Method for manufacturing a hybrid material lightweight ball head and thrust rod ball head

Abstract

The application discloses a manufacturing method of a mixed material lightweight ball head and a thrust rod ball head. The whole ball head is composed of two or more layers of polymer mixed material parts, and is respectively injection molded at different feeding positions. Firstly, according to the stress characteristics of each part of the ball head molecular mixed material, a layered structure is designed. According to the stress conditions of each part, the thickness and shape of different layers are determined, and the division between the inner layer and the outer layer is implemented. Then, the inner layer is injection molded first, and then the ball head semi-finished product with the inner layer is placed in a mold. From a direction different from the inner layer, the outer layer is repeatedly injection molded outside the inner layer, so as to form the two or more layers of polymer mixed material lightweight ball head. Through the structure design of the inner layer and the outer layer and the reasonable misplacement arrangement of the injection gate position, the overall material strength distribution of the polymer material ball head can be effectively improved, the local material strength is eliminated, the service life of the lightweight ball head is effectively prolonged, and the carrying load capacity of the thrust rod is improved.

Description

TECHNICAL FIELD

[0001] The application relates to a manufacturing method of a light-weight ball head and the ball head, in particular to a manufacturing method of a thrust rod ball head and the thrust rod ball head. BACKGROUND

[0002] For various reasons, light-weight polymer materials are increasingly used in automobile thrust rod ball heads to replace metal materials partially or entirely; the polymer mixed material injection molding thrust rod ball head and the thrust rod have the advantages of light weight, convenient manufacturing, easy mass production and lower cost, so the polymer mixed material injection molding thrust rod ball head and the thrust rod have been increasingly popular.

[0003] However, it is found in actual application that the polymer mixed material injection molding thrust rod ball head and the thrust rod have the problems of insufficient strength, low load bearing, easy cracking or failure, which greatly affect the application of polymer materials to replace metal, and therefore a reinforcing body needs to be further used to reinforce the thrust rod ball head; however, the solution simultaneously increases the difficulty and cost of the molding process. The reason for the phenomenon is various, but through careful analysis, it is found that the important reason for the phenomenon that the light-weight polymer material is easy to crack or fail when replacing metal materials to manufacture the thrust rod is that the existing light-weight polymer material is usually one-time injection molded, and the injection gate is injected from one side. The injection mode is relatively simple, but it is found in actual application that the position of the gate and the weld mark is a position with low material strength. When the ball head is loaded, cracking or failure is prone to occur at the position of the gate and the weld mark. Therefore, it is necessary to improve the position.

[0004] Through literature review, it is found that the existing lightweight thrust rod ball head or thrust rod is generally made by one-shot injection molding. In order to solve the problem of low material strength of gate and weld mark caused by one-shot injection molding, some reinforcing ribs or reinforcing layers are added outside or inside the high polymer material of the injection molding to improve the carrying load and rigidity of the high polymer material ball head or thrust rod. However, the existing method for improving the lightweight thrust rod ball head or thrust rod can improve the strength of the thrust rod, but it needs a larger design space for the ball head to arrange the reinforcing ribs or reinforcing layers. In reality, the design space of the ball head is small, and it is difficult to have enough space to arrange the reinforcing ribs or reinforcing layers. At the same time, arranging the reinforcing ribs or reinforcing layers not only uses more materials, increases the weight and cost, but also makes the mold cavity complex and difficult to process, so it is necessary to improve.

[0005] Through retrieval, the same technical solution of the present application has not been found, but some related materials have been found, mainly as follows:

[0006] 1. Patent CN113043527B discloses a method for manufacturing a lightweight composite thrust rod. The method is to first set a tooling including a center body and a pressing block, then wrap a continuous fiber reinforced thermoplastic composite material in a strip form around the outer periphery of the center body for multiple turns, and then press a continuous shaped outer periphery layer reinforcement with the pressing block. Then, the outer periphery layer reinforcement is filled with long fiber reinforced thermoplastic composite material or short fiber reinforced thermoplastic composite material in an injection molding manner. Finally, a rubber metal ball hinge is pressed and assembled into both ends to form a complete thrust rod. The thrust rod formed by this method has superior performance and higher strength, and can withstand greater tensile strength without being easily torn. However, the disadvantage is that the continuous fiber reinforced thermoplastic composite material is used for wrapping reinforcement, and the process is complex and the cost is high.

[0007] 2. Patent CN111452581A discloses a thrust rod ball head and a thrust rod thereof. The thrust rod ball head is manufactured by a high polymer material one-piece molding method. However, the injection gate and the weld line of the high polymer ball head are weak positions of the thrust rod, which are prone to failure when carrying tensile load, and the carrying load is not high, and the safety factor is low. At the same time, the wall thickness of the high polymer ball head is relatively thick, and process defects are prone to occur during production and manufacturing.

