Ring Forging Research Articles

Investigation on collaborative regulation shape, fibrous macrostructure and microstructure of raceway groove in BG801 steel bearing ring with mounted edge

Whether the macro- and micro-structure of bearing ring forging is desired or not greatly decides the property of ring parts. An unreasonable forging design or processing easily leads to the fibrous macrostructure outcrop in the raceway damaging service life. In this study, a novel forging design method of symmetry design on raceway groove (RG) and mounted edge for ball bearing ring with mounted edge structure was proposed. Meanwhile, the height diameter ratio (HDR) of the billet was adjusted to achieve metal fibers distributed along the RG shape in both forging and parts, which was verified by experiments. Fibrous macrostructures of BG801 steel are mainly dominated by primary carbides M23C6/I-M6C and assisted by precipitated carbides II-M6C along matrix shear regions. The microstructure on the RG can be regulated by deformation temperature, in which the texture transforms from Cube to Rotated-Cube than to {332} 〈120〉, the size and content of retained austenite (RA) increase and twin substructure appear within lath martensite with temperature. By optimizing parameters HDR = 1.1 and deformation at 1050 °C, the high strength and hardness of RG were achieved that yield strength (YS), ultimate tensile strength (UTS), and hardness were 671 MPa, 1560 MPa, and 419.9 HV, respectively. The strengthening effect is not only attributed to the desired microstructure of thin film-like RA, dislocation martensite and carbides, but also fine grain strengthening of the prior austenite grain (PAG) that induces almost half of strengthen contribution.

Production Scheduling Optimization during Thermoforming of Ring Forgings Based on Genetic Algorithms

In the aerospace industry, many important components are made of ring forgings with characteristics of multi-variety and multi-batch. Such components have many steps and complex parameters in the thermoforming process. The process orders are dynamic and time-varying, and, thus, optimizing the total production time and energy consumption is difficult. To solve the mentioned troublesome and time-consuming problem, this work transformed the workpiece’s required heating temperature and time index into the furnace temperature change and holding time index. Based on a genetic algorithm, an integrated production scheduling optimization of ring forging heating and model forming was established. The genetic algorithm for model improvement was optimized. The optimization objective was changed by using different fitness calculation methods. A multi-time simulation algorithm was designed to calculate each heating furnace’s time and furnace temperature. The proposed optimization method was used for a thermoforming process of ring forgings. When the optimization objective was designed to consider energy consumption and time consumption comprehensively, the average time saving was 6.93%, and the average energy saving was 12.99%. When the optimization objective was designed to prioritize energy consumption, the average time saving was 3.89%, and the average energy saving was 16.53%. When the optimization objective was designed to prioritize time consumption, the average time saving was 10.35%, and the average energy saving was 10.63%. Using the scheduling results for production, compared with the practical factory data, the errors in the simulation time and energy consumption were 2.4% and 1.6%. The results show that the scheduling efficiency of integrated thermoforming production is significantly improved by using this optimization model, and the simulation results have high reliability. The energy consumption of orders is greatly reduced, and the total production time is greatly shortened.

Effect of regression and re-aging treatment on tensile yield strength anisotropy of 7050 aluminum alloy

In this study, the evolution rule of yeild strength and microstructure along the axial, hoop and radial directions of 7050 aluminum alloy ring forging during Regression and re-aging (RRA) heat treatment was studied by using the experimental technology of tensile property test and transmission electron microscope (TEM) and Electron backscatter diffraction (EBSD) observation. During the RRA process, the evolution rule of intragranular and intergranular precipitates along axial, hoop and radial directions of 7050 aluminum alloy ring forging was described by establishing a model. After the pre-aging stage, the yield strength of samples along the axial, hoop and radial directions of forgings shows obvious anisotropy, and the anisotropy decreases gradually after regression and re-aging treatment. The results show that the cause of the larger yield strength anisotropy is the inhomogeneous size and distribution of precipitates after the pre-aging stage; After the regression stage, the cause of the reduction of the yield strength anisotropy is due to the homogeneous distribution of intragranular precipitates; After re-aging treatment, the reasons of further reduction of the yield strength anisotropy are because of more homogeneous distribution of intragranular precipitates and the discontinuous of intergranular precipitates.

A new section line extraction method of ring forgings based on normal vector and L1-median

Ring forgings are widely used in industrial fields. It is an important way that the key dimensions of ring forgings are obtained by laser scanning to ensure the processing quality. It is difficult to extract high-precision section line of ring forgings from laser point clouds with a lot of noise. This paper presents a new method for extracting section line from raw point cloud of ring forging. An optimization algorithm is created based on the normal vector and L1-median, which is used to iteratively shrink the sampling points for obtaining the section line of ring forgings. L1-median has the characteristics of noise immunity, adding normal vector can get more detailed features. The extraction of high-precision section line of ring forgings is realized. Taking the second-order ring forging and the third-order ring forging as the experimental object, experiments are carried out to verify the effectiveness of the model.

