Roller assembly and method of manufacturing the same

Abstract

The application relates to the technical field of rollers, and provides a roller assembly and a manufacturing method thereof. The roller assembly comprises a plate connecting piece, a roller and a limiting fixing piece. The plate connecting piece comprises a connecting end part and a main body part which are connected in sequence. The roller is sleeved on the main body part, and the material of the roller is plastic. The limiting fixing piece is connected with the main body part and the roller, and is used for limiting and fixing the roller.

Description

Technical Field

[0001] This application relates to the field of roller technology, and more particularly to roller assemblies and methods for manufacturing the same. Background Technology

[0002] Roller assemblies are widely used in sliding guide systems of various mechanical equipment, such as drawer slides, automated conveying equipment, and moving parts of furniture. Their core function is to convert sliding friction into rolling friction through the rolling motion of the rollers, thereby reducing resistance and wear during equipment operation.

[0003] Existing roller assemblies typically include a plate connector for connecting to the equipment plate, a rotatable roller fitted onto the plate connector, and a limiting and fixing member for confining the roller on the plate connector. The plate connector is fixed to the equipment plate via its connecting end, the roller is fitted around the outer periphery of the main body of the plate connector, and the limiting and fixing member is installed at the end of the main body to prevent the roller from detaching from the main body.

[0004] In existing technologies, the rollers used in the aforementioned roller assemblies are mostly made of metal, such as iron-based rollers made using powder metallurgy or steel rollers made through machining. However, metal rollers have the following technical drawbacks during long-term use: First, the metal roller and the main body of the plate connector (usually also made of metal) form a metal-metal friction pair, resulting in high rotational resistance. Regular lubrication is required, and the lubricating oil easily contaminates the equipment and surrounding environment, making it unsuitable for clean environments. Second, metal rollers generate significant noise during rotation, failing to meet the growing demand for quiet operation. Third, the hardness of the metal roller is higher than that of the guide surface of the slide rail, easily causing scratches or wear on the slide rail surface during rolling contact, shortening the overall service life of the slide rail system. Fourth, the manufacturing of metal rollers using powder metallurgy or machining methods involves complex processes, low production efficiency, and difficulty in ensuring dimensional consistency between different batches, increasing the difficulty of subsequent assembly. Summary of the Invention

[0005] This application aims to solve at least one of the technical problems existing in the related art. To this end, this application proposes a roller assembly and a method for manufacturing the same.

[0006] The roller assembly according to the first aspect of this application includes:

[0007] A sheet metal connector, comprising a connecting end and a main body connected in sequence;

[0008] A roller is fitted onto the main body, and the roller is made of plastic.

[0009] A limiting and fixing component connects the main body and the roller, and the limiting and fixing component is used to limit and fix the roller.

[0010] According to one embodiment of this application, a protruding post is formed at one end of the main body away from the connecting end, and the protruding post is formed with an annular limiting portion;

[0011] The limiting and fixing member is sleeved on the protruding post, and the annular limiting part is used to limit the limiting and fixing member;

[0012] The limiting fastener extends toward the roller so that the roller is located between the limiting fastener and the connecting end.

[0013] According to one embodiment of this application, the roller includes a sleeve portion and an extension portion connected in sequence. The sleeve portion is sleeved on the main body portion, and the extension portion extends in a direction away from the connecting end and forms a receiving cavity. The limiting and fixing member is located in the receiving cavity.

[0014] According to one embodiment of this application, the limiting fastener can switch between a disassembled state and a fixed state. In the disassembled state, the limiting fastener is detached from the main body and the roller, and the roller is movable relative to the main body. In the fixed state, the limiting fastener is fixedly connected to the roller and the plate connector.

[0015] According to one embodiment of this application, the limiting and fixing member is a snap ring.

[0016] The method for manufacturing the roller assembly as described above according to the second aspect of this application includes the following steps:

[0017] S1: Based on the three-dimensional model of the roller, flow simulation and warpage deformation analysis of the roller injection molding process are performed using mold flow analysis software to obtain the flow front distribution data of the melt in the mold cavity and the warpage deformation distribution data of each region of the roller.

[0018] S2: Based on the flow front distribution data and the warpage deformation distribution data, determine the injection position and runner size of the mold's gating system, as well as the spatial arrangement of each cooling pipe in the mold's cooling system.

[0019] S3: Based on the injection point, the flow channel size, and the spatial arrangement, manufacture an injection mold for forming the roller;

[0020] S4: After heating the polyoxymethylene material to the plasticizing temperature, it is injected into the cavity of the injection mold. After holding pressure and cooling, it is demolded to obtain the roller made of plastic material.

[0021] S5: The roller is sleeved on the outer periphery of the main body of the plate connector, and the limiting and fixing member is installed on the main body and abuts against the end of the roller, so that the roller is axially limited on the main body and can rotate freely relative to the main body.

[0022] According to one embodiment of this application, step S1 specifically includes the following steps:

[0023] S11: Based on the three-dimensional model of the roller, establish the geometric model of the roller in the mold flow analysis software, and construct a finite element mesh model based on the geometric model;

[0024] S12: Based on the finite element mesh model, set the physical property parameters of polyoxymethylene material and the boundary conditions of injection molding process, and obtain the flow front distribution data and the warpage deformation distribution data after running the simulation.

[0025] S13: Based on the flow front distribution data, identify the end region where the melt is last filled in the cavity, and determine the injection point and runner size of the mold's gating system based on the position of the end region;

[0026] S14: Based on the warping deformation distribution data, identify local areas in each region of the roller where the deformation exceeds a preset threshold, and adjust the spatial arrangement of each cooling pipe in the cooling system of the mold based on the spatial location of the local area.

[0027] S15: Based on the injection position, the flow channel size, and the adjusted spatial arrangement of each of the cooling pipes, manufacture the injection mold for forming the roller.

[0028] According to one embodiment of this application, after step S4 and before step S5, the process further includes an annealing step for the roller:

[0029] S41: Remove the roller, made of plastic material obtained by injection molding, from the injection mold;

[0030] S42: Place the roller in the annealing equipment;

[0031] S43: Raise the temperature inside the annealing equipment to a predetermined annealing temperature, which is lower than the decomposition temperature of the polyoxymethylene material.

[0032] S44: The roller is held at the predetermined annealing temperature for a predetermined duration so that the residual stress inside the roller is gradually released at the predetermined annealing temperature;

[0033] S45: Reduce the temperature inside the annealing equipment to room temperature and remove the annealed roller from the annealing equipment.

[0034] According to one embodiment of this application, the sheet metal connector is integrally injection molded with the roller as a metal insert:

[0035] S51: Obtain the plate connector, the plate connector comprising a connecting end and a main body connected in sequence;

[0036] S52: Place the plate connector in the preheating device and heat the plate connector to a predetermined preheating temperature using the preheating device;

[0037] S53: The sheet metal connector heated to the predetermined preheating temperature is placed into the injection mold, and the main body of the sheet metal connector occupies the central area of ​​the cavity, and an annular space for forming the roller is formed between the outer periphery of the main body and the inner wall of the cavity.