[0008] 3、Patent publication number CN116181783A discloses a method for improving the torsion resistance and deflection resistance of a lightweight thrust rod and a thrust rod, the thrust rod is a lightweight thrust rod, the main bodies of the rod body part and the ball head part are made of high molecular composite material; thrust rod reinforcing plates are compounded on the upper and lower surfaces of the high molecular composite material of the main bodies of the rod body part and the ball head part, and the thrust rod reinforcing plates on the upper and lower surfaces of the high molecular composite material of the thrust rod improve the overall torsion resistance of the thrust rod. The rod body of the thrust rod includes a rod body part and a ball head part, the ball head part is located at the two ends of the rod body part, and the main bodies of the rod body part and the ball head part are made of high molecular composite material; thrust rod reinforcing plates are compounded on the upper and lower surfaces of the high molecular composite material of the main bodies of the rod body part and the ball head part. However, this patent does not propose how to solve the problem of uneven material strength in the local area of the ball head or the rod body.

[0009] 4、Patent publication number CN210881569U discloses a split type composite lightweight connecting rod assembly, which includes a ball hinge, a rod body and a joint, the joint is made of composite material, the rod body is made of metal or continuous fiber reinforced composite material, the rod body and the joint are connected, the ball hinge is installed in the joint, and the rod body and the joint are integrally injection molded or fixedly connected, so that the end of the rod body is connected with the joint. The high molecular composite ball head of this patent is made of a high molecular material by one-time injection molding, and the injection gate and the vicinity of the welding line of the high molecular ball head are weak positions of the thrust rod, which are prone to failure when bearing tensile load, the bearing load is not high, the safety factor is low, and meanwhile, the production and manufacturing process is limited, and when a high molecular ball head with high wall thickness is made, process defects are prone to occur, resulting in that the thrust rod is difficult to bear high load.

[0010] According to the analysis of the searched cases, we find that using a lightweight ball head is a general trend, but how to improve the strength of the lightweight ball head and prevent the thrust rod ball head made of high molecular material or the thrust rod from local cracking or failure of the high molecular material is a topic worthy of study, especially how to improve the low strength of the injection gate and the welding mark part of the thrust rod ball head made of high molecular material, which leads to the difficulty of continuously improving the bearing load of the high molecular composite thrust rod and the easy cracking and failure, which is a problem that needs to be focused on and further researched and improved. SUMMARY

[0011] The present application aims at solving the problem of low overall load strength of the ball head caused by the low local material strength of the injection gate and the weld mark area of the existing high polymer material ball head, and provides a method for manufacturing a mixed material lightweight ball head, which can effectively improve the overall material strength distribution of the ball head and eliminate the low local material strength of the injection gate and the weld mark area of the existing high polymer ball head.

[0012] To achieve this goal, the present application provides a method for manufacturing a mixed material lightweight ball head, which divides the high polymer mixed material part of the whole ball head into two or more layers and respectively injection molds them at different feeding positions. First, according to the stress characteristics of each part of the mixed material ball head, the structure of the layers is designed, the thickness and shape of each layer are determined according to the stress of each part, and the division between the inner layer and the outer layer is implemented. Then, the inner layer is injection molded first, and the semi-finished ball head with the inner layer is placed in the mold, and the outer layer is injection molded again outside the inner layer from a direction different from that of the inner layer, forming a two-layer or more high polymer mixed material lightweight ball head.

[0013] Further, the high polymer mixed material part of the mixed material lightweight ball head is divided into 2-4 layers, and each adjacent two layers are respectively the inner layer and the outer layer, wherein the inner layer is close to the inner surface of the ball head center, and the outer layer is close to the outer surface of the ball head center. The multi-layer structure of the inner layer and the outer layer forms the high polymer mixed material part of the thrust rod ball head.

[0014] Further, the structure design of the layers is according to the structure requirements and stress conditions of the ball head, the thickness and shape of each layer, and the comprehensive optimization design of the material, to ensure that the stress of each part in each layer is balanced and the stress imbalance is eliminated.

[0015] Further, the division between the inner layer and the outer layer according to the thickness and shape requirements of each part is to divide the layers in a ring shape along the vertical cross-sectional radial direction of the ball head ball hinge center axis and the rod body center axis, forming two or more ring-shaped fractals, and then combining the two fractals to form the interlayer shell of each inner layer and outer layer of the ball head, constituting the inner and outer surface layers of the inner layer and the outer layer.

[0016] Further, the surface layer of the inner layer and the outer layer is a special-shaped surface layer, which has different special-shaped ring surfaces at different axial positions along the ball head ball hinge center axis and the rod body center axis, and forms different special-shaped ring curved surface layer bodies of different inner layers and outer layers through the combination of different special-shaped ring surfaces in each axial direction.

[0017] Furthermore, the injection molding process involves the inner and outer layers having injection gates located in different positions and directions during the injection molding process; that is, injection molding is performed through injection gates in different directions.

[0018] Furthermore, the injection gates for each layer are designed to avoid high-stress areas.

