Processing method for reducing surface roughness of torque converter pump hub

Abstract

The present invention provides a machining method for reducing the surface roughness of a torque converter pump hub, primarily addressing the technical problem of torque converter pump hubs failing to meet design requirements using existing machining methods. The present method involves subjecting a torque converter pump hub blank to a series of forging, rough machining, heat treatment, semi-finishing, finishing, and cold extrusion processes, resulting in a finished torque converter pump hub with a roughness that meets the required specifications. This method significantly reduces surface roughness without changing the original machining accuracy of the pump hub, thereby ensuring that all aspects of its performance meet design requirements.

Description

Technical Field

[0001] The invention relates to a processing method for a pump hub, and in particular to a processing method for reducing the surface roughness of a pump hub / cover wheel of a hydraulic torque converter. Background Art

[0002] The torque converter pump hub is the component that drives the oil pump. Its outer surface serves as the sealing surface for the pump's oil seal, placing high demands on surface roughness and roundness. Because the pump hub is welded to the impeller body, the high temperatures generated during welding can cause deformation, resulting in outer roundness that fails to meet the required roundness. This requires post-weld machining of the outer surface, but due to structural limitations, this is typically done by turning. This method, however, fails to meet design requirements for surface roughness.

[0003] The torque converter cover wheel is a part connected to the engine. Its inner surface is the friction counterpart of the locking clutch friction plate, and the surface roughness requirement is relatively high. However, due to the limitation of the part structure, the cover wheel is generally processed by turning, and the surface roughness is also difficult to meet the requirements. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problem that the surface roughness of the pump hub / cover wheel of the torque converter cannot meet the design requirements using the existing processing methods, and to provide a processing method for reducing the surface roughness of the pump hub / cover wheel of the torque converter.

[0005] In order to achieve the above objectives, the technical solutions of the present invention are as follows:

[0006] A processing method for reducing the surface roughness of a torque converter pump hub is characterized in that it comprises the following steps:

[0007] S1, forging the torque converter pump hub blank into shape according to design requirements;

[0008] S2, rough machining the pump hub blank using a CNC lathe, leaving a machining allowance of 0.65 to 1.25 mm;

[0009] S3, heat treating the rough-machined pump hub blank according to the hardness requirements of the torque converter pump hub product;

[0010] S4, semi-finishing the heat-treated pump hub blank by a CNC lathe, leaving a machining allowance of 0.15 to 0.25 mm on the outer cylindrical surface to obtain a semi-finished pump hub;

[0011] S5, inspect the semi-finished pump hub. If the outer surface roughness is less than or equal to Ra3.2 and the machining allowance of the outer diameter is 0.15-0.25 mm, weld the qualified semi-finished pump hub to the impeller body and cool it, and proceed to step S6; otherwise, return to step S4;

[0012] S6, finishing the semi-finished pump hub on a CNC lathe to remove the excess;

[0013] S7, cold extruding the outer cylindrical surface of the semi-finished pump hub after fine machining;

[0014] S8, performing a test on the cold-extruded semi-finished pump hub. If the surface roughness of the semi-finished pump hub is less than or equal to Ra0.5, proceed to step S9; otherwise, return to step S7;

[0015] S9, perform a second inspection on the cold-extruded pump hub semi-finished product. If the outer circle size is φ50.95~φ50.975mm and the roundness of the outer circle is less than or equal to 0.02, it means that the cold-extruded pump hub semi-finished product is qualified, and then the pump hub finished product is obtained; otherwise, return to step S6.

[0016] Furthermore, in step S1, the pump hub blank is made of alloy structural steel, which has good heat treatment hardenability, good comprehensive mechanical properties after heat treatment, and small welding deformation.

[0017] Furthermore, in step S3, the hardness requirement of the pump hub product is HRC35~HRC45, and the heat treatment process first performs quenching treatment and then tempering treatment, wherein the quenching temperature is 850℃~900℃, the quenching time is 90~110 minutes, and the tempering temperature is 420℃~460℃, and the tempering time is 120~140 minutes.