Research on outer diameter measurement method of ring forging based on standard deviation resampling

The utilization rate of forging materials and the forging process parameters are affected by the shape and size of forgings. The measurement of the shape and size of forgings plays a key role in forging quality and efficiency of industrial production. At present, the laser measurement method is commonly used in forging measurement. The relatively large errors in the laser measurement are mainly caused by the dust at the measurement site, the angular deviation of the object and laser scanner, and the system error of the laser scanner. Therefore, a measurement method of outer diameter of ring forgings based on standard deviation algorithm is presented in this paper. Firstly, after resampling by the standard deviation algorithm, the more accurate data are obtained. Secondly, the good arc feature of the point cloud data is obtained by means of mean filter. Finally, the outer diameter of ring forgings is obtained by using ellipse fitting based on least squares principle. The feasibility of this method is verified by measuring two ring forgings with different outer diameters in the experiment.

A new method of processing laser scanning data of radial section dimensions for ring forgings

Ring forgings are widely used in petrochemical, power generation, aerospace, nuclear industry and other industrial fields. In the forging process, the radial section size data greatly affect the forging accuracy of ring forgings. Therefore, a new method of processing laser scanning data of radial section dimensions for ring forgings is proposed. Firstly, the information space set of laser scanning data is established. This information space is divided by continuous concentric circles. Secondly, according to the information relationship between the various areas in the information space, the uniform isomorphism factor is defined. By combining the gradient descent method with the uniform isomorphic factor, the undetermined coefficients are solved. Thirdly, the reduction ratio is set according to the density of scanning data points. By combining the reduction ratio with the undetermined coefficients, the number of points needed to be reserved in each area of a concentric circle is determined. The remaining points and the repetitive points in the intersection of two concentric circles are deleted. Finally, the method is repeated until the last point of the laser scanning data. In this way, the laser scanning data of radial section for ring forging is processed. When the method is applied in the experiment, the size data of radial section is extracted from the processing data of laser scanning radial section line. Two groups of dimension data measurement experiment for standard and non-standard ring forgings are carried out respectively. The dimensions measured from the unprocessed and processed data points are compared with true values. The dimensions measured from the processed data have higher accuracy and smaller error. The feasibility of this method is proved.

A stitching method of radial section line of scanned point cloud data for ring forgings

The dimensions of ring forgings can be analyzed by the point cloud data of ring forgings scanned by laser. The dimensions are the key to evaluating the parameters of ring forgings. Due to the limitation of the scanning angle of the laser scanner, the complete data of the radial section line for the ring forging cannot be obtained through one scan. So the point cloud data of multiple scans are stitched to get the complete data of radial section line. In response to the stitching question, a point cloud data stitching method for ring forgings is proposed in this study. Firstly, the coarse stitching is carried out by using the relationship between the center coordinates of the two data sets. Then, the repeated region is found by the improved Beetle Antennae Search Algorithm (BASA). The repeated region is divided into three parts to find corresponding points in the process of precise stitching. The complete radial section line data can be obtained. Finally, the stitched radial section line is transformed into a complete 3D ring forging model. The comparison experiment results show that the algorithm proposed in this study is simple and fast. The accuracy of this algorithm is verified by extracting the dimensions of the complete model for ring forging.

Study on Online Dimension Measurement Method of Large Ring Forging in Heat State

This work studied the model establishment for online measurement of the inner and outer diameters of large ring forging by analyzing the research status and combining the actual manufacturing condition of enterprises. One set of online measurement device was designed for non-contact online measurement of large ring forging. This device composed of green laser, CCD camera, guide rail, servo system, data processing system, etc. It can realize the distance size measurement of large ring with simple operation and high accuracy.

Online measuring method of radial section line for ring forgings

Ring forgings are widely used in industrial fields such as trains, construction machinery, bearings, ships, petrochemicals, power generation, aerospace, and nuclear industries. In the dynamic manufacturing process of forgings, the online measurement of radial section line and various dimensional data plays a crucial role in controlling the dimensional accuracy and reducing the reject rate. Therefore, an online measurement method of radial section line for ring forgings based on line laser scanning is proposed. First, a laser scanning measurement system is established for this method. The laser scanning data of the radial uppermost layer section is obtained through this system. Second, all the point cloud data is described as a topological space. The double inverse limit space of the original two-dimensional point cloud information space is established. The topological transitivity between these two spaces is studied. Third, according to the study of the topological transitivity, the relationship of the coordinate position between each point is obtained. Then, a complete radial section line of ring forgings is formed. Finally, the radial dimension data of ring forgings is obtained. Two groups of dimensional measurement experiments have been done. One of the experimental objects is standard ring forging, the other of the experimental objects is non-standard ring forging. The result of the experiment shows that all errors satisfy the requirement of measurement precision.

