Forming method of high polymer material injection molding carburetor plunger

Abstract

The invention provides a forming method for injection molding of a carburetor plunger through a high polymer material, and relates to the technical field of injection molding profile machining, the method comprises the steps that the thermoplastic high polymer material is provided as a raw material, the high polymer material can keep the structure stable in the use environment of-30 DEG C to 200 DEG C, and the wear resistance of the high polymer material meets the working condition requirement of the carburetor plunger; the tensile strength is not lower than 110 MPa; 2, the high polymer material prepared in the step 1 is put into an injection molding machine, melting and plasticizing are conducted in the charging barrel temperature range of 240-260 DEG C, then the high polymer material is injected into a carburetor plunger mold cavity prepared in advance under the pressure effect, after pressure maintaining and cooling are conducted, mold opening is conducted, and an injection molding blank of the carburetor plunger is obtained; wherein the mold is designed to be of a one-mold multi-cavity structure, and a plurality of plunger blanks are produced at the same time through one-time injection molding circulation. According to the carburetor plunger forming method, efficient, environment-friendly and low-consumption production is achieved.

Description

Technical Field

[0001] This invention relates to the field of injection molding profile processing, and in particular to a molding method for injection molding carburetor plungers using polymer materials. Background Technology

[0002] The carburetor plunger is the core moving component in a gasoline engine carburetor that precisely controls the fuel supply. It needs to slide frequently in operating conditions ranging from -30℃ to 200℃, and at the same time, it needs to have sufficient wear resistance and tensile strength to ensure the stability of fuel supply control during long-term use. This directly affects the engine's power output efficiency and fuel economy. For a long time, the industry has generally used aluminum alloy as the base material for carburetor plungers, and the traditional process route of aluminum alloy smelting, casting, extrusion, forging, multi-pass machining, and anodizing surface treatment is used. This process is suitable for the working conditions of plungers due to the rigidity and strength of aluminum alloy materials, and has been used in motorcycles, small general-purpose gasoline engines and other fields for a long time.

[0003] For example, a company specializing in the production of small gasoline engine parts always uses the above-mentioned traditional process when equipping plunger parts for common 125cc motorcycle carburetors: first, aluminum alloy raw materials are melted and cast into bars at a high temperature of over 700℃, then extruded and forged into rough blanks at high temperature, and then the initial dimensions are controlled by multiple machining processes such as turning the end face and outer circle on a lathe and machining the guide hole on a milling machine. Finally, anodizing is performed to form an oxide film on the plunger surface to improve its surface hardness and wear resistance, and to prevent the plunger from wearing out quickly when it slides repeatedly in the carburetor cavity.

[0004] However, there is a technical defect in the production process: as a necessary process before the plunger is finished, anodizing requires the use of highly corrosive chemical reagents such as sulfuric acid and sodium hydroxide. Not only do companies need to invest in special waste liquid collection and treatment equipment to meet environmental emission requirements, but they also increase the initial investment in production equipment and daily operation and maintenance costs. Furthermore, the bonding strength between the anodized layer and the aluminum alloy substrate is easily affected by fluctuations in process parameters such as bath temperature and treatment time. In some plungers, the oxide layer may peel off in a localized manner during subsequent installation and use. The peeled oxide debris may block the internal oil passages of the carburetor or cause an abnormal increase in the clearance between the plunger and the cavity, thereby compromising the accuracy of fuel quantity control and affecting the stability of gasoline engine operation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a molding method for injection-molded carburetor plungers made of polymer materials, which achieves time-saving, efficiency-enhancing, energy-saving, carbon-reducing, cost-reducing, and environmentally friendly carburetor plunger molding method.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] In a first aspect, a method for molding a carburetor plunger using a polymer material injection molding process, the method comprising:

[0008] Step 1: Provide thermoplastic polymer material as raw material. This polymer material should maintain structural stability in an operating environment of -30℃ to 200℃, and its wear resistance should meet the working conditions of carburetor plunger. Its tensile strength should not be less than 110MPa.

