Process for machining a nodular cast iron camshaft

Abstract

This invention discloses a machining process for ductile iron camshafts, belonging to the field of camshaft machining technology. The machining process for ductile iron camshafts includes machining the camshaft end holes and grooves, rough turning the camshaft outer diameter and length, rough grinding the cam, cam quenching and tempering, finish turning the outer diameter and length, drilling oil holes and milling the surface, finish grinding the main journal and outer diameter, finish grinding the cam, deburring and polishing, assembling the locating pin and signal wheel, flaw detection, cleaning, and packaging. This invention improves the accuracy and stability of camshaft positioning through positioning fixtures, improves the grinding efficiency of the camshaft using a centerless grinder, and enhances machining efficiency by performing deburring and polishing simultaneously. This invention, employing the above-mentioned machining process for ductile iron camshafts, simplifies the machining steps, improves production efficiency and machining accuracy, and increases product qualification rate.

Description

Technical Field

[0001] This invention relates to the field of camshaft machining technology, and in particular to a machining process for ductile iron camshafts. Background Technology

[0002] The camshaft is part of the engine's valve train, specifically responsible for driving the valves to open and close on time. Its function is to ensure that the engine draws in fresh combustible mixture into the cylinders at regular intervals during operation and promptly expels exhaust gases from the cylinders. The main body of the camshaft is a cylindrical rod approximately the same length as the cylinder bank, with several cams mounted on it to drive the valves. Ductile iron is characterized by its high strength and rigidity, capable of withstanding high pressure and resisting external loads, and possesses excellent corrosion resistance, making it resistant to rust and corrosion. Therefore, ductile iron is commonly used to manufacture camshafts.

[0003] Ductile iron camshafts are generally produced by casting. Cast camshaft blanks are often dimensionally uneven, prone to surface defects, and have a rough surface. Therefore, machining is necessary to obtain high-quality camshafts with high dimensional accuracy and smooth surfaces. However, current machining methods for ductile iron camshafts require multiple machines to machine the holes and slots at both ends, increasing the machining process. This not only prolongs the machining cycle and reduces efficiency due to the increased turnover of the camshaft, but also increases the clamping error due to varying clamping precision on different machines. This increases the positional and angular machining errors of the holes and slots, affecting the machining accuracy and coaxiality of the camshaft. Furthermore, during the finish machining of the camshaft, the journal outer diameter and other outer diameters are also machined on different machines, further reducing production efficiency and affecting the coaxiality of the camshaft, thus lowering the yield rate. Summary of the Invention

[0004] The purpose of this invention is to provide a machining process for ductile iron camshafts, simplifying the machining steps, improving the production efficiency and machining accuracy of camshafts, and increasing the product qualification rate.

[0005] To achieve the above objectives, the present invention provides a machining process for ductile iron camshafts, comprising the following steps:

[0006] S1. Install the positioning fixture on the four-axis rotary table of the machining center, install the camshaft casting on the positioning fixture, mill the end face, mill the positioning groove, and drill the center hole, drill the enlarged hole, tap, and drill the VVT ​​hole of the camshaft; after one end of the camshaft is processed, rotate the positioning fixture and mill the end face, drill the center hole, mill the positioning groove, drill the enlarged hole, and tap the other end of the camshaft.

[0007] S2. Rough turn the outer diameter and length of the camshaft using a CNC lathe;

[0008] S3. Use a grinding machine to rough grind the cams on the camshaft;

[0009] S4. Perform induction hardening and tempering on the camshaft;

[0010] S5. The outer diameter and length of the camshaft are precision machined using a CNC lathe;

[0011] S6. Use a machining center to drill oil holes on the camshaft and mill a flat surface on the camshaft;

[0012] S7. Use a centerless grinder to precision grind the journal and outer diameter of the camshaft;

[0013] S8. The cams of the camshaft are precision ground on a cam grinding machine;

[0014] S9. Remove burrs from the cam using a deburring device and polish the outer circle of the cam.

[0015] S10. Assemble the locating pin and signal wheel on the camshaft;

[0016] S11. Perform flaw detection on the camshaft;

[0017] S12. Clean and package the camshaft.

