Processing method of squirrel-cage precision elastic support and numerical control slotting cutter used for processing

Abstract

The application discloses a processing method of a mouse-cage type precise elastic support and a numerical control groove cutter used for processing, and belongs to the technical field of automobile part production. The method is as follows: cutting a blank part, processing the blank part to form a combined structure; constructing a structure frame; processing mounting holes; performing heat treatment to eliminate stress; grinding the structure frame; rough turning the structure frame; processing multiple rectangular windows to form a mouse-cage type elastic support structure; and precisely grinding the elastic support structure. The application reduces the risk of tool blade springing, reduces tool consumption cost, reduces the risk of workpiece deformation, promotes the improvement of precision finishing accuracy, avoids the risk of part deformation and precision reduction caused by intermittent cutting during finish turning, improves the qualified rate of the mouse-cage type precise elastic support, reduces the cutting force of the tool, guarantees the strength of the end surface groove cutter, and reduces the risk of tool vibration or breakage caused by the long tool protruding length of the processed end surface groove.

Description

Technical Field

[0001] This invention relates to a machining method for a squirrel-cage type precision spring and a CNC grooving tool for machining it, belonging to the field of spring production technology. Background Technology

[0002] The support system of an aero-engine rotor is a supercritical rotor system. During acceleration, the engine rotor needs to pass through the critical speed region with large vibrations. In order to ensure that the rotor passes through the critical speed region smoothly, an elastic damping support structure is generally used at the main support point, and the squirrel cage elastic support (hereinafter referred to as elastic support) is one of them.

[0003] The combined elastic support is a support structure in which an expansion ring is installed in the outer diameter groove of the small end of a squirrel-cage elastic support. The squirrel-cage elastic support acts as an adjustment spring for support stiffness and a centering spring; while the lubricating oil, under pressure, generates throttling losses through the fit between the outer diameter and end face of the expansion ring. The expansion ring mounting groove and outer diameter of the elastic support need to have very strict dimensional and geometric tolerance requirements to ensure that the elastic support and the connecting parts achieve a tight fit. Therefore, the processing qualification rate of the elastic support has always been low. To solve the problem of low qualification rate of elastic supports, research was conducted on the processing technology route of the elastic support.

[0004] The existing manufacturing steps for squirrel-cage precision projectiles are as follows:

[0005] Raw material (forging) -- rough turning of the outer shape -- semi-finish turning of the outer shape -- rough turning of the end face groove -- machining of the flange edge shape and mounting holes -- milling of multiple rectangular windows in the radial direction of the spring support -- finish turning of the inner and outer diameters of the spring support, the expansion ring mounting groove and the end face groove.

[0006] The above production steps have the following problems:

[0007] 1. Most spring support parts are made of stainless steel. This type of material is not easy to break chips during the cutting process. In addition, due to the deep end face groove design, it is easy to cause chip accumulation during the cutting process, which in turn leads to tool breakage, affecting processing efficiency and product quality.

[0008] 2. When machining the outer diameter of the spring support and the inlet face of the end face groove, it is necessary to ensure the radial depth of the expansion ring mounting groove, the cylindricity of the outer diameter, and the perpendicularity of the outer diameter to the end face groove. These high precision requirements make the machining extremely difficult, and even a slight deviation may lead to product defects.

[0009] 3. Due to its thin-walled characteristics, the large-end squirrel cage structure of the spring support faces the challenge of intermittent cutting when machining the inner and outer diameters, making it difficult to guarantee the stability and accuracy of the machining dimensions, which further reduces the product qualification rate. Summary of the Invention

[0010] To address the problems existing in the background art, the present invention provides a machining method for a squirrel-cage type precision spring and a CNC grooving tool for machining it.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: a method for processing a squirrel-cage type precision spring, the method comprising the following steps:

[0012] S1: Cut the forging raw material to form a blank with a preset thickness;

[0013] S2: The blank obtained in S1 is rough machined to form a combined structure with a small end in the shape of a tube and a large end in the shape of a flange;

[0014] S3: Using the small end stepped surface of the combined structure obtained in S2 as the entry point, use a CNC grooving tool to rough turn the end face groove to construct the structural frame of the squirrel cage spring support.

