A method for machining small precision oil injection holes with unequal bevel angles in the intermediate casing

Abstract

The present invention discloses a method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing. After rough and fine machining by methods such as scribing, counting, machining center, and stress relief, the small precision oil injection holes are subjected to electrospark reverse forming machining with appropriate control parameters, thereby solving the chip removal problem and precision requirements of precise small long holes. To this end, a multifunctional fixture is designed and manufactured. On the one hand, it meets the machining position requirements of the unequal bevel angles of the oil injection holes in the intermediate casing; on the other hand, after the electrode is aligned with the three-way tool setting block on the fixture or on the part, the exact position of the electrode in the XYZ directions relative to the inclined hole of the workpiece is determined, and then the electrode is moved to the corresponding machining position of the inclined hole, and it is convenient to accurately set parameters such as the electrospark reverse machining depth and reverse tool retraction position on the electric discharge machine.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and in particular to a method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing. Background Art

[0002] The intermediate casing is one of the important parts of a turbojet or turbofan engine. The front and rear ends are connected to the corresponding parts of the fan stage and the high-pressure stage respectively. The inner and outer ducts are connected by a support plate. The support plate has an oil inlet hole, a vent hole, and an oil return cavity. The core of the inner duct has a mounting hole for the front bearing of the high-pressure shaft. The lubricating oil of the bearing here is introduced from the larger oil inlet hole in the support plate, and then sprayed and lubricated through the small precision oil injection holes of unequal angles, such as Figure 1 As shown, the intermediate casing has multiple oil injection holes with different angles. The position and accuracy of the inclined holes are crucial to the oil injection quality and the effect of lubricating the bearings.

[0003] Currently, two methods for machining precision fuel injection holes are drilling and reaming using a jig or using a five-axis machining center with a drill bit and reamer. Neither method is suitable for machining fuel injection holes where the location of the fuel injection hole is limited and the tool cannot reach the interior of the part. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology. The purpose is to provide a method for processing small and precise oil injection holes with unequal angles in the intermediate casing, and solve the problem of part positioning and adjustment of the inclination angle by a reasonable fixture structure; by changing the conventional forming direction of the electric spark, the chip removal problem of the slender oil injection hole is solved; by setting a three-way tool setting block, the accurate three-way position correlation of the electrode relative to the inclined hole is solved.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing comprises the following steps:

[0007] The following steps are involved:

[0008] S1: After rough and fine machining, the intermediate casing is mounted on the positioning plate of the positioning fixture, and the intermediate casing is positioned to ensure that the axial direction of the first oil injection hole to be machined in the intermediate casing is in the vertical direction;

[0009] S2: Connect the electrode assembly to the machine tool, move the electrode so that it touches the second tool setting hole and the lower end surface corresponding to the first oil injection hole in the three-way tool setting block, and determine the three-way relative position of the electrode and the first oil injection hole to be machined;

[0010] S3: moving the electrode to the first oil injection hole to be processed in the intermediate casing, starting the machine tool to process the first oil injection hole, and forming the elongated first oil injection hole from bottom to top along the vertical direction;

[0011] S4: After the first oil injection hole of the intermediate casing is processed, the tilt angle of the positioning fixture is adjusted so that the second oil injection hole to be processed of the intermediate casing located on the positioning fixture is in a vertical direction;

[0012] S5: moving the electrode to the first tool setting hole corresponding to the second oil injection hole in the three-way tool setting block, so that the electrode touches the first tool setting hole and the lower end surface for tool setting, and determining the three-way relative position of the electrode and the second oil injection hole to be processed;

[0013] S6: moving the electrode to the second oil injection hole to be processed in the intermediate casing, starting the machine tool to process the second oil injection hole, and forming the elongated second oil injection hole from bottom to top along the vertical direction;

[0014] S7: Repeat steps S4 to S6 to process the remaining oil injection holes of the intermediate casing.

[0015] Furthermore, the intermediate casing in step S1 is roughed and finely machined by scribing, lathe, machining center and stress relief method, wherein a threaded bottom hole at the end is drilled and bored to achieve an accuracy of H8 for angular positioning.

[0016] Furthermore, the positioning fixture includes a base plate, a positioning plate, a column and a positioning bolt. The positioning plate is hinged to the base plate, the column is fixed to the top of the base plate, and the column is provided with a first positioning hole and a second positioning hole. The positioning bolt is used to connect with the first positioning hole and the second positioning hole respectively to fix the positioning plate on the base plate at different inclination angles.

[0017] Furthermore, a first protrusion is provided at one end of the positioning plate, a second protrusion is provided at one end of the base plate, and a notch is provided on the second protrusion. The first protrusion of the positioning plate is hinged in the notch via a pin screw.