[0018] Preferably, in step S1, the positioning fixture includes a base plate, which is mounted on a four-axis rotating disk. A plurality of positioning mechanisms for positioning camshafts are arranged parallel to each other on the base plate. Each positioning mechanism includes a support base and an axial positioning structure, both mounted on the base plate and located at opposite ends of the camshaft. The support base has a V-groove for supporting the camshaft. A mounting plate is located in the middle of the base plate, and the mounting plate has an axial clamping structure and an anti-misalignment block. The anti-misalignment block has an anti-misalignment groove at its top, which is adapted to the cam on the camshaft. An angular positioning structure is provided between the anti-misalignment block and the axial positioning structure. A clamping structure for clamping the camshaft is provided between the positioning mechanisms, located above the support base and the axial positioning structure. The clamping structure includes a rotary cylinder, and a pressure plate is provided on the piston rod of the rotary cylinder.

[0019] Preferably, the axial positioning structure includes a positioning seat, which is disposed on a base plate. The top of the positioning seat is provided with a positioning groove for placing the camshaft, and a positioning piece is provided on one side of the positioning seat to engage the positioning plate on the camshaft. The positioning piece is provided with a slot for the camshaft to pass through.

[0020] Preferably, the axial clamping structure includes a first mounting base, which is disposed on a mounting plate. The top of the first mounting base is provided with a clearance groove for the camshaft to pass through. A clamping plate is provided on one side of the top of the first mounting base. The clamping plate is provided with a groove for the camshaft to pass through. A guide post is provided on the clamping plate. A guide hole is provided on the first mounting base for the guide post to pass through. The guide post and the guide hole are slidably connected. A first spring is provided between the first mounting base and the clamping plate. The clamping plate is clamped against the cam end face under the action of the first spring.

[0021] Preferably, the angular positioning structure includes a second mounting base, which is disposed on a base plate. Two clamping plates are symmetrically arranged on one side of the second mounting base, clamping the hexagonal blocks of the camshaft. A sliding plate is disposed below the clamping plates. A sliding groove is disposed on one side of the second mounting base, and the sliding plate is located in the sliding groove and slidably connected to the sliding groove. A sliding hole penetrating the second mounting base is disposed at the upper part of the second mounting base. A sliding rod disposed on the sliding plate is located in the sliding hole and slidably connected to the sliding hole. A mounting groove communicating with the sliding hole is disposed on the second mounting base, and a second spring is disposed in the mounting groove. One end of the second spring is connected to the sliding rod. A moving structure for driving the clamping plates to move is disposed on the second mounting base.

[0022] Preferably, the moving structure includes a rotating block that drives the two clamping plates to move closer or further apart. The rotating block is located between the two clamping plates and is set at one end of the rotating shaft. A shaft hole is provided in the middle of the sliding hole for the rotating shaft to pass through. The rotating shaft is rotatably connected to the shaft hole. Sliding rods are located on both sides of the rotating shaft. A crank handle that drives the rotating shaft to rotate is provided at the other end of the rotating shaft.

[0023] Preferably, the axial clamping structure includes a clamping seat, which is mounted on a mounting plate. A first clamping plate is provided on one side of the clamping seat, and the middle part of the first clamping plate is rotatably connected to the clamping seat. A clamping cylinder is provided at the lower part of the clamping seat, and the piston rod of the clamping cylinder is hinged to the bottom end of the first clamping plate. A second clamping plate is provided at the top of the clamping seat, and the first and second clamping plates are clamped on the cam. A support block for supporting the camshaft is provided between the axial clamping structure and the support seat.

[0024] Preferably, in step S7, the centerless grinder includes a machine base, a sliding frame is provided at one top end of the machine base, a power element is provided on the machine base to drive the sliding frame to slide on the machine base, a grinding wheel is rotatably provided on the movable frame, a first motor is provided on the movable frame to drive the grinding wheel to rotate, a fixed frame is provided at the other top end of the machine base, a guide wheel is rotatably provided on the fixed frame, a second motor is provided on the fixed frame to drive the guide wheel to rotate, a support plate for supporting the camshaft is provided between the fixed frame and the sliding frame, the support plate is provided on the machine base, and the top of the support plate is an inclined surface that gradually slopes downward from the sliding frame towards the fixed frame; both the guide wheel and the grinding wheel are provided with avoidance rings for avoiding the cam.

[0025] Preferably, in step S9, the deburring device includes a base, on which a movable seat and a fixed seat are provided. Both the movable seat and the fixed seat are provided with a center for pressing the camshaft. The base is provided with a sliding element that drives the movable seat to slide on the base. The movable seat is provided with a rotary motor that drives the center to rotate. A first guide rail is provided on one side of the base along the length of the base. A first slide and a second slide are slidably provided on the first guide rail. A first carriage is slidably provided on the first slide. The sliding direction of the first carriage is perpendicular to the camshaft axis. A wire brush is rotatably provided on the first carriage. A second carriage is slidably provided on the second slide. The sliding direction of the second carriage is perpendicular to the camshaft axis. A polishing structure is provided on the second carriage.

