Method for determining the number of eccentric circles of irregular deformation of a bearing grinding workpiece

Abstract

The present application relates to a kind of eccentric circle quantity determination method of bearing grinding processing blank irregular deformation, the grinding process of bearing ring is analyzed, avoids complex research bearing ring blank workpiece grinding track, the determination method for judging the eccentric circle quantity of bearing ring blank workpiece is presented, can accurately reflect the material removal process of grinding workpiece and the deformation condition of blank part, and has important practical value for improving the excess shape of grinding blank part and grinding production process;The surface shape of bearing ring blank part is analyzed, the influence of bearing ring irregular deformation and eccentric circle shape on grinding process is fully considered, a grinding method in the form of piecewise function is established, and the machining efficiency and machining quality in the grinding process of bearing ring are improved.

Description

Technical Field

[0001] This invention relates to a processing technology, and more particularly to a method for determining the number of eccentric circles in the irregular deformation of a bearing grinding blank. Background Technology

[0002] The manufacturing process of bearing rings includes forging the workpiece, annealing, turning, heat treatment, grinding the blank workpiece, and grinding processes, such as... Figure 1 As shown, grinding is usually a key process that determines the final quality of bearing rings. However, turning and heat treatment processes cause turning stress deformation, clamping elastic deformation, and thermal stress deformation in the workpiece, which randomly change the size and shape of the workpiece blank during grinding. This will seriously affect the surface quality and processing efficiency of subsequent grinding. Therefore, it is necessary to analyze the turning and heat treatment processes in the manufacturing of bearing rings and study the influence of the size and shape of the workpiece blank during grinding on the grinding material removal rate model.

[0003] In the entire production and processing of bearing rings, turning is a crucial step in the ring cutting process. Turning removes excess metal and leaves a certain depth of allowance on the machined surface to obtain the refined blank required for grinding. For example... Figure 2 As shown in (a), the thin-walled structure of the bearing ring undergoes elastic deformation under the axial clamping force of the electromagnetic chuck during the turning process. When the bearing ring is removed after turning, the elastic deformation recovers and produces a certain shape deformation. Simultaneously, the material removal amount and cutting force differ at different machining locations during the turning process of the bearing ring, such as... Figure 2 As shown in (b), stress deformation occurs due to the different stress distribution on the machined surface of the refined blank. Because the bearing rings are affected by turning stress deformation and clamping elastic deformation, such as... Figure 2 As shown in (c), the machined surface deviates from the theoretical shape, resulting in roundness error. Summary of the Invention

[0004] To address the issues of machining efficiency and quality during bearing ring grinding, a method for determining the number of eccentric circles in bearing grinding blanks with irregular deformation is proposed.

[0005] The technical solution of this invention is as follows: a method for determining the number of eccentric circles in the irregular deformation of a bearing grinding blank. Based on the size of the bearing ring workpiece to be processed and the processing accuracy requirements, the fluctuation range of the initial grinding trajectory is empirically defined as Δl, and the distance from the center O of the bearing ring workpiece to the target distance of the grinding trajectory is R0. A polar coordinate system is established with the center O of the bearing ring workpiece and the processing start point. The grinding trajectory of the bearing ring workpiece is drawn in the polar coordinate system. The drawn grinding trajectory of the bearing ring workpiece is then converted to a rectangular coordinate system. The rectangular coordinate system is used to find all processing trajectory values ​​within the range of l+Δl in the continuous angle change segment, and to satisfy l+Δl≥R0+Δl. n such processing segments are found within the range of 0 to 360 degrees on the horizontal coordinate, indicating that there are n eccentric circles in the bearing ring with irregular deformation in the bearing grinding blank. The position of the eccentric circle corresponds to the range of angle change on the horizontal coordinate.

[0006] An application of a method for determining the number of eccentric circles in irregular deformation of bearing grinding blanks: Based on the influence of irregular deformation of bearing rings and the shape of eccentric circles on the grinding process, a piecewise function-form theoretical model of grinding material removal rate is established for grinding process design or calculation.

[0007] The beneficial effects of this invention are as follows: The method for determining the number of eccentric circles due to irregular deformation of bearing grinding blanks can accurately reflect the material removal process and deformation of the blank parts during grinding, and has important practical value for improving the shape of the allowance of grinding blank parts and the grinding production process; by analyzing the surface shape of the bearing ring blank parts, the influence of irregular deformation and eccentric circle shape of the bearing rings on the grinding process is fully considered, and a piecewise function-form theoretical model of grinding material removal rate is established, thereby improving the processing efficiency and processing quality during the grinding of bearing rings. Attached Figure Description

[0008] Figure 1 This is a diagram illustrating the grinding process of bearing rings.