[0018] Furthermore, a positioning ring is provided on the positioning plate, and the outer diameter of the positioning ring is consistent with the inner diameter of the large inner hole in the middle of the intermediate casing;

[0019] The positioning plate is further provided with a first through hole and a second through hole, the first through hole and the second through hole are connected to form a first stepped hole, a positioning pin is provided in the second through hole, the positioning end diameter of the positioning pin is consistent with the inner diameter of the threaded bottom hole formed by drilling and boring the intermediate receiver in step S1, and the positioning end of the positioning pin passes through the first through hole and is inserted into the threaded bottom hole of the intermediate receiver.

[0020] Furthermore, a fixing plate is provided on the back of the positioning plate, and a third through hole and a fourth through hole are provided on the fixing plate, the third through hole and the fourth through hole are connected to form a second stepped hole, the inner diameter of the fourth through hole is larger than the inner diameter of the third through hole, and the fourth through hole is connected to the second through hole on the positioning plate;

[0021] The positioning pin passes through the third through hole and the fourth through hole in sequence. A boss is provided on the side wall of the positioning pin. A spring is further provided in the fourth through hole of the fixing plate. The spring is sleeved on the positioning pin and is used to push the positioning end of the positioning pin into the threaded bottom hole of the intermediate casing.

[0022] An annular groove is further provided on the circumferential outer wall of the positioning pin, and an inserting plate is provided in the annular groove. The inserting plate is used to fix the positioning end of the positioning pin in the first through hole of the positioning plate.

[0023] Furthermore, the three-way tool setting block is fixed on the positioning plate or the intermediate casing, and the three-way tool setting block is provided with a first tool setting hole and a second tool setting hole.

[0024] Furthermore, the electrode assembly includes an electrode mounting base, an electrode sleeve, and an electrode. The mounting base includes a first connecting section and a second connecting section. One end of the first connecting section is connected to the machine tool, and the other end is connected to one end of the second connecting section to form an L-shaped structure. The angle formed between the first connecting section and the second connecting section is greater than 90°.

[0025] The other end of the second connecting section is connected to the electrode sleeve via a cross screw. The electrode is connected to the electrode sleeve, and the electrode and the first connecting section of the mounting base are parallel to each other.

[0026] Furthermore, after the processing of the first oil injection hole of the intermediate casing is completed in step S3, the electrode is returned to the second tool setting hole of the three-way tool setting block, and the electrode is set again to confirm whether the tool setting in S2 is correct. If it is correct, step S4 is performed;

[0027] After the processing of the second oil injection hole of the intermediate casing is completed in step S6, the electrode is returned to the first tool setting hole of the three-way tool setting block, and the electrode is set again to check whether the tool setting in S5 is correct.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] The present invention utilizes the positioning fixture provided in a hinge manner, so that the provided positioning plate is laterally positioned by the positioning bolt, thereby realizing precise adjustment of the inclination angle of the positioning plate, and meeting the requirements of precise processing of the two unequally inclined fuel injection holes in the intermediate casing; and when using the electrode assembly to process the fuel injection holes of the intermediate casing, the slender fuel injection holes are formed from bottom to top along the vertical direction, so that the electric chips generated by the electrode during the processing are easy to discharge, avoiding processing carbonization, and improving processing efficiency and forming accuracy; at the same time, the three relative tool blocks provided can facilitate electrode tool alignment, accurately determine the relative position of the electrode and the fuel injection hole, and further improve the processing accuracy of the fuel injection hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0031] Figure 1 It is a structural schematic diagram of the intermediate casing of the present invention;

[0032] Figure 2 This is a schematic structural diagram of the intermediate casing of the present invention being positioned on a positioning fixture;

[0033] Figure 3 A cross-sectional view of the intermediate casing of the present invention when positioned on a positioning fixture;

[0034] Figure 4 Schematic diagram of the structure of the electrode assembly of the present invention;

[0035] Figure 5 This is a schematic structural diagram of the electrode sleeve and the electrode when assembled according to the present invention;

[0036] Figure 6 This is a schematic structural diagram of the three-way tool setting block of the present invention;

[0037] Figure 7 It is a top view of the three-way tool setting block of the present invention;

[0038] Figure 8 For the present invention Figure 2 Schematic diagram of the structure after enlarging part A in the middle.