[0026] Preferably, the polishing structure includes a polishing block, which is V-shaped and arranged on the upper and lower sides of the mounting shaft. The mounting shaft is fixedly mounted on the second slide. The polishing block and the mounting shaft are hinged by a pin. The mounting shaft is provided with a torsion spring or hydraulic cylinder to make the polishing block contact the surface of the camshaft.

[0027] The advantages and positive effects of the ductile iron camshaft machining process described in this invention are as follows:

[0028] 1. This invention simultaneously processes the holes and slots at both ends of the camshaft, effectively ensuring the positional accuracy and angle of the holes and slots at both ends of the camshaft.

[0029] 2. Using positioning fixtures to position the camshaft improves the stability of camshaft positioning and helps to improve the machining accuracy of the holes and slots at both ends of the camshaft.

[0030] 3. The journal and outer diameter of the camshaft are precision ground on a centerless grinder. The precision grinding of the camshaft can be completed in a single setup, which improves the efficiency of precision grinding, ensures the coaxiality of each outer diameter, and increases the pass rate of camshaft machining. Furthermore, the centerless grinder uses the outer diameter of the camshaft as a reference for precision grinding, resulting in higher machining accuracy.

[0031] 4. Polishing is performed during the deburring process of the camshaft, which reduces the number of machining steps and helps improve the machining efficiency of the camshaft.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] Figure 1 This is a flowchart of the present invention;

[0034] Figure 2 This is a schematic diagram of the camshaft structure of the present invention;

[0035] Figure 3 This is a schematic diagram of the three-dimensional structure of the positioning tooling according to Embodiment 1 of the present invention;

[0036] Figure 4 This is a top view of the positioning fixture according to Embodiment 1 of the present invention;

[0037] Figure 5 This is a side view of the positioning fixture according to Embodiment 1 of the present invention;

[0038] Figure 6 This is a schematic diagram of the axial clamping structure according to Embodiment 1 of the present invention;

[0039] Figure 7 This is a schematic diagram of the angular positioning structure according to Embodiment 1 of the present invention;

[0040] Figure 8 This is a schematic diagram of the second mounting base structure according to Embodiment 1 of the present invention;

[0041] Figure 9 This is a schematic diagram of the cross-sectional structure of the angular positioning structure according to Embodiment 1 of the present invention;

[0042] Figure 10 This is a schematic diagram of the axial positioning structure according to Embodiment 1 of the present invention;

[0043] Figure 11 This is a schematic diagram of the centerless grinding machine structure according to Embodiment 1 of the present invention;

[0044] Figure 12 This is a schematic diagram of the deburring device according to Embodiment 1 of the present invention;

[0045] Figure 13 This is a schematic diagram of the three-dimensional structure of the positioning tooling according to Embodiment 2 of the present invention;

[0046] Figure 14 This is a side view of the positioning fixture according to Embodiment 2 of the present invention;

[0047] Figure 15 This is a schematic diagram of the axial clamping structure of Embodiment 2 of the present invention.

[0048] Figure Labels

[0049] 1. Base plate; 2. Mounting plate; 3. Camshaft; 4. Support seat; 5. Axial clamping structure; 6. Anti-misalignment block; 7. Angular positioning structure; 8. Axial positioning structure; 9. Corner cylinder; 10. Pressure plate; 11. First mounting seat; 12. Clearance groove; 13. Clamping plate; 14. Guide post; 15. First spring; 16. Second mounting seat; 17. Slide plate; 18. Clamping plate; 19. Slide groove; 20. Handle; 21. Rotating block; 22. Sealing plate; 23. Sliding hole; 24. Shaft hole; 25. Second spring; 26. Mounting groove; 27. Rotating shaft; 28. Slide rod; 29. ​​Positioning seat; 30. Positioning groove; 31. Positioning piece; 32. Positioning plate; 33. Hexagonal block; 34. Machine base; 35. Sliding frame; 36. Grinding wheel; 37. Fixed frame; 38. Guide wheel; 39. Support plate; 40. Base; 41. Movable seat; 42. Fixed seat; 43. Center; 44. First guide rail; 45. First slide; 46. First slide frame; 47. Second guide rail; 48. Wire brush; 49. Second slide; 50. Second slide frame; 51. Mounting shaft; 52. Polishing block; 53. Support block; 54. Tightening seat; 55. First clamping plate; 56. Second clamping plate; 57. Tightening cylinder. Detailed Implementation