[0038] S54: After heating the polyoxymethylene material to the plasticizing temperature, inject it into the annular space to allow the polyoxymethylene material to solidify and form on the outer periphery of the main body.

[0039] S55: After being cooled under pressure, the mold is removed to obtain an intermediate assembly in which the roller is integrally covered around the outer periphery of the main body.

[0040] According to one embodiment of this application, before step S4, a step is further included to determine the preferred combination of parameters for the injection molding process through orthogonal experiments:

[0041] S61: Determine multiple process parameters that affect the quality of the roller injection molding and multiple value levels of each process parameter, wherein the process parameters include injection temperature, mold temperature, injection time, holding pressure and holding time;

[0042] S62: Based on the process parameters and their value levels, an orthogonal experimental table is established, which contains multiple experimental schemes.

[0043] S63: Perform injection molding tests one by one according to the test schemes in the orthogonal test table to obtain the roller test pieces corresponding to each test scheme;

[0044] S64: The molding quality of each roller test piece is tested to obtain the molding quality test results of each group of test schemes;

[0045] S65: Based on the molding quality test results, determine the optimal value from multiple value levels of each process parameter, and use the combination of the optimal values ​​as the preferred combination of process parameters for the roller injection molding.

[0046] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is one of the structural schematic diagrams of the roller assembly provided by the present invention;

[0049] Figure 2 This is the second structural schematic diagram of the roller assembly provided by the present invention;

[0050] Figure 3 yes Figure 2 BB section view;

[0051] Figure 4 This is a flowchart of the manufacturing method of the roller assembly provided by the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] The following is combined Figures 1 to 4 This application describes the roller assembly and its manufacturing method.

[0054] According to the embodiments of the first aspect of this application, see [link / reference]. Figure 1 , Figure 2 and Figure 3 Roller assembly, including:

[0055] The plate connector 1 includes a connecting end 11 and a main body 12 connected in sequence;

[0056] Roller 2 is sleeved on the main body 12, and the roller 2 is made of plastic;

[0057] Three limiting and fixing components are connected to the main body 12 and the roller 2. The three limiting and fixing components are used to limit and fix the roller 2.

[0058] Understandably, the connecting end 11 of the plate connector 1 is fixed to the equipment plate, and the main body 12 serves as the rotating shaft or rotating support for the roller 2. The roller 2 is fitted onto the outer periphery of the main body 12 through its central hole and can rotate freely around the axis of the main body 12. Three limiting and fixing pieces are installed on the end of the main body 12 opposite to the connecting end 11, together with the connecting end 11, limiting the axial position of the roller 2, ensuring that the roller 2 remains in a predetermined position during rotation. Since the roller 2 is made of plastic (e.g., engineering plastics such as nylon, polyoxymethylene (POM), polyurethane, or polytetrafluoroethylene), when the roller 2 contacts the slide rail or guide surface on the equipment plate, the outer circumferential surface of the roller 2 rolls relative to the main body 12 under the action of friction, converting sliding friction into rolling friction, thereby reducing motion resistance. Simultaneously, during the rolling process, the plastic roller 2 forms a plastic-metal or plastic-plastic friction pair with the main body 12, whose coefficient of friction is much lower than that of a metal-metal friction pair, making the roller 2 rotate more flexibly and smoothly.

[0059] The beneficial effects of this implementation method are significant. First, by making the roller 2 of plastic, the friction pair between the roller 2 and the main body 12 is changed from metal-metal to plastic-metal or plastic-plastic. Plastic materials have self-lubricating properties, a low coefficient of friction, and can achieve low-resistance rotation without the need for lubricating oil, completely avoiding the hidden dangers of lubricating oil contaminating the equipment and surrounding environment. This is especially suitable for cleanrooms, food processing equipment, and other scenarios with strict cleanliness requirements. Second, the plastic roller 2 has good damping characteristics during rolling, effectively absorbing and suppressing vibrations. The operating noise is significantly lower than that of the metal roller 2, meeting the growing demand for quiet operation. Third, the hardness of the plastic roller 2 is lower than that of the metal slide rail, so it will not scratch or wear the slide rail surface during rolling contact, effectively protecting the guiding accuracy and service life of the slide rail system. In addition, the plastic roller 2 can be manufactured using injection molding, which is simple, efficient, and ensures dimensional consistency between different batches of products through precision molds, reducing subsequent assembly difficulty and costs.

[0060] In some examples, the material of the plate connector 1 can be metal (such as stainless steel, carbon steel, or aluminum alloy) to provide sufficient structural strength and bending stiffness. The material of the plastic roller 2 can be polyoxymethylene, nylon, or polyurethane. Polyoxymethylene has excellent wear resistance and dimensional stability, making it suitable for high-frequency sliding scenarios; nylon has good toughness and impact resistance, making it suitable for applications with large loads; polyurethane has a high coefficient of friction and elasticity, making it suitable for rolling guidance scenarios requiring a certain grip. The three limiting and fixing components can be snap rings, retaining rings, threaded lock nuts, or riveted flange structures, which cooperate with the end of the main body 12 to achieve axial limiting of the roller 2.

[0061] In some embodiments, see Figure 1 , Figure 2 and Figure 3 The main body 12 has a protruding post 121 formed at one end opposite to the connecting end 11, and the protruding post 121 has an annular limiting part 1211.

[0062] The three limiting and fixing pieces are sleeved on the protruding post 121, and the annular limiting part 1211 is used to limit the three limiting and fixing pieces.

[0063] The limiting and fixing 3 pieces extend toward the roller 2 so that the roller 2 is located between the limiting and fixing 3 pieces and the connecting end 11.

[0064] Understandably, the main body 12 of the plate connector 1 extends axially at its end away from the connecting end 11 to form a protruding post 121. The outer diameter of the protruding post 121 is usually smaller than the outer diameter of the main body 12, forming a stepped surface between them. An annular limiting part 1211 is provided at a predetermined position near the end of the protruding post 121 or along the axial direction. The annular limiting part 1211 can be a structure such as an annular flange, a snap ring groove, or an annular groove surrounding the outer circumference of the protruding post 121, used to cooperate with the limiting and fixing three pieces to achieve axial limiting. The limiting and fixing three pieces have a sleeve hole (e.g., a central through hole or an open groove) that matches the outer diameter of the protruding post 121. The limiting and fixing three pieces are sleeved on the protruding post 121 through the sleeve hole. In the assembled state, one side of the limiting and fixing three pieces (the side facing the main body 12) abuts against the stepped surface between the main body 12 and the protruding post 121, and the other side abuts against or is locked by the annular limiting part 1211, thereby being fixed axially at a predetermined position on the protruding post 121. At the same time, the outer peripheral portion of the limiting and fixing three pieces extends radially outward and passes over the inner hole edge of the roller 2, and the end face of its extension 22 is arranged opposite to the end face of the roller 2, so that the roller 2 is constrained within the axial space between the connecting end 11 and the limiting and fixing three pieces, so that it can rotate freely without coming off the main body 12.

