Processing method and tooling for an elongated shaft progressive oil passage

Abstract

The application discloses a processing method and tool for an elongated shaft gradually-changing oil channel and belongs to the technical field of machining. The processing tool comprises an upper cover, a lower cover and a clamping block. The bottom of the upper cover is of an open structure, and a hollow stand is arranged on the top of the upper cover. A through groove is formed in the side wall of the stand. The through groove is used for feeding a tool. The through groove corresponds to the structure of the gradually-changing oil channel to be processed. A second notch is arranged at the upper edge of the lower cover. A first marking line is arranged on the outer wall of the lower cover and is parallel to the axis of the lower cover. The clamping block is inserted into the lower cover and is attached to the lower cover. The clamping block is used for fixing the gradually-changing oil channel to be processed. A second marking line is arranged on the outer wall of the clamping block and corresponds to the position of the gradually-changing oil channel to be processed. The lower cover is used for being connected and fixed with the clamping block. The upper cover is fixedly connected above the lower cover. The gradually-changing oil channel to be processed is inserted into the stand. An oblique feeding and gradually-cutting mode is adopted for the linear groove part of the gradually-changing oil channel. The application solves the problem of defects in the processing of the gradually-changing oil channel.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically a machining method and tooling for a slender shaft with a gradually changing oil passage. Background Technology

[0002] The localization project for balancing valves is currently a key focus of production and research. The machining of the pilot valve core is the bottleneck issue in the entire balancing valve body. This part is a typical slender shaft component; the structure of the pilot valve core is described in [reference needed]. Figure 1 Three gradually changing oil passages 14 are evenly distributed on the thin shaft of the pilot valve core 5. The function of the gradually changing oil passages 14 in the pilot valve core 5 is to guide the oil to flow along the designed path, ensuring that the oil flows in the correct direction and at a stable velocity inside the balance valve. See also Figure 2 The main body of the gradient oil channel 14 is a straight groove structure, and the end structure of the gradient oil channel 14 is a 60° V-shaped gradient groove 15; the main machining difficulty is: 1. The machining dimensions of the gradient oil channel 14 are small, requiring a milling cutter diameter of Ø1.5, which makes it prone to breakage; 2. The parts cannot be clamped using the "one clamp, one push" method, resulting in the three gradient oil channels 14 not being evenly distributed, with some being deep and others shallow. 3. The 60° V-shaped gradient groove 15 cannot meet the requirements of the drawing, and the dimensions of the three gradient oil passages 14 are uneven.

[0003] Electrical discharge machining (EDM) fails to achieve the required surface roughness, thus affecting oil flow. Therefore, this machining method cannot be used. Summary of the Invention

[0004] This invention overcomes the shortcomings of existing technologies and proposes a machining method and tooling for a slender, gradually tapered oil passage. It is a process method capable of achieving steady-state machining of the pilot valve core in a balanced valve body. Based on the machining difficulties of the pilot valve core, the main problems to be solved are: 1. The rigidity of the part: with a length-to-diameter ratio of 17, it is a slender rod part, prone to resonance during machining, especially under axial force. 2. The single-clamp and single-push clamping method easily bends the part; changing the clamping method solves the problem of uneven machining of the oil passage groove. 3. Optimizing the machining method and cutting parameters to meet the dimensional and surface finish requirements of the part drawing. 4. Selecting appropriate tools and optimizing the machining method to ensure that the 60° V-shaped gradually tapered groove meets the drawing requirements.