Reduced algorithm of laser measurement data for geometric parameters of ring forgings based on Artificial Immune Algorithm

Measuring the geometric parameters of ring forgings by laser scanner is an important way to ensure the quality of processing. However, the amount of data obtained by scanner is huge and the noise is complex. The process of data processing is slow. It is impossible to ensure the real-time quality monitoring. Therefore, an improved Quadratic Error Metric (QEM) point cloud data reduction algorithm based on Artificial Immune Algorithm (AIA) is proposed in this study. As for AIA, the choice of antigen and antibody is the critical step. The candidate point cloud is used as the antibody. The antigen is divided into two parts. The first part is the cost function. The cost function is made up of the squares sum of the volumes for two tetrahedra. This is an improved algorithm of QEM. The second part is the optimal solution of the cost function. The antibodies are screened by using the specific reactions between antigens and antibodies, antibodies and antibodies. The point cloud data can be reduced by these specific reactions. Finally, the algorithm is applied to the experiment of measuring the geometric parameters of typical ring forging. The experimental results show that the reduced data can quickly reconstruct the model. The precision of the size parameters for the model can be ensured through the algorithm proposed in the study. Through the comparison experiments, the advantages of the reduced method of the algorithm are further proved. Meanwhile, the real-time performance of the on-line monitoring of the quality for the ring forging can be improved. The measuring method proposed is feasible according to the experimental results.

Online measuring method of the axial section line in ring forging process

The axial section line of the ring forging is the key parameter to measure whether the ring forging process meets the technical requirements. To ensure the quality of the ring forgings, an online measuring method of the axial section line in ring forging process is proposed in this study. First, the axial section line data of the ring forging is obtained online by laser scanning device. Then, the axial section line data is locally sorted and is screened to eliminate the edge noise. Second, the axial section line data is converted to line grey image data by merger and derivation theory. Finally, the line grey image data is smoothed by bilateral filtering based on information entropy selection factor. Then, the shape of the axial section line is constructed to complete the measurement of the axial section line. The experimental results show that the measurement speed of axial section line meets the requirements and the measurement accuracy of the axial section line meets the requirements.

Effects of hot ring forging on microstructure, texture and mechanical properties of AZ31 magnesium alloy

AZ31 alloy ring was processed by hot ring forging at different processing temperatures. Then the relationship between tensile properties and microstructural parameters including grain size and texture of the ring were investigated by using tensile test along three orthogonal directions. After hot ring forging, the grain structure of the AZ31 alloy ring is significantly refined and the grains grow gradually with increasing the finish die forging temperature. The texture feature in the ring changes with the forging temperature, a single peak basal texture is formed after finish die forging at lower temperature, while there exhibits a double-peak texture at higher temperature and the basal poles tilt further away from the center of (0002) pole figure with increasing the finish die forging temperature. Significant mechanical anisotropy is found for the ring and attributed to varied deformation mechanisms along different directions. Effects of grain size and texture on mechanical behavior are discussed.

Manufacturing of Nanostructured Rings from Previously ECAE‐Processed AA5083 Alloy by Isothermal Forging

The manufacturing of a functional hollow mechanical element or ring of the AA5083 alloy previously equal channel angular extrusion (ECAE) processed, which presents a submicrometric microstructure, is dealt with. For this purpose, the design of two isothermal forging dies (preform and final shape) is carried out using the design of experiments (DOE) methodology. Moreover, after manufacturing the dies and carrying out tests so as to achieve real rings, the mechanical properties of these rings are analysed as well as their microstructure. Furthermore, a comparison between the different forged rings is made from ECAE‐processed material subjected to different heat treatments, previous to the forging stage. On the other hand, the ring forging process is modelled through the use of finite element simulation in order to improve the die design and to study the force required for the isothermal forging, the damage value, and the strain the material predeformed by ECAE has undergone. With this present research work, it is intended to improve the knowledge about the mechanical properties of nanostructured material and the applicability of this material to industrial processes that allow the manufacturing of functional parts.

Measurement technology of the hot-state size for heavy shell ring forging

The measurement technology of the hot-state size for heavy shell ring forging is researched. A measurement technology is proposed and designed in this paper. The outer diameter is measured by laser scanning technology. The relationship between temperature and size is derived. Using this relationship, the inner diameter is measured by combining the outer diameter and temperature. The temperature is measured by infrared temperature measurement technology based on three-level interference filter. The measuring method is feasible according to the experimental result. Thereby, the measurement for hot-state size of heavy shell ring forging is achieved, and the requirement of the large forgings' green manufacture is fulfilled.