[0065] The beneficial effects of this embodiment are significant. First, the cooperation between the annular limiting part 1211 on the protruding post 121 and the limiting and fixing parts 3 achieves rapid and reliable axial positioning of the limiting and fixing parts 3 themselves, eliminating the need for permanent fixing operations such as riveting or welding at the end of the main body 12, making assembly simple and easy to disassemble and maintain. Second, the limiting and fixing parts 3 extend towards the roller 2, forming a boundary for defining the axial position of the roller 2 together with the connecting end 11, effectively preventing the roller 2 from moving or coming off the main body 12 axially during movement, ensuring the structural stability and reliability of the roller assembly in long-term reciprocating motion. In addition, the cooperation between the annular limiting part 1211 and the limiting and fixing parts 3 can adopt a detachable connection method (e.g., the cooperation between a retaining ring and a retaining ring groove), so that when the roller 2 is worn and needs to be replaced, only the limiting and fixing parts 3 need to be removed to remove the old roller 2 from the main body 12 and replace it with a new roller 2, without having to replace the entire plate connecting part 1, reducing maintenance costs and service life costs.

[0066] In some examples, the annular limiting part 1211 may be a retaining ring groove surrounding the outer periphery of the protruding post 121, and the limiting fixing three pieces are retaining rings (shaft elastic retaining rings), which are inserted into the retaining ring groove to achieve axial limiting of the limiting fixing three pieces. The limiting fixing three pieces may also be a gasket or retaining ring sleeved on the protruding post 121, and axially limited by the flange of the annular limiting part 1211.

[0067] In some embodiments, see Figure 1 , Figure 2 and Figure 3 The roller 2 includes a sleeve portion 21 and an extension portion 22 connected in sequence. The sleeve portion 21 is sleeved on the main body portion 12. The extension portion 22 extends away from the connecting end portion 11 and forms a receiving cavity 221. The limiting and fixing three pieces are located in the receiving cavity 221.

[0068] Understandably, during the assembly of the roller assembly, the connecting end 11 of the plate connector 1 is fixed to the equipment plate, and the roller 2 is fitted onto the outer periphery of the main body 12 via its sleeve portion 21. Subsequently, the limiting and fixing 3 pieces are fitted onto the protruding post 121 and fixed at a predetermined position on the protruding post 121 by the annular limiting portion 1211. Since the extension portion 22 of the roller 2 extends away from the connecting end 11 and surrounds the area where the limiting and fixing 3 pieces are located, the limiting and fixing 3 pieces are completely or partially housed in the receiving cavity 221 of the roller 2 after assembly. During equipment operation, the roller 2 rotates around the main body 12, and the limiting and fixing 3 pieces remain stationary and are fixedly connected to the protruding post 121. Since the limiting and fixing 3 pieces are located in the receiving cavity 221 inside the roller 2, the extension portion 22 of the roller 2 shields the limiting and fixing 3 pieces from the outside, so that the limiting and fixing 3 pieces are not exposed on the outer surface of the roller assembly.

[0069] The beneficial effects of this implementation are significant. First, by housing the three limiting and fixing components within the receiving cavity 221 formed by the roller 2 itself, the overall appearance of the roller assembly is simpler and flatter, avoiding the risk of scratching or snagging that might occur from exposed limiting and fixing components. This is particularly suitable for sliding guide devices that require a smooth outer surface or prevention of foreign matter entanglement. Second, the extension 22 provides physical shielding and protection for the three limiting and fixing components, effectively preventing dust, debris, or liquid from directly contacting them. This reduces the risk of corrosion, jamming, or failure of the limiting and fixing components due to contaminant intrusion, improving the reliability and service life of the roller assembly in harsh environments. Third, the three limiting and fixing components are built into the receiving cavity 221 of the roller 2, shortening the total axial length of the roller assembly, saving installation space, and facilitating the miniaturization and compact design of the equipment. Furthermore, this structure provides better spatial isolation between the rotating and fixed parts of the roller assembly. The outer circumferential surface of the roller 2 and the outer circumferential surface of the extension 22 form a continuous and smooth rolling surface, which helps reduce rolling resistance and improve motion stability.

[0070] In some examples, the inner diameter of the extension 22 of the roller 2 may be larger than the inner diameter of the sleeve 21, and the difference in inner diameter between the two forms a stepped surface. This stepped surface abuts against or is opposite to the end face of the limiting and fixing member 3 to help limit the axial position of the roller 2. The outer peripheral surface of the extension 22 may be coplanar with or smoothly transition to the outer peripheral surface of the sleeve 21 to form a complete contact surface of the roller 2.

[0071] According to the embodiments of the second aspect of this application, see Figure 4 A method for manufacturing a roller assembly includes the following steps:

[0072] S1: Based on the three-dimensional model of the roller 2, flow simulation and warpage deformation analysis of the injection molding process of the roller 2 are performed using mold flow analysis software to obtain the flow front distribution data of the melt in the mold cavity and the warpage deformation distribution data of each region of the roller 2.

[0073] S2: Based on the flow front distribution data and the warpage deformation distribution data, determine the injection position and runner size of the mold's gating system, as well as the spatial arrangement of each cooling pipe in the mold's cooling system.

[0074] S3: Based on the injection point, the flow channel size, and the spatial arrangement, manufacture an injection mold for molding the roller 2;

[0075] S4: After heating the polyoxymethylene material to the plasticizing temperature, it is injected into the cavity of the injection mold. After holding the pressure and cooling, it is demolded to obtain the roller 2 made of plastic material.

[0076] S5: The roller 2 is sleeved on the outer periphery of the main body 12 of the plate connector 1, and the limiting and fixing 3 pieces are installed on the main body 12 and abut against the end of the roller 2, so that the roller 2 is axially limited on the main body 12 and can rotate freely relative to the main body 12.

[0077] Understandably, firstly, based on the three-dimensional model of the roller 2, flow simulation and warpage analysis are performed on the injection molding process of the roller 2 using mold flow analysis software to obtain the flow front distribution data of the melt in the mold cavity and the warpage distribution data of each region of the roller 2. Specifically, the three-dimensional model of the roller 2 is imported into the mold flow analysis software, the physical properties of the polyoxymethylene material (including melt temperature, viscosity curve, thermal conductivity, etc.) are set, and the range of injection molding process parameters (including injection pressure, holding pressure, injection speed, mold temperature, etc.) is set. After running the simulation, the filling sequence and filling time distribution of the melt in the cavity are obtained, as well as the shrinkage rate and warpage distribution caused by uneven cooling in each region. Then, based on the flow front distribution data and the warpage distribution data, the injection position and runner size of the gating system of the mold, as well as the spatial arrangement of each cooling pipe in the cooling system of the mold, are determined. Specifically, based on the flow front distribution data, the final filling area and potential weld lines are identified. The injection port is positioned in the area with the thickest wall or at the center of the flow path to ensure uniform melt filling. Based on the warpage distribution data, the density of cooling channels is increased or their distance from the cavity surface is adjusted near areas with large warpage to enhance local cooling rates and reduce warpage caused by uneven cooling. Then, based on the injection port location, the runner dimensions, and the spatial arrangement, an injection mold for molding the roller 2 is manufactured. Specifically, the gating system of the mold is machined according to the determined injection port location and runner dimensions, and the cooling system of the mold is machined according to the determined spatial arrangement of the cooling channels, completing the mold assembly and debugging. Then, polyoxymethylene material is heated to the plasticizing temperature and injected into the cavity of the injection mold. After holding pressure and cooling, it is demolded to obtain the plastic roller 2. Specifically, polyoxymethylene granules are heated to a plasticizing temperature of 190°C to 230°C in the barrel of an injection molding machine. After melting, they are injected into the mold cavity by a screw. Under pressure, they are cooled to the solidification temperature, and then the mold is opened to remove the roller 2. Finally, the roller 2 is fitted onto the outer periphery of the main body 12 of the sheet metal connector 1, and the limiting and fixing three pieces are installed on the main body 12 and abut against the end of the roller 2, so that the roller 2 is axially limited on the main body 12 and can rotate freely relative to the main body 12. Specifically, the center hole of the roller 2 is aligned with the main body 12 and pushed axially to a predetermined position. Then, the limiting and fixing three pieces are installed on the end of the main body 12 away from the connecting end 11, so that the end face of the limiting and fixing three pieces abuts against the end face of the roller 2, thereby clamping the roller 2 between the connecting end 11 and the limiting and fixing three pieces, completing the assembly of the roller assembly.

