Method for machining a rectangular spline sleeve

Abstract

The application provides a processing method of a rectangular spline sleeve, and belongs to the field of mechanical processing. First, the outline and inner hole of the rectangular spline sleeve are processed, and heat treatment is performed; the tooth groove of the spline structure is milled on the outer circle of the rectangular spline sleeve; the four-square structure is ground and then the spline tooth is ground through self-made special fixture clamped on a numerical control grinding machine; finally, the excess part on the rectangular spline sleeve is removed, and surface treatment is performed. The numerical control grinding machine is creatively used to finish the key parts of the rectangular spline sleeve, so that the machining precision of the key size of the rectangular spline sleeve is effectively ensured. Through the self-made special fixture, the processing efficiency and the qualified rate are further improved.

Description

Technical Field

[0001] This invention belongs to the field of machining and relates to a machining method for a rectangular spline sleeve. Background Technology

[0002] Among the rectangular spline sleeves required for aircraft manufacturing, there is a special type used for transmitting torque. This spline sleeve has a complex structure, strict geometric tolerances, and high surface roughness requirements, making it extremely difficult to manufacture. For example... Figures 2 to 4 As shown, the main body of the spline sleeve is a rectangular external spline structure 2 located in the middle of the spline sleeve. One side is a square structure 1, and the other side is a 1 / 4 cylindrical structure 3, with a central inner hole 4. The spline teeth 6 of the main body spline structure 2 need to be evenly divided, with strict positional requirements between each tooth, and strict symmetry and roughness requirements for each spline tooth. Between two adjacent spline teeth 6, the bottom of the tooth groove is an arc-shaped bottom arc 7, which connects to the tooth roots on both sides through a tooth root transition arc 8. At the bottom of the tooth groove, a relief groove 5 is formed at the connection between the spline structure 2 and the square structure 1, with a fixed radius. The square structure 1 needs to be aligned with the spline, with the parallelism of each square surface relative to the center line of the spline sleeve not exceeding 0.05 mm, the surface roughness requirement not exceeding Ra 0.8 µm, and the symmetry of each pair of square surfaces relative to the center line of the spline sleeve not exceeding 0.05 mm. One side of the 1 / 4 cylindrical structure 3 needs to be aligned with the centerline of a spline tooth 6. Therefore, ordinary machining methods are difficult to meet the machining requirements, resulting in a low yield rate of rectangular spline sleeves and seriously affecting the aircraft delivery cycle. Summary of the Invention

[0003] This invention provides a method for processing rectangular spline sleeves, which solves the problem that ordinary processing methods are difficult to meet the high precision requirements of rectangular spline sleeves, resulting in a low product qualification rate.

[0004] The present invention adopts the following technical solution: A method for manufacturing a rectangular spline sleeve, the method comprising the following steps: Step 1, Spline pre-machining. Machin the outer shape and inner hole 4 of the rectangular spline sleeve, remove machining allowances, and then heat-treat the rectangular spline sleeve to obtain the required hardness. Specifically: Step 1.1, rough machining of bar stock: flatten one end face, machine three sections of outer circle with different diameters, drill 4 inner holes, make transition fillets, remove sharp edges, and flatten the other end face.

[0005] Step 1.2, rough milling of the square structure 1.

[0006] Step 1.3: After heat treatment, the rectangular spline sleeve is sandblasted.

[0007] Step 1.4, precision turning and precision boring: precision turn the spline structure 2 major diameter and the 1 / 4 cylindrical structure 3 diameter, precision bore the inner hole 4 diameter as the positioning reference for subsequent machining, precision turn the two end faces to control the length, and make chamfers.

[0008] Step 2, Machining the spline grooves: Mill the grooves of spline structure 2 on the outer circle of the rectangular spline sleeve. Specifically: Step 2.1, rough milling of spline tooth groove: Using the inner hole 4 for positioning, use a dial indicator to align the rectangular spline sleeve, mill the spline tooth groove, ensuring that the tooth groove is divided into six equal parts in the circumferential direction, and that the spline tooth 6 is symmetrical with respect to the center of the rectangular spline sleeve.

[0009] Step 2.2, finish milling the spline tooth groove: use a profile milling cutter on a horizontal milling machine to mill the bottom arc 7 and the tooth root transition arc 8 of the tooth groove.

