A rubber free-form surface design method for node products

Abstract

A method for designing a rubber free profile for a node product is disclosed. According to the interface size and stiffness performance requirements of the node product, the effective load-bearing length L of the rubber body is obtained by analytical calculation. At the same time, it is assumed that the line connecting the end of the rubber body between the core shaft and the outer sleeve is K1, and the connection point of the rubber profile is selected between the midpoint of K1 and the end of the outer sleeve N1 and the end of the core shaft N2. The end of the outer sleeve N1, each connection point and the end of the core shaft N2 are sequentially connected by line segments and the arc transition at the connection point is obtained to obtain the final shape of the rubber profile. The profile is moved inward to obtain the free profile of the rubber body. The present invention can quickly design a rubber free profile according to the structural characteristics of the metal parts of the traction node. The rubber free profile can achieve smooth deformation under the action of a large radial load. The deformed rubber free profile is approximately flat and has no wrinkles, and can meet the high load and long life requirements of the traction node.

Description

Technical Field

[0001] The present invention relates to a design method for a rubber free profile, and in particular to a design method for a rubber free profile of a node product, which can be used for designing rubber free profiles of various elastic elements with large load-bearing working conditions, including traction nodes, positioning nodes, motor nodes for high-speed EMUs, and common ball joint products. Background Art

[0002] Node products are usually made of rubber vulcanized metal core shafts and metal jackets into a whole, which plays a role of both support and vibration reduction. For example, the traction nodes, positioning nodes and motor nodes of high-speed EMUs must meet the performance requirements of vibration reduction and noise reduction. In the design and manufacturing process, a key issue to consider is the design of the rubber free surface under large load conditions. A good rubber free surface can greatly improve the product's load-bearing deformation capacity and fatigue performance, but the current rubber free surface design has a certain degree of randomness. The designed rubber free surface has wrinkles on the rubber free surface during the load-bearing deformation process, and there may be more than one wrinkle. The wrinkled area is often a dangerous area that is more prone to fatigue failure. In order to obtain a good rubber free surface, it is necessary to perform multiple rounds of optimization on the rubber free surface based on the simulation analysis results of the rubber free surface load deformation, but even so, it is difficult to obtain an ideal rubber free surface without wrinkles after load deformation.

[0003] For example, invention patent application with application number CN201710617061.6, entitled “Rubber profile design method for traction rod node and traction rod node”, invention patent application with application number CN201910675943.7, entitled “A rubber joint of an axle box rod and a method for improving fatigue resistance”, and invention patent application with application number CN201910753404.0, entitled “A conical rubber cross-section traction ball joint and a method for preventing rubber profile cracking”, all mention methods of improving product performance by profile design of the rubber free surface, but the above methods are designed specifically for specific environments, and require multiple adjustments to obtain a more ideal profile, and cannot form a universal method for application in different occasions. Summary of the invention

[0004] In view of the problem that the rubber free-profile of current node-type products needs to be designed individually and adjusted multiple times to meet the requirements, the present invention proposes a rubber free-profile design method for node-type products, which can quickly design the rubber free-profile according to the structural characteristics of the metal parts of the node-type products.

[0005] The technical means adopted by the present invention to solve the above problems are: a rubber free-profile design method for node-type products, according to the interface size and stiffness performance requirements of the node-type products, the effective load-bearing length L of the rubber body is obtained by analytical calculation; at the same time, it is assumed that the line connecting the ends of the rubber body between the core shaft and the outer sleeve is K1, and the connection points of the rubber profile are selected between the midpoint of K1 and the end N1 of the outer sleeve and the end N2 of the core shaft, and the end N1 of the outer sleeve, each connection point and the end N2 of the core shaft are connected with line segments in turn and the arc transition is made at the connection point to obtain the final shape of the rubber profile, and this profile is moved inward to obtain the free profile of the rubber body.

[0006] Furthermore, K1 is perpendicular to the outer surface of the outer sleeve.

[0007] Furthermore, the effective load-bearing length of the rubber body obtained by analytical calculation refers to the calculation of the inner diameter R1, the outer diameter R2 and the effective load-bearing L of the rubber layer according to the calculation formula of the isotropic stiffness of the rubber node.

[0008] Furthermore, the calculation formula of the isotropic stiffness adopts the following equations:

[0009]

[0010]

[0011]

[0012]

[0013] Where: L is the effective load-bearing length of the rubber body, G is the shear modulus of the rubber, R2 is the outer diameter of the rubber body, R1 is the inner diameter of the rubber body, M is the correlation coefficient of the rubber hardness, S is the ratio of the inner and outer diameter load-bearing areas, δ1, δ2, δ3, and δ4 are the stiffness calculation correction coefficients.

[0014] Further, selecting the connection points of the rubber profile between the midpoint of K1 and the end N1 of the sleeve and the end N2 of the core shaft means: selecting three connection points between the midpoint of K1 and the positions between N1 and N2 as the connection points of each segment of the rubber profile shape.