[0009] Step 2: The polymer material prepared in Step 1 is fed into the injection molding machine and melted and plasticized in the barrel temperature range of 240℃ to 260℃. Then, it is injected into the pre-prepared carburetor plunger mold cavity under pressure. After holding the pressure and cooling, the mold is opened to obtain the injection-molded blank of the carburetor plunger. The mold is designed as a multi-cavity structure, and multiple plunger blanks are produced simultaneously in one injection molding cycle.

[0010] Step 3: Perform subsequent machining on the carburetor plunger injection molding blanks obtained in Step 2. The machining parts include turning, drilling or precision grinding on the end face, outer circle or guide part of the plunger, so as to finally form a finished carburetor plunger that meets the size and accuracy requirements of the design drawings.

[0011] Furthermore, the multi-cavity structure described in step 2 has 6 or 8 cavities, enabling the simultaneous production of 6 or 8 plunger blanks in one injection molding cycle.

[0012] Furthermore, the machining described in step 3 includes turning the end face of the plunger blank to a fixed length, precision grinding the outer circle to achieve the specified dimensional tolerances and surface finish, and drilling or milling the necessary guide parts.

[0013] Furthermore, the density of the thermoplastic polymer material described in step 1 is 1.3 g / cm³. 3 Up to 1.5g / cm 3 .

[0014] Furthermore, the pressure holding and cooling described in step 2 has a holding pressure of 60 MPa to 80 MPa and a cooling time of 15 to 30 seconds.

[0015] Furthermore, the entire molding process, from raw materials to finished product, is completed within 6 hours.

[0016] Furthermore, after obtaining the carburetor plunger in step 3, the finished product can be put into use directly without surface treatment.

[0017] Furthermore, the carburetor plunger finished product produced by steps (2) and (3) has its key dimensional tolerance controlled within ±0.05 mm to meet the assembly and use requirements of the carburetor.

[0018] Furthermore, the thermoplastic polymer material described in step 1 has a coefficient of friction of no more than 0.3.

[0019] Furthermore, through the injection molding process in step 2, the energy consumption per unit product is reduced by more than 60% compared to the traditional aluminum alloy melting-forging molding process.

[0020] The above-described solution of the present invention has at least the following beneficial effects:

[0021] This method utilizes materials that meet environmental conditions ranging from -30℃ to 200℃, exhibit structural stability, tensile strength of not less than 110MPa, and density of 1.3-1.5g / cm³. 3 Using thermoplastic polymer materials with a friction coefficient of no more than 0.3 as raw materials, and with a 6- or 8-cavity injection mold, the injection blank is formed by melting and plasticizing at a barrel temperature of 240°C to 260°C, holding pressure of 60-80MPa, and cooling time of 15-30 seconds. The finished product is then machined in an orderly manner through end face turning to fix the length, outer diameter precision grinding, and drilling and milling of the guide parts. The finished product does not require additional surface treatment. Therefore, it overcomes the technical problems of cumbersome melting, casting-extrusion, forging, multi-process machining and anodizing in the production of traditional aluminum alloy carburetor plungers, which are characterized by high temperature and high energy consumption, environmental pollution from surface treatment, long production cycle and difficulty in controlling precision. As a result, it achieves the technical effect of completing production from raw materials to finished products within 6 hours, reducing unit product energy consumption by more than 60% compared with traditional processes, controlling key dimensional tolerances within ±0.05 mm, and making the finished products ready for use. It realizes the synergistic improvement of process simplification, energy saving and carbon reduction, cost optimization and environmental protection.

[0022] The beneficial effects of this invention can be attributed to improvements in yield, quality, precision, and efficiency; savings in energy consumption, raw materials, and processes; and improvements in processing, operation, control, and use. Specifically, these include:

[0023] 1. Fewer processes and shorter time: The original process of melting, casting, extrusion, forging, machining and surface treatment of products takes 48 hours to produce from raw materials to finished products. The present invention takes only 6 hours from raw materials to finished products. The original process was to process and shape one product at a time. The present invention is to use injection molding, which can produce 6 or 8 products from one mold.