[0010] Step 3, Grinding the square structure 1. After clamping the rectangular spline sleeve with a self-made special fixture, it is mounted on the CNC grinding machine; a dial indicator is used to align the rectangular spline sleeve so that the two side planes of the square structure 1 are perpendicular to the machine tool reference plane, and the surface is ground by using the "grinding back angle" method of the CNC grinding machine.

[0011] The self-made special fixture is in the shape of a stepped shaft. The outer diameter of the small diameter section fits with the inner hole 4 of the rectangular spline sleeve, serving as the cylindrical positioning surface 10. The large diameter section is the cylindrical clamping surface 9, used to clamp onto a CNC grinding machine. The end of the small diameter section is provided with an external thread. The rectangular spline sleeve is fitted onto the cylindrical positioning surface 10 until the end face is in contact with the stepped surface. Install washers and nuts to fix the rectangular spline sleeve.

[0012] Step 4, Grinding the spline teeth 6. Using the finely ground square structure 1 as a reference, use a dial indicator to align the spline teeth 6. Use the "manual grooving" method of a CNC grinding machine to grind the sides of the spline teeth 6. Install two grinding wheels on the CNC grinding machine, one facing the grinding wheel spindle and the other facing away from the grinding wheel spindle, respectively responsible for grinding the two sides of the spline teeth 6, avoiding positioning errors caused by repeated clamping.

[0013] Step 5, post-processing of the spline. Remove the excess portion from the rectangular spline sleeve and perform surface treatment to complete the machining of the rectangular spline sleeve. Specifically: Step 5.1, Milling 1 / 4 of the cylindrical structure 3. Clamp the rectangular spline assembly on the milling machine, align it, and then mill away 3 / 4 of the cylinder.

[0014] Step 5.2, Surface treatment. The rectangular spline sleeve is chrome plated, phosphate oxidized, and degreased.

[0015] The beneficial effects of this invention are as follows: This invention creatively uses a CNC grinding machine to precision machine the key parts of the rectangular spline sleeve, which effectively ensures the machining accuracy of the key dimensions of the rectangular spline sleeve. Furthermore, by using a self-made special fixture, the machining efficiency and pass rate are further improved. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the process of the present invention; Figure 2 Wrap the main view around the rectangular spline; Figure 3 Place the right view over the rectangular spline; Figure 4 Surround the left view with the rectangular spline; Figure 5 This is a schematic diagram of a self-made special fixture.

[0017] Wherein: 1-square structure; 2-spline structure; 3-1 / 4 cylindrical structure; 4-inner hole; 5-relief groove; 6-spline tooth; 7-bottom arc of tooth groove; 8-transition arc of tooth root; 9-cylindrical clamping surface; 10-cylindrical positioning surface. Detailed Implementation

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Taking the machining of a rectangular spline sleeve with specifications of 6×12×16×3.5 as an example, the specific implementation of the present invention is further illustrated. The rectangular spline sleeve has a total length of 38mm. The main body is a spline structure 2, with a length of 33mm, 6 teeth, a diameter of 12mm for the bottom arc 7 of the tooth groove, a major diameter of 16mm for the spline, and a width of 3.5mm for the spline teeth 6. A square structure 1 extends axially from one side of the spline structure 2, with a length of 5mm and a side length of 12mm. A quarter-cylindrical structure 3 extends axially from the other side of the spline structure 2, with a diameter of 12mm. An inner hole 4, with a diameter of 8mm, is provided through the center of the rectangular spline sleeve. The machining method for the above-mentioned rectangular spline sleeve is as follows: Figure 1 As shown, the specific processing steps are as follows: Step 1: Spline pre-machining. Machin the outer shape and inner hole 4 of the rectangular spline sleeve, remove machining allowances, and perform heat treatment on the rectangular spline sleeve to achieve the required hardness, preparing it for spline machining. This is further divided into the following sub-steps: Step 1.1: Rough turning of the bar stock. On a CNC lathe, flatten one end face, turn three sections of outer diameter with different dimensions, drill 4 inner holes, make transition fillets, remove sharp edges, turn it over and flatten the other end face, leaving a 0.5mm allowance for each part's dimensions for finishing.

[0020] Step 1.2: Rough milling of the square structure 1. Mill all four sides on a vertical milling machine, leaving a 1mm allowance for finishing. Remove burrs and sharp edges after milling.

[0021] Step 1.3: Heat treatment and sandblasting. The rectangular spline sleeve is heat treated to achieve the required hardness. After heat treatment, the rectangular spline sleeve is sandblasted with diamond abrasive to remove the oxide salts and oxide scale from the surface.