[0018] Furthermore, in step S5, before returning to step S4, the unqualified semi-finished products are first judged. If there is machining allowance, the process returns to step S4 for repair; if there is no machining allowance, the semi-finished products are scrapped.

[0019] Furthermore, in step S7, the tool used for cold extrusion is a diamond-type roller burnishing extrusion cutter. Since lathe processing cannot achieve the surface roughness required by the design, and grinding and other processing methods cannot be used due to structural limitations of this type of product, the surface needs to be cold extruded. The diamond-type roller burnishing extrusion cutter is suitable for parts with a wide hardness range, and the surface roughness of the parts after extrusion is low without affecting the original processing accuracy.

[0020] Furthermore, the cold extrusion and the finishing of step S6 use the same CNC lathe. After finishing, the turning tool is switched to a diamond-type roller burnishing extrusion tool used for cold extrusion. The pump wheel body is rotated and the extrusion tool is pressed against the outer cylindrical surface of the pump wheel hub. The extrusion tool is moved to achieve extrusion of the outer cylindrical surface.

[0021] Furthermore, in step S7, before returning to step S6, the unqualified products after the second inspection are judged. If there is machining allowance, the process returns to step S6 for repair; if there is no machining allowance, the products are scrapped.

[0022] In addition, the present invention also provides a processing method for reducing the surface roughness of a torque converter cover wheel, which is special in that it includes the following steps:

[0023] S1, stamping the torque converter cover wheel blank according to design requirements;

[0024] S2, welding the cover wheel blank to the cover wheel and the connecting block, cooling them, and then placing them on a CNC lathe for rough machining, leaving a machining allowance of 0.1 to 0.15 mm to obtain a cover wheel semi-finished product;

[0025] S3, finishing the cover wheel semi-finished product on a CNC lathe to remove the excess;

[0026] S4, cold extruding the inner surface of the semi-finished cover wheel after fine processing;

[0027] S5, performing a test on the semi-finished cover wheel after fine processing. If the inner surface roughness of the semi-finished cover wheel is Ra0.2-Ra0.6, proceed to step S6; otherwise, return to step S4;

[0028] S6, perform two inspections on the semi-finished cover wheel after cold extrusion. If the wall thickness is 3.7~4.0mm and the flatness of the inner cavity surface is less than or equal to 0.05, it means that the semi-finished cover wheel after cold extrusion is a qualified product, and then the cover wheel finished product is obtained; otherwise, return to step S3.

[0029] Furthermore, in step S1, the cover wheel blank is made of carbon structural steel, which has good cold forming performance, is easy to stamp, and has good welding performance.

[0030] Furthermore, in step S4, the cold extrusion and the finishing of step S3 are performed using the same CNC lathe. After finishing, the turning tool is switched to a diamond-type roller burnishing extrusion tool used for cold extrusion. The cover wheel is rotated and the extrusion tool is pressed against the inner cavity surface of the cover wheel, and the extrusion tool is moved to achieve extrusion of the inner cavity surface.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The pump hub processing method of the present invention obtains a finished torque converter pump hub having a roughness that meets the requirements by subjecting the torque converter pump hub blank to forging, rough machining, heat treatment, semi-finishing, finishing, and cold extrusion. This method significantly reduces the surface roughness of the pump hub without changing the original machining accuracy, thereby ensuring that all aspects of its performance meet the design requirements.

[0033] 2. The processing method of the cover wheel of the present invention reduces the roughness of the inner surface of the cover wheel by sequentially subjecting the cover wheel blank to stamping, rough processing, fine processing and cold extrusion processing, thereby obtaining a finished torque converter cover wheel with roughness meeting the requirements.

[0034] 3. The processing method of the present invention can be applied to the mass production of torque converter pump hubs, pump wheels and cover wheels.

[0035] 4. The processing method of the present invention has simple technology, small investment and great effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the structure of the torque converter pump wheel;

[0037] Figure 2 This is a schematic diagram of the torque converter cover wheel structure;

[0038] Figure 3 This is a reference diagram of the extrusion blade used in the cold extrusion process in the embodiment of the present invention.