[0050] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0051] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0052] Example 1

[0053] like Figure 1 As shown. A machining process for a ductile iron camshaft includes the following steps:

[0054] S1. Install the positioning fixture on the four-axis rotary table of the machining center, install the camshaft 3 casting blank on the positioning fixture of the machining center, mill the end face, mill the positioning groove 30, and drill the center hole, drill the reamed hole, tap, and drill the VVT ​​hole for the camshaft 3; after one end of the camshaft 3 is processed, rotate the positioning fixture 180° through the four-axis rotary table, and mill the end face, drill the center hole, mill the positioning groove 30, drill the reamed hole, and tap the other end of the camshaft 3.

[0055] By using a positioning fixture to clamp the camshaft 3 once, the holes and slots at both ends of the camshaft 3 can be machined, which helps to improve the positional and angular accuracy of the holes and slots at both ends of the camshaft 3.

[0056] S2. Use a CNC lathe to rough machine the outer diameter and length of the camshaft 3.

[0057] S3. Use a grinding machine to rough grind the cam on the camshaft 3.

[0058] S4. Perform induction hardening and tempering on camshaft 3.

[0059] S5. The outer diameter and length of the camshaft 3 are precision machined using a CNC lathe.

[0060] S6. Use a machining center to drill oil holes on the camshaft 3 and mill a flat surface on the camshaft 3.

[0061] S7. Use a centerless grinder to finish grind the journal and outer diameter of the camshaft 3.

[0062] A centerless grinder was used to simultaneously finish grind the journal and outer diameter of the camshaft 3. After fixing the camshaft 3 once, the finish grinding of each outer diameter of the camshaft 3 was completed, ensuring the coaxiality requirements of each outer diameter of the camshaft 3. After using a centerless grinder for simultaneous finish grinding, the overall inspection runout pass rate of the camshaft 3 increased from about 60% to over 99%.

[0063] S8. The cam of camshaft 3 is precision ground on a cam grinding machine.

[0064] S9. Remove burrs from the cam using a deburring device and polish the outer circle of the cam.

[0065] S10. Mount the locating pin and signal wheel on the camshaft 3.

[0066] S11. Perform flaw detection on camshaft 3.

[0067] S12. Clean and package the camshaft 3.

[0068] like Figure 2-5As shown. The positioning fixture includes a base plate 1, which is fixedly mounted on a four-axis rotary table of the machining center. The four-axis rotary table drives the base plate 1 to rotate. Several positioning mechanisms for positioning camshafts 3 are arranged parallel to each other on the base plate 1. Each positioning mechanism includes a support base 4 and an axial positioning structure 8, both of which are fixedly mounted on the base plate 1. The support base 4 and the axial positioning structure 8 are located at both ends of the camshaft 3, providing support to the camshaft 3 from both ends. The support base 4 is provided with a V-groove for supporting the camshaft 3.

[0069] like Figure 10 As shown, the axial positioning structure 8 includes a positioning seat 29, which is fixedly mounted on the base plate 1. The top of the positioning seat 29 has a positioning groove 30 for placing the camshaft 3; the positioning groove 30 is a V-shaped groove. A positioning piece 31, which engages with the positioning plate 32 on the camshaft 3, is mounted on one side of the positioning seat 29 via screws. The positioning piece 31 has a slot through which the camshaft 3 passes. The camshaft 3 is positioned by the positioning piece 31 and the positioning plate 32 on the camshaft 3.

[0070] A mounting plate 2 is provided in the middle of the base plate 1, and the mounting plate 2 is fixed to the base plate 1. An axial clamping structure 5 and an anti-misalignment block 6 are provided on the mounting plate 2.

[0071] like Figure 6 As shown. The axial clamping structure 5 includes a first mounting base 11, which is fixedly mounted on the mounting plate 2. The top of the first mounting base 11 has a clearance groove 12 for the camshaft 3 to pass through. A clamping plate 13 is provided on one side of the top of the first mounting base 11, and the clamping plate 13 has a groove for the camshaft 3 to pass through. A guide post 14 is fixedly mounted on the clamping plate 13, and a guide hole is provided on the first mounting base 11 for the guide post 14 to pass through. The guide post 14 is slidably connected to the guide hole. The guide post 14 and the guide hole guide the horizontal movement of the clamping plate 13, ensuring that the clamping plate can only move horizontally. A first spring 15 is provided between the first mounting base 11 and the clamping plate 13. The first spring 15 is sleeved on the outside of the guide post 14, and both ends of the first spring 15 are fixedly connected to the clamping plate 13 and the first mounting base 11, respectively. The clamping plate 13 is clamped against the cam end face under the action of the first spring 15.

