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The use of re-production skills in bearing and outer ring machining
Source: China Bearing Network Time: 2014-07-15
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Keywords: Rolling bearing, oversize, re-production skills
Application of Remanufacturing Technology to Oversize of Bearing Inner and Outer Ring
LI Jiang-ying1, LI Yan-yan2, LIN Shi-min2, LIN Song1, JIANG Qing-guo3, PENG Xing-li1
(1. The North China University of Technology, College of Mechanical and Electrical Engineering, Beijing 100144; 2. Aoyuksin Surface Engineering Technology Company Co., Ltd., Beijing 101400; 3. The former Beijing People's Bearing Factory. Beijing, 102213)
Abstract: This paper analyzes the location and reason that lead to oversize in the processing of bearing inner race and outer race. We explained the principle and application of the remanufacturing technology which includes the re-melting at normal temperature and AK brush plating under inverse and variable electrical pulse in details, and then we introduced the process of remanufacturing technology, at last we did metallographic analysis experiment to Interpret the result of repairing oversize of bearing inner race and outer race. The quality of the remanufacturing bearing has fulfilled the standards of new produced one, which has been verified by many repair examples. The process cycle has been lowered down to half, and the cost of the remanufacturing bearing also has been cut down by 50 percent compared to produce new one and the performance can fulfill usage requirements as well achieve good results, all of those conform to the development Of circular economy.
Keywords: rolling bearing; oversize; remanufacturing technology
As an important mechanical basic component for the matching and repair of various electromechanical products, its function and horizontal slow quality have a direct impact on the accuracy and function of the main engine. The development of China's bearing profession is rapid; however, it is still relatively large compared with the international bearing industry. Distance. During the bearing production process; the machining tolerance in the bearing and the outer ring seriously affects the bearing quality; and the machining parts are out of tolerance; it not only brings a huge economic loss to the bearing production company in the data cost; The loss of time and money that cannot be delivered to the product on time is immeasurable. The direct or direct economic loss caused by the bearing profession is at least 100 million yuan per year; and the repeated production has created a great impetus for the environment and the environment. Pollution.
The circular economy is based on the efficient use and recycling of resources; the principle of reduction, reuse and re-production; the social production and re-production activities with low consumption, low emission and high efficiency. Circular economy As long as the production can give higher added value to the waste resources. Apply the re-production skills to the bearing and the outer ring processing tolerance; the theory indicates that the production cycle of the remanufactured bearing can be reduced by half; the cost of making the production is at least lower than that of the new product. More than 50%; the quality of the product reaches the new product specification. Satisfying the application needs and the role is outstanding; the maximum limit saves resources and power.
1 Bearing ferrule processing is out of the way because of the characteristics of large or extra large bearing processing technology; processing over tolerance problems often occur on large or extra large bearing parts; more common in the inner circle of the inner ring, the outer circle of the outer ring And the side of the inner and outer rings and other parts. These parts are mainly used for equipment and equipment bearings; it is matched with the bearing seat or shaft; it is an important cooperative working surface of the bearing.
In the processing process of bearing ring; grinding is the process that ends with the accuracy of the scale of the ferrule. The size and shape of the ferrule after grinding have reached the skill needs of the product; the final super-finishing process does not cost The scale of the ferrule; only improve the quality of its appearance. Therefore, the shortcomings such as the processing of the ferrule are prone to occur in the grinding process (of course, there may be an extension of some disadvantages of the genetic elements forming the ferrule of the previous process. In the following; the following is the analysis of the disadvantages of the outer diameter and inner diameter of the ferrule:
1. The outer diameter of the ferrule is out of tolerance. 1) The grinding machine feed arrangement is not accurate,
.2) the temperature difference between the workpiece and the gauge is too large,
.3) The workpiece to be ground is too large or too much.
.4) The grinding parameters are too large; the grinding depth is too large,
.5) The grinding wheel is worn or trimmed poorly,
.6) The grinding wheel is too large,
.7) Longitudinal or horizontal feed is too fast,
.8) Operation or adjustment error.
1. 2 ferrule outer diameter wear. 1) front guide plate excellent guide wheel operation line,
.2) too much at the entrance,
.3) The rear guide plate's outstanding guide wheel busbar prevents the workpiece from rotating normally.
.4) the guide plate at the exit extends too long; the workpiece has too much backlog; the workpiece "stops" the appearance,
.5) the middle of the workpiece is too high; the workpiece at the exit is beaten,
.6) The rear guide is lower than the guide busbar,
.7) The orientation of the baffle on the side of the grinding wheel is not properly adjusted.