[0039] The reference numerals are as follows:

[0040] 1- pump impeller body, 2- pump impeller hub. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Example 1

[0043] The present invention is applicable to parts or components that cannot meet the roughness requirements by grinding, polishing or other processing methods due to design structure limitations. This embodiment uses the processing method of the torque converter pump hub 2 as an example to specifically illustrate the method.

[0044] Combine Figure 1 and Figure 3 As shown, the present invention provides a processing method for reducing the surface roughness of a torque converter pump hub, which specifically includes the following steps:

[0045] S1, forging the torque converter pump hub blank according to design requirements.

[0046] The structure of the pump impeller is as follows Figure 1 As shown, it includes a pump impeller body 1 and a pump hub 2 connected thereto. In this embodiment, the pump hub blank is made of alloy structural steel, which has a hardness of ≤HRC50, a surface roughness of ≤Ra0.8, and good heat treatment hardenability. After heat treatment, it has good comprehensive mechanical properties and minimal welding deformation.

[0047] S2, use CNC lathe to rough-process the forged pump hub blank.

[0048] The rough machining described in this embodiment is to use a CNC lathe to turn the forged pump hub blank, mainly to remove excess material after forging, provide a clamping and positioning reference for subsequent processes, and leave a machining allowance of 0.65 to 1.25 mm.

[0049] S3, heat treating the pump hub blank after rough machining.

[0050] The heat treatment temperature and time are set based on the hardness requirements of the finished pump hub. This embodiment requires the hardness of the pump hub 2 to reach HRC35-HRC45. Therefore, the heat treatment of the pump hub blank is set to first undergo quenching and then tempering. The quenching temperature is 850-900°C for 90-110 minutes, and the tempering temperature is 420-460°C for 120-140 minutes. After the heat treatment is completed, a hardness tester is used to measure the hardness. If the hardness is too high, the tempering temperature and time are adjusted before continuing the heat treatment. If the hardness is too low, the quenching temperature, tempering temperature, and corresponding treatment time are adjusted before continuing the heat treatment until the hardness meets the requirements. After heat treatment, the structural state and dimensions of the pump hub blank remain unchanged; only the hardness changes, thereby improving the overall performance of the pump hub blank.

[0051] S4, using a CNC lathe to semi-finish the heat-treated pump hub blank to obtain a pump hub semi-finished product.

[0052] This finishing process uses a CNC lathe to turn the pump hub blank after heat treatment, whose hardness meets the requirements. It mainly processes the part outside the outer circle of the pump hub blank to the size required by the drawing, leaving a processing allowance of 0.15 to 0.25 mm on the outer circle. Machining the outer circle can improve its surface quality, thereby obtaining a semi-finished pump hub product, which is fully prepared for subsequent finishing.

[0053] S5. Inspect the semi-finished pump hub. Generally, a roughness meter is used to inspect the surface roughness of the semi-finished pump hub, and a vernier caliper is used to inspect the outer diameter of the semi-finished pump hub (this embodiment measures whether the machining allowance meets the requirements). If the surface roughness of the semi-finished pump hub is less than or equal to Ra3.2, and the machining allowance of the outer diameter is 0.15-0.25mm, it is qualified. The semi-finished pump hub that has passed the inspection is welded to the impeller body and cooled, and then enter step S6; otherwise, the semi-finished product that fails the inspection is judged first. If there is machining allowance, return to step S4 for repair; if there is no machining allowance, it is scrapped.

[0054] S6, finish machining the semi-finished pump hub on a CNC lathe to remove the excess.

[0055] Specifically, the qualified pump hub semi-finished product is welded to the pump impeller body 1. After cooling, the pump impeller body 1 welded with the pump hub semi-finished product is placed on a CNC lathe, and the outer circle of the welded pump hub semi-finished product is fine-machined to remove the machining allowance (0.15 to 0.25 mm) left by the semi-finishing.

