is eccentrically moved around the inner cavity central axis of the super-fine long stainless steel pipe 6 for one cycle, and the machining of the broken groove 601 of the super-fine long stainless steel pipe is completed, which realizes one-time machining and significantly improves the machining efficiency.

[0181] By eccentrically moving the discharge end 101 of the tool electrode 1 around the inner cavity central axis of the stainless steel pipe 6, the single-sided feed amount of each end face of the discharge end 101 is the same, which ensures the consistency of the machining depth of the broken groove 601, thereby improving the machining precision of the broken groove 601.

[0182] The discharge end 101 of the tool electrode 1 has the same shape as the broken groove 601, i.e., the discharge end 101 is convex and the broken groove 601 is concave. The cross-sectional size of the convex shape is the same as the cross-sectional shape of the concave shape. In this way, after the discharge end 101 of the tool electrode 1 is eccentrically moved around the inner cavity central axis of the super-fine long stainless steel pipe 6 for one cycle, the depth and inclined angle of the machined broken groove 601 are the required depth and inclined angle of the broken groove 601, and the machining precision is significantly improved.

[0183] The application discards the traditional turning processing mode of the ultra-fine long stainless steel pipe, and utilizes the working end 102 of the tool electrode 1 to discharge and remove the surface metal of the ultra-fine long stainless steel pipe 6 to process the breaking groove 601, that is, in the processing process, the tool electrode 1 does not contact the surface of the ultra-fine long stainless steel pipe, and the deformation of the ultra-fine long stainless steel pipe is avoided, and the damage problem of the ultra-fine long stainless steel pipe caused by the cutting force is overcome.

[0184] The application utilizes the eccentric motion of the discharge end 101 of the tool electrode 1 around the inner cavity central axis of the ultra-fine long stainless steel pipe to process the breaking groove 601 of the ultra-fine long stainless steel pipe, that is, in the processing process, the ultra-fine long stainless steel pipe does not need to move, and the annular breaking groove 601 on the outer surface of the ultra-fine long stainless steel pipe can be processed, and the problem that the coaxiality of the ultra-fine long stainless steel pipe is poor in the rotation process and affects the processing precision is overcome.

[0185] In the processing, the ultra-fine long stainless steel pipe is only needed to be placed in the V-shaped groove on the equal-height positioning block 3 and the auxiliary bearing block 4, and the upper surface of the ultra-fine long stainless steel pipe is limited by the clamping plate 5, so that the clamping and positioning of the ultra-fine long stainless steel pipe can be realized, the clamping is convenient, and the stability of the ultra-fine long stainless steel pipe 6 in the processing process can be ensured.

[0186] Embodiment 1

[0187] The annular groove processing device comprises a tool electrode 1, a bearing assembly and a driving assembly which are installed on a machine tool, wherein the bearing assembly is used for clamping the stainless steel pipe 6, and the driving assembly is used for driving the tool electrode 1 to move eccentrically around the inner cavity central axis of the stainless steel pipe 6 to realize the electric spark processing of the breaking groove 601 of the stainless steel pipe, so as to solve the problem that the breaking groove is difficult to be processed on the ultra-fine long stainless steel pipe.

[0188] Specifically, one end of the tool electrode 1 is in the shape of a circular ring, the inner circular end of the circular ring is matched with the shape of the breaking groove 601, and the other end of the tool electrode 1 is an electrically conductive end 104 which is electrically connected with an output end of a power supply device arranged on the machine tool, so as to introduce the current and transmit the current to the inner circular end, at this time, the inner circular end is a discharge end 101 which is sleeved on the outer end surface of the stainless steel pipe 6; in the processing, the stainless steel pipe 6 is electrically connected with another output end of the power supply device, and the discharge end 101 of the tool electrode 1 moves eccentrically around the inner cavity central axis of the stainless steel pipe 6, wherein in the process of the eccentric motion of the tool electrode 1, the distance between the end surface of the discharge end 101 and the end surface of the stainless steel pipe 6 to be processed is constantly changed, the distance of 10-50 μm is the working state, that is, the working end 102, and the distance greater than 50 μm is the non-working state, that is, the non-working end 103. Among them, all the processing tracks of the working ends 102 together form the breaking groove 601 of the ultra-fine long stainless steel pipe.