[0015] Furthermore, the three connection points are selected as follows: connect the midpoint of K1 with N1 and N2 respectively to obtain lines K2 and K3, assuming that the angle between K2 and K1 is A1, and the angle between K3 and K1 is A2; set a line K4 between the midpoint P1 of K2 and K1, so that the angle B1 between K4 and K2 is (90°-A1) / 2; set a line K5 between the midpoint P2 of K3 and K1, so that the angle B2 between K5 and K3 is (90°-A2) / 2; assume that the intersection between K4 and K5 is P3; then P1, P2, and P3 are connection points.

[0016] Furthermore, sequentially connecting the end N1 of the sleeve, each connection point and the end N2 of the core shaft with line segments and transitioning the connection points with arcs means: sequentially connecting N1, P2, P3, P1 and N2 with line segments, and connecting the line segments on both sides of each point with arcs at P2, P3 and P1.

[0017] Furthermore, the distance between the end of the rubber body and the end of the outer sleeve calculated according to the length L of the rubber body is assumed to be D, and the arc diameters at points P1, P2, and P3 are respectively r1, r2, and r3, D≤r1≤2D, D / 3≤r2≤D / 2, and D / 3≤r3≤D / 2.

[0018] Furthermore, D is calculated as: D=(HL) / 2, where H is the length of the jacket.

[0019] Furthermore, moving the profile inwards means moving the final shape of the rubber profile toward the connecting line K1 until it is tangent to K1.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention can quickly design a rubber free-form surface according to the structural characteristics of the metal parts of the traction node. The rubber free-form surface can achieve smooth deformation under the action of a large radial load. The deformed rubber free-form surface is approximately flat without wrinkles, and can meet the high load-bearing and high life requirements of the traction node.

[0022] 2. The design of the rubber free surface of the present invention is regular, and the ideal surface can be obtained without multiple rounds of optimization. This method can be directly applied to the design of rubber free surfaces of various elastic elements with large load-bearing requirements, including traction nodes, positioning nodes, motor nodes for high-speed EMUs, and ordinary ball joint products, thereby greatly improving the design efficiency.

[0023] 3. The rubber free-form surface designed in the present invention can realize smooth deformation under the action of large radial load. The deformed rubber free-form surface is approximately flat without wrinkles, and can meet the high load-bearing and long life requirements of the traction node. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a node product in Example 1, in which only the rubber body is cut away;

[0025] Figure 2 A schematic diagram of setting three connection points in Example 1;

[0026] Figure 3 This is a schematic diagram of the positions of three connection points in Example 1;

[0027] Figure 4This is a schematic diagram of the shape of the rubber free-form surface of Example 1;

[0028] Figure 5 This is a schematic diagram of the final rubber free-form surface of Example 1;

[0029] Figure 6 This is a schematic diagram of the rubber surface after deformation in Example 1;

[0030] In the figure: 1. mandrel, 2. rubber body, 3. outer sleeve. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings. The accompanying drawings are only for illustrative purposes and are only schematic diagrams, not actual pictures, and cannot be understood as limiting the present patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; it is understandable to those skilled in the art that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0032] Embodiment 1

[0033] like Figure 1-Figure 5 As shown in the figure, a design method for the rubber free profile of a node product is provided. Since different node products are used in different environments and have different performance requirements and installation conditions, the effective bearing length L of the rubber body 2 in the product is firstly calculated by the following set of equations of the isotropic stiffness of the rubber node according to the interface size and stiffness performance requirements of the product:

[0034]

[0035]

[0036]

[0037]

[0038] Among them: L is the effective bearing length of rubber body 2, G is the shear modulus of rubber, R2 is the outer diameter of rubber body 2, R1 is the inner diameter of rubber body 2, M is the correlation coefficient of rubber hardness, S is the ratio of inner and outer diameter bearing area, δ1, δ2, δ3, δ4 are the stiffness calculation correction coefficients. In the above equations, there are only three unknown quantities, namely L, R1, and R2, but there are four equations. The calculation results meet the requirements through four stiffness calculation correction systems δ1, δ2, δ3, and δ4.

[0039] When the length L of the rubber body 2 is determined, since the sizes of the core shaft 1 and the outer sleeve 3 are determined, the distance D between the end of the loaded rubber body 2 and the end of the outer sleeve 3 is calculated as: D = (HL) / 2, where H is the length of the outer sleeve.

[0040] Because the rubber body 2 of the node product is a body of revolution, when designing its free-form surface, it is only necessary to form a plane shape on a cross section and then rotate it. Figure 1-Figure 5 As shown, this embodiment is designed based on the plane figure of the cross section.

[0041] In the first step, a line segment K1 is drawn along the edge of the rubber body 2 with a calculated length L. K1 connects the outer sleeve 3 and the core shaft 1 and is perpendicular to the outer surface of the outer sleeve 3, that is, perpendicular to the center line of the core shaft 1.

[0042] The second step is to connect the midpoint of K1 with the end N1 of the sleeve 3 and the end N2 of the mandrel 1 by line segments K3 and K2 respectively, and set the angle between K2 and K1 to be A1, and the angle between K3 and K1 to be A2.