[0015] S4: Place the structural frame obtained in S3 with the small end facing upwards, and use the end face and inner diameter of the large end as the positioning reference to machine the mounting holes on the large end.

[0016] S5: Heat-treat the structural frame obtained in S4 to relieve stress;

[0017] S6: Grinding the small end face and large end face of the structural frame obtained from S5;

[0018] S7: The inner diameter, outer diameter, and expansion ring mounting groove of the structural frame obtained by rough turning S6 using a vertical lathe;

[0019] S8: Mill multiple rectangular windows on the outer wall of the large end of the structural frame obtained in S7 to form a rat cage spring support structure.

[0020] S9: The inlet end face of the end face groove of the spring support structure obtained in S8, the inner diameter of the spring support structure, the inner diameter positioning step surface of the spring support structure, and the outer diameter of the spring support structure are all finely ground.

[0021] S10: The inner and outer diameters of the flange end face of the large end of the spring support structure obtained in S9 are precision ground.

[0022] The CNC grooving tool S3 includes an insert, a tool holder, and a tool shank; a tool holder is installed at one end of the tool shank, and an insert is installed on the tool holder; the insert has an arc-shaped structure, the arc-shaped top of the arc is the cutting part, the front end of the cutting part is machined with a clearance angle, the upper end of the cutting part is machined with a rake angle, and the rake face of the cutting part is machined with a chip removal groove; the tool holder is machined with a secondary clearance angle along the clearance angle of the cutting part, and the two sides of the tool holder are machined with arcs in the same direction, both arcs contracting towards the middle.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. This invention changes the original process of "milling multiple radial windows - finish turning end face groove" to "finish turning end face groove - milling multiple radial windows". The finish turning of the end face groove is changed from intermittent cutting to continuous cutting, which reduces the risk of tool breakage and reduces tool consumption costs.

[0025] 2. This invention adds a stress relief process after rough machining the shape of the spring support and the end face groove, which reduces the risk of workpiece deformation and promotes the improvement of finishing accuracy;

[0026] 3. The present invention adopts a machining method combining turning and grinding, that is, after the stress relief process, a process method of semi-finish turning, milling and grinding is used to avoid the risk of part deformation and reduced accuracy caused by intermittent cutting during precision turning, and improves the pass rate of squirrel cage precision spring support.

[0027] 4. The CNC grooving tool of the present invention reduces the cutting force of the tool while ensuring the strength of the end face grooving tool, thereby reducing the risk of tool vibration or breakage caused by the long tool protrusion length when machining the end face grooving. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a cage-type precision spring after being processed using the processing method of the present invention;

[0029] Figure 2 This is a schematic diagram of the process component obtained in step S2 of the processing method of the present invention;

[0030] Figure 3 This is a schematic diagram of the process component obtained in step S3 of the processing method of the present invention;

[0031] Figure 4 This is a schematic diagram of the process component obtained in step S4 of the processing method of the present invention;

[0032] Figure 5 This is a schematic diagram of the structure of the process component obtained in step S6 of the processing method of the present invention;

[0033] Figure 6 This is a schematic diagram of the structure of the process component obtained in step S7 of the processing method of the present invention;

[0034] Figure 7 This is a schematic diagram of the structure of the process component obtained in step S8 of the processing method of the present invention;

[0035] Figure 8 This is a schematic diagram of the structure of the process component obtained by processing step S9 of the present invention;

[0036] Figure 9 This is a schematic diagram of the process component obtained in step S10 of the processing method of the present invention;

[0037] Figure 10 This is a schematic diagram of the structure of the CNC grooving tool of the present invention;