[0072] The top of the anti-misalignment block 6 is provided with an anti-misalignment groove, which is adapted to the cam on the camshaft 3. The anti-misalignment block 6 is designed to ensure the placement angle of the camshaft 3. Only when the placement angle of the camshaft 3 is met can the cam be placed into the anti-misalignment groove.

[0073] like Figure 7-9As shown. An angular positioning structure 7 is provided between the anti-misalignment block 6 and the axial positioning structure 8. The angular positioning structure 7 includes a second mounting base 16, which is fixedly mounted on the base plate 1. Two clamping plates 18 are symmetrically arranged on one side of the second mounting base 16. The clamping plates 18 clamp the hexagonal block 33 of the camshaft 3, thereby clamping the camshaft 3 and preventing it from rotating, thus achieving angular positioning. A sliding plate 17 is fixedly mounted below the clamping plates 18. A sliding groove 19 is provided on one side of the second mounting base 16. The sliding plate 17 is located in the sliding groove 19 and is slidably connected to the sliding groove 19. The sliding groove 19 can be configured as a dovetail groove or a T-groove. An elongated sliding hole 23 is provided on the upper part of the second mounting base 16, penetrating the second mounting base 16. A sliding rod 28 fixedly mounted on the sliding plate 17 is located in the sliding hole 23 and is slidably connected to the sliding hole 23. A mounting groove 26 communicating with the sliding hole 23 is provided on the second mounting base 16, and a second spring 25 is provided in the mounting groove 26. One end of the mounting slot 26 is provided with a sealing plate 22 to seal the mounting slot 26, and the sealing plate 22 is fixed on the second mounting base 16. The two ends of the second spring 25 are fixedly connected to the sealing plate 22 and the slide rod 28 respectively. Under the action of the second spring 25, the slide rod 28 drives the clamping plate 18 to clamp on the opposite sides of the hexagonal block 33.

[0074] The second mounting base 16 is equipped with a moving structure that drives the clamping plates 18 to move. The moving structure includes a rotating block 21 that moves the two clamping plates 18 closer together or further apart, and the rotating block 21 is located between the two clamping plates 18. The rotating block 21 is a rectangular block. The rotating block 21 is fixedly mounted on one end of the rotating shaft 27. A shaft hole 24 is provided in the middle of the sliding hole 23 for the rotating shaft 27 to pass through, and the rotating shaft 27 is rotatably connected to the shaft hole 24. Sliding rods 28 are located on both sides of the rotating shaft 27. A crank handle 20 that drives the rotating shaft 27 to rotate is fixedly mounted on the other end of the rotating shaft 27.

[0075] A clamping structure for pressing the camshaft 3 is provided between the positioning mechanisms, and the clamping structure is located above the support base 4 and the axial positioning structure 8. The clamping structure includes a rotary cylinder 9, which is fixedly mounted on the base plate 1. A pressure plate 10 is provided on the piston rod of the rotary cylinder 9. The rotary cylinder 9 drives the pressure plate 10 to rotate and press down, thereby pressing the pressure plate 10 against the camshaft 3. A rubber protective layer is fixedly provided on the lower surface of the pressure plate 10 to protect the surface of the camshaft 3.

[0076] In use, first, fix the base plate 1 on the four-axis rotary disk, place the camshaft 3 on the support seat 4 and the first mounting seat 11, insert the cam into the anti-misalignment groove, and the clamping plate 13 pushes the cam on the camshaft 3 to move axially under the action of the first spring 15. The positioning plate 32 on the camshaft 3 contacts the positioning piece 31, and the positioning piece 31 positions the camshaft 3. Turn the crank handle 20, and the crank handle 20 drives the rotating block 21 to rotate through the rotating shaft 27. The distance between the rotating block 21 and the slide plate 17 increases, and the slide plate 17 moves in the slide groove 19 under the action of the first spring 15. The clamping plate 18 clamps on the opposite side of the hexagonal block 33. Start the angle cylinder 9, and the angle cylinder 9 drives the pressure plate 10 to rotate 90° and then press down, pressing the camshaft 3 between the pressure plate 10, the support seat 4, and the pressure plate 10 and the first mounting seat 11, thereby fixing the camshaft 3. One end of the camshaft 3 is machined with holes and grooves. After one end is machined, the four-axis rotary disk drives the base plate 1 to rotate 180° to machine the other end of the camshaft 3 with holes and grooves. After machining, the rotary cylinder 9 is reset, the crank handle 20 is turned, and the sliding plate 17 is moved in the slide groove 19 through the rotating block 21. The clamping plate 18 moves away from the hexagonal block 33, and the camshaft 3 is removed from the tooling.