[0019] Furthermore, the injection gates in different directions are selected based on the material strength distribution of each layer, using a complementary material strength approach between the two layers to achieve material strength balance in all directions. This ensures that the weak areas (mainly the gates and weld lines) of the inner and outer layers are staggered, thereby avoiding the phenomenon of excessively low material strength in any area of ​​the entire ball head. Specifically, the gate position for the first injection molding of the inner layer is set at the top of the ball head assembly, centered on the intersection of the Z-axis and X-axis, with the extension of the X-axis as the axis of symmetry, and offset to one side by an angle of 15-30 degrees along the extension of the X-axis. The gate position for the second injection molding of the outer layer is symmetrically set on the ball head assembly with respect to the first gate position, again centered on the intersection of the Z-axis and X-axis, with the extension of the X-axis as the axis of symmetry, and offset to the other side by an angle of 15-30 degrees along the extension of the X-axis.

[0020] Furthermore, the inner and outer layers may be made of the same mixed polymer material or different mixed polymer materials, but regardless of whether they are the same or different materials, each layer must be injection molded separately.

[0021] A thrust rod ball head manufactured according to the above-described method for manufacturing a lightweight ball head using hybrid materials includes a ball joint and a lightweight hybrid material wrapped around the ball joint. The lightweight hybrid material is characterized in that it is a composite layer consisting of two or more layers, each injection-molded and layered around the ball joint, with each pair of layers consisting of an inner layer and an outer layer. The inner layer is located closer to the center of the ball head, while the outer layer is located closer to the center of the ball head. The combination of the inner and outer layers forms the polymer hybrid material portion of the thrust rod ball head.

[0022] Furthermore, the inner and outer layers are irregularly shaped annular rings, and along the direction of the ball joint center axis and the rod center axis, the cross section of each axial direction segment has a different annular surface. The inner and outer surfaces of the irregularly shaped annular curved surfaces of the inner and outer layers are formed by combining different irregularly shaped annular surfaces in each axial direction.

[0023] Further, the inner and outer surfaces of the special-shaped annular curved layer body have different special-shaped annular surfaces at different axial positions along the center axis of the ball head and the center axis of the rod body, and the inner and outer surfaces of the special-shaped annular curved layer body are formed by combining the different special-shaped annular surfaces in different axial directions; the ball head part along the center axis Z of the ball head has an annular cross section along the Z axis, the center of the ball head part is a ball hinge hole, and the outer surface of the ball head part is a non-integral special-shaped cylindrical surface formed by a circular arc and a direct combination; and the thrust rod part along the center axis X of the rod body has a hollow annular cross section around the X axis.

[0024] Further, the thickness of each layer of the inner layer and the outer layer is determined according to the shape and stress condition of the ball head; and the thickness of each layer of the inner layer and the outer layer is controlled to be between 3-15mm, so as to ensure that sufficient structural layers are formed.

[0025] Further, the inner layer and the outer layer are made of the same mixed high molecular material or different mixed high molecular materials.

[0026] The present application has the following advantages:

[0027] The present application improves the overall material strength distribution of the high molecular material ball head by the structural design and reasonable misplacement arrangement of the injection gate position of the inner layer and the outer layer, eliminates the local area material strength that is too low, improves the overall material strength of the high stress area, thereby enhancing the load bearing capacity of the ball head, effectively prolonging the service life of the lightweight ball head, and improving the crack and failure resistance of the high molecular mixed material thrust rod ball head and the thrust rod; and has the following advantages:

[0028] 1. The lightweight injection molding part of the ball head is divided into two or more injection molding, forming a two-layer or more composite layer structure, which can effectively improve the material strength distribution of the local area of the ball head, and avoid the phenomenon that the material strength at the injection gate and the weld mark position of the high molecular mixed material of the ball head is too low caused by one-time injection molding;

[0029] 2. On the basis of adopting the layered structure, the profile shape of each layer is further adjusted, the adhesion and friction between the layers are enhanced through the special-shaped profile structure, the delamination or mutual rotation between the layers is prevented, and the bonding force between the layers is effectively improved;

[0030] 3. Each layer adopts one injection gate, and the injection gate is arranged in a relatively low stress area according to the stress distribution of the thrust rod ball head under external load, so as to maximize the load bearing capacity of the thrust rod;

[0031] 4. The injection gates of the outer layer and the inner layer are arranged at different positions, which are relatively low stress positions after the thrust rod ball head is loaded, and the injection gates are arranged respectively opposite to each other, and the gate and the weld line positions are staggered with each other, so that the material strength of the weak area of the injection molded thrust rod ball head is improved, thereby improving the bearing load and the safety factor of the thrust rod ball head as a whole;

[0032] 5. The outer layer and the inner layer can use the same high molecular mixed material, or use different high molecular mixed materials, and the appropriate fiber material can be added in the mixed material in the local or all layers. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a thrust rod ball head;

[0034] Figure 2 It is a three-dimensional structural schematic diagram of the thrust rod ball head after the ball hinge is removed;

[0035] Figure 3 It is a structural schematic diagram of the thrust rod ball head after the ball hinge is removed;