[0022] Step 1.4: Finish turning and finish boring. Finish turn the spline structure 2 to a major diameter of 16mm and the 1 / 4 cylindrical structure 3 to a diameter of 12mm; finish bore the inner hole 4 to a diameter of 8mm, as a positioning reference for subsequent machining; finish turn both end faces, control the length of the rectangular spline sleeve to 38mm, and make chamfers.

[0023] Step 2: Machining the spline grooves. The spline grooves are milled into the outer circle of the rectangular spline sleeve. This is further divided into the following sub-steps: Step 2.1: Rough milling of spline tooth grooves. Using the inner hole 4 as a reference, align the rectangular spline sleeve with a dial indicator, mill the spline tooth grooves, controlling the groove width to 2.3mm and the spline tooth 6 width to 4.2mm, leaving a 0.7mm allowance for grinding. Ensure that the tooth groove circumference is divided into six equal parts, and that spline tooth 6 is symmetrical with respect to the center of the rectangular spline sleeve; remove burrs and sharp edges after milling.

[0024] Step 2.2: Finish milling the spline tooth groove. On a horizontal milling machine, use a profile milling cutter to mill the bottom arc 7 of the tooth groove to a diameter of 12mm, and the tooth root transition arc 8 to a radius of 0.2mm. The special profile milling cutter used has a diameter of 100mm, an angle of 60°, a working profile arc radius of 6mm, and a profile transition arc radius of 0.2mm. The milling cutter retracts from the four-sided structure 1 direction, controlling the position of the retraction groove 5 to be 26mm from the end face.

[0025] Step 3: Grinding the square structure 1. Since the rectangular spline sleeve cannot be directly clamped onto a CNC grinding machine, a special fixture needs to be made for machining. For example... Figure 5As shown, the self-made special fixture is generally in the shape of a stepped shaft. The outer diameter of the small diameter section mates with the inner hole 4 of the rectangular spline sleeve, serving as the cylindrical positioning surface 10. The large diameter section is the cylindrical clamping surface 9, used for clamping onto the CNC grinding machine. The end of the small diameter section has an external thread. The rectangular spline sleeve is fitted onto the cylindrical positioning surface 10 until the end face is in contact with the stepped surface. Washers and nuts are installed to fix the rectangular spline sleeve. The diameter of the cylindrical clamping surface 9 is 16mm, the diameter of the cylindrical positioning surface 10 is 8mm, and the threaded part is an M6 thread. Then, the cylindrical clamping surface 9 of the self-made special fixture is fixed onto the CNC grinding machine. A dial indicator is used to align the rectangular spline sleeve so that the two side planes of the square structure 1 are perpendicular to the machine tool reference plane. The "grinding back angle" method of the CNC grinding machine is used, with the angle set to 0°, and an 11V9 grinding wheel is selected for surface grinding. Since real-world cutting tools do not have a 0° clearance angle, the normal "clearance angle grinding" process does not include a 0° setting. A 0° clearance angle setting is commonly used in rapid feed and retraction programs to ensure the grinding wheel moves along the tool tangent, preventing collisions. Furthermore, because the grinding wheel does not participate in cutting when moving along the 0° clearance angle direction, the spindle system has relatively weak rigidity in this direction. If a 0° clearance angle setting is used directly for grinding a flat surface, significant tool deflection will occur after the grinding wheel contacts the rectangular spline sleeve. Therefore, compensation for tool deflection is necessary. A CNC grinding machine is used to "grind the taper," with axial compensation of 0.2° and feed direction compensation of 0.05° to ensure the flatness of the ground surface. During grinding, a CNC grinding machine uses a "step-by-step feed" method to decompose the machining allowance, with each feed amount set to 0.1mm. Finally, a zero-feed cycle grinding is performed to ensure the machining accuracy and surface quality of the square structure meet the requirements.

[0026] Step 4: Grinding spline teeth 6. Using the finely ground square structure 1 as a reference, align spline teeth 6 with a dial indicator; use the "manual grooving" method on a CNC grinding machine to grind the sides of spline teeth 6. Install two 12V9 grinding wheels on the CNC grinding machine, one facing the grinding wheel spindle and the other facing away from the grinding wheel spindle, respectively responsible for grinding the two sides of spline teeth 6, avoiding positioning errors caused by repeated clamping; use the "eccentricity" method on the CNC grinding machine to adjust the position of the grinding wheel from the center line of spline teeth 6 to ±1.744mm, controlling the dimensional accuracy of spline teeth 6; during the grinding process, use the "step-by-step feed" method on the CNC grinding machine to decompose the machining allowance, with each feed amount set to 0.1mm. Finally, perform a zero-feed cycle grinding to ensure that the machining accuracy and surface quality of spline teeth 6 meet the requirements.

