Machining method of supporting bearing

Abstract

The invention relates to the technical field of machining, in particular to a machining method of a support bearing, which comprises the following steps: after finish turning of the support bearing, sequentially carrying out rough grinding of an inner hole, accurate grinding of an outer circle and an end surface, accurate grinding of a large end surface by adopting a surface grinding machine, final accurate grinding of the inner hole and milling of an oil wedge surface. According to the method, the traditional process route of'reference in advance 'is changed, clamping scratches before final accurate grinding of the inner hole are effectively avoided, and the stability of the roughness of the large end face is guaranteed through surface contact machining of a surface grinding machine; and meanwhile, temporary coloring treatment is conducted on the large end face obtained after accurate grinding, a visual contrast layer easy to identify is formed, the problems of inner hole scratches, end face roughness fluctuation and machining reflection interference are effectively solved, and the machining quality, consistency and production efficiency of the supporting bearing are improved.

Description

Technical Field

[0001] This invention relates to the field of machining technology, and in particular to a machining method for a support bearing. Background Technology

[0002] In recent years, with changes in the international situation, my country's shipbuilding industry has developed rapidly, maintaining a leading global market share. As a crucial component of marine diesel engines, the turbocharger's technological level directly affects the engine's efficiency. The support bearing is the core component of the turbocharger, connecting the assembly relationships of the entire turbocharger turbine assembly. Therefore, to ensure the assembly quality of the turbocharger, the dimensional control and geometric tolerance control of the inner bore, outer circle, and large end oil wedge surface of the support bearing are particularly important.

[0003] The original process is described in detail below: 10. Rough turning: Clamp the small outer diameter with a three-jaw chuck, align the workpiece, smooth the large end face, turn the large outer diameter (leaving a 2mm allowance), turn the inner hole (leaving a 2mm allowance), and chamfer the hole opening with a 1×30° angle. 20. Rough turning: Turn around, use the three-jaw chuck to machine the large outer diameter, flatten the end face, align the workpiece to machine the outer diameter, machine the end face to the total length (leave 2mm allowance), machine the small outer diameter (leave 2mm allowance), length D (drawing dimension). 30 Heat treatment: Annealing of castings to relieve stress; 40 precision turning: The large outer diameter has been machined with a soft three-jaw chuck, the large end face is flat, and the small end face is machined to remove 0.5mm of allowance. Then, it is machined according to the drawing requirements. A single-sided grinding allowance of 0.15mm is left on the outer diameter, end face and bearing retainer inner hole. The remaining positions are machined to the required position. 50 precision turning: turn around, use a soft three-jaw chuck to clamp the small outer diameter, flatten the end face, turn the end face and the large outer diameter (leave a 0.15mm grinding allowance on one side), and chamfer the inner hole of the outer diameter (the theoretical dimension on the drawing plus the allowance). 60 CNC milling: The workshop provides its own mandrel to clamp the parts, mills the positioning semi-circular hole of the parts according to the drawing requirements, drills the upper hole of the outer circle, and then mills the upper plane of the outer circle; 70 clamp: Mill the sharp edges and chamfer 0.5×45°, and chamfer the outer and inner edges of each hole according to the drawing (plus grinding allowance); 80 Grinding the inner hole: Install the fixture, align the inner hole of the fixture and the fixture positioning surface so that the runout is no more than 0.01, install the workpiece, align the inner hole of the part so that the runout is no more than 0.03, tighten, and grind the inner hole to the final size; 90 Grinding the outer diameter and end face: The workpiece is loaded into the mandrel, clamped by two centers, and ground to the final size requirement according to the drawing requirements, with a grinding allowance of 0.007mm left on the large end face; 100 Grinding of the large end face: Grind the large end face according to the final length requirements of the drawing; 110 CNC Milling Oil Wedge Surface: Mill the oil wedge surface on the workpiece using a milling tool according to the drawing; 120 Polishing large end face: Scrape off the oil wedge surface, clean the parts to meet the drawing requirements, engrave the lettering as required by the drawing, and polish the large end face until it meets the drawing requirements. 130 Inspection: Perform magnetic particle crack detection according to the drawings and specifications; 140 clamps: Cleaning parts; special cleanliness levels are handled according to drawings and specifications.