[0036] Figure 4 It is a three-dimensional schematic diagram of the inner layer structure of the thrust rod ball head;

[0037] Figure 5 It is a front view of the inner layer structure of the thrust rod ball head;

[0038] Figure 6 It is a three-dimensional schematic diagram of the outer layer structure of the thrust rod ball head;

[0039] Figure 7 It is a front view of the outer layer structure of the thrust rod ball head;

[0040] Figure 8 It is a schematic diagram of two injection gate position settings of the thrust rod ball head;

[0041] Figure 9 It is a three-dimensional schematic diagram of two injection gate position settings of the thrust rod ball head;

[0042] Figure 10 It is a three-dimensional structural schematic diagram of the thrust rod composed of the ball head of the application;

[0043] Figure 11 It is a three-dimensional structural schematic diagram of another embodiment of the application;

[0044] Figure 12 It is a sectional structural schematic diagram of the ball head part of Figure 11

[0045] Figure 13 It is a sectional structural schematic diagram of the ball head part in another direction of Figure 11

[0046] Figure 14 This is a schematic diagram of the glue injection port location setting in Example 2. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0048] The inventors, in their research on lightweight polymer ball heads, discovered that, due to various factors, polymer injection-molded thrust rods and their thrusters are becoming increasingly common. These polymer injection-molded thrust rods and their thrusters are lightweight, easy to manufacture, convenient for mass production, and have lower costs. However, practical applications have revealed that injection-molded thrust rods and their thrusters made from polymer mixtures suffer from low load-bearing capacity and are prone to cracking or failure, significantly impacting the application of polymers as a substitute for metals. While there are many reasons for this phenomenon, careful analysis revealed problems in the injection molding methods for thrust rods or ball heads. In existing injection-molded thrust rods or ball heads, a single injection molding process is often used. Furthermore, in this single injection molding process, regardless of whether there are one or more injection gates, they are all located on the same side. While this facilitates material feeding, experiments have shown that the areas near the injection gate and weld line in this type of molding are weak points in the thrust rod, making them prone to failure under tensile loads, resulting in low load-bearing capacity and safety issues. The performance of the push rod ball head is relatively low, making improvement necessary. Furthermore, the polymer material portion of the lightweight push rod ball head is generally manufactured using a single injection molding process. While recent advancements have included creating different polymer material skins first, followed by injection molding of the inner main body within the skin, or adding a reinforcing skeleton to the inner surface, these are still improvements based on the single-molding method. Although these methods can improve the performance of the push rod ball head in some aspects, they do not solve the root-related problems inherent in single-molding. Therefore, improvement is necessary, and this invention addresses these issues. Further explanation will follow through with examples. Example 1

[0049] Through append Figures 1-10 As can be seen, a lightweight automotive thrust rod ball joint and its manufacturing method are described, and the overall structure of the lightweight automotive thrust rod is shown in the attached figure. Figure 10 As shown, it includes a thrust rod body 3, a thrust rod ball head 1, and a thrust rod ball hinge 2. The thrust rod ball hinge 2 is installed inside the thrust rod ball head 1, and the thrust rod ball head 1 is inserted into the thrust rod body 3 via a connecting seat 4 to form an integral thrust rod. The thrust rod body 3 has a center-to-center distance of 1000mm between the two ball heads, a sleeve diameter of 50mm, and a sleeve wall thickness of 6mm.

[0050] The push rod body 3 is a hollow rod made of metal hollow pipe, the push rod ball head 1 is a composite of high polymer mixed material and metal ball sleeve, the push rod ball hinge 2 is an elastic rubber metal ball hinge, and the push rod ball hinge 2 has two and is respectively installed at two ends of the push rod body 3.

[0051] The push rod ball head 1 is an injection molding part, which is combined with the push rod body 3 by injection molding, and local grooves are formed at two ends of the push rod body 3, and plugs are welded at the two ends to prevent injection plastic from entering the pipe body of the push rod body 3 during injection molding.

[0052] It is worth noting that, in order to improve the material strength distribution in injection molding, the injection molding part of the push rod ball head 1 (i.e. the high polymer mixed material part of the ball head) is respectively injection molded in the form of secondary injection molding during injection molding, so as to form a mixed high polymer material ball head shell with two layers of inner layer 5 and outer layer 6; wherein the inner layer 5 is the inner surface close to the ball hinge central axis and the rod body central axis, and the outer layer 6 is the outer surface close to the ball hinge central axis and the rod body central axis (as shown in the accompanying drawings). Figure 1 、 2

[0053] Moreover, the inner layer 5 and the outer layer 6 are combined into a special-shaped annular shell body; the special-shaped annular shell body means that each layer of the inner layer 5 and the outer layer 6 has different annular surfaces along the ball hinge central axis Z and the rod body central axis X direction, and the inner and outer surfaces of the different inner layer 5 and outer layer 6 are combined by different special-shaped annular surfaces in the axial direction, so as to form the irregular special-shaped thin shell high polymer mixed material layer structure of the inner layer 5 and the outer layer 6 (as shown in the accompanying drawings). Figure 3