[0039] Markings and corresponding parts names in the accompanying drawings:

[0040] 1. Base plate; 2. Upright column; 3. Hexagon socket screw; 4. Cylindrical pin; 5. Positioning plate; 6. Three-way tool setting block; 7. Pin screw; 8. Electrode assembly; 9. Positioning bolt; 10. Insert plate; 11. Spring; 12. Positioning pin; 13. Electrode; 14. Electrode sleeve; 15. Cross screw; 16. Electrode mounting seat; 17. First positioning hole; 18. First tool setting hole; 19. Second tool setting hole; 20. First tool setting surface; 21. Second tool setting surface; 22. First oil injection hole; 23. Second oil injection hole. DETAILED DESCRIPTION

[0041] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0042] Example

[0043] like Figures 2 to 8 As shown, the present invention includes the following steps:

[0044] S1: The intermediate casing to be processed is rough-machined and fine-machined by means of marking, lathe, machining center, stress relief, etc., and a threaded bottom hole at the end of the intermediate casing is drilled and bored to achieve an accuracy of H8, so that the threaded bottom hole can be used for angular positioning later.

[0045] Before positioning the intermediate casing on the positioning plate 5 of the positioning fixture, first pull the positioning pin 12 outward, then insert the insert plate 10 into the annular groove of the positioning pin 12, and use the set insert plate 10 to fix the positioning pin 12 so that the positioning end of the positioning pin 12 is retracted into the first through hole on the positioning plate 5, and then the intermediate casing is installed in the positioning ring of the positioning plate 5, and the intermediate casing is rotated so that the intermediate casing is roughly in the processing position, and then the insert plate 10 is pulled out, and under the action of the spring 11, the positioning end of the positioning pin 12 is pushed to be inserted into the threaded bottom hole of the intermediate casing after drilling and boring, and finally the intermediate casing is fixed to the positioning plate 5 with four screws to ensure that the first oil injection hole 22 to be processed in the intermediate casing is in the plumb direction.

[0046] S2: Install the electrode assembly 8 on the EDM machine and calibrate it with a lever micrometer, then turn on the tool setting mode, move the electrode 13 to the second tool setting hole 19 in the three-way tool setting block 6, and move the electrode 13 in four directions in the second tool setting hole 19 for contact tool setting, that is, the electrode 13 touches the tool in the second tool setting hole 19 along the X, -X, Y, and -Y directions of the EDM machine to determine the X and Y position coordinates of the electrode 13 on the spark machine, and then use the end face of the electrode 13 to touch the second tool setting surface 21 of the three-way tool setting block 6 to determine the Z position coordinate of the electrode 13 on the spark machine.

[0047] S3: Move the electrode 13 in manual mode or automatic program mode so that the electrode 13 is located at the first oil injection hole 22 to be processed in the intermediate casing, and then set the reverse feed depth parameters and the corresponding electrical parameters of the first oil injection hole 22, start the EDM machine, and process the first oil injection hole 22 of the intermediate casing.

[0048] After completing the processing of the first oil injection hole 22 of the intermediate casing, move the electrode 16 in manual mode or automatic program mode so that the electrode 16 returns to the second tool setting hole 19 of the three-way tool setting block 6, repeat the tool setting steps in S2, and set the electrode 16 again. Check and confirm whether the tool setting in S2 is correct. If it is correct, proceed to step S4.

[0049] S4: Loosen the positioning bolts 9 on the two columns 2 and remove the positioning bolts 9 from the second positioning holes. Then rotate the positioning plate 5 and adjust the inclination angle of the rotating positioning plate 5 so that the mounting holes on the positioning plate 5 are aligned with the first positioning holes 17 on the columns 2. Install the positioning bolts 9 in the first positioning holes 17 and the mounting holes, thereby positioning and locking the positioning plate 5 on the columns 2, and keeping the second oil injection hole 23 to be processed on the intermediate casing on the positioning plate 5 in the vertical direction.

[0050] S5: Move the electrode 16 to the first tool setting hole 18 of the three-way tool setting block 6 again, touch the tool with the electrode 16 in the first tool setting hole 18 along the X, -X, Y, -Y directions of the machine tool, determine the X, Y position coordinates of the electrode 16 on the machine tool, and then use the end face of the electrode 16 to touch the first tool setting surface 20 of the three-way tool setting block 6 to determine the Z position coordinate of the electrode 16 on the machine tool.

[0051] S6: Move the electrode 16 to the second oil injection hole 23 to be processed in the intermediate casing in manual mode or automatic program mode, then set the reverse feed depth parameters and the corresponding electrical parameters of the second oil injection hole 23, start the EDM machine, and process the second oil injection hole 23 of the intermediate casing.

[0052] S7: After completing the processing of the second oil injection hole 23 of the intermediate casing, move the electrode 16 to the first tool setting hole 18 of the three-way tool setting block 6 in manual mode or automatic program mode, and set the tool again according to the tool setting steps in step S5 to check and confirm whether the tool setting in step S5 is correct.