[0024] 2. High processing precision, good product consistency, strong continuity, no need for professional technicians, as long as the mold is well designed, mass production is possible;

[0025] 3. Low energy consumption. The original product requires temperatures above 400°C for the three processes of melting, extrusion, and forging from materials to finished product, and melting requires temperatures above 700°C. However, the maximum injection molding temperature of this invention does not exceed 300°C.

[0026] 4. Cost reduction: The original product material was aluminum alloy with a density of 2.7 g / cm³. 3 The polymer material of this invention has a density of 1.4 g / cm³. 3 The number of products of the same volume can be increased by about 100%. Attached Figure Description

[0027] Figure 1 This is a schematic flowchart of a molding method for a polymer material injection-molded carburetor plunger provided by an embodiment of the present invention. Detailed Implementation

[0028] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0029] like Figure 1 As shown, an embodiment of the present invention provides a method for molding a polymer material injection-molded carburetor plunger, the method comprising the following steps:

[0030] Step 1: Provide thermoplastic polymer material as raw material. This polymer material should maintain structural stability in an operating environment of -30℃ to 200℃, and its wear resistance should meet the working conditions of carburetor plunger. Its tensile strength should not be less than 110MPa.

[0031] Step 2: The polymer material prepared in Step 1 is fed into the injection molding machine and melted and plasticized in the barrel temperature range of 240℃ to 260℃. Then, it is injected into the pre-prepared carburetor plunger mold cavity under pressure. After holding the pressure and cooling, the mold is opened to obtain the injection-molded blank of the carburetor plunger. The mold is designed as a multi-cavity structure, and multiple plunger blanks are produced simultaneously in one injection molding cycle.

[0032] Step 3: Perform subsequent machining on the carburetor plunger injection molding blanks obtained in Step 2. The machining parts include turning, drilling or precision grinding on the end face, outer circle or guide part of the plunger, so as to finally form a finished carburetor plunger that meets the size and accuracy requirements of the design drawings.

[0033] In this embodiment of the invention, a thermoplastic polymer material with a stable structure, wear resistance suitable for carburetor plunger operating conditions, and a tensile strength of not less than 110 MPa is used as the raw material. This material is melted and plasticized in an injection molding machine at a barrel temperature of 240°C to 260°C, injected into a multi-cavity carburetor plunger mold cavity, and cooled under pressure to obtain an injection-molded blank. The end faces, outer diameters, or guide parts of the blank are then machined, drilled, or precision ground. This overcomes the technical problems of poor material adaptability, cumbersome production processes, low single-mold production efficiency, and difficulty in achieving precision due to a lack of targeted blank processing when using aluminum alloy as the base material in traditional carburetor plungers. Consequently, the invention achieves precise matching between the raw material and the plunger operating conditions, significantly simplifies the production process, allows for the production of multiple blanks in a single injection to improve production efficiency, and ensures that the finished product consistently meets the dimensions and precision requirements of the design drawings after targeted machining.