[0054] The special-shaped annular curved surface layer body inner and outer surfaces have different special-shaped annular surfaces at different axial positions along the ball hinge central axis and the rod body central axis direction, and the inner and outer surfaces of the different inner layer 5 and outer layer 6 are combined by different special-shaped annular surfaces in the axial direction; wherein the inner layer 5 is divided into a ball head part 7, a push rod part 8 and a special-shaped transition part 9; the ball head part 7 along the ball hinge central axis Z has an annular cross section along the Z axis, the ball head part 7 center is a ball hinge hole 10, and the side outer surface 11 of the ball head part 7 is a non-integer special-shaped cylindrical surface combined by a circular arc; the push rod part 8 along the rod body central axis X direction is a hollow annular cross section around the X axis (as shown in the accompanying drawings); and the push rod part 8 and the ball head part are combined together through the special-shaped transition part 9, so as to form the integrated inner layer annular shell body combination. Figure 4 5

[0055] ​​​​The outer layer 6 is also divided into an outer layer ball head sub-body 12, an outer layer thrust rod sub-body 13 and an outer layer transition body 14. The outer layer ball head sub-body 12 is an outer layer structure wrapped around the ball head sub-body 7 along the ball head ball hinge central axis Z. The inner surface 15 of the outer layer ball head sub-body 12 is matched with the side surface outer surface of the ball head sub-body 7 to wrap the ball head sub-body 7 from the side. The outer surface of the outer layer ball head sub-body 12 is wrapped with a high polymer material with a certain thickness. The outer layer thrust rod sub-body 13 is a cylindrical barrel wrapped around the annular structure of the thrust rod sub-body 8. The outer layer thrust rod sub-body 13 is sleeved on the cylindrical outer surface of the thrust rod sub-body 8. The outer layer transition body 14 is a transition connecting body matched with the special-shaped transition body 9. The special-shaped transition body 9 is wrapped by the outer layer transition body 14 (as shown in the attached drawings) to form an integrated outer layer annular shell assembly. Figure 6 and 7 The inner layer 5 and the outer layer 6 are tightly attached to each other to form a two-layer inner and outer layer high polymer material structure with different thicknesses in different areas to enhance the torsional resistance of the ball head.

[0056] The thickness between the layers of the inner layer 5 and the outer layer 6 is determined according to the shape and stress of the ball head and is controlled to be between 3-15mm to ensure sufficient structural layers.

[0057] The inner layer 5 and the outer layer 6 can be the same mixed high polymer material or different mixed high polymer materials and are formed by two-shot injection molding.

[0058] Moreover, it is especially necessary to adjust the injection gate position of each layer according to the material strength distribution between the layers and the stress distribution under external load, so that the material strength distribution between the layers can be mutually compensated. The overall material strength distribution of the ball head high polymer mixed material is changed by multi-layer injection molding to improve the material strength of the weak area, thereby achieving the purpose of improving the load bearing capacity and safety factor of the overall mixed material structure thrust rod.

[0059]

[0060] ​Through computer cloud force analysis, the position of the greatest force on the thrust rod ball head is the top of the ball head at both ends of the thrust rod. Through density analysis of the injection plastic, it is found that the density of the injection plastic at the injection port position is the highest, and thus the force is the best. Therefore, the position with the greatest force is selected as the injection port position, and the inside and outside two layers are set in a staggered manner, so that the stress unevenness of the greatest force position of the ball joint can be effectively eliminated, and the strength of the greatest force position of the ball head can be improved. The two injection gate positions selected are as follows: the first injection gate position 16 of the inner layer 5 is set at the top of the ball head part 7, the intersection point 18 of the Z axis and the X axis is taken as the center, the extension line 19 of the X axis is taken as the symmetric axis, and the position deviated by an angle a of 15-30 degrees to one side of the X axis extension line is taken as the first injection gate position 16. The second injection gate position 17 of the outer layer 6 is set symmetrically with the first injection gate position 16, the intersection point 18 of the Z axis and the X axis is taken as the center, the extension line 19 of the X axis is taken as the symmetric axis, and the position deviated by an angle b of 15-30 degrees to the other side of the X axis extension line is taken as the second injection gate position 17 (as shown in the accompanying drawings). Figure 9 The two positions are staggered for injection molding, which is relatively easy to implement, and good overall thrust rod ball head strength can be obtained. The two injection gate positions are different by 30-60 degrees, and are separately set at the position with the greatest force, so that the stress unevenness of the greatest force position can be effectively eliminated.