[0053] S8: Repeat steps S4 to S7 to continue processing the remaining injection holes of the intermediate casing;

[0054] S9: Pull out the positioning pin 12 and insert the insert plate 10, then remove the four screws on the positioning plate 5, take out the intermediate casing and clean it, and complete the processing of the small precision oil injection holes with unequal angles on the intermediate casing.

[0055] The positioning fixture described in the above steps includes a base plate 1, a positioning plate 5, a column 2 and a positioning bolt 9. The positioning plate 5 is hinged to the base plate 1, and the column 2 is fixed to the top of the base plate 1 by a hexagon socket screw 3 and a cylindrical pin 4. The column 2 is provided with a first positioning hole 17 and a second positioning hole. The positioning bolt 9 is used to connect with the first positioning hole 17 and the second positioning hole respectively to fix the positioning plate 5 on the base plate 1 at different inclination angles.

[0056] Since the two or more small precision oil injection holes in the intermediate casing are distributed at unequal angles, the angle formed by the axis of the first oil injection hole 22 and the axis of the oil inlet hole of the intermediate casing is α1, the angle formed by the axis of the second oil injection hole 23 and the axis of the oil inlet hole of the intermediate casing is α2, and so on. The angle formed by the axis of the nth oil injection hole and the axis of the oil inlet hole of the intermediate casing is α n , and α1, α2, α nAre not equal, in this technical solution, priority is given to processing the two fuel injection holes of the intermediate casing. The traditional processing method is limited by the position of the fuel injection holes, which makes it impossible for the tool to extend into the interior of the intermediate casing to process the two fuel injection holes. Therefore, in order to ensure the precise processing of the two fuel injection holes with different inclination angles of the intermediate casing, this technical solution designs a positioning fixture for positioning the intermediate casing, wherein one end of the positioning plate 5 is connected to the base plate 1 by a hinge, so that the positioning plate 5 can be rotated arbitrarily in the vertical plane, and the inclination angle of the positioning plate 5 in the vertical plane is adjusted; in order to ensure that the positioning plate 5 can meet the processing of the two fuel injection holes with different inclination angles, a first positioning hole 17 and a second positioning hole are provided on the column 2, and the positioning plate 5 faces Mounting holes are provided on both sides of the column 2. When the first oil injection hole 22 of the intermediate casing needs to be processed, the positioning plate 5 is rotated so that the mounting hole on the positioning plate 5 is aligned with the second positioning hole, and then the positioning plate 5 is fixed to the vertical shaft 2 by using the positioning bolt 9. When the positioning plate 5 is in this tilted state, it can ensure that the first oil injection hole 22 to be processed of the intermediate casing located on the positioning plate 5 is in a vertical direction; and when the second oil injection hole 23 on the intermediate casing needs to be processed, the positioning plate 5 is rotated so that the mounting hole on the positioning plate 5 is aligned with the first positioning hole 17, and the positioning plate 5 is fixed to the vertical shaft 2 by using the positioning bolt 9. When the positioning plate 5 is in this tilted angle state, it can ensure that the second oil injection hole 23 to be processed of the intermediate casing located on the positioning plate 5 is in a vertical direction.

[0057] A first protrusion is provided at one end of the positioning plate 5 , a second protrusion is provided at one end of the base plate 1 , and a notch is provided on the second protrusion. The first protrusion of the positioning plate 5 is hinged in the notch via a pin screw 7 .

[0058] In this embodiment, in order to realize the free rotation of the positioning plate 5 on the base plate 1 and to realize the adjustment of the inclination angle of the positioning plate 5, two first protrusions are provided at the end of the positioning plate 5 facing the base plate 1, and a second protrusion for connecting with the first protrusion is provided at one end of the base plate 1, so that the first protrusion of the positioning plate 5 is embedded in the notch of the second protrusion of the base plate 1, and the pin screw 7 is sequentially passed through the first protrusion and the second protrusion, so that the first protrusion of the positioning plate 5 is hinged to the second protrusion of the base plate 1, thereby realizing the free rotation of the positioning plate 5 on the base plate 1.

[0059] The pin screw 7 in this embodiment is tightened by a double nut, and an appropriate gap is left between the nut and the second protrusion to prevent friction between the nut and the positioning plate 5 when the positioning plate 5 rotates, so that the positioning plate 5 can rotate freely around the pin screw 7.