[0078] The beneficial effects of this implementation method are significant. First, by using flow analysis software to simulate the injection molding process of roller 2 and analyze warpage deformation, the filling behavior of the melt in the cavity and the deformation trend after cooling can be predicted in advance. The determination of the injection position, runner size, and cooling pipe layout is based on scientific simulation rather than empirical trial and error, avoiding the cycle and cost waste caused by repeated mold repairs and trials in traditional mold development, and significantly improving the rationality and success probability of mold design. Second, by optimizing the spatial layout of cooling pipes based on warpage deformation distribution data, the cooling rate difference in different areas of roller 2 can be effectively controlled, greatly reducing the amount of warpage deformation after injection molding. This significantly improves the roundness, coaxiality, and dimensional accuracy of roller 2, thereby ensuring smooth and jam-free rotation of roller 2 after assembly, and improving the working accuracy and service life of roller assembly. Third, polyoxymethylene material has good self-lubricating and wear-resistant properties. Rollers 2 made of it can achieve low-resistance rotation without the need for lubricating oil. The injection molding process produces the final usable size in one step, without the need for subsequent machining, resulting in high production efficiency and low cost.

[0079] In some embodiments, step S1 specifically includes the following steps:

[0080] S11: Based on the three-dimensional model of the roller 2, establish the geometric model of the roller 2 in the mold flow analysis software, and construct a finite element mesh model based on the geometric model;

[0081] S12: Based on the finite element mesh model, set the physical property parameters of polyoxymethylene material and the boundary conditions of the injection molding process, and obtain the flow front distribution data and the warpage deformation distribution data after running the simulation.

[0082] S13: Based on the flow front distribution data, identify the end region where the melt is last filled in the cavity, and determine the injection point and runner size of the mold's gating system based on the position of the end region;

[0083] S14: Based on the warping deformation distribution data, identify local areas in each region of the roller 2 where the deformation exceeds a preset threshold, and adjust the spatial arrangement of each cooling pipe in the cooling system of the mold based on the spatial location of the local area.

[0084] S15: Based on the injection position, the flow channel size, and the adjusted spatial arrangement of each of the cooling pipes, manufacture the injection mold for forming the roller 2.

[0085] Understandably, firstly, based on the three-dimensional model of roller 2, a geometric model of roller 2 is established in the mold flow analysis software, and a finite element mesh model is constructed based on the geometric model. Specifically, the three-dimensional CAD model of roller 2 is imported into mold flow analysis software (such as Moldflow or Moldex3D). The software performs surface meshing or solid meshing on the geometric model, generating a finite element mesh model composed of a large number of tetrahedral or hexahedral elements. This mesh model discretizes the geometry of roller 2 into a finite number of elements and nodes, providing a numerical solution basis for subsequent flow and heat transfer calculations.

[0086] Then, based on the finite element mesh model, the physical properties of the polyoxymethylene (POM) material and the boundary conditions of the injection molding process are set. After running the simulation, the flow front distribution data and the warpage deformation distribution data are obtained. Specifically, the physical properties of the POM material are set in the mold flow analysis software, including melt temperature, viscosity curve, specific heat capacity, thermal conductivity, PVT (pressure-volume-temperature) curve, and shrinkage rate, etc.; at the same time, the boundary conditions of the injection molding process are set, including injection pressure, holding pressure, injection speed, mold temperature, melt temperature, and cooling time, etc. After the software runs the simulation, it outputs the flow front position of the melt in the cavity over time (i.e., the wavefront position during the filling process), and the warpage deformation distribution data of each region of roller 2 after cooling and shrinkage.

[0087] Subsequently, based on the flow front distribution data, the final filling region of the melt in the cavity is identified, and the injection point location and runner dimensions of the mold's gating system are determined based on the location of this final region. Specifically, the flow front distribution data records the filling sequence of the melt advancing from the injection port to the far end in the cavity. The final filling region is typically the location in the cavity furthest from the injection port, with the longest flow path or the thinnest cross-section. During filling, the melt temperature is lower and the flow resistance is higher in this region, making it prone to defects such as incomplete filling or weld lines. The injection port location is determined to be relatively close to this final region (e.g., the geometric center of the cavity or a region with a larger wall thickness) to make the filling path length of the melt in the cavity more even. The diameter dimensions of the main runner and branch runners are determined according to the filling pressure requirements of the final region to ensure that the melt can completely fill the entire cavity under a reasonable injection pressure.

[0088] Simultaneously, based on the warpage deformation distribution data, local areas in each region of the roller 2 where the deformation exceeds a preset threshold are identified, and the spatial arrangement of each cooling pipe in the mold's cooling system is adjusted based on the spatial location of these local areas. Specifically, the warpage deformation distribution data reflects the uneven shrinkage caused by differences in cooling rates in each region of the roller 2. The warpage deformation of each region is compared with a preset deformation threshold (e.g., an allowable deformation value set based on the dimensional tolerance of the roller 2) to identify local areas where the deformation exceeds the standard. Based on the spatial location of these local areas in the mold cavity, the arrangement density of the cooling pipes and their distance from the cavity surface are adjusted. For example, the number of cooling pipes is increased or the distance between the pipes and the cavity wall is shortened near areas with large deformation to enhance the local cooling effect, reduce the difference in cooling rate between this region and adjacent regions, and thus reduce the final warpage deformation.

[0089] Finally, based on the injection point, the runner dimensions, and the adjusted spatial arrangement of the cooling pipes, the injection mold for molding the roller 2 is manufactured. Specifically, the gate is machined on the mold parting surface according to the determined injection point, the main runner and branch runners are machined according to the runner dimensions, and cooling water holes are drilled on the mold template according to the adjusted spatial arrangement of the cooling pipes, thus completing the mold processing, assembly, and debugging.