[0038] Figure 11 yes Figure 10 Top view;

[0039] Figure 12 This is a schematic diagram of the unidirectional circular arc structure of the tool holder. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] A method for manufacturing a squirrel-cage type precision spring clip, the method comprising the following steps:

[0042] S1: Cut the forging raw material to form a blank with a preset thickness;

[0043] S2: The blank obtained in S1 is rough machined to form a combined structure with the small end 1 being tubular and the large end 2 being flange-shaped, such as... Figure 2 As shown;

[0044] S3: Using the small end stepped surface 3 of the combined structure obtained in S2 as the entry point, a deep end face groove 4 is rough-machined using a CNC grooving tool to construct the structural frame of the squirrel-cage spring support, such as... Figure 3 As shown;

[0045] In order to promote the complete release of internal stress of the parts, the inner frame of the squirrel cage is rough machined using a CNC grooving tool before stress relief, that is, the deep end face groove 4 is machined.

[0046] The CNC grooving tool S3 includes an insert 8, a tool holder 9, and a tool shank 10. The insert 8 is made of YA6 cemented carbide. The tool holder 9 and the tool shank 10 are made of 9SiCr low-alloy steel, which has good heat treatment stability. After heat treatment, it has high strength and good toughness, which can effectively ensure the cutting stability of the tool. The tool holder 9 is installed at one end of the tool shank 10, and the insert 8 is installed on the tool holder 9. The tool holder 9 is an arc-shaped structure that supports the insert 8 and is connected to the tool shank 10. The tool shank 10 is a cuboid structure and is used to install in the machine tool turret. The cutting part 8 and the tool holder 9 are connected by brazing. Taking into account the toughness and strength of the tool holder 10, the heat treatment hardness requirement is HRC43~48. The side clearance angle of the cutting part 8 is 2°-3°. The insert 8 has an arc-shaped structure, and the arc-shaped top of the arc is the cutting part. The front end of the cutting part is machined with a clearance angle 11 to avoid the machined surface. The upper end of the cutting part is machined with a rake angle 12 along the axial direction of the tool holder 10. The rake face of the cutting part is machined with a crescent-shaped chip removal groove 13. The tool holder 9 is machined with a secondary clearance angle 14 along the clearance angle 11 of the cutting part. The two sides of the tool holder 9 are machined with arcs 15 in the same direction. The arcs 15 are similar in shape to the arc of the groove on the machined end face and taper towards the middle to avoid the machined surface.

[0047] Because the ratio of groove depth to groove width in end face groove 4 exceeds 7 times, the tool holder 9 has a high risk of breakage. Therefore, the clearance angle 11 is set to 10° and the clearance angle 12 is set to 12°. The cutting edge adopts a spherical cutting part to increase the sharpness of the tool and thus reduce the cutting reaction force borne by the tool holder. At the same time, the tool body thickness is increased, the conformal tool holder and the transition radius are used to increase the strength of the tool body. The thickness of the tool holder is changed from the standard 25mm to 32mm to enhance the strength of the tool holder; and the transition position between the tool holder and the tool shank adopts an arc structure to increase the support of the tool shank relative to the tool holder.

[0048] S4: Place the structural frame obtained in S3 with the small end 1 facing upwards, using the end face and inner diameter of the large end 2 as the positioning reference. Add auxiliary support (preferably an adjustable support column, similar to bolt adjustment to support the flange edge and prevent downward deformation during machining) to the lower end face of the large end 2. Then machine the mounting holes 7 on the large end 2, such as... Figure 4 As shown;

[0049] S5: Heat-treat the structural frame obtained in S4 to relieve stress;

[0050] S6: Grind the small and large end faces of the structural frame obtained from S5 to ensure the required distance between the small end face and the inlet end face of end face groove 4, and to ensure the required distance and parallelism (0.02mm) between the large and small end faces. Ensure the parallelism of both end faces serves as the reference for subsequent finishing. Figure 5 As shown;