[0060] A positioning ring is also provided on the positioning plate 5, and the outer diameter of the positioning ring is consistent with the inner diameter of the large inner hole in the middle of the intermediate receiver; a first through hole and a second through hole are also provided on the positioning plate 5, and the first through hole is connected to the second through hole to form a first stepped hole, and a positioning pin 12 is provided in the second through hole, and the positioning end diameter of the positioning pin 12 is consistent with the inner diameter of the threaded bottom hole formed by drilling and boring the intermediate receiver in the step S1, and the positioning end of the positioning pin 12 passes through the first through hole and is inserted into the threaded bottom hole of the intermediate receiver.

[0061] In order to improve the positioning accuracy of the intermediate casing to be processed on the positioning plate 5 in this embodiment, a positioning ring is further provided at the central position of the positioning plate 5. The positioning ring is in a convex structure as a whole, and a positioning connecting hole is provided at the central position of the positioning plate 5. The raised part of the positioning ring is located in the connecting hole of the positioning plate 5, so as to realize the positioning connection between the positioning ring and the positioning plate 5. The maximum outer diameter of the positioning ring is consistent with the inner diameter of the large inner hole in the middle of the intermediate casing. When positioning, the large inner hole in the middle of the intermediate casing is assembled on the positioning ring of the positioning plate 5, and the end face of the intermediate casing is attached to the positioning panel of the positioning plate 5, which limits the five degrees of freedom of the intermediate casing positioning and realizes the preliminary positioning of the intermediate casing.

[0062] In order to achieve another degree of rotational freedom restriction for the intermediate casing on the positioning plate 5, a positioning pin 12 is further provided on the positioning plate 5. When in use, after the intermediate casing is positioned and mounted on the positioning ring on the positioning plate 5, the intermediate casing is rotated so that the threaded bottom hole formed by drilling and boring in step S1 of the intermediate casing is rotated to be aligned with the positioning pin 12, and then the positioning pin 12 is inserted into the threaded bottom hole of the intermediate casing to play a positioning role, thereby achieving the purpose of restricting the rotational freedom of the intermediate casing located on the positioning plate 5.

[0063] The positioning plate 5 is also provided with four assembly holes, which correspond one to one with the other four threaded holes at the end of the intermediate casing, and are respectively connected to the four threaded holes of the intermediate casing by four cylindrical head hexagonal screws, so that the intermediate casing is stably fixed on the positioning plate 5. After the above operation, when the positioning plate 5 is connected to the second positioning hole on the column 2, the first oil injection hole 22 to be processed in the intermediate casing fixed on the positioning plate 5 is exactly in the vertical direction; when the positioning plate 5 is connected to the first positioning hole 17 on the column 2, the second oil injection hole 23 to be processed in the intermediate casing fixed on the positioning plate 5 is exactly in the vertical direction.

[0064] A fixing plate is also provided on the back of the positioning plate 5, and a third through hole and a fourth through hole are provided on the fixing plate. The third through hole and the fourth through hole are connected to form a second stepped hole, the inner diameter of the fourth through hole is larger than the inner diameter of the third through hole, and the fourth through hole is connected to the second through hole on the positioning plate 5; the positioning pin 12 passes through the third through hole and the fourth through hole in sequence, and a boss is provided on the side wall of the positioning pin 12. A spring 11 is also provided in the fourth through hole of the fixing plate, and the spring 11 is sleeved on the positioning pin 12. The spring 11 is used to push the positioning end of the positioning pin 12 to be inserted into the threaded bottom hole of the intermediate receiver.

[0065] In this embodiment, when the positioning pin 12 is inserted into the threaded bottom hole of the intermediate receiver, in order to prevent the positioning pin 12 from falling off from the threaded bottom hole of the intermediate receiver during the processing and affecting the processing accuracy of the intermediate receiver, a fixing plate is further provided on the back of the positioning plate 5, and a spring 11 is provided in the fixing plate. In order to ensure that the spring 11 can push the positioning end of the positioning pin 12 to be inserted into the threaded bottom hole of the intermediate receiver, a boss is provided on the positioning pin 12 so that the elastic force generated by the spring 11 can act on the boss, thereby pushing the positioning pin 12 to position the threaded bottom hole of the intermediate receiver; and in order to be able to constrain the other end of the spring 11, a third through hole and a fourth through hole are provided in the fixing plate. The third through hole and the fourth through hole are connected to form a second step hole, thereby limiting the spring 11.

[0066] An annular groove is further provided on the circumferential outer wall of the positioning pin 12 , and an inserting plate 10 is provided in the annular groove. The inserting plate 10 is used to fix the positioning end of the positioning pin 12 in the first through hole of the positioning plate 5 .