[0034] In a preferred embodiment of the present invention, step 1 involves providing a thermoplastic polymer material as a raw material. This polymer material maintains structural stability under operating conditions ranging from -30°C to 200°C, and its wear resistance meets the requirements of the carburetor plunger. Its tensile strength is not less than 110 MPa. The density of the thermoplastic polymer material described in step 1 is 1.3 g / cm³. 3 Up to 1.5g / cm 3 The thermoplastic polymer material mentioned in step 1 has a friction coefficient of no more than 0.3. Specifically, this includes: based on the usage requirements of carburetor plungers, which frequently slide in operating conditions from -30℃ to 200℃, possess sufficient wear resistance, and have a tensile strength of no less than 110MPa, selecting suitable thermoplastic polymer material categories, and then conducting multiple index tests on the candidate materials using material performance testing equipment. During the testing process, the candidate thermoplastic polymer material samples are first placed in a temperature-controlled environmental chamber to simulate low-temperature environments of -30℃ and high-temperature environments of 200℃, respectively. After setting a continuous duration, the material structure is observed to see if there are any unstable phenomena such as cracking or deformation, ensuring that the material maintains structural stability within this temperature range. Subsequently, a wear resistance testing device is used to simulate the sliding conditions of the carburetor plunger in the cavity, and a friction and wear test is conducted on the material sample to determine whether its wear resistance can meet the long-term use requirements of the plunger. At the same time, a tensile test is conducted on the material sample using a tensile strength testing device to ensure that its tensile strength value is no less than 110MPa. Based on this, the density and coefficient of friction of the material were further tested, and a density of 1.3 g / cm³ was selected. 3 Up to 1.5g / cm 3Materials within the specified range were selected to achieve plunger lightweighting. Materials with a friction coefficient of no more than 0.3 were chosen to reduce wear during plunger sliding. After completing all performance index tests and confirming that the materials met the requirements, the thermoplastic polymer material was determined as the raw material for producing carburetor plungers, preparing for subsequent injection molding processes.

[0035] In this embodiment of the invention, because a density of 1.3 g / cm³ is used... 3 Up to 1.5g / cm 3 The technology utilizes thermoplastic polymer materials with a friction coefficient of no more than 0.3, which can maintain structural stability in operating environments ranging from -30℃ to 200℃, have wear resistance suitable for carburetor plunger conditions, and a tensile strength of no less than 110MPa. This overcomes the technical problems of traditional carburetor plunger materials, such as high density leading to heavy components, high friction coefficient easily aggravating sliding wear, and difficulty in maintaining stable structure and sufficient tensile strength in a wide temperature range, making it unsuitable for long-term adaptation to frequent plunger sliding and large temperature fluctuations. This achieves the goal of lightweight carburetor plunger design to reduce overall machine load, reduce sliding wear between the plunger and carburetor cavity to extend service life, and ensure that the plunger maintains structural stability and reliable mechanical properties even in extreme temperature environments, meeting the technical requirements for long-term use.

[0036] In a preferred embodiment of the present invention, in step 2, the polymer material prepared in step 1 is fed into an injection molding machine and melted and plasticized within a barrel temperature range of 240°C to 260°C. Then, under pressure, it is injected into a pre-prepared carburetor plunger mold cavity. After pressure holding and cooling, the mold is opened to obtain the injection-molded blank of the carburetor plunger. The mold is designed as a multi-cavity structure, producing multiple plunger blanks simultaneously in one injection molding cycle. The multi-cavity structure in step 2 has 6 or 8 cavities, enabling the simultaneous production of 6 or 8 plunger blanks in one injection molding cycle. The pressure holding and cooling process described herein has a holding pressure of 60MPa to 80MPa and a cooling time of 15 to 30 seconds. Through the injection molding process in step 2, the energy consumption per unit product is reduced by more than 60% compared to the traditional aluminum alloy melting-forging molding process. Specifically, the process includes: first, uniformly feeding the thermoplastic polymer material granules prepared in step 1 into the hopper of the injection molding machine; starting the injection molding machine and setting the barrel temperature parameters; gradually raising the temperature of the barrel from the feeding section to the nozzle section to the range of 240°C to 260°C to ensure that the polymer material is fully heated, melted, and plasticized in the barrel to form a uniform molten material. Simultaneously, the pre-prepared carburetor plunger mold is inspected. This mold has a structure of 6 or 8 cavities, and the mold cavity size is completely matched with the design size of the carburetor plunger blank. The main runner and branch runner inside the mold have been adjusted to evenly distribute the molten material to each cavity. After the material in the injection molding machine barrel is completely melted, the injection molding machine applies pressure to inject the molten polymer material into the mold cavity through the nozzle, ensuring that the molten material quickly and fully fills the 6 or 8 cavities. After the material injection is completed, the injection molding machine maintains a holding pressure of 60MPa to 80MPa to prevent shrinkage or deformation of the molten material inside the cavity due to cooling and shrinkage. At the same time, the mold cooling system is turned on, and the cooling time is controlled between 15 and 30 seconds, so that the molten material inside the cavity gradually solidifies and forms the mold. After the material has fully solidified, the injection molding machine drives the mold to open, and the ejection mechanism inside the mold ejects 6 or 8 carburetor plungers into the injection molded blanks at one time, completing a single injection molding cycle. The entire injection molding process does not require high-temperature melting of more than 700°C as in traditional aluminum alloy processes. The energy consumption per unit product is reduced by more than 60% compared to traditional aluminum alloy melting and forging molding processes.