[0051] S7: The inner diameter, outer diameter, and expansion ring mounting groove 8 of the structural frame obtained by rough turning S6 using a vertical lathe, such as... Figure 6 As shown;

[0052] S8: Multiple rectangular windows 5, evenly distributed and penetrating the thickness of the outer wall of the large end 2 of the structural frame obtained in S7, are milled to form a rat-cage-type spring support structure, such as... Figure 7 As shown;

[0053] S9: The inlet end face of the end face groove 4 of the spring support structure obtained in S8, the inner diameter of the spring support structure, the inner diameter positioning step surface of the spring support structure, and the outer diameter of the spring support structure are all precision ground to ensure the perpendicularity and other geometric tolerance requirements between the small end face and the outer diameter. Figure 8 As shown;

[0054] S901: Grind the outer diameter of the small end of the spring support structure and the inlet end face of the end face groove 4 to ensure the size between the outer diameter of the small end and the bottom surface of the expansion ring mounting groove 8 described in S7, and limit the roundness of the ground outer diameter and the perpendicularity of the ground outer diameter to the large end face of the spring support (runout ≤ 0.02mm, roundness ≤ 0.01mm).

[0055] S902: Grind the inner diameter of the large end of the spring support structure based on the outer diameter to meet the requirements of inner diameter roundness (≤0.01mm) and relative outer diameter runout (≤0.02mm).

[0056] S10: The inner and outer diameters of the flange end face of the large end 2 of the elastic support structure obtained in S9 are precision ground to ensure the parallelism (≤0.02) of the upper and lower end faces of the flange. Figure 9 As shown.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for manufacturing a squirrel-cage type precision spring, characterized in that: The method includes the following steps: S1: Cut the forging raw material to form a blank with a preset thickness; S2: The blank obtained in S1 is rough machined to form a combined structure in which the small end (1) is tubular and the large end (2) is flange-shaped; S3: Using the small end step surface (3) of the combined structure obtained in S2 as the entrance, use a CNC grooving tool to rough turn the end face groove (4) to construct the structural frame of the squirrel cage spring support; The CNC grooving tool includes a cutting tool (8), a tool holder (9), and a tool shank (10); a tool holder (9) is installed at one end of the tool shank (10), and a cutting tool (8) is installed on the tool holder (9); the cutting tool (8) has an arc-shaped structure, the arc-shaped top end of the arc is the cutting part, the front end of the cutting part is machined with a clearance angle (11), the upper end of the cutting part is machined with a front angle (12), and the front face of the cutting part is machined with a chip removal groove (13); the tool holder (9) is machined with a secondary clearance angle (14) along the clearance angle (11) of the cutting part, and the two sides of the tool holder (9) are machined with arcs (15) in the same direction, and both arcs (15) shrink towards the middle; S4: Place the structural frame obtained in S3 with the small end (1) facing upwards, and use the end face and inner diameter of the large end (2) as the positioning reference to process the mounting hole (7) on the large end (2). S5: Heat-treat the structural frame obtained in S4 to relieve stress; S6: Grinding the small end face and large end face of the structural frame obtained from S5; S7: The inner diameter, outer diameter, and expansion ring mounting groove (8) of the structural frame obtained by rough turning S6 using a vertical lathe; S8: Mill multiple rectangular windows (5) on the outer wall of the large end (2) of the structural frame obtained in S7 to form a rat cage spring support structure; S9: The inlet end face of the end face groove (4) of the spring support structure obtained in S8, the inner diameter of the spring support structure, the inner diameter positioning step surface of the spring support structure, and the outer diameter of the spring support structure are all finely ground. S901: Grinding the outer diameter of the small end of the spring support structure and the inlet end face of the end face groove (4); S902: Grind the inner diameter of the large end of the spring support structure based on the outer diameter; S10: The inner and outer diameters of the flange end face of the large end (2) of the elastic support structure obtained in S9 are finely ground.

Images