[0005] This invention is achieved through the following technical solution: A machining fixture for a slender, tapered oil passage includes an upper cover, a lower cover, and a clamping block; the bottom of the upper cover is an open structure, and a hollow column is provided on the top of the upper cover; a through groove is provided on the side wall of the column; the through groove is used for tool entry; the through groove corresponds to the structure of the tapered oil passage to be machined. The lower cover is a cylindrical structure with openings at both the top and bottom, and a second notch is provided at the upper edge of the lower cover. A first engraving line is provided on the outer wall of the lower cover, and the first engraving line is parallel to the axis of the lower cover. The locking block is a cylindrical structure, and a cylindrical fixing groove is provided coaxially at the center of the locking block. The outer diameter of the locking block is adapted to the inner diameter of the lower cover, so that the locking block is inserted into the lower cover and fits against it. The fixing groove is used to insert and fix the gradient oil channel to be processed. A second engraving line is provided on the outer wall of the locking block, and the second engraving line is parallel to the axis of the locking block, and the position of the second engraving line corresponds one-to-one with the position of the gradient oil channel to be processed. The lower cover is used to connect and fix with the locking block, and the upper cover is fixedly connected above the lower cover. The gradient oil channel to be processed is inserted into the column.

[0006] Furthermore, the side wall of the lower cover is symmetrically provided with threaded holes, and the threaded holes are internally threaded with side fastening screws; the lower cover and the locking block are connected and fixed by the side fastening screws.

[0007] Furthermore, the top cover has a cylindrical structure, and a first notch is provided on the side of the top cover near the through groove. The width of the first notch and the second notch are the same.

[0008] Furthermore, the upper end of the first engraving line is connected to the second notch.

[0009] Furthermore, the main body of the gradient oil passage is a straight groove structure, and the structure at the end of the gradient oil passage is a V-shaped gradient groove; the through groove is a linear structure groove, and the bottom of the through groove is an enlarged structural groove. The linear structure groove and the enlarged structural groove correspond to the structure of the gradient oil passage to be processed and the V-shaped gradient groove at its end.

[0010] Furthermore, the top of the upper cover is connected to an upper cover fastening screw, which secures the upper cover and the lower cover together.

[0011] A method for machining a slender shaft with a gradually changing oil passage, employing the aforementioned machining fixture, and including the following steps: S1. First, clamp the bottom of the clamping block onto the chuck, fix the bottom of the gradient oil channel to be processed in the fixing groove of the clamping block, and align it. S2. Next, put the lower cover on the outer wall of the card block and connect and fix the lower cover and the outer circle of the card block into one piece; and align the first graduation line with a second graduation line; fix the upper cover above the lower cover, and extend the part of the gradient oil channel to be processed into the column, and align the through groove with the first graduation line and the corresponding second graduation line. S3. Use the appropriate cutting tool to insert into the through groove to process the gradient oil passage; after processing one gradient oil passage, disassemble the lower cover and the retaining block, rotate the upper cover and the lower cover, align the first graduation line on the lower cover with the next second graduation line on the retaining block and fix it again, and process the next gradient oil passage.

[0012] Furthermore, the main body of the gradient oil passage is a straight groove structure, and the structure at the end of the gradient oil passage is a V-shaped gradient groove. For the straight groove structure part of the gradient oil passage, the oblique infeed progressive cutting method is adopted, that is, cutting layer by layer from the surface to the inside in a Z-shaped manner along the axis of the straight groove structure.

[0013] Furthermore, for the V-shaped gradient groove at the end of the gradient oil passage, the cutting tool used during machining is a pointed knife with the same angle as the V-shaped gradient groove, and the cutting axis direction during machining is along the normal axis to gradually cut the V-shaped gradient groove.

[0014] Furthermore, the clamping block is a CNC machine tool tool holder, and the chuck is a three-jaw chuck. The CNC machine tool tool holder is clamped by the three-jaw chuck, and the center of the three-jaw chuck coincides with the zero point of the machine tool's rotating axis.

[0015] The beneficial effects of this invention compared to the prior art are as follows: 1. This invention can control the error of the center of the part coinciding with the zero point of the machine tool's rotating axis within 0.01mm.

[0016] 2. Create an enclosing fixture to enclose the entire part and open a machining window for the oil groove. Also, create a 120° scale position on the fixture to facilitate the machining of the three oil grooves and increase the rigidity of the fixture.

[0017] 3. Tool selection and cutting method: In terms of tool selection, the axial force generated by the φ3 slender shaft during the feed is avoided. The feed method in the initial stage of the entire cutting process adopts a gradual cutting method, which reduces the cutting resistance at the moment of contact between the tool and the workpiece and prevents the workpiece from deforming.