[0037] In this embodiment of the invention, the injection molding technique involves feeding a qualified polymer material into an injection molding machine, melting and plasticizing it at a barrel temperature of 240°C to 260°C, and then injecting it into a 6- or 8-cavity carburetor plunger mold cavity under pressure. The mold is then opened to obtain the blank after holding pressure at 60MPa to 80MPa and cooling for 15 to 30 seconds. This overcomes the technical problems of traditional aluminum alloy melting-forging processes, which require temperatures above 700°C, involve complex procedures leading to high energy consumption per unit product, and produce only a small number of blanks per mold cycle, resulting in low production efficiency. Consequently, the technique achieves a reduction of over 60% in energy consumption per unit product compared to traditional processes, while simultaneously enabling the production of 6 or 8 plunger blanks per injection molding cycle, thus improving production efficiency.

[0038] In a preferred embodiment of the present invention, step 3 involves further machining the carburetor plunger injection molding blanks obtained in step 2. The machining includes turning, drilling, or precision grinding the end face, outer diameter, or guide portion of the plunger to ultimately form a finished carburetor plunger that meets the dimensional and precision requirements of the design drawings. The machining in step 3 sequentially includes turning the end face of the plunger blank to a fixed length, precision grinding the outer diameter to achieve the specified dimensional tolerances and surface finish, and machining the necessary guide portions. The drilling or milling process includes: first, fixing each carburetor plunger injection molding blank obtained in step 2 onto a special fixture on a lathe; adjusting the lathe parameters so that the cutting tool is aligned with the end face of the blank; starting the lathe to machine the end face of the blank; precisely removing excess material from the end face according to the axial length of the plunger specified in the design drawings, so that the axial length of each plunger blank is uniformly at the fixed dimension required by the design; completing the end face turning fixed length operation; and then transferring the end face turned plunger blank to the working tool of an external cylindrical grinding machine. On the component fixing device, according to the outer diameter tolerance and surface finish standards specified in the design drawings, the grinding wheel speed, feed rate, and other parameters of the cylindrical grinding machine are adjusted. The cylindrical grinding machine is then started to perform precision grinding on the outer diameter surface of the plunger blank. During the machining process, the outer diameter and surface condition are monitored in real time using precision measuring tools to ensure that the outer diameter meets the tolerance requirements and the surface finish meets the usage standards. Finally, the structural requirements for the plunger guide part in the design drawings are checked. If the guide part requires drilling, the plunger blank after precision grinding is installed on the worktable fixture of the drilling machine. According to the hole position, diameter, and depth parameters specified in the drawings, the drilling position and depth of the drilling machine are adjusted, and the drilling machine is started to perform drilling. If the guide part requires a specific shape structure, it is fixed on the fixture of the milling machine. According to the shape requirements of the guide structure, a suitable milling cutter is selected, the machining path and parameters of the milling machine are adjusted, and the milling machine is operated to mill the guide part. After all machining processes are completed, a carburetor plunger product that meets the size and precision requirements of the design drawings is obtained.