[0009] Figure 2 A schematic diagram of the machining process for bearing rings;

[0010] Figure 3 This is a schematic diagram of the bearing ring grinding structure of the present invention;

[0011] Figure 4 This is a schematic diagram of the bearing ring grinding process of the present invention;

[0012] Figure 5a This is a schematic diagram of the blank workpiece in an ideal state according to the present invention;

[0013] Figure 5b This is a schematic diagram of an eccentric circular bearing ring structure according to the present invention;

[0014] Figure 5c This is a schematic diagram of the bearing ring structure with two eccentric circles according to the present invention;

[0015] Figure 5d This is a schematic diagram of the bearing ring structure with three eccentric circles according to the present invention;

[0016] Figure 6 This is a polar coordinate schematic diagram of an eccentric circular bearing ring structure according to the present invention;

[0017] Figure 7a This is a diagram showing the initial grinding trajectory of the bearing ring blank in the ideal state in the rectangular coordinate system of this invention.

[0018] Figure 7b This is a diagram showing the initial grinding trajectory of an eccentric circular blank workpiece of a bearing ring in the rectangular coordinate system of this invention.

[0019] Figure 7c This is a diagram showing the initial grinding trajectory of two eccentric circular blanks of the bearing ring in the rectangular coordinate system of this invention.

[0020] Figure 7d This is a diagram showing the initial grinding trajectory of the three eccentric circular blanks of the bearing ring in the rectangular coordinate system of this invention. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0022] A schematic diagram of the structure for grinding bearing rings is shown below. Figure 3 As shown in the figure, O is the center of the workpiece. s O is the center of the grinding wheel. P1 R is the center of the eccentric circle of the blank allowance distribution. D R is the radius of the electromagnetic chuck. O The outer radius of the bearing ring is given. The outer diameter surface of the workpiece being ground is supported by front and rear support blocks respectively. Electromagnetic force is used to attract the end face to a fixture called a support plate. The spindle is in a rotating drive state. Under the combined action of the clamping force of the two support blocks and the grinding force of the grinding wheel, the initial grinding trajectory is removed, that is, the irregular deformation and eccentric circular structure of the bearing ring are removed, thus improving the roundness of the part. The outer diameter and outer groove can be machined with a constant wall thickness, achieving the specified concentricity and roundness of the groove and outer diameter.

[0023] To facilitate the analysis and calculation of bearing ring grinding, the bearing ring machining process is simplified as follows: Figure 4 As shown, R O4 R is the radius of the starting position of the grinding wheel feed. O3R is the minimum radius for the irregular deformation of the bearing ring grinding blank. O2 R is the radius of the maximum irregular deformation of the bearing ring grinding blank. O1 R is the radius of the starting position of the stable stage of bearing ring grinding. O0 This refers to the radius after the bearing ring grinding process is completed, i.e., the target dimension radius of the grinding process.

[0024] The grinding of bearing rings can be divided into the following four processes:

[0025] 1) At the start of grinding, the grinding wheel is at a safe distance, meaning it rapidly approaches the workpiece. During this stage, the grinding wheel does not contact the workpiece, and no grinding material is removed. Figure 4 A(R) O3 -R O4 As shown in the figure.

[0026] 2) As the grinding wheel continues to feed closer to the workpiece, the grinding feed of the wheel enters the insufficient contact grinding stage, that is, the grinding wheel grinds the irregular deformation area of ​​the workpiece blank, such as... Figure 4 B(R) O2 -R O3 As shown in the figure, the irregular deformation is caused by the turning stress deformation, clamping elastic deformation and heat treatment process. At this time, due to the influence of the irregular deformation of the blank surface and the eccentric circular structure, the contact between the grinding wheel and the workpiece during the grinding feed is insufficient and unstable, so the amount of workpiece material removed by grinding is small and unstable.

[0027] 3) When the grinding process with the grinding wheel reaches a certain time, the grinding wheel and the bearing ring enter the stage of full contact grinding, such as... Figure 4 C(R) O1 -R O2 As shown in the figure, the irregular deformation of the blank surface is removed to a certain extent by grinding. During the grinding process, the grinding wheel and the workpiece are in full contact. However, due to the elastic deformation of the system composed of workpiece-grinding wheel-machine tool, the amount of material removed by the grinding wheel is not stable but shows a gradual increasing trend.