[0067] In order to facilitate manual positioning of the intermediate receiver in this embodiment, an insert plate 10 is also provided, and an annular groove matching the insert plate 10 is provided on the positioning pin 12. When the intermediate receiver needs to be positioned and installed on the positioning plate 5, the positioning pin 12 is pulled so that the positioning end on the positioning pin 12 is retracted into the first through hole of the positioning plate 5. At this time, the annular groove provided on the positioning pin 12 is just flush with the bottom surface of the fixing plate. Therefore, after the insert plate 10 is inserted into the annular groove of the positioning pin 12, the positioning pin 12 can be temporarily fixed under the action of the insert plate 10. After the intermediate receiver is installed on the positioning plate 5, the insert plate 10 is removed from the annular groove of the positioning pin 12. At this time, the positioning pin 12 can be quickly extended from the first through hole of the positioning plate 5 under the action of the spring 11 and inserted into the threaded bottom hole of the intermediate receiver.

[0068] The three-way tool setting block 6 is fixed to the positioning plate 5 by screws. The three-way tool setting block 6 is provided with a first tool setting hole 18 and a second tool setting hole 19 .

[0069] In order to improve the precision machining of the two oil injection holes of the intermediate casing with unequal angles in the present technical solution, a three-way tool setting block 6 is provided on the positioning plate 5. The three-way tool setting block 6 includes a fixing portion and a tool setting portion. The fixing portion is connected to the tool setting portion and the angle formed is β. The fixing portion is fixed to the positioning plate 5 by a positioning pin and a screw, thereby fixing the three-way tool setting block 6 on the positioning plate 5. During installation, the position where the three-way tool setting block 6 is fixed on the positioning plate 5 corresponds to the positioning surface of the positioning plate 5 and the position of the positioning ring in the central part of the positioning plate.

[0070] In another embodiment, the three-way tool block 6 is directly positioned and clamped on the intermediate casing part. This design can eliminate the positioning error of the three-way tool block 6 relative to the positioning ring on the positioning fixture, thereby improving the positioning accuracy; in this embodiment, the electrode 16 moves along three directions when processing the intermediate casing, and its distance is the three-way distance measured by the three-dimensional simulation modeling of the three-way tool block 6 installed on the intermediate casing, or the distance is the calculated distance.

[0071] The tool setting portion of the three-way tool setting block 6 is provided with a first tool setting hole 18 and a second tool setting hole 19. The first tool setting hole 18 and the second tool setting hole 19 are two non-parallel tool setting holes, that is, the first tool setting hole 18 is used for tool setting when processing the second oil injection hole 23 of the intermediate casing, and the second tool setting hole 19 is used for tool setting when processing the first oil injection hole 22 of the intermediate casing, thereby realizing tool setting for the two oil injection holes with different bevels of the intermediate casing.

[0072] When setting the tool, turn on the tool setting mode, then move the electrode 13, touch the two tool setting hole walls on the tool setting part in the X, -X, Y, -Y directions of the machine tool, and determine the position of the electrode 13 in the X and Y directions of the machine tool when processing the two oil injection holes of the intermediate casing; the bottom of the tool setting part of the three-part relative tool block 6 is two sections of tool setting surfaces that are not on the same horizontal plane, that is, the bottom of the tool setting part is provided with a first tool setting surface 20 and a second tool setting surface 21, wherein the angle β formed by the extension line of the first tool setting surface 20 and the fixed part is 90°+α2, and the angle β formed by the second tool setting surface 21 and the fixed part is 90°+α1; when it is necessary to process the first oil injection hole 22 of the intermediate casing, adjust the inclination angle of the positioning plate 5 so that the positioning plate 5 passes through the positioning bolt 9 It is fixed at the second positioning hole of the column 2. At this time, the second tool surface 21 is in the horizontal direction. The upper end face of the electrode 13 is used to touch the second tool surface 21 of the three-way tool block 6 to determine the Z-direction position of the electrode 13 in the machine tool when processing the first oil injection hole 22. Similarly, when processing the second oil injection hole 23 of the intermediate casing, the inclination angle of the positioning plate 5 is adjusted, and the positioning plate 5 is fixed to the first positioning hole 17 of the column 2 by the positioning bolt 9. At this time, the first tool surface 20 is in the horizontal direction. The upper end face of the electrode 13 is used to touch the second tool surface 20 to determine the Z-direction position of the machine tool where the electrode is located when processing the second oil injection hole 23, thereby realizing the precise processing of two oil injection holes with different bevel angles in the intermediate casing.

[0073] After the electrode 13 completes the tool setting of the corresponding oil injection hole, the electrode 13 moves along the X, Y, and Z directions of the machine tool. The moving distances are the three directional distances of the tool setting position confirmed when the positioning plate 5 is designed relative to the position of the oil injection hole of the part.