[0090] The beneficial effects of this implementation method are significant. First, by establishing a finite element mesh model and setting material property parameters and process boundary conditions, the injection molding process of roller 2 is transformed into a quantifiable numerical simulation model. This allows subsequent flow analysis and warpage analysis to be based on precise mathematical calculations, avoiding the blindness of empirical design. Second, by identifying the final filled region of the melt based on the flow front distribution data and determining the injection point and runner size accordingly, the melt flow path length can be effectively shortened, flow resistance reduced, and the melt can achieve uniform filling in the cavity, avoiding molding defects such as insufficient filling, weld lines, or air pockets, thus improving the integrity and density of roller 2 molding. Third, by identifying areas with excessive deformation based on the warpage deformation distribution data and adjusting the cooling pipe layout accordingly, a differentiated layout of the cooling system can be achieved. This allows for precise control of the cooling rate in different areas, effectively reducing warpage deformation caused by uneven cooling, and significantly improving the roundness, coaxiality, and dimensional accuracy of roller 2.

[0091] In some embodiments, after step S4 and before step S5, the step of annealing the roller 2 is further included:

[0092] S41: Remove the roller 2, made of plastic material obtained by injection molding, from the injection mold;

[0093] S42: Place the roller 2 in the annealing equipment;

[0094] S43: Raise the temperature inside the annealing equipment to a predetermined annealing temperature, which is lower than the decomposition temperature of the polyoxymethylene material.

[0095] S44: The roller 2 is kept at the predetermined annealing temperature for a predetermined duration so that the residual stress inside the roller 2 is gradually released at the predetermined annealing temperature;

[0096] S45: Reduce the temperature inside the annealing equipment to room temperature and remove the annealed roller 2 from the annealing equipment.

[0097] Understandably, in step S41, the plastic roller 2, obtained through injection molding, is removed from the injection mold. After the roller 2 has undergone pressure holding and cooling solidification in the injection mold, the mold is opened and the roller 2 is ejected from the cavity using an ejection mechanism. At this point, although the roller 2 has been formed into the desired shape, residual stress remains inside due to uneven cooling shrinkage, freezing of molecular chain orientation, and other factors. In step S42, the roller 2 is placed in an annealing treatment device. The annealing treatment device can be a constant temperature oven or an oil bath. The roller 2 is placed inside the device in a free state or suspended manner to ensure uniform heating of all surfaces. In step S43, the temperature inside the annealing treatment device is raised to a predetermined annealing temperature, which is lower than the decomposition temperature of the polyoxymethylene material. The decomposition temperature of polyoxymethylene (POM) materials is typically around 250°C, and the annealing temperature is set between 140°C and 160°C. This temperature is lower than the thermal decomposition temperature of the material but higher than its glass transition temperature, allowing the molecular chain segments to acquire sufficient mobility for rearrangement. In step S44, the roller 2 is held at the predetermined annealing temperature for a predetermined duration to allow the residual stress inside the roller 2 to be gradually released. The holding time is determined based on the wall thickness and size of the roller 2, typically 0.5 to 1 hour per millimeter of wall thickness, to ensure uniform temperature inside the roller 2 and sufficient release of residual stress. During annealing, the molecular chain segments inside the roller 2 gain kinetic energy under thermal action, undergoing slow creep and rearrangement, gradually releasing the orientation and thermal stresses frozen during injection molding, causing the molecular chains to tend towards a stable conformation with lower free energy. In step S45, the temperature inside the annealing equipment is lowered to room temperature, and the annealed roller 2 is removed from the annealing equipment. The cooling process needs to be controlled at a rate (e.g., 20°C to 30°C per hour) to avoid the re-induction of thermal stress due to rapid cooling. After cooling to room temperature, roller 2 is removed. At this point, the residual stress inside roller 2 has been significantly reduced, and its dimensional stability has been improved.

[0098] The beneficial effects of this implementation method are significant. First, the residual stress inside the roller 2 is effectively released through annealing, preventing dimensional changes or creep deformation caused by stress relaxation during use, thus ensuring the long-term dimensional stability and geometric accuracy of the roller 2. Second, annealing causes the molecular chain segments to rearrange under thermal action, improving the crystalline structure of the polyoxymethylene material, enhancing the toughness and impact resistance of the roller 2, and reducing the risk of cracking due to stress concentration during assembly or use. Third, the annealed roller 2 will not warp or deform due to the release of internal stress during subsequent assembly and long-term use, ensuring the fitting accuracy and smooth rotation between the roller 2 and the plate connector 1, and extending the service life of the roller assembly.

[0099] In some embodiments, the sheet metal connector 1 is integrally injection molded with the roller 2 as a metal insert:

[0100] S51: Obtain the plate connector 1, the plate connector 1 including a connecting end 11 and a main body 12 connected in sequence;

[0101] S52: Place the plate connector 1 in the preheating device and heat the plate connector 1 to a predetermined preheating temperature through the preheating device;

[0102] S53: The sheet metal connector 1, heated to the predetermined preheating temperature, is placed into the injection mold, and the main body 12 of the sheet metal connector 1 occupies the central area of ​​the cavity, and an annular space for forming the roller 2 is formed between the outer periphery of the main body 12 and the inner wall of the cavity.

[0103] S54: After heating the polyoxymethylene material to the plasticizing temperature, inject it into the annular space to allow the polyoxymethylene material to solidify and form on the outer periphery of the main body 12.

[0104] S55: After holding pressure and cooling, the mold is removed to obtain an intermediate assembly in which the roller 2 is integrally covered around the outer periphery of the main body 12.

[0105] Understandably, firstly, the plate connector 1 is obtained, which includes a connecting end 11 and a main body 12 connected in sequence. The plate connector 1 can be pre-made from a metal material (such as stainless steel, carbon steel, or aluminum alloy) through processes such as cold heading, turning, or stamping. Its connecting end 11 is used for fixed connection with the equipment plate, and its main body 12 extends axially to serve as a rotating support for the roller 2. Then, the plate connector 1 is placed in a preheating device, which heats the plate connector 1 to a predetermined preheating temperature. The heating method of the preheating device can be electric heating, infrared heating, or hot air circulation heating. The preheating temperature is usually set between 120°C and 150°C, so that the temperature of the metal insert is close to the temperature of the polyoxymethylene melt. Next, the sheet metal connector 1, heated to the predetermined preheating temperature, is placed into the injection mold, with the main body 12 of the sheet metal connector 1 occupying the central area of ​​the cavity. An annular space for molding the roller 2 is formed between the outer periphery of the main body 12 and the inner wall of the cavity. Specifically, the cavity of the injection mold is annular. The preheated sheet metal connector 1 is placed in the mold, and its connecting end 11 can be fixed by the positioning structure of the mold. The main body 12 extends along the axial direction of the cavity, and a uniform gap is maintained between the outer peripheral surface of the main body 12 and the inner wall of the cavity. This gap is the filling space for the subsequent molding of the roller 2. Subsequently, polyoxymethylene material is heated to the plasticizing temperature and injected into the annular space, allowing the polyoxymethylene material to solidify and form on the outer periphery of the main body 12. After being heated to a plasticizing temperature of 190°C to 230°C in the injection molding machine barrel, the polyoxymethylene (POM) material is injected into the annular gap of the mold cavity via a screw. The molten POM material fills the entire annular space around the outer periphery of the main body 12 and fits tightly against the outer surface of the main body 12. Since the main body 12 has been preheated to near the melt temperature, premature cooling upon contact with the cold insert is avoided, preventing significant delamination at the interface. Finally, after holding pressure and cooling, the material is demolded, resulting in an intermediate assembly in which the roller 2 is integrally wrapped around the outer periphery of the main body 12. Pressure is maintained during the holding pressure stage to compensate for material cooling and shrinkage. After cooling, the mold is opened and the material is ejected, resulting in an intermediate assembly in which the sheet metal connector 1 and the roller 2 are integrally joined. The roller 2 and the main body 12 can form a rotational fit relationship without additional assembly.