[0028] 4) Finally, as the grinding wheel continues to feed, the irregular deformation and eccentric shape on the surface of the bearing ring are completely removed, and the grinding process of the bearing ring enters the stable grinding stage, such as... Figure 4 D(R) O0 -R O1 As shown in the figure, at this time, the elastic deformation of the elastic system composed of the grinding wheel and the workpiece is in a stable state, and the grinding material removal rate of the bearing ring no longer changes.

[0029] After machining, bearing rings require heat treatment to improve the surface properties of the bearing ring raceways. For example... Figure 5aAs shown, ideally, bearing rings should be perfectly round before and after heat treatment, which is also the ideal surface for grinding. However, actual bearing rings are affected by turning stress deformation and clamping elastic deformation, as well as the different degrees of expansion of different parts of the workpiece during the heat treatment process, resulting in significant thermal stress. This further causes irregular deformation of the bearing rings after heat treatment, leading to poor coaxiality of the grinding allowance and a structure resembling an eccentric circle. Figure 5b , 5c As shown in Figure 5d. O is the center of the workpiece circle, O P O P1、 O P2 and O P3 To facilitate the study of uneven distribution of grinding allowance in bearing rings, the distribution of grinding allowance at different degrees is divided into the following categories, with the center of the eccentric circle as the reference point. Figure 5b The diagram shows an eccentric circle. Figure 5c The two eccentric circles shown Figure 5d The bearing ring structure shown has 3 eccentric circles and more (hereinafter referred to as 'eccentricity number') to facilitate quantitative analysis and calculation of subsequent grinding processes.

[0030] The amount of eccentricity makes the grinding trajectory of the bearing ring blank workpiece more complex and has a significant impact on the grinding quality. To determine the amount of eccentricity in the bearing ring blank workpiece, [further details are needed]. Figures 5a-5d Taking bearing rings with 0, 1, 2, and 3 eccentric circles as examples, the study examines the degree of eccentricity of bearing rings. Figure 5a As shown, the grinding trajectory of an ideal blank part consists of a circle O with radius R0, and a point on circle O is arbitrarily defined as C. Figure 5b As shown, the grinding trajectory consists of circle O and eccentric circle O P Composition, eccentric circle O P The radius is r, and the distance from the center O to the eccentric circle O P The distance between the two circles is e, and the intersection points of the two circles are defined as points E and F. Line segment EF belongs to the eccentric circle O. P Let point D be any point on line segment EF, and let l be the distance from the center O of circle O to point D. Let point C be any point on circle O, and let Δθ be the distance between DO and OO. P The angle between the grinding trajectory and circle O is represented by the shaded area A.

[0031] Will Figure 5b The midpoint and circle annotation method is a common method for annotating multiple eccentric circles on bearing rings, such as... Figure 5c As shown, the centers of the two eccentric circles of the blank workpiece are O and O, respectively. P1 and O P2 eccentric circle O P1 The radius is r, and the distance from the center O to the eccentric circle O P1 The distance between circle O and eccentric circle O is e1.P1 The intersection points are points E and F, and line segment EF belongs to the eccentric circle O. P1 Let point D1 be any point on line segment EF, and let l1 be the distance from the center O of the circle to point D1. Let Δθ1 be the distance between D1O and OO. P1 The included angle. Eccentric circle O P2 The radius is r, and the distance from the center O to the eccentric circle O P2 The distance between circle O and eccentric circle O is e2. P1 The intersection points are points G and F, and line segment GF belongs to the eccentric circle O. P2 Let point D2 be any point on line segment GF, and let l2 be the distance from the center O of the circle to point D2. Let Δθ2 be the distance between D2O and OO. P2 The angle between the two points is defined as C, and any point on circle O is chosen as C. Similarly, the relevant points and circle markings for the blank parts of the three eccentric circles can be obtained, such as... Figure 5d As shown.

[0032] like Figure 5a As shown, the bearing ring is an ideal standard circle, and the distance from the workpiece center O to point C on the grinding trajectory is constant OC = R. O This means that the bearing ring blank does not have an eccentric circle. For example... Figure 5b As shown, the bearing ring blank workpiece has an eccentric circle O. P The distance l from the center O to point D on the grinding trajectory is greater than R. O At this point, the center O of the circle reaches the eccentric circle O. P1 The distance e is greater than zero in ΔDOO P Applying the law of cosines, the relationship between the center O of the circle and the distance l from point D on the grinding trajectory is expressed as the following formula.