[0077] like Figure 11 As shown. The centerless grinder includes a base 34, with a sliding frame 35 at one top end and a fixed frame 37 at the other top end. A power element is mounted on the base 34 to drive the sliding frame 35 to slide on the base 34. The power element is a conventional cylinder, hydraulic cylinder, electric cylinder, or lead screw and nut assembly, which drives the sliding frame 35 to move closer to or away from the fixed frame 37 on the base 34. A guide wheel 38 is rotatably mounted on the fixed frame 37, and a motor is mounted on the fixed frame 37 to drive the guide wheel 38 to rotate. A grinding wheel 36 is rotatably mounted on the movable frame, and a motor is mounted on the movable frame to drive the grinding wheel 36 to rotate. A support plate 39 for supporting a camshaft 3 is provided between the fixed frame 37 and the sliding frame 35, and the support plate 39 is fixedly mounted on the base 34. The top of the support plate 39 is an inclined surface that gradually slopes downwards from the sliding frame 35 towards the fixed frame 37. Both the guide wheel 38 and the grinding wheel 36 are equipped with avoidance rings for avoidance cams. The cam on the camshaft 3 is located inside the avoidance ring to prevent the cam from affecting the grinding wheel 36's grinding of the outer circle and journal of the camshaft 3.

[0078] In use, the camshaft 3 is placed on top of the support plate 39. The sliding frame 35 is moved by a power element. The grinding wheel 36 on the sliding frame 35 pushes the camshaft 3 towards the guide wheel 38, pressing the camshaft 3 between the guide wheel 38 and the grinding wheel 36. The rotational speed of the grinding wheel 36 is much higher than that of the guide wheel 38, and the grinding wheel 36 grinds the journal and outer diameter. The centerless grinder does not require centering of the camshaft 3, making it convenient to use.

[0079] like Figure 12As shown. The deburring device includes a base 40, on which a movable seat 41 and a fixed seat 42 are mounted. Both the movable seat 41 and the fixed seat 42 are provided with a center 43 for clamping the camshaft 3. A sliding element is provided on the base 40 to drive the movable seat 41 to slide on the base 40. The sliding element is a conventional cylinder, hydraulic cylinder, electric cylinder, or lead screw and nut assembly. The sliding element drives the movable seat 41 to slide on the base 40, thereby clamping and fixing the camshaft 3 through the center 43. A rotary motor is provided on the movable seat 41 to drive the center 43 to rotate, thereby driving the camshaft 3 to rotate through the center 43. A first guide rail 44 is provided on one side of the base 40 along the length of the base 40. A first slide block 45 and a second slide block 49 are slidably mounted on the first guide rail 44. A first carriage 46 is slidably mounted on the first slide block 45. A second guide rail 47 is provided on the first slide block 45 to guide the sliding of the first carriage 46. The sliding direction of the first carriage 46 is perpendicular to the axis of the camshaft 3. A wire brush 48 is rotatably mounted on the first slide 46, and a motor is mounted on the first slide 46 to drive the wire brush 48 to rotate. The wire brush 48 is used to deburr the camshaft 3. A lead screw is mounted on the base 40 to move the first slide 45, and a lead screw is mounted on the first slide 45 to move the first slide 46. A second slide 50 is slidably mounted on the second slide 49, and the sliding direction of the second slide 50 is perpendicular to the axis of the camshaft 3. A polishing structure is provided on the second slide 50. The polishing structure is used to polish the camshaft 3. A lead screw is mounted on the base 40 to move the second slide 49, and a lead screw is mounted on the second slide 49 to move the second slide 50.