[0039] In this embodiment of the invention, the subsequent machining techniques of turning the end face to a fixed length, precision grinding the outer circle to achieve the specified dimensional tolerances and surface finish, and drilling or milling the necessary guide parts on the carburetor plunger injection molding blank obtained in step 2 are adopted. This overcomes the technical problems in traditional carburetor plunger machining, such as inconsistent dimensional references caused by chaotic process sequence, difficulty in achieving the required outer circle accuracy and surface finish, and the impact of guide part machining deviations on assembly adaptability, which in turn cause the finished product to fail to stably meet the design requirements. This achieves the technical effect of accurately establishing the axial dimensional reference of the plunger, ensuring that the outer circle meets the assembly accuracy and surface finish requirements, ensuring that the guide part structure is accurately adapted to the carburetor assembly, and ultimately making the finished product fully meet the dimensional and accuracy requirements of the design drawings.

[0040] In a preferred embodiment of the present invention, the entire molding process from raw materials to finished products is completed within 6 hours. Specifically, it includes: first, initiating the raw material preparation process, selecting thermoplastic polymer materials that meet performance requirements, and completing the screening, inspection, and quantitative preparation of the materials within 1 hour to ensure that the materials can be directly used in subsequent processes; then, starting the injection molding process, feeding the prepared polymer materials into the injection molding machine, setting the barrel temperature to 240°C to 260°C, and completing the melting and plasticization of the materials within 1.5 hours; subsequently, injecting the materials into a 6- or 8-cavity mold cavity, holding them at a pressure of 60 MPa to 80 MPa for 15 to 30 seconds, and then cooling the materials. The shaping process involves completing a single injection molding cycle and removing all plunger blanks within one hour, accumulating approximately 2.5 hours. Following this, the machining process begins, transferring the injection-molded blanks sequentially to lathes, cylindrical grinders, drilling machines, or milling machines. Within two hours, end face turning to length, external cylindrical grinding, and drilling or milling of guide parts are completed systematically. Dimensional and precision checks are conducted concurrently to ensure machining quality. Finally, the final inspection and finishing of the finished products is completed in 0.5 hours, confirming that all finished products meet the design drawings. The entire process, from raw material preparation to finished product output, is strictly controlled within 6 hours, significantly shortening the production cycle compared to the traditional aluminum alloy plunger production cycle of over 48 hours.

[0041] In this embodiment of the invention, the use of thermoplastic polymer materials as raw materials, melting and plasticizing at a barrel temperature of 240°C to 260°C, injection molding with 6 or 8 cavities in one mold, controlling the holding pressure at 60MPa to 80MPa and the cooling time at 15 to 30 seconds during the injection molding process, combined with a simplified process route of orderly machining (first turning the end face of the plunger blank to a fixed length, then precision grinding the outer diameter, and finally drilling or milling the guide part), enables the entire molding process from raw material to finished product to be completed within 6 hours. Therefore, this overcomes the cumbersome process of traditional aluminum alloy carburetor plungers, which require high-temperature melting at over 700°C, casting, extrusion, forging, multiple machining processes, and anodizing, and takes more than 48 hours from raw material to finished product, resulting in a long production cycle and difficulty in quickly responding to the demand for mass production. This achieves the technical effect of shortening the production cycle of carburetor plungers, improving production efficiency, and quickly matching the mass production demand in the field of motorcycle or small general-purpose gasoline engine parts.

[0042] In a preferred embodiment of the present invention, after obtaining the carburetor plunger finished product in step 3, the finished product can be directly put into use without surface treatment. Specifically, after completing the machining of the carburetor plunger injection molding blank in step 3, the performance and condition of the obtained carburetor plunger finished product are first tested. The focus is on checking whether the surface finish, wear resistance and dimensional accuracy of the finished product meet the requirements of carburetor assembly and use. Since the thermoplastic polymer material used itself has the wear resistance to meet the working conditions of the carburetor plunger, and the key parts such as the outer circle of the finished product have reached the specified surface finish after orderly machining, there is no need to improve the surface hardness and wear resistance through anodizing treatment like traditional aluminum alloy plungers. After the test confirms that the various indicators of the finished product are qualified, only compressed air or special cleaning tools are needed to remove the fine debris and dust generated by machining on the surface of the finished product. After simple cleaning, the finished product can be packaged and then directly put into the assembly process of gasoline engine carburetors. No additional surface treatment process is carried out throughout the process.