[0004] Using the above procedures, a support bearing for a certain machine model (see [link]) is manufactured. Figure 1 During the milling process, internal hole scratches occur, and the surface roughness of the large end face is unstable. The surface roughness of batches of parts fluctuates between RZ1.6 and RZ6.4, failing to fully meet the RZ2.5 requirement. Each batch requires rework to meet the part drawing requirements. When milling the large end face oil wedge surface, the excessive gloss (grinding is necessary to ensure the surface roughness requirement, but grinding results in a reflective finish) makes it difficult to observe the finishing line during oil wedge surface machining, as the reflection is glaring and obscures the dimensions. The original process used grinding and polishing of the large end face to solve the reflectivity problem; however, grinding easily affects surface quality, while polishing easily causes scratches on the large end face surface. These problems severely delay production, reduce production efficiency and product quality, and increase processing costs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for processing a support bearing, which solves the problems of easy scratching of the inner hole, unstable roughness of the large end face, and difficulty in observation and ensuring processing accuracy due to end face reflection during oil wedge milling in existing processing technology.

[0006] To achieve the above objectives, the present invention provides a method for processing a support bearing, comprising the following steps: S1: Rough machining of the support bearing, including rough machining of the outer diameter, inner hole and end face of the large and small ends respectively; S2: Heat treatment is performed on the parts after rough machining; S3: Perform precision machining on the heat-treated parts, including precision machining of the inner hole, outer circle and end face of the bearing retainer, and leave grinding allowance at the small end; S4: Perform CNC milling on the precision-machined parts to mill the positioning semi-circular holes and drill the outer circular holes; S5: Perform chamfering by fitter; S6: Roughly grind the inner hole, retaining the finishing allowance; S7: Fine grind the outer diameter, small end face and inner side of the large end, and rough grind the outer side of the large end; S8: Use a surface grinder to precision grind the large end face to the final dimensional requirements; S9: Fine-grind the inner hole to the final size; S10: Perform oil wedge milling on the large end face.

[0007] In step S3, The grinding allowance reserved at the small end is 0.1mm.

[0008] In step S6, When rough grinding the inner hole, leave a 0.15mm allowance according to the inner hole size.

[0009] In step S7, The parts are clamped using a tapered mandrel for precision grinding of the outer diameter and end face. Before clamping, the runout of the outer diameter of the tapered mandrel should not exceed 0.003mm.

[0010] In step S8, The part is clamped using a surface grinder. After positioning the small end face of the support bearing, the large end face is ground to the final size.

[0011] In step S9, A spring clip is used to clamp the outer diameter of the part for fine grinding of the inner hole, and a copper pad is placed between the clip and the part.

[0012] Specifically, step S10 includes: S101: Color treatment is applied to the large end face after fine grinding to form a uniform coloring layer; S102: Perform oil wedge milling on the large end face after coloring; S103: Clean and remove the coloring layer on the large end face.

[0013] The coloring layer is used to reduce surface reflection when milling the oil wedge surface, and the color difference between the color layer and the machined surface is used to clearly identify the machining boundary.

[0014] The coloring process involves applying a temporary oil-based coating to the large end face.

[0015] This invention discloses a method for machining a support bearing. By adjusting the machining sequence, the fine grinding of the inner hole is placed after the fine grinding of the outer diameter and the fine grinding of the large end face. This effectively avoids the problem of scratches on the inner hole caused by using the finely machined inner hole as a reference and then machining other parts through a mandrel, thus improving the surface quality and consistency of the inner hole. A surface grinder is used instead of the original cylindrical grinder for end face machining. The large end face is ground by surface contact using the grinding wheel end face, changing the situation of rapid wheel wear and unstable machining quality caused by line contact grinding in the original process. This significantly improves the stability and machining accuracy of the large end face roughness, consistently achieving a roughness better than RZ2.5. Simultaneously, a temporary coloring treatment is applied to the finely ground large end face. During subsequent milling of the oil wedge surface, the clear color contrast between the unmachined colored area and the machined area (where the coloring layer is removed) allows the operator to clearly and accurately identify the machining boundary (tail line) of the oil wedge surface, thereby ensuring the dimensional accuracy of the oil wedge surface. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0017] Figure 1 This is a schematic diagram of the supporting bearing structure.

[0018] Figure 2 This is a schematic diagram of the roughing process in step S1 of the present invention.

[0019] Figure 3 This is a schematic diagram of the operation of the precision machining process in step S3 of the present invention.

[0020] Figure 4 This is a schematic diagram of the operation of step S3, rough grinding of the inner hole, in this invention.

[0021] Figure 5 This is the general drawing of the grinding inner hole tooling of the present invention.

[0022] Figure 6 This is a schematic diagram of the tapered mandrel of the present invention.

[0023] Figure 7 This is a schematic diagram of the operation of step S7 of the present invention, which involves fine grinding of the outer circle, small end face, inner side of the large end, and rough grinding of the outer side of the large end.