[0189] The center of the inner circle end of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6, and there is a clearance gap between the discharge end 101 and the outer end surface of the stainless steel pipe 6, wherein the end surface diameter of the discharge end 101 is 20 mm, which is 10 times the outer diameter of the stainless steel pipe 6, so as to facilitate the determination of the value of the single-sided feed amount O1O2; during processing, the tool electrode 1 is driven to swing by the driving assembly, and at this time, the discharge end 101 of the tool electrode 1 is in an eccentric motion state around the central axis of the inner cavity of the stainless steel pipe 6.

[0190] The automatic centering module on the machine tool is used to measure S 11 , S 12 , S 13 , S 14 are respectively 2.055 mm, 2.060 mm, 2.065 mm, and 2.050 mm, and at this time, S1=2.058 mm.

[0191] S2=10 μm; H1=0.5 mm, H2=0.3 mm, and S1=2.058 mm, and at this time, O1O2=2.248 mm.

[0192] After adjusting the center of the discharge end 101 of the tool electrode 1 to coincide with the central axis of the inner cavity of the stainless steel pipe 6, the tool electrode 1 is in an eccentric motion state under the action of the driving assembly.

[0193] The conductive end 104 of the tool electrode 1 is electrically connected to one output end of the power supply device arranged on the machine tool, and the stainless steel pipe 6 is electrically connected to the other output end of the power supply device, wherein the power supply device includes a pulse power source, and the two output ends thereof are respectively connected to the positive and negative electrodes of the pulse power source for outputting pulse voltage.

[0194] During processing, the electrical parameters satisfy:

[0195] The pulse width is 40 μs, the pulse interval is 26 μs, the average processing current is 1 A, and the average processing voltage is 40 V.

[0196] Specifically, the above-mentioned driving assembly includes a transmission rod 2, one end of the transmission rod 2 is connected to the tool electrode 1, and the other end of the transmission rod 2 is installed on the machine tool, and the transmission rod 2 can be controlled to swing through the machine tool, thereby driving the discharge end 101 of the tool electrode 1 to make eccentric motion around the central axis of the inner cavity of the stainless steel pipe 6. During processing, the stainless steel pipe 6 remains stationary.

[0197] During processing, the non-electrical parameters satisfy:

[0198] The swing speed of the transmission rod 2 is 0.5 rpm, the processing gap S2 is 10 μm, the processing speed is 0.04 g / min, and the single-sided feed amount O1O2 is 2.248 mm.

[0199] Specifically, the bearing assembly includes the equal-height positioning block 3 and the auxiliary support block 4 installed on the machine tool, so as to place the stainless steel pipe 6 on the equal-height positioning block 3 and the auxiliary support block 4 to clamp the stainless steel pipe 6.

[0200] Two equal-height positioning blocks 3 are arranged, and the two equal-height positioning blocks 3 are respectively located on the two sides of the position to be machined of the stainless steel pipe 6, and the distance between the two equal-height positioning blocks 3 is 30mm.

[0201] Two auxiliary support blocks 4 are arranged, and the two equal-height positioning blocks 3 are located between the two auxiliary support blocks 4, so as to support and position the two ends of the stainless steel pipe 6 through the two auxiliary support blocks 4.

[0202] The upper end faces of the equal-height positioning block 3 and the auxiliary support block 4 are flush, and the upper end faces of the equal-height positioning block 3 and the auxiliary support block 4 are provided with V-shaped grooves, and the stainless steel pipe 6 is placed in the V-shaped grooves to limit the stainless steel pipe 6.

[0203] Further, the clamping plate 5 is arranged on the equal-height positioning block 3, the clamping plate 5 covers the V-shaped groove and is clamped on the equal-height positioning block 3, so as to limit the stainless steel pipe 6 and further improve the stability of the stainless steel pipe 6. For example, the angle of the V-shaped groove is 90°, and the depth is 10mm.

[0204] Before placing the stainless steel pipe 6 on the equal-height positioning block 3, the tool electrode 1 needs to be centered first, then the stainless steel pipe 6 is inserted into the discharge end 101 of the tool electrode 1, and finally the stainless steel pipe 6 is clamped by the equal-height positioning block 3, the auxiliary support block 4 and the clamping plate 5, and the stainless steel pipe 6 is centered by the equal-height positioning block 3 and the auxiliary support block 4.

[0205] One end of the transmission rod 2 is connected with the tool electrode 1, and is parallel to the center line of the discharge end 101 of the tool electrode 1; during machining, the other end of the transmission rod 2 is installed on the machine tool, so as to drive the transmission rod 2 to swing through the machine tool, and then drive the tool electrode 1 to move through the transmission rod 2, so as to realize the eccentric motion of the discharge end 101 of the tool electrode 1 around the central axis of the inner cavity of the stainless steel pipe 6.