[0106] The beneficial effects of this implementation are significant. First, by using the sheet metal connector 1 as an insert and integrally injection molding it with the roller 2, the roller 2 directly covers the outer periphery of the main body 12 during the molding process, eliminating the subsequent assembly process of fitting the roller 2 onto the main body 12, simplifying the manufacturing process of the roller assembly, and reducing assembly costs and time. Second, since the roller 2 and the main body 12 form a tight fit through injection molding, there is no need to reserve an assembly gap between the inner wall of the sleeve portion 21 of the roller 2 and the outer wall of the main body 12, resulting in a closer fit between the mating surfaces. This reduces the radial runout and axial movement of the roller 2 during rotation, improving the rotational accuracy and smoothness of the roller assembly. Third, the preheating treatment of the metal insert allows the polyoxymethylene material to form a good thermal fusion interface with the insert surface during filling, effectively enhancing the bonding strength between the plastic roller 2 and the metal main body 12, and avoiding interface separation or loosening caused by differences in thermal expansion and contraction during use. In addition, the one-piece injection molding process ensures that the roller assembly is a complete rotating mating body at the factory, eliminating the need for users or downstream assembly lines to perform additional roller assembly operations, thus improving the overall delivery quality of the product and the user experience.

[0107] In some embodiments, prior to step S4, a step is further included to determine the preferred combination of parameters for the injection molding process through orthogonal experiments:

[0108] S61: Determine multiple process parameters that affect the injection molding quality of the roller 2 and multiple value levels of each process parameter, wherein the process parameters include injection temperature, mold temperature, injection time, holding pressure and holding time;

[0109] S62: Based on the process parameters and their value levels, establish an orthogonal experimental table, which contains multiple experimental schemes;

[0110] S63: Perform injection molding tests one by one according to the test schemes in the orthogonal test table to obtain the roller 2 test pieces corresponding to each test scheme;

[0111] S64: The molding quality of each roller 2 test piece is tested to obtain the molding quality test results of each group of test schemes;

[0112] S65: Based on the molding quality test results, determine the optimal value from multiple value levels of each process parameter, and use the combination of the optimal values ​​as the preferred combination of process parameters for the injection molding of the roller 2.

[0113] It is understandable that before step S4 (injecting polyoxymethylene material into the injection mold, holding pressure, cooling, and then demolding to obtain the plastic roller 2), there is a step of determining the optimal combination of parameters for the injection molding process through orthogonal experiments. Specifically, firstly, multiple process parameters affecting the injection molding quality of the roller 2 and multiple value levels for each process parameter are determined. The process parameters include injection temperature, mold temperature, injection time, holding pressure, and holding time. Among them, injection temperature affects the fluidity of the melt and the degree of material degradation; mold temperature affects the cooling rate and crystallinity; injection time affects the shear heat during the filling process and the flow pattern of the melt front; holding pressure affects the shrinkage compensation effect and product density; and holding time affects the effective shrinkage compensation time before the gate solidifies. Three to five value levels are selected for each process parameter (for example, five levels for injection temperature between 190℃ and 230℃, and five levels for mold temperature between 40℃ and 100℃). Then, based on each process parameter and its value levels, an orthogonal experimental table is established, which contains multiple experimental schemes. In an orthogonal experimental design table (e.g., L25(5^6)), the levels of each process parameter are evenly distributed across the columns of the table, forming multiple (e.g., 25) experimental schemes. Each experimental scheme corresponds to a specific combination of levels for each process parameter. Subsequently, injection molding experiments are performed one by one according to the experimental schemes in the orthogonal experimental design table, yielding roller 2 test pieces for each scheme. Specifically, the process parameters of the injection molding equipment are set according to the experimental schemes, and injection cycles are executed. A predetermined number of roller 2 samples (e.g., 10 per group) are produced for each scheme, and the corresponding test numbers are labeled. Then, the molding quality of each roller 2 test piece is tested, yielding the molding quality test results for each experimental scheme. Specifically, the test indicators may include the outer diameter accuracy, inner hole roundness, warpage, appearance defects (such as shrinkage marks, flash, weld lines), and mechanical properties (such as hardness and impact toughness) of the roller 2. The test results are recorded in a data table corresponding to the orthogonal experimental design table. Finally, based on the molding quality test results, the optimal values ​​are determined from multiple value levels of each process parameter, and the combination of these optimal values ​​is used as the preferred process parameter combination for the injection molding of the roller 2. Specifically, range analysis or variance analysis is performed on the test results to calculate the mean quality index of each process parameter at different levels, and the optimal value of each parameter for optimizing the molding quality of the roller 2 is determined (e.g., injection temperature 215℃, mold temperature 80℃, injection time 2.5s, holding pressure 80MPa, holding time 6s). These value combinations are then used as the preferred process parameter combinations for subsequent mass production.

[0114] The beneficial effects of this implementation method are significant. First, orthogonal experiments cover multiple process parameters and their multi-level combinations with fewer trials, significantly reducing the number of trials compared to full factorial experiments (e.g., a full factorial experiment with 5 parameters and 5 levels requires 3125 trials, while an orthogonal experiment only requires 25), thus significantly reducing the time and cost of process development. Second, the orthogonal experimental table has balanced dispersion and neat comparability, allowing the effect of each parameter to be independently evaluated. Range analysis can accurately identify the order of primary and secondary influences of each process parameter on the molding quality of roller 2 and the optimal value direction, providing a scientific basis for the rational setting of process parameters. Third, the optimal combination of process parameters determined based on experimental results has been verified by actual injection molding, ensuring that roller 2 achieves optimal levels in terms of dimensional accuracy, appearance quality, and mechanical properties. This avoids repeated mold trials and modifications that may result from relying solely on experience to set parameters, improving the success rate of mold development and mass production.

[0115] In some embodiments, step S5 specifically includes the following steps:

[0116] S51: Pass the connecting end 11 of the plate connector 1 through the mounting hole on the outer plate, and fix the connecting end 11 to the outer plate by a riveting process.

[0117] S52: After the connecting end 11 is fixed to the outer plate, the roller 2, which has been injection molded, is axially sleeved on the outer periphery of the main body 12;

[0118] S53: After the roller 2 is sleeved on the outer periphery of the main body 12, the limiting and fixing 3 pieces are installed radially at the end of the main body 12;

[0119] S54: The inner edge of the limiting and fixing 3 pieces engages with the end of the main body 12, and the outer edge of the limiting and fixing 3 pieces covers the end face of the roller 2, so as to restrict the roller 2 from detaching from the main body 12 axially.