[0080] The polishing structure includes a polishing block 52, which is V-shaped and positioned on the upper and lower sides of the mounting shaft 51. A polishing strip is provided on the side of the polishing block 52 closest to the camshaft, and the camshaft is polished using this strip. The mounting shaft 51 is fixedly mounted on the second carriage 50. One end of the polishing block 52 is hinged to the mounting shaft 51 via a pin, and a torsion spring is mounted on the pin to bring the polishing block 52 into contact with the surface of the camshaft 3. Under the action of the torsion spring, the polishing block 52 contacts the surface of the camshaft 3, thereby polishing the surface of the camshaft 3. Alternatively, a hydraulic cylinder can be used to rotate the polishing block 52 to bring it into contact with the surface of the camshaft 3. Specifically, the middle of the polishing block 52 is hinged to the mounting shaft 51, and one end of the polishing block 52 is hinged to a hydraulic cylinder. The hydraulic cylinder raises and lowers the end of the polishing block 52, thereby bringing the polishing strip on the polishing block 52 into contact with the surface of the camshaft 3 for polishing.

[0081] In use, the movable seat 41 is moved to fix the camshaft 3 between the centers 43. The rotating motor is started, and the rotating motor drives the camshaft 3 to rotate through the centers 43. Starting the motor drives the wire brush 48 to rotate, moving the first slide 45, which slides along the first guide rail 44. Moving the first carriage 46, which slides along the second guide rail 47, brings the wire brush 48 into contact with the camshaft 3, deburring the camshaft 3. After deburring, the second slide 49 and the second carriage 50 are moved, bringing the surface of the polishing block 52 into contact with the surface of the camshaft 3, polishing the surface of the camshaft 3. This simultaneous deburring and polishing of the camshaft 3 reduces the number of machining steps and clamping operations, thus improving processing efficiency and quality.

[0082] Example 2

[0083] like Figure 13-15 As shown. The difference between this embodiment and Embodiment 1 is that the axial clamping structure 5 in this embodiment is different from that in Embodiment 1. The axial clamping structure 5 includes a clamping seat 54, which is fixedly mounted on the mounting plate 2. A first clamping plate 55 is provided on one side of the clamping seat 54, and the middle part of the first clamping plate 55 is rotatably connected to the clamping seat 54 by a pin. A clamping cylinder 57 is provided at the lower part of the clamping seat 54, and the piston rod of the clamping cylinder 57 is hinged to the bottom end of the first clamping plate 55. A second clamping plate 56 is provided at the top of the clamping seat 54, and the first clamping plate 55 and the second clamping plate 56 clamp the cam. In order to facilitate the clamping of the camshaft 3 by the first clamping plate 55 and the second clamping plate 56, both the first clamping plate 55 and the second clamping plate 56 are provided with bosses. A support block 53 for supporting the camshaft 3 is provided between the axial clamping structure 5 and the support seat 4, and the support block 53 is provided with an arc-shaped groove for accommodating the cam.

[0084] In use, the clamping cylinder 57 extends, and the clamping cylinder 57 drives the first clamping plate 55 to rotate. The first clamping plate 55 clamps the cam between the first clamping plate 55 and the second clamping plate 56. One end of the camshaft 3 abuts against the positioning plate 31 to achieve axial positioning of the camshaft 3.