[0206] In this way, the discharge end 101 of the tool electrode 1 eccentrically moves around the central axis of the inner cavity of the stainless steel pipe 6 for one cycle, and the machining of the stainless steel pipe breaking groove 601 is completed, which realizes one-time machining and significantly improves the machining efficiency.

[0207] Embodiment 2

[0208] A machining method of an annular groove, comprising the following steps:

[0209] Step 1: Adjust the position of the tool electrode 1 by using the machine tool, so that the plane where the discharge end 101 of the tool electrode 1 is located is perpendicular to the worktable surface 9 of the machine tool;

[0210] Specifically, the worktable surface 9 of the machine tool is a horizontal plane, and the tool electrode 1 is vertically installed on the machine tool and connected with the transmission rod installed on the machine tool.

[0211] Step 2: Clamping the stainless steel pipe 6 by using the bearing assembly, and aligning the stainless steel pipe 6;

[0212] Specifically, first, fix two pieces of equal-height positioning blocks 3 and two pieces of auxiliary supporting blocks 4 on the worktable 9, and use a dial indicator to align the side surface of the equal-height positioning blocks 3 and the auxiliary supporting blocks 4 with the X-axis of the machine tool, and use the machine tool to adjust the position of the equal-height positioning blocks 3 and the auxiliary supporting blocks 4, wherein the parallelism error is ≤0.01mm.

[0213] Then, place the stainless steel pipe 6 on the equal-height positioning blocks 3, and before placing, first pass the stainless steel pipe 6 through the inner circle end of the lower end of the tool electrode 1, and ensure that the stainless steel pipe 6 is in a horizontal position through the equal-height positioning blocks 3, and the distance between the two equal-height positioning blocks 3 is 30mm;

[0214] Then, place the two ends of the stainless steel pipe 6 on the auxiliary supporting blocks 4, and finally fix them with the clamping plate 5.

[0215] Step 3: Adjust the center line of the discharge end 101 of the tool electrode 1 to coincide with the central axis of the inner cavity of the stainless steel pipe 6 by using the machine tool;

[0216] Specifically, first, adjust the position of the stainless steel pipe 6 by moving the bearing assembly in the X-axis direction of the machine tool, so that the position to be machined of the stainless steel pipe 6 is located in the discharge end 101 of the tool electrode 1;

[0217] Then, measure the values of S 11 , S 12 , S 13 , and S 14 by using the automatic centering module of the machine tool, and if the four values are equal or the error is within ±0.02mm, the center of the discharge end 101 of the tool electrode 1 coincides with the central axis of the inner cavity of the stainless steel pipe 6, and if not, continue to adjust the position of the bearing assembly by the machine tool until the requirements are met.

[0218] Step 4: Use kerosene and water as working fluid, and use the tool electrode 1 to perform electric spark machining on the stainless steel pipe 6 in the working fluid.

[0219] S101: Control the eccentric motion of the discharge end 101 of the tool electrode 1 around the central axis of the inner cavity of the stainless steel pipe 6;

[0220] Specifically, the machine tool drives the transmission rod 2 to swing in the swing plane YZ, and then controls the discharge end 101 of the tool electrode 1 to perform eccentric motion around the inner cavity axis of the stainless steel pipe 6 through the transmission rod 2; the eccentric motion direction 8 is as shown in Figure 7

[0221] The swing speed of the transmission rod 2 is 0.5 rpm.

[0222] S 11 , S 12 , S 13 , S 14 The actual measured values are 2.055 mm, 2.060 mm, 2.065 mm, and 2.050 mm, and at this time, S1=2.058 mm.

[0223] The processing gap S2 is 10 μm.

[0224] The single-sided feed amount O1O2=S1+(H1-H2)-S2=2.058+(0.5-0.3)-0.01=2.248 mm.

[0225] The processing speed is 0.04 g / min.

[0226] S102: When the tool electrode 1 performs eccentric motion, the tool electrode 1 is powered to perform electric spark machining.

[0227] Specifically, the electrical parameters satisfy:

[0228] The pulse width is 40 μs, the pulse interval is 26 μs, the average processing current is 1 A, and the average processing voltage is 40 V.

[0229] The above processing method is used to process the fracture grooves of #01-#10 ultra-fine long stainless steel pipes, and the processing parameters are shown in Table 1.