[0074] The electrode assembly 8 includes an electrode mounting seat 16, an electrode sleeve 14 and an electrode 13. The mounting seat 16 includes a first connecting section and a second connecting section. One end of the first connecting section is connected to the machine tool, and the other end is connected to one end of the second connecting section to form an L-shaped structure, and the angle formed between the first connecting section and the second connecting section is 90°+(α1+α2) / 2; the other end of the second connecting section is connected to the electrode sleeve 14 through a cross screw, and the electrode 13 is connected to the electrode sleeve 14, and the electrode 13 and the first connecting section of the mounting seat 16 are parallel to each other.

[0075] In this embodiment, the number of oil injection holes to be processed in the intermediate casing is two, and the mounting seat 8 is provided, including a first connecting section and a second connecting section, the first connecting section and the second connecting section are connected to form an L-shaped elbow structure, and the angle formed by the first connecting section and the second connecting section is 90°+(α1+α2) / 2, so that it can be ensured that the electrode 13 on the mounting seat 16 can be extended into the interior of the intermediate casing to make way for the electrode 13 during processing; wherein the first connecting section is provided for connecting to the electric spark machine, and the second connecting section is provided for connecting to the electrode sleeve 14, the electrode 13 is installed on the electrode sleeve 14, and the electrode 13 is in a parallel state with the first connecting section of the mounting seat 16, and they are both in the vertical direction, so that when the machine tool drives the mounting seat 16 to move in the vertical direction, it can ensure that the provided electrode 13 can move synchronously in the vertical direction to process the oil injection holes of the intermediate casing.

[0076] Since the two slender oil injection holes of the intermediate casing need to be processed in this technical solution, and the axis of the internal oil injection hole of the intermediate casing intersects with the interior of the intermediate casing, conventional mechanical processing tools cannot be inserted and machining methods cannot be used, so spark forming is used for processing. Moreover, since the two oil injection holes are both slender, the diameter of the oil injection holes is less than 1mm, and some holes are longer than 30mm, the electric slag generated during the processing is difficult to discharge, and it is easy to short-circuit and carbonize during electrical processing, resulting in low processing efficiency and difficulty in ensuring accuracy. For this reason, this technical solution designs the mounting seat 8 into an L-shaped elbow structure. During the processing, the forming method of the oil injection hole is changed, that is, electric spark forming processing from bottom to top is adopted. The electric slag generated during the processing is discharged smoothly from the hole into the tank liquid along with the pulsation of the spark liquid under the action of gravity, effectively solving the chip removal problem. The processing is produced by using appropriate current, voltage, waveform, etc., ensuring the accuracy of the formed oil injection hole.

[0077] In another embodiment, when the number of the injection holes to be processed in the intermediate casing is n, the angle formed by the first connecting section and the second connecting section of the mounting seat 8 is 90°+(α max +α min ) / 2, ensuring that during the processing, the electrode 13 can be extended into the intermediate casing to process the oil injection hole.

[0078] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing, characterized in that: The following steps are involved: S1: Installing the intermediate casing after rough and fine machining onto the positioning plate (5) of the positioning fixture, positioning the intermediate casing, and ensuring that the axial direction of the first oil injection hole (22) to be machined in the intermediate casing is in the vertical direction; S2: Connecting the electrode assembly (8) to the machine tool, moving the electrode (13) so that it touches the second tool setting hole (19) and the second tool setting surface (21) corresponding to the first oil injection hole (22) in the three-way tool setting block (6), and determining the three-way relative position of the electrode (13) and the first oil injection hole (22) to be processed; S3: moving the electrode (13) to the first oil injection hole (22) to be processed in the intermediate casing, starting the machine tool to process the first oil injection hole (22), and forming the elongated first oil injection hole (22) from bottom to top in the vertical direction by the electrode (13); S4: After the first oil injection hole (22) of the intermediate casing is processed, the tilt angle of the positioning fixture is adjusted so that the second oil injection hole (23) to be processed of the intermediate casing located on the positioning fixture is in a vertical direction; S5: moving the electrode (13) to the first tool setting hole (18) corresponding to the second oil injection hole (23) in the three-way tool setting block (6), so that the electrode (13) touches the first tool setting hole (18) and the first tool setting surface (20), and determining the three-way relative position of the electrode (13) and the second oil injection hole (23) to be processed; S6: moving the electrode (13) to the second oil injection hole (23) to be processed in the intermediate casing, starting the machine tool to process the second oil injection hole (23), and forming the elongated second oil injection hole (23) from bottom to top in the vertical direction by the electrode (13); S7: Repeat steps S4 to S6 to process the remaining fuel injection holes of the intermediate casing; The electrode assembly (8) comprises an electrode mounting seat (16), an electrode sleeve (14), and an electrode (13); the electrode mounting seat (16) comprises a first connecting section and a second connecting section; one end of the first connecting section is connected to the machine tool, and the other end is connected to one end of the second connecting section to form an L-shaped structure; and the angle formed between the first connecting section and the second connecting section is greater than 90°; The other end of the second connecting section is connected to the electrode sleeve (14) via a cross screw, the electrode (13) is connected to the electrode sleeve (14), and the electrode (13) and the first connecting section of the electrode mounting seat (16) are parallel to each other; The axis of the first oil injection hole (22) forms an angle α1 with the axis of the oil inlet hole of the intermediate casing, the axis of the second oil injection hole (23) forms an angle α2 with the axis of the oil inlet hole of the intermediate casing, and the angle formed between the first connecting section and the second connecting section is 90°+(α1+α2) / 2.