[0018] 4. Machining of a 60° V-shaped gradient groove: The tool used during machining is a pointed tool with a 60° included angle. The tool axis direction is normal machining, while the V-shaped groove is machined axially. The difference between the two is 1.13°. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the existing pilot valve core. Figure 2 for Figure 1 Sectional view along line AA in the middle; Figure 3 This is a schematic diagram of the upper cover structure; Figure 4 This is a schematic diagram of the lower cover structure; Figure 5 This is a side sectional view of the lower cover; Figure 6 This is a schematic diagram of the structure after the upper and lower covers are connected; Figure 7 This is a diagram of the gradual cutting trajectory. Figure 8A comparison diagram showing the effects of axial machining and normal axial inclining machining.

[0020] The following are the labels in the diagram: 1. Top cover; 2. Bottom cover; 3. Side fastening screw; 4. Top cover fastening screw; 5. Pilot valve core; 6. Locking block; 7. First gradation line; 8. Column; 9. Through groove; 10. First notch; 11. Second notch; 13. Second gradation line; 14. Gradient oil passage; 15. V-shaped gradient groove. Detailed Implementation

[0021] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0022] See Figures 3 to 6 This embodiment proposes a machining fixture for a slender shaft with a gradual change in oil passage, which is suitable for machining a slender shaft with a gradual change in oil passage. In this embodiment, the object to be machined is a pilot valve core. The machining fixture includes an upper cover 1, a lower cover 2, and a clamping block 6. The upper cover 1 has a semi-enclosed structure and is cylindrical in shape. The bottom of the upper cover 1 is open, and a hollow column 8 is provided on the top of the upper cover 1. A through groove 9 is provided on the side wall of the column 8. The through groove 9 is a linear groove with an enlarged bottom, and the through groove 9 is used for tool entry. The linear groove and the enlarged bottom correspond to the structure of the gradient oil passage 14 to be machined on the pilot valve core 5 and the V-shaped gradient groove 15 at its end. A first notch 10 is provided on the side of the upper cover 1 near the through groove 9, and an upper cover fastening screw 4 is connected to the top of the upper cover 1.

[0023] The lower cover 2 is a cylindrical structure with open top and bottom. Threaded holes are symmetrically arranged on the side walls of the lower cover 2, and side fastening screws 3 are threaded into the threaded holes. A second notch 11 is provided at the upper edge of the lower cover 2. The width of the first notch 10 and the second notch 11 is the same. A first engraving line 7 is provided on the outer wall of the lower cover 2. The first engraving line 7 is parallel to the axis of the lower cover 2, and the upper end of the first engraving line 7 is connected to the second notch 11.

[0024] The locking block 6 has a cylindrical structure with a cylindrical fixing groove coaxially arranged at its center. The outer diameter of the locking block 6 is adapted to the inner diameter of the lower cover 2, allowing the locking block 6 to be inserted into and fit against the lower cover 2. The fixing groove is used to insert and fix the pilot valve core 5. Three second gradations 13 are evenly distributed on the outer wall of the locking block 6. The second gradations 13 are parallel to the axis of the locking block 6, and the positions of the second gradations 13 correspond one-to-one with the positions of the gradient oil passages 14 to be machined on the pilot valve core 5. The locking block 6 is a standard part, and the outer circle of the locking block 6 is of standard size. The clearance between the outer circle of the locking block 6 and the lower cover 2 is 0.02mm.

[0025] The method of using a machining fixture for a slender shaft with a gradually changing oil passage is as follows: 1) First, clamp the bottom of the clamping block 6 onto the three-jaw chuck, fix the bottom of the pilot valve core 5 in the fixing groove of the clamping block 6, align the pilot valve core 5, and ensure that the rotation accuracy of the pilot valve core 5 is within 0.01mm; specifically, the clamping block 6 is a CNC machine tool tool holder (BT40), the chuck is a three-jaw chuck, the CNC machine tool tool holder is clamped by the three-jaw chuck, and the center of the three-jaw chuck coincides with the zero point of the machine tool's rotating axis.