[0120] S55: The axial movement of the roller 2 is limited by the three limiting and fixing parts, so that the roller 2 only has the degree of freedom to rotate around the axis of the main body 12 on the outer periphery of the main body 12.

[0121] Understandably, firstly, the connecting end 11 of the plate connector 1 is passed through the mounting hole on the outer plate, and then riveted to the outer plate using a press-fit process. Specifically, the outer plate has a mounting hole pre-drilled to match the outer diameter of the connecting end 11. The connecting end 11 is inserted into the mounting hole from one side of the plate, causing it to protrude from the other side. Then, axial pressure is applied to the connecting end 11 using a press-fit device, causing it to plastically deform and expand in diameter, forming an interference fit with the mounting hole, thereby firmly riveting the plate connector 1 to the outer plate. At this time, the main body 12 of the plate connector 1 extends outward along the axial direction, providing rotational support for the roller 2. Then, after the connecting end 11 is fixed to the outer plate, the roller 2, which has been injection molded, is axially fitted onto the outer periphery of the main body 12. Specifically, the center hole of roller 2 is aligned with the free end of main body 12 and pushed in along the axial direction of main body 12, so that roller 2 is fitted around the outer periphery of main body 12 and can rotate around main body 12. Next, after roller 2 is fitted around the outer periphery of main body 12, the limiting and fixing three pieces are radially installed on the end of main body 12. For example, when the limiting and fixing three pieces are elastic retaining rings, retaining rings are opened by retaining ring pliers and radially inserted into retaining ring grooves at the end of main body 12. Subsequently, the inner edge of the limiting and fixing three pieces engages with the end of main body 12, and the outer edge of the limiting and fixing three pieces covers the end face of roller 2 to prevent roller 2 from axially disengaging from main body 12. That is, the inner edge of the limiting and fixing three pieces engages and is fixed with the retaining ring groove or annular limiting part 1211 of main body 12, and its outer edge extends radially to the outside of the end face of roller 2, opposite to the end face of roller 2. Finally, the axial movement of the roller 2 is limited by the three limiting and fixing components, so that the roller 2 only has the degree of freedom to rotate around the axis of the main body 12 on the outer periphery of the main body 12. That is, the roller 2 is clamped and positioned in the axial direction by the connecting end 11 and the three limiting and fixing components, and cannot move axially, but can rotate freely around the axis of the main body 12, thereby realizing the rolling guidance function.

[0122] The beneficial effects of this implementation method are significant. First, by first riveting the connecting end 11, then fitting the roller 2, and finally installing the limiting and fixing parts, the plate connector 1 is in a state where the roller 2 does not obstruct the connection when it is fixed to the outer plate. The riveting operation is not interfered with by the roller 2, ensuring riveting quality and ease of operation. Second, the limiting and fixing parts are installed radially at the end of the main body 12. Compared with the axial screw-in locking method, the radial snap-in installation does not require rotation, is faster, and does not require special tools (except for snap ring pliers), simplifying the assembly process and improving production efficiency. Third, the structure of the limiting and fixing parts having the inner edge engaging with the main body 12 and the outer edge covering the end face of the roller 2 reliably limits the roller 2 in the axial direction. At the same time, a small gap is maintained between the outer edge and the end face of the roller 2, allowing the roller 2 to rotate freely without frictional resistance, ensuring the rotational flexibility and service life of the roller assembly.

[0123] In some embodiments, after step S4 and before step S5, the method further includes a step of detecting and sorting the inner diameter of the roller 2:

[0124] S81: Obtain the roller 2 obtained by injection molding, the roller 2 having an inner hole for fitting around the outer periphery of the main body 12;

[0125] S82: The actual inner diameter of the inner hole is measured using a testing tool to obtain the actual inner diameter measurement value;

[0126] S83: Calculate the dimensional deviation of the inner hole based on the difference between the actual inner diameter measurement value and the preset standard inner diameter value;

[0127] S84: Determine whether the dimensional deviation falls within the preset acceptable deviation range. If the dimensional deviation falls within the acceptable deviation range, mark the roller 2 as a qualified product. If the dimensional deviation exceeds the acceptable deviation range, mark the roller 2 as a non-qualified product.

[0128] S85: Based on the actual inner diameter measurement value of the qualified product, each qualified product is sorted and classified according to the size range to which the actual inner diameter measurement value belongs, and the qualified products belonging to the same size range are delivered to the plate connector 1 with the corresponding outer diameter size of the main body 12 for assembly.

[0129] It is understood that in step S81, the roller 2 obtained after injection molding is acquired. The roller 2 has an inner hole for fitting around the outer periphery of the main body 12. After injection molding, the inner hole size of the roller 2 may have a certain degree of dispersion due to fluctuations in the injection molding process (such as differences in shrinkage rate, mold temperature fluctuations, changes in holding pressure, etc.). There may be slight dimensional differences between different batches and even between different molds of the same batch. In step S82, the actual inner diameter of the inner hole is measured using a testing tool to obtain the actual inner diameter measurement value. The testing tool can be a high-precision go / no-go gauge, pneumatic gauge, electronic plug gauge, or coordinate measuring machine, etc. During measurement, it is necessary to ensure that the testing tool is coaxial with the inner hole being measured to obtain an accurate actual inner diameter value. In step S83, the dimensional deviation of the inner hole is calculated based on the difference between the actual inner diameter measurement value and the preset standard inner diameter value. The standard inner diameter value is a reference value determined based on the outer diameter of the main body 12 of the plate connector 1 and the designed fitting clearance. The dimensional deviation is the measured value minus the standard value; a positive value indicates that the inner diameter is too large, and a negative value indicates that the inner diameter is too small. In step S84, it is determined whether the dimensional deviation falls within the preset acceptable deviation range. If the dimensional deviation falls within the acceptable deviation range, the roller 2 is marked as a qualified product; if the dimensional deviation exceeds the acceptable deviation range, the roller 2 is marked as a defective product. The acceptable deviation range is determined comprehensively based on the tolerance zone of the outer diameter of the main body 12 and the required assembly clearance between the roller 2 and the main body 12. For example, the deviation range is set to -0.02mm to +0.04mm. If the inner diameter is too large and exceeds this range, the roller 2 may wobble on the main body 12; if the size is too small, the roller 2 may not be able to fit or may get stuck during rotation. Such rollers are rejected as defective products and will not proceed to subsequent assembly processes. In step S85, based on the actual inner diameter measurement value of the qualified products, each qualified product is sorted and classified according to the size range to which the actual inner diameter measurement value belongs. Qualified products belonging to the same size range are then distributed to the plate connector 1 with the corresponding outer diameter size of the main body 12 for assembly. Specifically, the qualified inner diameter range is further subdivided into multiple size ranges (e.g., -0.02mm to 0mm, 0mm to +0.02mm, +0.02mm to +0.04mm, etc.), and rollers 2 whose measured inner diameter falls within the same range are grouped together. Correspondingly, the outer diameter of the main body 12 of the plate connector 1 is also divided into corresponding groups according to the actual processing size. Rollers 2 whose inner diameter size range matches the outer diameter size range of the main body 12 are paired and assembled with the plate connector 1, thereby achieving grouped matching.