Further evaluation of boric acid vis-à-vis other lubricants for cold forming applications

The effectiveness of boric acid as lubricant has been evaluated in ring forging and deep drawing operations. The elapsed lay-by time between boric acid coating preparation and forming operation has significant influence on the friction factor. Fresh surfaces provide least friction since longer lay-by time permits absorption of moisture from the environment and tend to increase friction. Forging speed has no effect on the performance of boric acid lubricant. The average of peak forces obtained with tools having different surface coatings indicated that the hardness of the coating also has no effect on the effectiveness of the boric acid lubricant.

Effect of deformation and heat treatment on fabrication of large sized ring by mandrel forging of hollow ingot

Mandrel forging is a relatively simple process but needs multiple forging steps. A pierced blank is used as a preform for the conventional ring forging process and manufactured from solid ingot by several open die forging steps, such as cogging, upsetting and piercing. Since conventional ring forging process is a very complicated manufacturing process, it is not so efficient and cost‐effective process. In this study, ring forging process is developed using a hollow ingot as a preform. When a hollow ingot is used, open die forging steps to manufacture a pierced blank are not necessary. Hollow ingot has been directly forged into the ring by mandrel forging. Design variables for the new process are mainly related to characteristics of final forged ring product such as ingot size, forging amount and rotation speed. However, these variables are significantly affected by one parameter, that is, deformation amount by which the deformation energy, microstructure and mechanical properties of forged ring are determined. Therefore, mechanical properties with respect to the deformation amount are investigated by hot forging test of a staircase model. Process parameters of cast ingot and mandrel forging are studied on the condition that deformation amount of forged shell at each position can be reached to some values.

중공 잉곳을 이용한 대형 링 단조품 제조공정 설계 연구

Ring forging process is more appropriate for high-length and thin walled ring, because it utilizes the forging press and hence does not require heavy-duty ring rolling mill. Although ring forging process is very simple and economic for facilities, the process is not efficient because of multi-forging-step and low material utilization. An effective ring forging process is developed using a hollow ingot. When a hollow ingot is used with a workpiece, the ingot can be forged into a final ring without multi-stage pre-forging process, such as, cogging, upsetting, and piercing, etc.. Finally it has advantages of the material utilization and process improvement because a few reheating and forging process are not necessary to make workpiece for ring forging. The important design variables are the applied plastic deformation energy to eliminate cast structure and make uniform properties. In this study, the mechanical properties after forging of hollow cast ingot were investigated from the experiment using circumferential sectional model. Also, the effects of process variables were studied by FEM simulation on the basis of thermo-visco-plastic constitutive equation. Applied strain is different at each position in length direction because diameter of hollow ingot is different in length direction. The different strain distribution become into a narrow gap by additional plastic deformation during diameter extension process.

Analysis of Reforming Process of Large Distorted Ring in Final Enlarging Forging.

In the construction of reactors or pressure vessels for oil chemical plants and nuclear power stations, mono block open-die forging rings are often utilized. Generally, a large forged ring is manufactured by means of enlarging forging with reductions of the wall thickness. During the enlarging process the circular ring is often distorted and becomes an ellipse in shape. However the shape control of the ring is a complicated work. This phenomenon makes the matter still worse in forging of larger rings. In order to make precision forging of large rings, we have developed the forging method using a v-shape anvil. The v-shape anvil is geometrically adjusted to fit the distorted ring in the final circle and reform automatically the shape of the ring during enlarging forging. This paper has analyzed the reforming process of distorted ring by computer program based on F.E.M. and examined the effect on the precision of ring forging.

Influence of overtempering on the micromechanical aspects of a Mn-Cr steel used in turbogenerator

Overtempering characteristics of Mn-Cr steel used in retaining rings have been considered. The microstructures of the steel at various tempering temperatures have been determined. Mechanical properties at room temperature along with fractographic characteristics of the tensile and impact test specimens have been evaluated. The metallographic results show that massive carbide precipitation begins at 450‡ C onwards on stress relief. The mechanical test results indicate that the determination of the percentage reduction in area in tensile test, energy absorbed in impact test, and both tensile and impact fractographs give an accurate picture of the health of a retaining ring forging.

Forging of a metal powder preform ring

During the last few years metal powder components have assumed an important position in industry, as they are being used successfully in a wide range of applications. Considering the process of the ring forging of a metal powder preform, the pressure distribution at the roll—workpiece interface, the roll force and the roll torque have been analysed, the assumption being made that the process is similar to rolling with one of the unequal rolls driven under the constraints imposed by the compression resulting from the progressive reduction in radial thickness as the roll gap is reduced. The correctness of the yield criterion and the interfacial friction law used during the analysis have also been verified experimentally. The results so obtained are discussed critically to illustrate the interaction of the various parameters involved and are presented graphically for a particular case of the cold forging of a metal powder preform ring.