[0024] Figure 8 This is a schematic diagram of the structure of the grinding tool for the large end face of the support bearing of the present invention.

[0025] Figure 9 This is a schematic diagram of the operation of step S9, the fine grinding of the inner hole, in this invention.

[0026] Figure 10This is a schematic diagram of the original process for precision grinding the outer circle and end face.

[0027] Figure 11 This is a flowchart of the processing method for the support bearing of the present invention. Detailed Implementation

[0028] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0029] Please see Figures 1 to 11 This invention provides a method for processing a support bearing, comprising the following steps: S1: Rough machining of the support bearing, including rough machining of the outer diameter, inner hole and end face of the large and small ends respectively.

[0030] In this embodiment, please refer to Figure 2 First clamping (corresponding to the original process 10): Use a three-jaw chuck to clamp the small outer circle of the part, align the workpiece, smooth the large end face, turn the large outer circle (leaving a 2mm allowance), turn the inner hole (leaving a 2mm allowance), and finally, perform a 1×30° chamfering on the opening of the rough-turned inner hole. Second clamping (corresponding to step 20 of the original process): Turn the part around and use a three-jaw chuck to clamp the large outer diameter that has been rough-turned in the first clamping, ensuring that the end face of the part is flush with the end face of the chuck. Align the rough-turned outer diameter and turn the other end face of the part to the total length, leaving a 2mm machining allowance for the total length. At the same time, rough-turn the small outer diameter of the part, leaving a 2mm single-sided allowance, and machine it to the preliminary dimension of axial length D (D is the dimension marked on the drawing).

[0031] S2: Heat treatment is performed on the parts after rough machining.

[0032] S3: Perform precision machining on the heat-treated parts, including precision machining of the inner hole, outer circle and end face of the bearing, and leave grinding allowance at the small end.

[0033] Specifically, the grinding allowance reserved at the small end is 0.1mm.

[0034] In this embodiment, please refer to Figure 3 First clamping (corresponding to the original process 40): Use a soft three-jaw chuck to clamp the large outer diameter that has been rough-turned, and use the large end face of the part as the axial positioning reference to turn the small end face of the part to remove 0.5mm of machining allowance; then finish turn the bearing retainer inner hole, related outer diameters and each end face.

[0035] Second clamping (corresponding to step 50 of the original process): Turn the part around and use a soft three-jaw chuck to clamp the small outer diameter of the part, positioning it with the corresponding end face flat. After clamping and alignment, finish turn the other end face and the large outer diameter (leaving a grinding allowance of 0.15mm on each side), and chamfer the inner hole of the outer diameter.

[0036] S4: Perform CNC milling on the finished parts to mill the positioning semi-circular holes and drill the outer circular holes.

[0037] S5: Perform chamfering by fitter.

[0038] In this embodiment, the processes of steps S1-S5 of the present invention are performed according to the original process (see 10-70 of the original process in the background art for details). The only difference is that when finishing the small end in step S3, it is no longer finished to the final size, and a grinding allowance of 0.1mm needs to be reserved for the small end.

[0039] S6: Roughly grind the inner hole, leaving room for finishing.

[0040] Specifically, when rough grinding the inner hole, leave a margin of 0.15mm according to the inner hole size.

[0041] In this embodiment, an internal grinding fixture is used during operation (see [link to documentation]). Figure 5 First, install the fixture onto the machine tool and align it, ensuring that the runout of the fixture's inner hole and locating end face is no greater than 0.01mm. Then, place the part into the fixture and align it again, controlling the runout of the part's inner hole to within 0.03mm. After confirming that everything is correct, tighten and secure it. In the positioning and clamping state, perform grinding on the inner hole, leaving a 0.15mm allowance according to the final dimensions of the inner hole as shown in the drawing (see [reference]). Figure 4 This completes the rough grinding process of the inner hole.

[0042] S7: Fine grind the outer diameter, small end face and inner side of the large end, and rough grind the outer side of the large end.

[0043] Specifically, a tapered mandrel is used to clamp the parts for precision grinding of the outer diameter and end face. Before clamping, the runout of the outer diameter of the tapered mandrel should not exceed 0.003mm.

[0044] In this embodiment, a tapered mandrel is used to clamp the part for fine grinding of the outer diameter and end face. Before clamping, the runout of the outer diameter of the tapered mandrel is no more than 0.003 mm. Furthermore, since step S6 only rough-grinds the inner hole, its dimensions have not yet met the final requirements. Therefore, the mandrel used for fine grinding of the outer diameter in the original process cannot be used directly. Thus, a high-precision tapered mandrel needs to be redesigned and machined according to the current inner hole dimensions of the part (see [link to documentation]). Figure 6Before external cylindrical grinding, re-measure the runout of the tapered mandrel to be no more than 0.003mm. After passing the test, clamp the part and re-measure the runout of the mandrel. After passing the test again, finish grind the two outer diameters, the small end, and the inner side of the large end of the part to the final size. Leave a 0.05mm allowance on the large end face during semi-finish grinding (see [reference]). Figure 7 ).