[0033]

[0034] Because the area of ​​the shaded region A (the difference between the grinding path and circle O) is relatively small, the eccentricity e of the bearing ring is very small. Therefore, e 2 The value of can be ignored, and the relational expression can be simplified to the following formula.

[0035]

[0036] Draw a polar coordinate diagram of the grinding trajectory of a bearing ring blank with an eccentric circle, as shown below. Figure 6 As shown, the center O of the bearing ring is the pole, the intersection of the polar coordinate X-axis and the grinding trajectory is point G, and the center of the eccentric circle is O. P Circle O and Circle O P The intersection points are E and F, θ1 is the angle between points GOF and GOE, point D is on line segment EF, and Δθ is the angle between point DO and OO. PThe angle between θ and θ is within the range of θ2-θ1.

[0037] by Figures 5a-5d Taking the bearing rings with 0, 1, 2, and 3 eccentric circles as an example, (the grinding trajectory can be measured using a roundness tester) Figure 6 The polar coordinate annotation method shown is a general method for annotating multiple eccentric circles on bearing rings. It expands the bearing ring grinding trajectory in the polar coordinate system to a rectangular coordinate system, starting from point G. For example... Figures 7a-7d As shown.

[0038] like Figure 7a As shown, the fluctuation range of the initial grinding trajectory is defined as Δl. A point on the ideal initial grinding trajectory is defined as point C. The distance from point C to the X-axis is less than R0 + Δl, meaning that the ideal workpiece does not have an eccentric circle. Figure 5a .

[0039] like Figure 7b As shown, the fluctuation range of the initial grinding trajectory is defined as Δl, and the distance from point C to the X-axis is less than R0 + Δl. A point on the initial grinding trajectory within the range θ2-θ1 is arbitrarily chosen and defined as point D. The distance from point D to the X-axis is l + Δl. At this point, l + Δl ≥ R0 + Δl, meaning that the bearing ring has an eccentric circle. θ1 and θ2 respectively correspond to... Figure 5b point E And point F. The method of comparing the magnitudes of l+Δl and R0+Δl is used as a general method to identify the amount of eccentricity of bearing rings.

[0040] Will Figure 7b The method of marking each point serves as a general method for marking the initial grinding trajectory of bearing rings in a rectangular coordinate system. For example... Figure 7c As shown, the fluctuation range of the initial grinding trajectory is defined as Δl, and the distance from point C to the X-axis is less than R0 + Δl. A point on the initial grinding trajectory within the range θ2-θ1 is defined as point D1, and the distance from point D1 to the X-axis is l1 + Δl, where l1 + Δl ≥ R0 + Δl. A point on the initial grinding trajectory within the range θ3-θ2 is defined as point D2, and the distance from point D2 to the X-axis is l2 + Δl, where l2 + Δl ≥ R0 + Δl. That is, the bearing ring has two eccentric circles, corresponding to... Figure 5c Where θ1, θ2 and θ3 correspond to Figure 5c Points E, F, and G.

[0041] like Figure 7d As shown, according to the above method for identifying the number of eccentricities in the bearing rings, it can be seen that in this case, l1+Δl≥R0+Δl, l2+Δl≥R0+Δl, and l3+Δl≥R0+Δl, that is, the bearing ring has three eccentric circles, corresponding to... Figure 5d .

[0042] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for determining the number of eccentric circles in bearing grinding blanks with irregular deformation, characterized in that, Based on the size and machining accuracy requirements of the bearing ring workpiece to be processed, the grinding allowance distribution of different degrees is divided into several eccentric circles, and the grinding trajectory is formed by the circles. O and any eccentric circle O P Composition, circle O and eccentric circles O P The intersection points are defined as points E and F, and line segment EF belongs to the eccentric circle. O P Let point D be any point on line segment EF, and the center of the circle be... O The distance to point D is l Empirically defined, the fluctuation range of the initial grinding trajectory is: The center of the bearing ring workpiece O The distance to the target grinding trajectory is R 0, with the center of the bearing ring workpiece O Establish a polar coordinate system with the machining starting point, and plot the grinding trajectory of the bearing ring workpiece in the polar coordinate system. Then, transform the plotted grinding trajectory to a rectangular coordinate system. In the rectangular coordinate system, find all machining trajectory values ​​within the continuous angle variation segment. Within the range, and satisfy The processing segment is found within the range of 0 to 360 degrees on the horizontal axis. This indicates the number of n eccentric circles in the bearing ring where there are irregular deformations in the bearing grinding blank. The position of the eccentric circle corresponds to the range of the horizontal axis angle.

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