[0061] The entire thrust rod manufacturing process is as follows:

[0062] First step: process the metal pipe and ball joint of the intermediate thrust rod 1, the main process is to process the recess for embedding the plastic part at both ends of the metal pipe, and to weld the plug at both ends of the metal pipe respectively to prevent the high polymer material from flowing into the inside of the metal pipe during injection molding, and to round the sharp edges;

[0063] Second step: preheat the processed metal pipe and ball joint and put them into the inner layer plastic molding mold to injection mold the inner layer part of the high polymer material ball head at one end;

[0064] Third step: remove the excess plastic such as the gate produced in the previous step, and put the other end of the metal pipe into the inner layer plastic molding mold to injection mold the inner layer part of the high polymer material ball head at the other end;

[0065] Fourth step: remove the excess plastic such as the gate produced in the previous step, and put the inner layer plastic part of the ball head molded in the second step into the outer layer plastic molding mold to injection mold the outer layer of the high polymer material ball head at one end;

[0066] Fifth step: remove the gate and other excess plastic from the previous step, and put the inner layer of the ball head formed in the third step into the outer layer plastic forming mold, and inject the other end of the ball head outer layer of the polymer material; form a thrust rod integral product.

[0067] Through stress analysis of the ball head injected according to this method, it is found that the use of this inner and outer two-layer injection method from different positions can effectively improve the tensile strength of the thrust rod ball joint and prolong the service life; compared with the conventional one-time injection molding of the thrust rod ball head, the service life can be prolonged by 1.5 times. Example two

[0068] The principle of example two is the same as example one, except that the structure is slightly different (such as the attached Figures 11-13The application discloses a lightweight connecting rod and a manufacturing method of a lightweight connecting rod ball head, as shown in the drawings. The lightweight connecting rod comprises a connecting rod body 201 and two lightweight connecting rod ball heads 202, and the two lightweight connecting rod ball heads 202 are connected to two ends of the connecting rod body 201 respectively. The lightweight connecting rod ball head 202 and the connecting rod body 201 are connected together through injection molding to form a connecting rod with lightweight ball hinges at two ends. The lightweight connecting rod ball head 202 is a lightweight ball head with a high polymer material as a main shell material; the lightweight connecting rod ball head 202 comprises a metal ball hinge 203, and the metal ball hinge 203 is wrapped with a mixed high polymer material ball head shell 204; the ball head shell 204 is a high polymer structure combination of three layers of high polymer materials, and the three layers of high polymer materials are a bottom layer 205, an intermediate layer 206 and a surface layer 207 respectively, and the adjacent two layers of the bottom layer 205, the intermediate layer 206 and the surface layer 207 are an inner layer and an outer layer respectively, wherein the inner layer is close to the inner surface of the ball hinge central axis 208 and the rod body central axis 209, and the outer layer is close to the outer surface of the ball hinge central axis 208 and the rod body central axis 209; that is, between the bottom layer 205 and the intermediate layer 206, the bottom layer 205 is the inner layer, and the intermediate layer 206 is the outer layer of the bottom layer 205; between the intermediate layer 206 and the surface layer 207, the intermediate layer 206 is the inner layer, and the surface layer 207 is the outer layer. The bottom layer 205, the intermediate layer 206 and the surface layer 207 are injection molded in a three-time injection molding mode during injection molding; that is, the bottom layer 205 is injection molded first; then, according to stress analysis of the injection molding of the bottom layer 205, the intermediate layer is arranged at the position with the maximum stress of the bottom layer 205 on the outer surface of the bottom layer 205; the intermediate layer 206 is injection molded by using different high polymer materials through different pouring port positions of the bottom layer 205, so as to eliminate the stress uneven phenomenon generated in the injection molding of the bottom layer 205; then, according to stress analysis, the surface layer 207 is injection molded by using different high polymer materials or the same high polymer material at the positions with the maximum stress of the bottom layer 205 and the intermediate layer 206 at different positions on the outer surface of the intermediate layer 206. The bottom layer 205, the intermediate layer 206 and the surface layer 207 are injection molded in different directions respectively, so that the internal stress of the lightweight high polymer material is more uniform, and the stress concentration phenomenon is reduced.

[0069] The manufacturing process of the connecting rod ball head is as follows:

[0070] Step 1: Place the machined metal ball head sleeve in the injection mold and fix the position;

[0071] Step 2: First, injection mold the bottom layer 205, and injection mold the pouring port 210 (as shown in the drawings) of the ball head shell bottom layer 205 from the middle position of the top of the bottom layer 205, so that the bottom layer 205 high polymer material and the metal ball hinge 203 together form a semi-finished product; the bottom layer 205 is made of nylon plastic; Figure 14

[0072] ​Step 3: Remove the semi-finished bottom layer 205 and metal ball joint 203, remove excess plastic such as the gate produced in the previous step, and place them into the intermediate layer 206 molding mold. Inject and mold the intermediate layer 206 part on the basis of the bottom layer 205. The intermediate layer gate 211 is set in a radial direction with the metal ball joint axis as the center, offset to one side by 30-45 degrees (as shown in the attached figure). Figure 14 (As shown); the middle layer uses a resin material containing glass fiber or carbon fiber. The resin matrix mainly includes PP, PA6, PA66, PBT, etc. The fiber content can be 5%, 10%, 15%, 20%, 30%, or 40%, which makes the overall torsional strength of the rod higher.