[0056] S7, the outer surface of the semi-finished pump hub after fine processing is polished with a diamond roller (such as Figure 3 As shown) for cold extrusion.

[0057] The purpose of this step is to reduce the roughness of the outer cylindrical surface to meet the requirements of the drawing. The cold extrusion and the finishing process of step S6 are performed on the same CNC lathe. After finishing, the turning tool is switched to a diamond roller burnishing extrusion tool used for cold extrusion. The pump wheel body is rotated and the extrusion tool is pressed against the outer cylindrical surface of the pump wheel hub. The extrusion tool is moved to perform cold extrusion on the outer cylindrical surface.

[0058] S8, inspecting the semi-finished pump hub after cold extrusion.

[0059] After cold extrusion, the semi-finished pump hub is inspected. The roughness of the outer surface is tested with a roughness meter, the outer diameter of the pump hub is tested with a micrometer, and the roundness of the outer circle of the pump hub is tested with a roundness meter to ensure that the following conditions are met:

[0060] ①Surface roughness is less than or equal to Ra0.5;

[0061] ② The outer circle size is φ50.95~φ50.975mm, and the roundness of the outer circle is less than or equal to 0.02.

[0062] If conditions ① and ② are met at the same time, it means that the semi-finished pump hub after cold extrusion is a qualified product, and then the finished pump hub is obtained.

[0063] If condition ① is not met, return to step S7 for rework until the roughness meets the requirements, thereby obtaining a finished pump hub.

[0064] If condition ② is not met, it is first judged. If there is machining allowance, it returns to step S6 for repair; if there is no machining allowance, it is scrapped.

[0065] If both conditions ① and ② are not met, the part is first judged. If there is machining allowance, the part is returned to step S6 for repair, and then continues to step S7, followed by further inspection. If there is no machining allowance, the part is scrapped.

[0066] The surface roughness of the finished pump hub obtained by the method of this embodiment is less than or equal to Ra0.5, the outer circle size is φ50.95~φ50.975mm, and the roundness of the outer circle is less than or equal to 0.02, which fully meets the design and use requirements of the pump hub 2 without changing the original processing accuracy and has excellent comprehensive performance.

[0067] Example 2

[0068] This embodiment provides a processing method for reducing the surface roughness of a torque converter cover wheel, the method specifically comprising the following steps:

[0069] S1, stamping the torque converter cover wheel blank according to design requirements.

[0070] like Figure 2 As shown, the cover wheel blank in this embodiment is made of carbon structural steel, a material with excellent cold-forming properties, ease of stamping, and good weldability. The carbon structural steel used for the cover wheel is hot-rolled, pickled, low-carbon structural steel plate, which has high requirements for mechanical properties and surface quality, but relatively low requirements for hardness and surface roughness. Specifically, the mechanical property requirements are: a tensile strength of no less than 400 MPa and a yield strength of no less than 255 MPa; the surface quality requirements are: no cracks, scars, folds, bubbles, inclusions, or other defects that could be detrimental to use.

[0071] S2, welding the cover wheel blank to the cover wheel and the connecting block, cooling, and then placing it on a CNC lathe for rough processing, removing excess material after stamping, leaving a processing allowance of 0.10 to 0.15 mm, and obtaining a cover wheel semi-finished product.

[0072] S3, finish machining the cover wheel semi-finished product on a CNC lathe to remove the excess.

[0073] S4, cold extrusion is performed on the inner surface of the semi-finished cover wheel after fine processing.

[0074] The cold extrusion method of this embodiment is the same as that of the semi-finished pump hub, that is, the same CNC lathe is used for the finishing process in step S3. After finishing, the turning tool is switched to a diamond roller burnishing extrusion tool (such as a diamond roller burnishing tool) used for cold extrusion. Figure 3 As shown), rotate the cover wheel and press the extrusion knife on the inner cavity surface of the cover wheel, and move the extrusion knife to achieve extrusion of the inner cavity surface.