[0085] Therefore, the above-mentioned machining process for ductile iron camshafts in this invention can simplify the machining steps of ductile iron camshafts, improve the production efficiency and machining accuracy of camshafts, and increase the product qualification rate.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for machining a nodular cast iron camshaft, characterized in that, Includes the following steps: S1. Install the positioning fixture on the four-axis rotary table of the machining center, install the camshaft casting on the positioning fixture, mill the end face, mill the positioning groove, drill the center hole of the camshaft, drill and enlarge the hole, tap, and drill the VVT ​​hole; after one end of the camshaft is processed, rotate the positioning fixture and mill the end face, drill the center hole, mill the positioning groove, drill and enlarge the hole, and tap the other end of the camshaft. S2. Rough turn the outer diameter and length of the camshaft using a CNC lathe; S3. Use a grinding machine to rough grind the cams on the camshaft; S4. Perform induction hardening and tempering on the camshaft; S5. The outer diameter and length of the camshaft are precision machined using a CNC lathe; S6. Use a machining center to drill oil holes on the camshaft and mill a flat surface on the camshaft; S7. Use a centerless grinder to precision grind the journal and outer diameter of the camshaft; S8. The cams of the camshaft are precision ground on a cam grinding machine; S9. Remove burrs from the cam using a deburring device and polish the outer circle of the cam. S10. Assemble the locating pin and signal wheel on the camshaft; S11. Perform flaw detection on the camshaft; S12. Clean and package the camshaft; In S1, the positioning fixture includes a base plate, which is mounted on a four-axis rotating disk. Several positioning mechanisms for positioning camshafts are arranged parallel to each other on the base plate. Each positioning mechanism includes a support base and an axial positioning structure, both mounted on the base plate and located at opposite ends of the camshaft. The support base has a V-groove for supporting the camshaft. A mounting plate is located in the middle of the base plate, and the mounting plate has an axial clamping structure and an anti-misalignment block. The anti-misalignment block has an anti-misalignment groove at its top, which matches the cam on the camshaft. An angular positioning structure is provided between the anti-misalignment block and the axial positioning structure. A clamping structure for clamping the camshaft is located between the positioning mechanisms, above the support base and the axial positioning structure. The clamping structure includes a rotary cylinder, and a pressure plate is mounted on the piston rod of the rotary cylinder. The axial positioning structure includes a positioning seat, which is set on a base plate. The top of the positioning seat is provided with a positioning groove for placing the camshaft, and a positioning piece is provided on one side of the positioning seat to engage the positioning plate on the camshaft. The positioning piece is provided with a slot for the camshaft to pass through. The angular positioning structure includes a second mounting base, which is mounted on a base plate. Two clamping plates are symmetrically arranged on one side of the second mounting base, clamping the hexagonal blocks of the camshaft. A sliding plate is located below the clamping plates. A sliding groove is provided on one side of the second mounting base, with the sliding plate located within and slidably connected to the groove. A sliding hole penetrating the second mounting base is provided at the upper part of the second mounting base. A sliding rod on the sliding plate is located within and slidably connected to the sliding hole. A mounting groove communicating with the sliding hole is provided on the second mounting base, with a second spring installed within the mounting groove. One end of the second spring is connected to the sliding rod. A moving structure for moving the clamping plates is provided on the second mounting base. The moving structure includes a rotating block that drives two clamping plates to move closer or further apart. The rotating block is located between the two clamping plates and is set at one end of a rotating shaft. A shaft hole is provided in the middle of the sliding hole for the rotating shaft to pass through. The rotating shaft is rotatably connected to the shaft hole. Sliding rods are located on both sides of the rotating shaft. A crank handle that drives the rotating shaft to rotate is provided at the other end of the rotating shaft. The axial clamping structure includes a clamping seat, which is mounted on a mounting plate. A first clamping plate is provided on one side of the clamping seat, and the middle of the first clamping plate is rotatably connected to the clamping seat. A clamping cylinder is provided at the lower part of the clamping seat, and the piston rod of the clamping cylinder is hinged to the bottom end of the first clamping plate. A second clamping plate is provided at the top of the clamping seat, and the first and second clamping plates are clamped on the cam. A support block for supporting the camshaft is provided between the axial clamping structure and the support seat. In S9, the deburring device includes a base, on which a movable seat and a fixed seat are provided. Both the movable seat and the fixed seat are provided with a center for pressing the camshaft. The base is provided with a sliding element that drives the movable seat to slide on the base. The movable seat is provided with a rotary motor that drives the center to rotate. A first guide rail is provided on one side of the base along the length of the base. A first slide and a second slide are slidably provided on the first guide rail. A first carriage is slidably provided on the first slide. The sliding direction of the first carriage is perpendicular to the camshaft axis. A wire brush is rotatably provided on the first carriage. A second carriage is slidably provided on the second slide. The sliding direction of the second carriage is perpendicular to the camshaft axis. A polishing structure is provided on the second carriage. The polishing structure includes a polishing block, which is V-shaped and arranged on the upper and lower sides of the mounting shaft. The mounting shaft is fixedly mounted on the second slide. The polishing block and the mounting shaft are hinged by a pin. The mounting shaft is equipped with a torsion spring or hydraulic cylinder to make the polishing block contact the surface of the camshaft.

2. A process for machining of nodular cast iron camshaft as claimed in claim 1 wherein: In S7, the centerless grinder includes a machine base, a sliding frame is provided at one top end of the machine base, a power element is provided on the machine base to drive the sliding frame to slide on the machine base, a grinding wheel is rotatably mounted on the sliding frame, a first motor is provided on the sliding frame to drive the grinding wheel to rotate, a fixed frame is provided at the other top end of the machine base, a guide wheel is rotatably mounted on the fixed frame, a second motor is provided on the fixed frame to drive the guide wheel to rotate, a support plate for supporting the camshaft is provided between the fixed frame and the sliding frame, the support plate is mounted on the machine base, and the top of the support plate is an inclined surface that gradually slopes downward from the sliding frame towards the fixed frame; both the guide wheel and the grinding wheel are provided with avoidance rings for avoiding the cam.

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