[0130] The beneficial effects of this implementation method are significant. First, by inspecting and judging the inner diameter of each roller 2 piece by piece, rollers 2 with out-of-tolerance inner diameters are eliminated in advance, preventing unqualified rollers 2 from entering the assembly process and causing assembly difficulties or malfunctions, thus ensuring the final assembly pass rate and product quality of the roller assembly. Second, by sorting and classifying qualified products according to their inner diameter range and pairing them with the corresponding outer diameter sheet metal connectors 1, selective assembly based on actual dimensions is achieved. Compared with random assembly, this selective assembly method can obtain more consistent and precise fitting clearances, ensuring that the roller 2 can rotate smoothly on the main body 12 and avoiding shaking or abnormal noise caused by excessive clearances, significantly improving the assembly quality and performance of the roller assembly. Third, this inspection and sorting step allows for a more relaxed dimensional tolerance requirement in the injection molding process—even if there are certain fluctuations in the inner diameter of the roller 2, high-quality assembly can still be achieved through subsequent group selection, reducing the difficulty of process control and scrap rate in the injection molding process, and improving the overall manufacturing economy.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application and should be covered within the scope of the claims of this application.

Claims

1. A roller assembly, characterized in that, include: A sheet metal connector, comprising a connecting end and a main body connected in sequence; A roller is fitted onto the main body, and the roller is made of plastic. A limiting and fixing component connects the main body and the roller, and the limiting and fixing component is used to limit and fix the roller.

2. The roller assembly according to claim 1, characterized in that, A protruding post is formed at one end of the main body away from the connecting end, and the protruding post has an annular limiting part; The limiting and fixing member is sleeved on the protruding post, and the annular limiting part is used to limit the limiting and fixing member; The limiting fastener extends toward the roller so that the roller is located between the limiting fastener and the connecting end.

3. The roller assembly according to claim 1, characterized in that, The roller includes a sleeve portion and an extension portion connected in sequence. The sleeve portion is sleeved on the main body portion, and the extension portion extends away from the connecting end and forms a receiving cavity. The limiting and fixing member is located in the receiving cavity.

4. The roller assembly according to claim 1, characterized in that, The limiting fastener can switch between a disassembled state and a fixed state. In the disassembled state, the limiting fastener is detached from the main body and the roller, and the roller can move relative to the main body. In the fixed state, the limiting fastener is fixedly connected to the roller and the plate connector.

5. The roller assembly according to claim 1, characterized in that, The limiting and fixing component is a snap ring.

6. A method for manufacturing a roller assembly as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Based on the three-dimensional model of the roller, flow simulation and warpage deformation analysis of the roller injection molding process are performed using mold flow analysis software to obtain the flow front distribution data of the melt in the mold cavity and the warpage deformation distribution data of each region of the roller. S2: Based on the flow front distribution data and the warpage deformation distribution data, determine the injection position and runner size of the mold's gating system, as well as the spatial arrangement of each cooling pipe in the mold's cooling system. S3: Based on the injection point, the flow channel size, and the spatial arrangement, manufacture an injection mold for forming the roller; S4: After heating the polyoxymethylene material to the plasticizing temperature, it is injected into the cavity of the injection mold. After holding pressure and cooling, it is demolded to obtain the roller made of plastic material. S5: The roller is sleeved on the outer periphery of the main body of the plate connector, and the limiting and fixing member is installed on the main body and abuts against the end of the roller, so that the roller is axially limited on the main body and can rotate freely relative to the main body.

7. The method for manufacturing the roller assembly according to claim 6, characterized in that, Step S1 specifically includes the following steps: S11: Based on the three-dimensional model of the roller, establish the geometric model of the roller in the mold flow analysis software, and construct a finite element mesh model based on the geometric model; S12: Based on the finite element mesh model, set the physical property parameters of polyoxymethylene material and the boundary conditions of injection molding process, and obtain the flow front distribution data and the warpage deformation distribution data after running the simulation. S13: Based on the flow front distribution data, identify the end region where the melt is last filled in the cavity, and determine the injection point and runner size of the mold's gating system based on the position of the end region; S14: Based on the warping deformation distribution data, identify local areas in each region of the roller where the deformation exceeds a preset threshold, and adjust the spatial arrangement of each cooling pipe in the cooling system of the mold based on the spatial location of the local area. S15: Based on the injection position, the flow channel size, and the adjusted spatial arrangement of each of the cooling pipes, manufacture the injection mold for forming the roller.

8. The method for manufacturing the roller assembly according to claim 6, characterized in that, After step S4 and before step S5, the process further includes an annealing treatment of the roller: S41: Remove the roller, made of plastic material obtained by injection molding, from the injection mold; S42: Place the roller in the annealing equipment; S43: Raise the temperature inside the annealing equipment to a predetermined annealing temperature, which is lower than the decomposition temperature of the polyoxymethylene material. S44: The roller is held at the predetermined annealing temperature for a predetermined duration so that the residual stress inside the roller is gradually released at the predetermined annealing temperature; S45: Reduce the temperature inside the annealing equipment to room temperature and remove the annealed roller from the annealing equipment.

9. The method for manufacturing the roller assembly according to claim 6, characterized in that, The sheet metal connector is integrally injection molded with the roller as a metal insert: S51: Obtain the plate connector, the plate connector comprising a connecting end and a main body connected in sequence; S52: Place the plate connector in the preheating device and heat the plate connector to a predetermined preheating temperature using the preheating device; S53: The sheet metal connector heated to the predetermined preheating temperature is placed into the injection mold, and the main body of the sheet metal connector occupies the central area of ​​the cavity, and an annular space for forming the roller is formed between the outer periphery of the main body and the inner wall of the cavity. S54: After heating the polyoxymethylene material to the plasticizing temperature, inject it into the annular space to allow the polyoxymethylene material to solidify and form on the outer periphery of the main body. S55: After being cooled under pressure, the mold is removed to obtain an intermediate assembly in which the roller is integrally covered around the outer periphery of the main body.

10. The method for manufacturing the roller assembly according to claim 6, characterized in that, Before step S4, the process also includes a step of determining the optimal combination of parameters for the injection molding process through orthogonal experiments: S61: Determine multiple process parameters that affect the quality of the roller injection molding and multiple value levels of each process parameter, wherein the process parameters include injection temperature, mold temperature, injection time, holding pressure and holding time; S62: Based on the process parameters and their value levels, an orthogonal experimental table is established, which contains multiple experimental schemes. S63: Perform injection molding tests one by one according to the test schemes in the orthogonal test table to obtain the roller test pieces corresponding to each test scheme; S64: The molding quality of each roller test piece is tested to obtain the molding quality test results of each group of test schemes; S65: Based on the molding quality test results, determine the optimal value from multiple value levels of each process parameter, and use the combination of the optimal values ​​as the preferred combination of process parameters for the roller injection molding.

Images