[0073] Step 4: Remove the semi-finished product of the intermediate layer 206, remove excess plastic such as the gate from the previous step, and then place it into the injection molding mold for the surface layer 207. Inject the surface layer 207 onto the upper surface of the intermediate layer 206. The surface layer gate 212 is set in a radial direction with the metal ball joint axis as the center, rotating and deflecting 30-45 degrees to the other side of the intermediate layer 206 with the bottom layer 205 as the axis of symmetry (as shown in the attached diagram). Figure 14 (As shown); the surface layer is made of foamed polyurethane resin material;

[0074] Step 5: Remove excess plastic, such as the gate, produced in the previous step to form the connecting rod ball head product.

[0075] During the manufacturing process, it's important to note that the three-layer division is based on the thickness of the polymer composite material in each part of the connecting rod ball head and the stress conditions of each part. Furthermore, by changing the injection port position of each layer, the material strength distribution in localized areas of the overall polymer mixture is adjusted and altered, improving the overall ball head performance. Connecting rods manufactured using this method exhibit more uniform internal stress in the polymer material, which is more conducive to improving the comprehensive load-bearing capacity of the ball head and significantly extending its service life. Compared to connecting rods with ordinary one-piece molded lightweight polymer ball heads, the service life is more than 1.8 times longer.

[0076] The embodiments listed above are merely for clear and complete description of the technical solutions of the present invention in conjunction with the accompanying drawings; obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0077] The advantages of this invention are:

[0078] This invention utilizes two or more layered injection molding processes to create a ball head portion from a mixed polymer material. By altering the injection gate positions in each layer and rationally arranging the gate locations, the overall material strength distribution of the polymer ball head is improved. This eliminates localized areas of low material strength and increases the overall material strength in high-stress areas, thereby enhancing the ball head's load-bearing capacity, effectively extending the service life of the lightweight ball head, and improving the load-bearing capacity and safety factor of the polymer mixed material thrust rod ball head and its thrust rod. This invention has the following advantages:

[0079] The lightweight injection-molded portion of the thrust rod ball head is divided into two or more injection molding processes, forming a two- or more composite interlayer structure. This effectively improves the overall material strength distribution of the polymer ball head and avoids the phenomenon of low material strength at the injection gate and weld line locations in a single injection-molded polymer ball head, which leads to low load-bearing capacity of the polymer ball head thrust rod. By using the same dimensions (center-to-center distance between the two ball heads of the thrust rod 1000mm, sleeve diameter 50mm, sleeve wall thickness 6mm, structure as shown in the attached diagram)... Figure 10 , 11 The comparative examples (shown) were compared with Examples 1 and 2 in an experiment. The experimental conditions were as follows:

[0080] (1) Test force: ±500kN, indication accuracy 2%-FS±1%;

[0081] (2) Stroke: 150mm, ±0.5%FS;

[0082] (3) Main waveform: sine wave;

[0083] (4) Control methods: force, displacement;

[0084] (5) Vibration frequency range: 0.1-20Hz;

[0085] (6) Actuator installation: front and rear mounting ears for fixing;

[0086] (7) Test equipment: Automobile thrust rod fatigue testing machine;

[0087] (8) Test duration: 30 days (500,000 times).

[0088] The test results are as follows:

[0089]

[0090] The test results clearly show that the technical solution of the present invention has a significant improvement in overall performance and a significantly extended service life compared with the existing lightweight thrust rods, demonstrating outstanding technical effects.

[0091] 2. On the basis of adopting layered structure, further adjust the profile shape of each layer, enhance the friction between layers through the profile structure, prevent delamination or mutual rotation between layers, effectively improve the bonding force between layers.

[0092] 3. Each layer adopts an injection injection gate, and the injection gate is arranged in the relatively low stress area according to the stress distribution of the thrust rod ball head under external load, so as to maximize the carrying capacity of the thrust rod.

[0093] 4. The injection gates of adjacent layers are arranged at different positions, that is, the injection gates are arranged relatively at the positions with relatively low stress after the thrust rod ball head is loaded, and the gate and the weld line positions are staggered, so that the material strength of the weak area of the injection molded thrust rod ball head is improved, thereby improving the carrying capacity and safety factor of the thrust rod ball head as a whole.

[0094] 5. The adjacent outer layer and inner layer can use the same high polymer mixed material, or use different high polymer mixed materials, and appropriate fiber material can be added in the mixed material in the local or whole layer.