[0045] S8: Use a surface grinder to finely grind the large end face to the final dimensional requirements.

[0046] Specifically, a surface grinder is used to clamp the parts, and after positioning the small end face of the support bearing, the large end face is ground to the final size.

[0047] In this embodiment, because the small end face area of ​​the part is relatively small, a surface grinder is used to ensure stable clamping and safe machining (see [link]). Figure 8 During machining, place the part with its small end face down on the worktable of the surface grinder. Then, use the surface grinder tool to clamp the two sides of the outer diameter of the part to achieve reliable fixation. After clamping, start the surface grinder to grind the large end face to dimension X 0-0.012 and total length Y0-0.1, ensuring the flatness of 0.01, parallelism of 0.02 and roughness RZ2.5 as required by the drawing.

[0048] S9: Fine-grind the inner hole to the final size; Specifically, a spring clip is used to clamp the outer circle of the part for fine grinding of the inner hole, and a copper pad is placed between the clip and the part.

[0049] In this embodiment, a spring clip is used to clamp the outer diameter of the part. During clamping, copper pads are placed between the inner ring of the clip and the outer diameter surface of the part. After clamping, the part is aligned to ensure that the combined runout of the large outer diameter, the clamped outer diameter, and the large end face does not exceed 0.005mm. After successful alignment, the inner hole is precision ground to the final dimensions specified in the drawing on an internal grinding machine (see [reference]). Figure 9 After machining, the runout of the outer circle and end face of the part to the reference inner hole can be stably controlled between 0.003mm and 0.008mm, as measured by a coordinate measuring machine.

[0050] S10: Perform oil wedge milling on the large end face.

[0051] Specifically, S101: The large end face after fine grinding is colored to form a uniform coloring layer; S102: Perform oil wedge milling on the large end face after coloring; S103: Clean and remove the coloring layer on the large end face.

[0052] The coloring layer is used to reduce surface reflection when milling the oil wedge surface, and the color difference between it and the machined surface makes the machining boundary clearly identifiable.

[0053] The coloring process involves applying a temporary oil-based coating to the large end face.

[0054] In this embodiment, before performing the milling process, an oil-based marker is used to evenly color the entire large end face of the part (through testing of various colorants, it was finally confirmed that the pigment in the oil-based marker is insoluble in cutting fluid and easily cleaned by common cleaning agents). After completing the milling preparation, the part is clamped onto a dedicated oil wedge milling fixture, and milling is performed according to the CNC program. During the milling process, the coloring layer on the surface of the area being cut by the tool is removed, exposing the original color of the metal substrate; while the unprocessed area retains the coloring layer completely, thus forming a clear and intuitive color contrast between the processed and unprocessed areas, making the observation and judgment of the processing boundary clear and accurate. After milling, a fitter's scraping and cleaning treatment is performed, and an industrial cleaning agent is used to remove the residual coloring paint on the large end face, restoring the part to a clean surface state. This cleaning process will not cause scratches or other damage to the finely ground large end face surface. Finally, engraving and other processes are completed according to the drawing requirements.

[0055] The present invention addresses the problem of internal hole scratches in the bearing processing method. Since the internal hole is the datum, the original process first precision-machines the internal hole, then passes a mandrel through it to machine the outer diameter and end face, resulting in scratches on the internal hole when the mandrel is removed. To address this issue, a new processing method is developed that does not follow the principle of datum-first machining. The outer diameter and end face are machined first, followed by the internal hole. This method achieves good surface quality of the internal hole while ensuring that the outer diameter and end face meet the high-precision dimensional requirements and geometric tolerances of the drawings.

[0056] Regarding the issue of unstable surface roughness in large end faces: The original process used an external cylindrical grinder to process both the outer diameter and end face of the part in one pass. The outer diameter machining involved contact grinding with the outer diameter of the grinding wheel, resulting in stable machining quality and good surface roughness. However, when machining the end face, only the side of the grinding wheel could be used to grind the end face, resulting in line contact. Because line contact grinding wheels wear out quickly and the grinding wheel regrinding frequency cannot be controlled, the machining quality and surface roughness of the end face became unstable (see simplified diagram of the original machining method). Figure 10 It was decided to use a surface grinder to process the large end face, in order to solve the problem of unstable end face roughness while ensuring the machining dimensional accuracy and geometric tolerances.