[0026] 2) Next, place the lower cover 2 of the tooling onto the outer wall of the clamping block 6, and connect and fix the lower cover 2 and the outer circle of the clamping block 6 into one piece using the side fastening screws 3. The first gradation line 7 is aligned with one of the second gradation lines 13. The upper cover 1 is fixed above the lower cover 2 using the upper cover fastening screws 4, and the part of the pilot valve core 5 to be processed into the gradient oil passage 14 extends into the column 8. The linear structure groove on the through groove 9 is aligned with the first gradation line 7 and the corresponding second gradation line 13.

[0027] 3) Use the appropriate cutting tool to insert into the through groove 9 to process the gradient oil passage 14; after processing one gradient oil passage 14, loosen the side fastening screw 3, rotate the upper cover 1 and the lower cover 2, align the first engraving line 7 on the lower cover 2 with the next second engraving line 13 on the card block 6 and tighten the side fastening screw 3, process the next gradient oil passage 14, and so on to process 3 gradient oil passages 14.

[0028] 4) Then, remove the top cover 1 and machine the 4-￠2 hole on the pilot valve core 5.

[0029] This embodiment also proposes a machining method for a slender shaft with a gradual change in shape, wherein the machining tooling for the slender shaft with a gradual change in shape is used in accordance with the above-mentioned method for using the machining tooling for the slender shaft with a gradual change in shape. The corresponding cutting method is: 1) For the straight groove structure of the gradient oil passage 14, a slanted infeed progressive cutting method is used, that is, cutting layer by layer from the surface inward along the axis of the straight groove structure in a zigzag pattern. See [reference needed]. Figure 7 ; This cutting method reduces the axial force generated during tool feed, and by using the tool tip to pass through the center, the axial cutting force exerted by the tool on the workpiece is reduced. Throughout the initial stage of the entire cutting process, a gradual cutting method is used to reduce the cutting resistance at the moment of contact between the tool and the workpiece, preventing workpiece deformation.

[0030] 2) For the V-shaped gradient groove 15 at the end of the gradient oil passage 14, the cutting tool used is a pointed tool with a 60° included angle. The tool axis direction is used to gradually cut the V-shaped gradient groove 15 along the normal axis. The aforementioned gradual cutting along the normal axis means that the tool's feed angle is perpendicular to the axis of the gradient oil passage 14.

[0031] Currently, all machining of the V-shaped gradient groove 15 uses axial machining, meaning the tool enters from the bottom of the already machined straight groove structure, with the entry angle parallel to the axis of the gradient oil passage 14. The degree of axial machining differs from that of normal axial machining of the V-shaped gradient groove 15, differing by 1.13°. Therefore, axial machining of the V-shaped gradient groove 15 does not meet the drawing requirements and will result in shape deviations. See [reference needed] Figure 8 The V-shaped gradient groove 15 machined along the normal axis on the right side meets the requirement of 60°, while the V-shaped gradient groove 15 machined along the axis on the left side is 58.87°.

[0032] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the present invention, and all of these should be considered to fall within the scope of patent protection determined by the submitted claims.

Claims

1. A machining fixture for a slender shaft with a gradually changing oil passage, characterized in that, Includes an upper cover (1), a lower cover (2), and a locking block (6); the bottom of the upper cover (1) is an open structure, and a hollow column (8) is provided on the top of the upper cover (1); a through groove (9) is provided on the side wall of the column (8); the through groove (9) is used for tool feeding; the through groove (9) corresponds to the structure of the gradient oil passage (14) to be processed; The lower cover (2) is a cylindrical structure with openings at both the top and bottom. A second notch (11) is provided at the upper edge of the lower cover (2). A first engraving line (7) is provided on the outer wall of the lower cover (2), and the first engraving line (7) is parallel to the axis of the lower cover (2). The locking block (6) is a cylindrical structure. A cylindrical fixing groove is provided coaxially at the center of the locking block (6). The outer diameter of the locking block (6) is adapted to the inner diameter of the lower cover (2), so that the locking block (6) can be inserted into the lower cover (2) and fit against it. The fixed groove is used to insert and fix the gradient oil channel (14) to be processed; a second scribe line (13) is provided on the outer wall of the clamping block (6). The second scribe line (13) is parallel to the axis of the clamping block (6), and the position of the second scribe line (13) corresponds one-to-one with the position of the gradient oil channel (14) to be processed; the lower cover (2) is used to connect and fix with the clamping block (6), and the upper cover (1) is fixedly connected above the lower cover (2). The gradient oil channel (14) to be processed is inserted into the column (8); The top cover (1) is cylindrical. The top cover (1) has a first notch (10) on the side near the through groove (9). The width of the first notch (10) and the second notch (11) are the same. The upper end of the first engraving (7) is connected to the second notch (11).