Claims

1. A method for manufacturing a mixed-material lightened ball head, characterized by comprising: The polymer mixed material part of the whole ball head is divided into two or more layers, and is respectively injection molded at different feeding positions; first, according to the stress characteristics of each part of the polymer mixed material of the ball head, a layered structure design is performed; that is, according to the determined stress of each part, the thickness and shape of different layers are determined, and then the division between the inner layer and the outer layer is implemented; then the inner layer is injection molded first, and then the ball head semi-finished product with the inner layer is placed in the mold, and the outer layer is injection molded again by repeating the injection molding step outside the inner layer from a direction different from that of the inner layer, to form two or more layers of polymer mixed material lightweight ball head; ​ The division between the inner layer and the outer layer is respectively annularly layered along the vertical cross-sectional radial direction of the ball head ball hinge central axis and the rod body central axis, to form two or more annular fractals, and then the two annular fractals are combined to form the interlayer shell of each inner layer and outer layer of the ball head, to constitute the inner and outer surface layers of the inner layer and the outer layer; The injection molding is that the injection gates of the inner layer and the outer layer are respectively located at different positions during injection molding; that is, the injection molding is performed through injection gates in different directions; The injection gates in different directions are selected according to the stress analysis of each layer to complement the material strength between two layers, so that the weak areas of the inner layer and the outer layer are staggered with each other, thereby avoiding the phenomenon that the material strength of a certain area of the whole ball head is too low; wherein the injection gate position of the first injection molding of the inner layer is set at the top position of the ball head split body, the intersection point of the Z-axis and the X-axis is taken as the center, the extension line of the X-axis is taken as the symmetric axis, and the position deviated by an angle of 15-30 degrees to one side of the extension line of the X-axis is taken as the first gate position, and the injection gate position of the second injection molding of the outer layer is set at the symmetric position of the ball head split body and the first gate position, still taking the intersection point of the Z-axis and the X-axis as the center, taking the extension line of the X-axis as the symmetric axis, and taking the position deviated by an angle of 15-30 degrees to the other side of the extension line of the X-axis as the second gate position.

2. The method of claim 1, wherein: The polymer mixed material part of the whole ball head is divided into two or more layers, and is respectively injection molded at different feeding positions; first, according to the stress characteristics of each part of the polymer mixed material of the ball head, a layered structure design is performed; that is, according to the determined stress of each part, the thickness and shape of different layers are determined, and then the division between the inner layer and the outer layer is implemented; then the inner layer is injection molded first, and then the ball head semi-finished product with the inner layer is placed in the mold, and the outer layer is injection molded again by repeating the injection molding step outside the inner layer from a direction different from that of the inner layer, to form two or more layers of polymer mixed material lightweight ball head; 3. The method of claim 1, wherein: The layered structure design is a comprehensive optimization design of the type surface and thickness of each layer and the material according to the structural requirements and stress conditions of the ball head, to ensure that the stress conditions of each part in each layer are balanced and the internal stress imbalance is eliminated.

4. The method of claim 1, wherein: The type surface layer of the inner layer and the outer layer is a special-shaped type surface layer, which has different special-shaped annular surfaces at different axial positions along the ball hinge central axis and the rod body central axis, and different special-shaped annular curved surface layer bodies of different inner layers and outer layers are formed by the different special-shaped annular surfaces in each axial direction.

5. The method of claim 1, wherein: The inner layer and the outer layer are the same mixed polymer material or different mixed polymer material, but no matter the same material or different material, each layer must be injection molded respectively.

6. A thrust rod ball head made according to the method of claim 1, comprising a mandrel and a lightweight hybrid material wrapped around the mandrel, wherein, The lightweight mixed material is a composite layer wrapped on the spherical hinge by more than two times of injection molding, and each two layers are an inner layer and an outer layer respectively; wherein the inner layer is close to the inner surface of the spherical head center, and the outer layer is close to the outer surface of the spherical head center, and the inner layer and the outer layer are combined to form the polymer mixed material part of the spherical head of the push rod.

7. The thrust rod ball head of claim 6, wherein, The inner layer and the outer layer are shaped annular, and each axial direction section has different annular surfaces along the center axis of the spherical hinge and the center axis of the rod body, and the different annular surfaces in each axial direction are combined to form the inner and outer surfaces of the shaped annular curved layer body.

8. The thrust rod ball head of claim 7, wherein, The inner and outer surfaces of the shaped annular curved layer body have different shaped annular surfaces at different axial positions along the center axis of the spherical hinge and the center axis of the rod body, and the different shaped annular surfaces in each axial direction are combined to form the inner and outer surfaces of the shaped annular curved layer body; wherein the spherical head part along the center axis Z of the spherical hinge has an annular cross section along the Z axis, the center of the spherical head part is the spherical hinge hole, and the outer surface of the spherical head part is a non-integer annular shaped cylindrical surface composed of a circular arc and a straight line; and the push rod part along the center axis X of the rod body is a hollow annular cross section around the X axis.

9. The thrust rod ball head of claim 6, wherein, The thickness between the layers of the inner layer and the outer layer is determined according to the shape and stress of the spherical head; and the thickness of each layer of the inner layer and the outer layer is controlled between 3-15mm to ensure sufficient structural layer.

10. The thrust rod ball head of claim 6, wherein, The inner layer and the outer layer are the same mixed polymer material or different mixed polymer material.

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