1.3 ferrule inner diameter scale is out of tolerance (excessive inner diameter)
When using the electromagnetic centerless clamp to grind the inner hole; in addition to the above reasons;
.1) the scale of the supported surface is out of tolerance,
.2) The aperture of the workpiece being ground is too large; it exceeds the active feed stroke.
1.4 The elements inherited from the previous process. 1) The machining clamping force is too large or the turning stress is too large.
.2) Poor heat treatment process; excessive austenite, insufficient tempering, etc.
The reasons for these artificial elements or machine tools and equipment can lead to the process of processing the bearing rings; the ferrules are subject to shortcomings such as processing tolerance; the ferrule scale and shape can not meet the skill needs of the products; Obsolete.
2 processing over-production and re-production skills Beijing Aoyu Kexin Appearance Engineering Skills Co., Ltd. based on the raw materials, size, working conditions, processing and other methods of the bearing; use AK (Aoyu Kexin abbreviation) re-production skills; Inner and outer ring processing is super-deformed for re-production. The bearing processing is super-re-production and the skill is selected to use the AK mechanical parts re-production skill to correct the machining tolerance of the inner and outer diameters of the bearing ring and the inner side and the outer side of the outer ring; Rehabilitation to the original norm set; and satisfied with the functional needs of the new product; reaching or surpassing the new product specification.
2.1 Normal temperature cold remelting skills: Regarding the groove, pit or small area of ​​the non-rolling working surface orientation in the bearing and the outer ring, the machining is too poor; the selection of the mechanical parts remanufacturing skills in the normal temperature cold remelting Skills are reproduced.
AK normal temperature cold reflow welding repair skills in the entire welding process has the following characteristics: the material and the metallurgical connection of the matrix; the connection is strong, fine, does not fall, the parts are not hot, no deformation, no cracks, no annealing softening appearance; Suitable for all kinds of precision parts and fine parts damage welding, can be welded with shape; repair layer thickness is uniform and controllable; does not damage the benchmark; can be applied to damage repair that can not be machined, according to the special use of parts damage parts Functional needs; after the selection of different supplements; the function of the weld repair to reach the application needs; if you can choose 65Mn to meet the need for satisfactory hardness; select stainless steel to meet the anti-corrosion function, etc., special corrections for some unknown raw materials It is necessary to repair the raw materials together; it can be used as a supplement by taking scraps or powder from the unimportant parts of the parts.
According to the different raw materials of the bearing and its working conditions; can choose different materials for the repair and repair scale.
2.2 AK inverter electrical pulse brush plating technology on a large area machining tolerance as the appearance of the entire selection process ultra difference may AK inverter pulse brush plating skills re-production.
AK inverter pulse nano-brush plating technology has improved the coating density, coating thickness (unconstrained), hardness (1.5 times to 1. 7 times higher than traditional rapid nickel hardness), wear resistance (compared to traditional speed Nickel wear resistance improved by 1. 6~2. 5 times) and contact strength; anti-touch fatigue function is good (anti-touch fatigue life is improved from 105r to 106r), and the service temperature is high (from 200 °C to 400 °C); The internal stress is reduced; the metal plating can be deposited on two or more kinds of raw materials together; the metal plating can be deposited on the unknown raw materials and the lazy raw materials. The fatigue life reflects the strength, hardness, and resistance of the nano-brush plating. Inductive function; overcomes the problem that the plating contact strength of brush plating can not be achieved in the past. The coating still has high hardness and excellent wear resistance at 400 ° C. Align the bearings with different materials and their working conditions; Different function of the metal plating solution for scale recovery; its function is equivalent to new products.
3 Re-manufacturing skill flow 3. 1 Processing over-difference bearing into the factory will be determined by the measurement to be the bearing of the machining tolerance into the re-production workshop to be repaired.
3.2. Measuring and processing the over-contrast bearing to determine the bearing material, working conditions, processing over-constrained parts, area and processing tolerance; to determine which processing over-production re-production skills are selected. The area is relatively large; When the over-difference is in the range of 0. 001~2mm, the AK inverter pulse brush plating technique is used, and the bearing with the excess value exceeds this scale; the normal temperature cold remelting skill correction can be selected.
3.3 Remanufacturing of processed over-difference bearings. 1) Pre-disposal: After the inspection and measurement, the processing of the over-poor parts shall be pre-disposed; for the formal implementation of the re-production skills, the preparatory work shall be completed.