[0230] Table 1 Processing parameters

[0231]

[0232] Processing requirements: the fracture groove wall thickness is 0.3±0.05 mm, and the bevel angle α is 90°.

[0233] The detection results are shown in Table 2.

[0234] Table 2 Detection results

[0235]

[0236] The electrode consumption ratio is E / W*100%, where E is the change in the diameter size of the discharge end of the tool electrode, and W is the initial diameter size of the inner end of the tool electrode. ​

[0237] As can be seen from Table 2, the average value of the groove depth of the broken groove of the 10 pieces of processed stainless steel pipes of the present application is 0.2146 mm, the standard deviation is 0.01427, the coefficient of dispersion is 0.07, the broken groove angle is all 90°, the average value of the broken groove wall thickness is 0.299 mm, the standard deviation is 0.006681, and the coefficient of dispersion is 0.02. It can be seen that the processing method of the present application can realize the broken groove processing of the ultra-fine long stainless steel pipe, the processed broken groove has high precision and stability, the ultra-fine long stainless steel pipe is not damaged, and the tool electrode has small loss.

[0238] Those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments can be completed by a computer program instructing relevant hardware, and the program can be stored in a computer readable storage medium. The computer readable storage medium includes a magnetic disk, an optical disk, a read-only memory, a random access memory, etc.

[0239] The above description is only a preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered by the protection scope of the present application.

Claims

1. An apparatus for machining an annular groove, characterized by: The tool electrode comprises a discharge end, and the discharge end comprises a plurality of electric spark machining points arranged circumferentially around a workpiece to be machined, and each electric spark machining point comprises an active state and an inactive state. When the distance between the electric spark machining point and the surface to be machined is greater than a threshold value, the electric spark machining point is in the inactive state. When the distance between the electric spark machining point and the surface to be machined is less than or equal to the threshold value, the electric spark machining point is in the active state. The active states of the plurality of electric spark machining points arranged circumferentially around the workpiece to be machined realize machining of an annular groove on the surface to be machined. The threshold value is a discharge distance between the electric spark machining point and the surface to be machined that meets machining requirements. The plurality of electric spark machining points arranged circumferentially around the workpiece to be machined form a continuous circular ring, and the inner circle end of the circular ring matches the shape of the annular groove. The discharge end of the tool electrode is sleeved on the workpiece to be machined, and during machining, the tool electrode is controlled to perform eccentric motion by a machine tool, and the workpiece to be machined remains stationary, and the circular ring-shaped discharge end of the tool electrode performs eccentric motion around the central axis of the inner cavity of the workpiece to be machined. The machining direction is the circumferential direction of the outer end surface of the workpiece to be machined, and the center line of the circumferential direction coincides with the central axis of the inner cavity of the workpiece to be machined.

2. The processing apparatus of claim 1, wherein: The plurality of electric spark machining points arranged circumferentially around the workpiece to be machined are continuously and uninterruptedly distributed circumferentially around the workpiece to be machined.

3. The apparatus of claim 1, wherein: The circular ring-shaped discharge end of the tool electrode is a rigid structure and is sleeved on the workpiece to be machined.

4. The apparatus of claim 3, wherein: In the initial state, the center line of the circular ring-shaped discharge end of the tool electrode coincides with the central axis of the inner cavity of the workpiece to be machined.

5. The apparatus of claim 3 wherein: During the machining process in which the discharge end performs eccentric motion around the central axis of the inner cavity of the workpiece to be machined, the single-sided feed amount O1O2 satisfies: O1O2=S1+(H1-H2)-S2 wherein H1 is the wall thickness of the workpiece to be machined, H2 is the wall thickness of the annular groove, S1 is the distance between the discharge end of the tool electrode and the surface to be machined before machining, and S2 is the machining gap.

6. The apparatus of claim 5, wherein: Before machining, the distance S1 between the discharge end of the tool electrode and the surface to be machined satisfies: wherein S 11 , S 12 , S 13 , S 14 are actual excess gap values between four points selected on the circular ring-shaped discharge end of the tool electrode and the surface to be machined, the four points being uniformly distributed on the circular ring-shaped discharge end.

7. The apparatus of claim 1 wherein: The threshold value is 0-50 μm.

8. The apparatus of claim 3, wherein: The machining device further comprises a driving assembly for controlling the eccentric motion of the discharge end of the tool electrode and a bearing assembly for clamping the workpiece to be machined. The driving assembly and the bearing assembly are installed on a machine tool.

9. A method of machining an annular groove, characterized by: The machining device is used for machining an annular groove.

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