2. The method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing according to claim 1, characterized in that: The intermediate casing in step S1 is roughed and finely machined by scribing, lathe, machining center and stress relief method, wherein a threaded bottom hole at the end is drilled and bored to achieve an accuracy of H8 for angular positioning.

3. The method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing according to claim 2, characterized in that: The positioning fixture comprises a base plate (1), a positioning plate (5), a column (2) and a positioning bolt (9), wherein the positioning plate (5) is hinged to the base plate (1), the column (2) is fixed to the top of the base plate (1), the column (2) is provided with a first positioning hole (17) and a second positioning hole, and the positioning bolt (9) is used to connect with the first positioning hole (17) and the second positioning hole respectively, so as to fix the positioning plate (5) on the base plate (1) at different inclination angles.

4. The method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing according to claim 3, characterized in that: One end of the positioning plate (5) is provided with a first protrusion, one end of the bottom plate (1) is provided with a second protrusion, and the second protrusion is provided with a notch, and the first protrusion of the positioning plate (5) is hinged in the notch via a pin screw (7).

5. The method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing according to claim 3, characterized in that: A positioning ring is also provided on the positioning plate (5), and the outer diameter of the positioning ring is consistent with the inner diameter of the large inner hole in the middle of the intermediate casing; The positioning plate (5) is further provided with a first through hole and a second through hole, the first through hole and the second through hole are connected to form a first stepped hole, a positioning pin (12) is provided in the second through hole, the positioning end diameter of the positioning pin (12) is consistent with the inner diameter of the threaded bottom hole formed by drilling and boring the intermediate casing in step S1, and the positioning end of the positioning pin (12) passes through the first through hole and is inserted into the threaded bottom hole of the intermediate casing.

6. The method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing according to claim 5, characterized in that: A fixing plate is further provided on the back of the positioning plate (5), and a third through hole and a fourth through hole are provided on the fixing plate, wherein the third through hole and the fourth through hole are connected to form a second stepped hole, the inner diameter of the fourth through hole is larger than the inner diameter of the third through hole, and the fourth through hole is connected to the second through hole on the positioning plate (5); The positioning pin (12) passes through the third through hole and the fourth through hole in sequence, a boss is provided on the side wall of the positioning pin (12), and a spring (11) is further provided in the fourth through hole of the fixing plate. The spring (11) is sleeved on the positioning pin (12), and the spring (11) is used to push the positioning end of the positioning pin (12) into the threaded bottom hole of the intermediate casing; An annular groove is further provided on the circumferential outer wall of the positioning pin (12), and an insert plate (10) is provided in the annular groove. The insert plate (10) is used to fix the positioning end of the positioning pin (12) in the first through hole of the positioning plate (5).

7. The method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing according to claim 3, characterized in that: The three-way tool setting block (6) is fixed on the positioning plate (5) or the intermediate casing, and the three-way tool setting block (6) is provided with a first tool setting hole (18) and a second tool setting hole (19).

8. The method for machining small precision oil injection holes with unequal bevel angles in an intermediate casing according to claim 1, characterized in that: After the processing of the first oil injection hole (22) of the intermediate casing is completed in step S3, the electrode (13) is returned to the second tool setting hole (19) of the three-way tool setting block (6), and the electrode (13) is tool set again to confirm whether the tool setting in S2 is correct. If it is correct, step S4 is performed; After the processing of the second oil injection hole (23) of the intermediate casing is completed in step S6, the electrode (13) is returned to the first tool setting hole (18) of the three-way tool setting block (6), and the electrode (13) is set again to check whether the tool setting in S5 is correct.

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