.2) Select the suitable AK bearing inner and outer ring to process the over-reproduction skills and re-manufacture the processing. As shown in the following figure: Figure 1 shows the normal temperature cold remelting skill correction bearing machining tolerance; Figure 2 shows the AK inverter Electric pulse brush plating skills to correct bearing processing.
.3) Post-disposal: Firstly, the machining of the modified part (or grinding with the AK tooling grinding skill) to the specification scale; satisfactory scale accuracy is required.
3.4 Remanufactured bearing quality inspection Remanufactured bearing fulfillment bearing occupational quality specification is a new product specification; the selection of precise and professional quality inspection skills is a prerequisite for ensuring that the remanufactured parts have outstanding performance functions.
The final inspection and inspection of the finished reworked bearing; including the scale accuracy, contact strength, finish, hardness and other objectives. Repeated re-production experiments on bearing machining tolerance; finally selected the best skill plan. Within one week More than 40 pieces of ¢900mm double row bearings were produced; the raw material was 20Cr2Ni4A; the processing tolerance was 0. 25mm. After the completion of the production, there was no correction trace; no color difference; scale public service ± 0. 01mm; hardness 53~55HRC; rough appearance Degree Ra = 0. 04μm; passed the color flaw detection test; arrived at the new product specification. As shown in Figure 3.
Fig.1 Normal temperature cold remeltingFig.2 Brush platingFig.3 After the correction, the 3.5 packaged factory-qualified bearing sets up and then makes the file and then leaves the factory.
4 Re-production role and benefit analysis 4. 1 re-production skills analysis 4.1.1 normal temperature cold remelting skills correction results selection of the base material is high carbon chromium bearing steel GCr15; replenishment is stainless steel. Use normal temperature according to the operating specifications The cold remelting skill is corrected for the machining tolerance of the bearing ring; the metallographic sample prepared in the tolerance position is etched with 4% nitric acid solution; the arrangement characteristics of the coating are investigated under the KYKY-EM3200 digital scanning electron microscope. As shown in Fig. 4, the area of ​​a indicates the matrix arrangement; the area of ​​b indicates the arrangement of the fusion zone; the area of ​​c indicates the arrangement of the stainless steel material. The metallographic experiment shows that the arrangement of the fusion zone is coarser than that of the matrix; however, the fusion zone is slightly micron. 10 μm; There was no change in the matrix arrangement of the area; the matrix arrangement and the replenishment were metallurgical; no cracks occurred.
Fig. 4 Microscopic arrangement after cold remelting correction 4.1.2 AK inverter electric pulse brush plating skill correction results The raw material is high carbon chromium bearing steel GCr15 bearing processing tolerance shortcomings AK inverter electric pulse electricity Brush plating skills for re-production. Corrected according to the operating procedures; preparation of metallographic samples in the tolerance position; corrosion with 4% nitric acid solution; investigation of coating characteristics under the KYKY-EM3200 digital scanning electron microscope. Figure 5 shows the area of ​​the substrate, and the area b indicates the arrangement of the brush plating. The metallographic experiment shows that the thickness of the brush plating is about 200 μm; the plating layer is a single nickel coating; the arrangement is fine and uniform; the thickness of the nickel coating is uniform; Layer representation.
Fig. 5 Micro-arrangement after brush plating correction The boring method is applied to the nickel plating layer; the boring tool is 45° with the sample; the non-primary appearance is removed; the interface between the substrate and the coating is exposed; the appearance of the coating is not present; the coating is clarified Excellent connection.
4.6 Analysis of bearing remanufacturing benefits Apply AK re-production skills to production theory; compare with new product production; as shown in Figure 6: the production cycle of remanufactured bearings can be reduced by half; re-production costs are at least 50% lower than new products. Above; the quality of production reaches the new product specification.
Figure 6 Action comparison 5 Conclusion The re-creation skills are in the condition of not changing the shape of the parts and the raw materials of the parts; the functional skills of the parts are recovered to new products and even beyond the new production skills; it is a component of green production. The re-production skills are highly compatible. The strategic need for China to build an innovative country and build a circular economy; meet the needs of the country's long-term strategy of “saving energy, resources, and accomplishing sustainable development.†After re-production of the processing tolerance of different raw material bearing rings; Prove that AK re-production skills can fully satisfy the needs of remanufacturing of bearing processing; it is an efficient, energy-saving and environmentally friendly production skill.
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