[0043] The third step is to draw a straight line K4 between the midpoint P1 of K2 and K1, so that the angle B1 between K4 and K2 is (90°-A1) / 2; draw a straight line K5 between the midpoint P2 of K3 and K1, so that the angle B2 between K5 and K3 is (90°-A2) / 2.

[0044] The fourth step is that the midpoint P1 of K2, the midpoint P2 of K3, and the intersection point P3 of K4 and K5 are the connection points of the segments of the rubber free surface, that is, the line segment between N1 and P2, the line segment between P3 and P3, the line segment between P3 and P1, and the line segment between P1 and N2 constitute the four segments of the rubber free surface; at the three connection points P1, P2, and P3, the arcs r1, r2, and r3 are used to transitionally connect the line segments at both ends, and D≤r1≤2D, D / 3≤r2≤D / 2, and D / 3≤r3≤D / 2.

[0045] In the fifth step, the connecting line formed in the fourth step is translated toward the rubber body 2 as a whole until it is tangent to K1. The shape corresponding to the connecting line at this time is the shape of the free surface of the rubber.

[0046] At this point, the design of the free profile of the rubber on the axial section is completed. In the actual production process, the above shape is rotated and symmetrical to obtain the design of the free profile of the entire rubber body 2. This method can be easily applied to various node products, greatly improving the design speed, and Figure 6 As shown, this profile can achieve smooth deformation under a large radial load, and the deformed rubber free profile is flat without wrinkles, which can meet the high load and long life requirements of the traction node.

[0047] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Technicians in the relevant technical field may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the present invention, and the protection scope of the present invention should be defined by the claims.

Claims

1. A method for designing a rubber free-form surface of a node product, characterized in that: According to the interface size and stiffness performance requirements of node products, the effective load-bearing length L of the rubber body is obtained by analytical calculation; at the same time, assuming that the line connecting the end of the rubber body between the core shaft and the outer sleeve is K1, and K1 is perpendicular to the outer surface of the outer sleeve, the connection point of the rubber surface is selected between the midpoint of K1 and the end N1 of the outer sleeve and the end N2 of the core shaft, and the end N1 of the outer sleeve, each connection point and the end N2 of the core shaft are connected with line segments in turn, and the arc transition is made at the connection point to obtain the final shape of the rubber surface, and this surface is moved inward to obtain the free surface of the rubber body; The effective load-bearing length L of the rubber body obtained by analytical calculation refers to the calculation formula of the rubber node's isotropic stiffness to calculate the inner diameter R1, outer diameter R2 and effective load-bearing length L of the rubber layer; Selecting the connection points of the rubber profile between the midpoint of K1 and the end N1 of the jacket and the end N2 of the mandrel means: selecting three connection points between the midpoint of K1 and the positions between N1 and N2 as the connection points of each segment of the rubber profile shape; The three connection points are selected as follows: connect the midpoint of K1 with N1 and N2 respectively to obtain lines K2 and K3, assuming that the angle between K2 and K1 is A1, and the angle between K3 and K1 is A2; set a line K4 between the midpoint P1 of K2 and K1, so that the angle B1 between K4 and K2 is (90°-A1) / 2; set a line K5 between the midpoint P2 of K3 and K1, so that the angle B2 between K5 and K3 is (90°-A2) / 2; assume that the intersection of K4 and K5 is P3; then P1, P2, and P3 are connection points.

2. The method for designing a rubber free-form surface of a node product according to claim 1, characterized in that: The calculation formula for the isotropic stiffness is based on the following set of equations: Where: L is the effective load-bearing length of the rubber body, G is the shear modulus of the rubber, R2 is the outer diameter of the rubber body, R1 is the inner diameter of the rubber body, M is the correlation coefficient of the rubber hardness, S is the ratio of the inner and outer diameter load-bearing areas, δ1, δ2, δ3, and δ4 are the stiffness calculation correction coefficients.

3. The method for designing a rubber free-form surface of a node product according to claim 1, characterized in that: Connecting the end N1 of the sleeve, each connection point and the end N2 of the core shaft with line segments in sequence and making arc transitions at the connection points means: connecting N1, P2, P3, P1 and N2 with line segments in sequence, and connecting the line segments on both sides of each point with arcs at P2, P3 and P1.

4. The method for designing a rubber free-form surface of a node product according to claim 3, characterized in that: The distance between the end of the rubber body and the end of the outer sleeve calculated according to the length L of the rubber body is assumed to be D, and the arc diameters at points P1, P2, and P3 are r1, r2, and r3 respectively, D≤r1≤2D, D / 3≤r2≤D / 2, and D / 3≤r3≤D / 2.

5. The method for designing a rubber free-form surface of a node product according to claim 4, characterized in that: D is calculated as: D = (HL) / 2, where H is the length of the jacket.

6. The method for designing a rubber free-form surface of a node product according to claim 1, characterized in that: Moving the mold surface inward means moving the final shape of the rubber mold surface toward the connecting line K1 until it is tangent to K1.

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