[0057] Regarding the issue of glare on the oil wedge end face: Since the large end face (oil wedge end face) is machined using a grinding machine, its glossy surface causes glare when observing the finishing line of the oil wedge surface with a flashlight during milling. This glare is dazzling and makes observation difficult, making it impossible to fully guarantee the oil wedge dimensions. Because the original grinding and polishing process would reduce the surface quality of the large end face, it was decided to abandon the original grinding and polishing method and explore a new pigment that is easy to color, insoluble in cutting fluid, and easy to clean. This would solve the glare problem without affecting the end face machining quality, thus ensuring the machining quality of the oil wedge surface.

[0058] In summary, by combining the above three new processing methods and approaches, the original process was improved, ultimately resulting in a new processing route for the parts.

[0059] The present invention has the following beneficial effects: 1. It solved the problem of scratches on the inner hole, ensured the surface quality of the inner hole of the part, avoided rework, improved production efficiency, and reduced production costs; 2. It solved the problem of unstable surface roughness of the large end face, improved the surface roughness of the large end face, improved product quality, avoided rework, improved production efficiency, and reduced production costs; 3. It solves the problem of reflection on the large end face, improves production efficiency, ensures processing quality, and reduces the processing difficulty for operators (the large end face after grinding in the original process is not as clear as the large end face coloring observation in the new method). 4. Reduced processing difficulty and increased processing efficiency (The original process used a cylindrical grinding machine to process the large end face, which was not easy to guarantee the accuracy requirement of 0.01mm in the end face thickness. It required measuring while processing to make up the allowance, which required high operator skills. However, with the surface grinding machine in the new method, it is only necessary to flatten the small end and measure the allowance before starting processing). 5. Improved the machining quality of parts, better guaranteed the dimensional and behavioral tolerance requirements of parts, and facilitated part assembly (the roughness of the large end face is improved. The best machining roughness of the original process is RZ1.6, while the new method can achieve RZ0.6; the form and position tolerances are better. The runout of the outer circle and end face of the parts under the original process mostly fluctuates within 0.012mm, while the form and position tolerances of the new method can reach 0.003mm-0.008mm).

[0060] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A method of machining a support bearing, characterized in that, The method comprises the following steps: S1: rough turning the support bearing, including rough turning the outer circle, inner hole and end face of the large end and small end respectively; S2: heat treating the rough-turned part; S3: finish turning the heat-treated part, including finish turning the inner hole, outer circle and end face of the bearing groove, and reserving grinding allowance on the small end; S4: numerically milling the finish-turned part, milling the positioning semicircular hole and drilling the outer hole; S5: performing bench work chamfering processing; S6: rough grinding the inner hole, reserving finish machining allowance; S7: finish grinding the outer circle, small end face and large end inner side, and rough grinding the large end outer side; S8: using a surface grinder to finish grind the large end face to the final size requirement; S9: finish grinding the inner hole to the final size; S10: performing oil wedge face milling processing on the large end face.

2. The method of claim 1, wherein the support bearing is a ball bearing. In step S3, the grinding allowance reserved on the small end is 0.1 mm.

3. The method of claim 1, wherein the support bearing is a ball bearing. In step S6, when rough grinding the inner hole, 0.15 mm allowance is reserved according to the size of the inner hole.

4. The method of claim 1, wherein the support bearing is a ball bearing. In step S7, a tapered mandrel is used to clamp the part for finish grinding the outer circle and end face, and the runout of the outer circle of the tapered mandrel before clamping is not greater than 0.003 mm.

5. The method of claim 1, wherein the support bearing is a ball bearing. In step S8, a surface grinding tool is used to clamp the part, the small end face of the support bearing is positioned, and then the large end face is ground to the final size.

6. The method of claim 1, wherein the support bearing is a ball bearing. In step S9, a spring collet is used to clamp the outer circle of the part for finish grinding the inner hole, and copper sheet is padded between the collet and the part.

7. The method of claim 1, wherein the support bearing is a ball bearing. The step S10 specifically comprises: S101: performing coloring processing on the finish-ground large end face to form a uniform colored layer; S102: performing oil wedge face milling processing on the colored large end face; S103: cleaning to remove the colored layer on the large end face.

8. The method of claim 7, wherein the support bearing is a ball bearing. The colored layer is used to weaken the surface reflection when milling the oil wedge face, and the processing boundary is clearly identified through the color difference between the colored layer and the processing surface.

9. The method of claim 7, wherein the support bearing is a ball bearing. The coloring processing is coating the large end face with temporary oil-based paint.

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