2. The machining fixture for a slender shaft with a gradually changing oil passage according to claim 1, characterized in that, The lower cover (2) has symmetrically arranged threaded holes on its side wall, and the threaded holes are connected to side fastening screws (3); the lower cover (2) is connected and fixed to the card block (6) by the side fastening screws (3).

3. The machining fixture for a slender shaft with a gradually changing oil passage according to claim 1, characterized in that, The main body of the gradient oil passage (14) is a straight groove structure, and the structure at the end of the gradient oil passage (14) is a V-shaped gradient groove (15); the through groove (9) is a linear structure groove, and the bottom of the through groove (9) is an enlarged structure groove. The linear structure groove and the enlarged structure groove correspond to the structure of the gradient oil passage (14) to be processed and the V-shaped gradient groove (15) at its end.

4. The machining fixture for a slender shaft with a gradually changing oil passage according to claim 1, characterized in that, The top of the upper cover (1) is connected to the upper cover fastening screw (4), and the upper cover (1) and the lower cover (2) are fixedly connected by the upper cover fastening screw (4).

5. A method for machining a slender shaft with a gradually changing oil passage, characterized in that, The machining fixture for a slender shaft with a gradually changing oil passage as described in any one of claims 1-4 includes the following steps: S1. First, clamp the bottom of the clamping block (6) onto the chuck, fix the bottom of the gradient oil channel (14) to be processed in the fixing groove of the clamping block (6), and align it; S2. Next, put the lower cover (2) on the outer wall of the card block (6) and fix the lower cover (2) and the outer circle of the card block (6) into one piece; and align the first gradation line (7) with a second gradation line (13); fix the upper cover (1) above the lower cover (2), and extend the part of the gradient oil channel (14) to be processed into the column (8), and align the through groove (9) with the first gradation line (7) and the corresponding second gradation line (13); S3. Use the corresponding cutting tool to insert into the through groove (9) to process the gradient oil passage (14); after processing one gradient oil passage (14), disassemble the lower cover (2) and the locking block (6), rotate the upper cover (1) and the lower cover (2), align the first scribe line (7) on the lower cover (2) with the next second scribe line (13) on the locking block (6) and fix it again, and process the next gradient oil passage (14).

6. The machining method for a slender shaft with a gradually changing oil passage according to claim 5, characterized in that, The main body of the gradient oil passage (14) is a straight groove structure, and the structure at the end of the gradient oil passage (14) is a V-shaped gradient groove (15). For the straight groove structure part of the gradient oil passage (14), the oblique infeed cutting method is adopted, that is, cutting layer by layer from the surface to the inside along the axis of the straight groove structure in a Z-shaped manner.

7. The machining method for a slender shaft with a gradually changing oil passage according to claim 6, characterized in that, For the V-shaped gradient groove (15) at the end of the gradient oil passage (14), the cutting tool used during machining is a pointed knife with the same angle as the V-shaped gradient groove (15), and the cutting axis direction during machining is to gradually cut the V-shaped gradient groove (15) along the normal axis.

8. The machining method for a slender shaft with a gradually changing oil passage according to claim 5, characterized in that, The chuck (6) is a CNC machine tool holder, and the chuck is a three-jaw chuck. The CNC machine tool holder is clamped by the three-jaw chuck, and the center of the three-jaw chuck coincides with the zero point of the machine tool's rotating axis.

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