[0027] Step 5: Post-processing of the spline. Remove the excess portion from the rectangular spline sleeve and perform surface treatment to complete the machining of the rectangular spline sleeve. This is further divided into the following sub-steps: Step 5.1: Milling 1 / 4 cylindrical structure 3. Clamp the rectangular spline assembly on the milling machine, align it, and mill away 3 / 4 of the cylinder; after milling, remove burrs and sharp edges.

[0028] Step 5.2: Surface treatment. The rectangular spline sleeve is chrome plated, phosphate oxidized, and degreased to protect the surface of the rectangular spline sleeve and prevent oxidation.

[0029] The above embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for processing a rectangular spline sleeve, characterized in that, The main body of the rectangular spline sleeve is a spline structure with a rectangular external spline (2), located in the middle of the spline sleeve. One side of it is a square structure (1), and the other side is a 1 / 4 cylindrical structure (3), with an inner hole in the center (4). The processing method includes the following steps: Step 1, Spline pre-machining; Step 2, machine the spline grooves; Step 3, grind the square structure (1); After using a self-made special fixture to clamp the rectangular spline sleeve, it is clamped on the CNC grinding machine. A dial indicator is used to align the rectangular spline sleeve so that the two side planes of the square structure (1) are perpendicular to the machine tool reference plane. The CNC grinding machine is used to grind the back angle to perform surface grinding. The self-made special fixture is in the shape of a stepped shaft. The outer diameter of the small diameter section matches the inner hole (4) of the rectangular spline sleeve and serves as a cylindrical positioning surface (10). The large diameter section is a cylindrical clamping surface (9) used to clamp onto a CNC grinding machine. The end of the small diameter section is provided with an external thread. The rectangular spline sleeve is fitted onto the cylindrical positioning surface (10) until the end face is in contact with the stepped surface. Install washers and nuts to fix the rectangular spline sleeve. During the grinding process, the CNC grinding machine adopts a "step-by-step feeding" method, with each feed amount set to 0.1mm, and finally a zero-feed cycle grinding is performed. Step 4, polish the key teeth (6); Using the finely ground square structure (1) as a reference, the spline teeth (6) are aligned with a dial indicator; the side of the spline teeth (6) is ground by using the "manual tool groove" method of a CNC grinding machine. During the grinding process, two grinding wheels are installed on the CNC grinding machine, one facing the grinding wheel spindle and the other facing away from the grinding wheel spindle, respectively responsible for grinding the two sides of the spline teeth (6), avoiding the positioning error caused by repeated clamping; Step 5, post-processing of splines.

2. The processing method of a rectangular spline sleeve according to claim 1, characterized in that, Step 1 specifically includes: Step 1.1: Flatten one end face, machine three sections of outer circle with different diameters, drill inner hole (4), make transition fillet, remove sharp edge, and flatten the other end face; Step 1.2, rough milling of the square structure (1); Step 1.3: After heat treatment, the rectangular spline sleeve is sandblasted. Step 1.4: finish machine the major diameter of the spline structure (2), the diameter of the 1 / 4 cylindrical structure (3), finish bore the diameter of the inner hole (4) as the positioning reference for subsequent processing, finish machine the length of both end faces, and make chamfers.

3. The processing method of a rectangular spline sleeve according to claim 1, characterized in that, Step 2 specifically includes: Step 2.1: Position the inner hole (4), use a dial indicator to align the rectangular spline sleeve, mill the spline tooth groove, and ensure that the tooth groove is divided into six equal parts in the circumferential direction, and that the spline tooth (6) is symmetrical with respect to the center of the rectangular spline sleeve. Step 2.2: Mill the bottom arc (7) of the tooth groove and the transition arc (8) of the tooth root using a profile milling cutter on a horizontal milling machine.

4. The processing method of a rectangular spline sleeve according to claim 1, characterized in that, Step 5 specifically includes: Step 5.1, Milling 1 / 4 cylindrical structure (3): Clamp the rectangular spline set on the milling machine, align it and then mill off 3 / 4 of the cylinder; Step 5.2: Chrome plating, phosphate oxidation, and degreasing of the rectangular spline sleeve.

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