[0075] S5, performing a test on the semi-finished cover wheel after fine processing. If the surface roughness of the semi-finished cover wheel is Ra0.2-Ra0.6, proceed to step S6; otherwise, return to step S4;

[0076] S6, perform two inspections on the semi-finished cover wheel after cold extrusion. If the wall thickness is 3.7~4.0mm and the flatness of the inner cavity surface is less than or equal to 0.05, it means that the semi-finished cover wheel after cold extrusion is qualified, and then the finished cover wheel is obtained; otherwise, the semi-finished product that fails the inspection is judged first. If there is machining allowance, return to step S3 for repair; if there is no machining allowance, it is scrapped.

[0077] By using the processing method of this embodiment, the surface roughness of the cover wheel product finally obtained is Ra0.2-Ra0.6, and the flatness is less than or equal to 0.05, which fully meets the roughness requirements of the cover wheel product.

[0078] Although a number of embodiments of the present invention have been shown and described above, it will be apparent to those skilled in the art that any changes or modifications to the above embodiments should fall within the scope of protection of the present invention as long as they fall within the spirit of the present invention.

Claims

1. A processing method for reducing the surface roughness of a torque converter pump hub, characterized in that: The following steps are involved: S1, forging the torque converter pump hub blank into shape according to design requirements; S2, rough machining the pump hub blank using a CNC lathe, leaving a machining allowance of 0.65 to 1.25 mm; S3, heat treating the rough-machined pump hub blank according to the hardness requirements of the torque converter pump hub product; S4, semi-finishing the heat-treated pump hub blank by a CNC lathe, leaving a machining allowance of 0.15 to 0.25 mm on the outer cylindrical surface to obtain a semi-finished pump hub; S5, inspect the semi-finished pump hub. If the outer surface roughness is less than or equal to Ra3.2 and the machining allowance of the outer diameter is 0.15-0.25 mm, weld the qualified semi-finished pump hub to the impeller body and cool it, and proceed to step S6; otherwise, return to step S4; S6, finishing the semi-finished pump hub on a CNC lathe to remove the excess; S7, cold extruding the outer cylindrical surface of the semi-finished pump hub after fine processing; the cold extrusion and the fine processing in step S6 are performed using the same CNC lathe, and after fine processing, the turning tool is switched to a diamond roller burnishing extrusion tool used for cold extrusion, the pump wheel body is rotated and the extrusion tool is pressed against the outer cylindrical surface of the pump hub, and the extrusion tool is moved to achieve extrusion of the outer cylindrical surface; S8, performing a test on the cold-extruded semi-finished pump hub. If the surface roughness of the semi-finished pump hub is less than or equal to Ra0.5, proceed to step S9; otherwise, return to step S7; S9, perform a second inspection on the cold-extruded pump hub semi-finished product. If the outer circle size is φ50.95~φ50.975mm and the roundness of the outer circle is less than or equal to 0.02, it means that the cold-extruded pump hub semi-finished product is qualified, and then the pump hub finished product is obtained; otherwise, return to step S6.

2. The method for reducing the surface roughness of a torque converter pump hub according to claim 1, characterized in that: In step S1, the pump hub blank is made of alloy structural steel.

3. The method for reducing the surface roughness of a torque converter pump hub according to claim 2, characterized in that: In step S3, the hardness requirement of the pump hub product is HRC35~HRC45. The heat treatment process first performs quenching treatment and then tempering treatment. The quenching temperature is 850℃~900℃, the quenching time is 90~110 minutes, and the tempering temperature is 420℃~460℃, and the tempering time is 120~140 minutes.

4. The method for reducing the surface roughness of a torque converter pump hub according to claim 3, characterized in that: In step S5, before returning to step S4, the unqualified semi-finished products are first judged. If there is machining allowance, the process returns to step S4 for repair; if there is no machining allowance, the semi-finished products are scrapped.

5. The method for reducing the surface roughness of a torque converter pump hub according to claim 4, characterized in that: In step S7, before returning to step S6, the unqualified products after the second inspection are judged. If there is machining allowance, return to step S6 for repair; if there is no machining allowance, the products are scrapped.

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