[0043] In this embodiment of the invention, because the finished carburetor plunger is obtained in step 3 and can be used directly without surface treatment, the technical problem that traditional aluminum alloy carburetor plungers require anodizing surface treatment, which requires the use of highly corrosive chemical reagents, additional investment in waste liquid treatment equipment to increase costs, and the oxide layer is easy to fall off, affecting the operating stability of the gasoline engine, is overcome. Thus, the technical effects of eliminating the surface treatment process, reducing production equipment investment and maintenance costs, avoiding chemical reagent pollution of the environment, ensuring the long-term stability of the carburetor plunger, and reducing interference with the operation of the gasoline engine are achieved.

[0044] In a preferred embodiment of the present invention, the carburetor plunger finished product made by steps (2) and (3) has a key dimensional tolerance controlled within ±0.05 mm to meet the assembly and use requirements of the carburetor. Specifically, this includes: firstly, establishing a dimensional accuracy control system from the two core links of injection molding and machining to ensure that the key dimensional tolerance of the finished product is stable within ±0.05 mm. In the injection molding stage of step 2, high-precision machining equipment is used to mill and polish the 6-cavity or 8-cavity cavity during mold manufacturing, so that the dimensional tolerance of the key parts of the cavity is preset within ±0.03 mm. At the same time, positioning pins and guide pillars are set in the mold to ensure the mold closing accuracy. During the injection molding process, the barrel temperature is strictly controlled, with temperature fluctuations between 240℃ and 260℃ kept within ±5℃ to avoid uneven temperature leading to blank shrinkage and deformation. During the holding pressure stage, a stable pressure of 60MPa to 80MPa is maintained, and the cooling time is precisely controlled between 15 seconds and 30 seconds. The blank is removed from the mold only after it has completely solidified to reduce stress deformation during demolding. Then, the blank proceeds to step 3, the machining stage. A high-precision CNC lathe is used for end face turning, with the spindle speed and feed rate set to 1500 rpm and 0.02 mm per rpm, respectively. During the turning process, a digital vernier caliper is used to measure the axial length in real time to ensure that the axial dimensional tolerance after end face turning is controlled within ±0.02 mm. The outer cylindrical grinding is performed using a CNC cylindrical grinding machine with an 800-grit grinding wheel. The grinding feed rate is controlled at 0.005 mm per stroke. The outer diameter is measured with a micrometer after each grinding stroke until the outer diameter dimensional tolerance reaches ±0.05 mm. At the same time, the surface finish of the outer diameter is ensured to meet the standard. When machining the guide parts, a drilling machine or milling machine is positioned by a CNC system. The drilling accuracy is controlled at ±0.03 mm. The milling of the forming surface is calibrated with a dial indicator to calibrate the workpiece position. After all machining processes are completed, a tool microscope is used to comprehensively inspect the key dimensions of the plunger to confirm that the tolerances are all within ±0.05 mm. This ensures that the finished product can accurately fit the carburetor cavity and meet the requirements for assembly and fuel quantity control.

[0045] In this embodiment of the invention, the injection molding process of melting and plasticizing the barrel at a temperature of 240°C to 260°C, holding pressure of 60MPa to 80MPa, and cooling time of 15 to 30 seconds in step 2, combined with the orderly machining techniques such as end face turning to fixed length and outer circle precision grinding in step 3, controls the key dimensional tolerance of the carburetor plunger within ±0.05 mm. Therefore, it overcomes the technical problems of traditional aluminum alloy plungers, which are difficult to control in terms of dimensional accuracy and prone to abnormal fit clearance after multiple complicated processes, and cannot stably meet the requirements of carburetor assembly and fuel quantity control. Thus, it achieves the technical effect of ensuring precise fit between the plunger and the carburetor cavity, stable control of fuel supply, and ensuring engine power output efficiency and fuel economy.

[0046] In an embodiment of the present invention, a new polymer material was developed. The working conditions and functions of the full-volume plunger are shown in the table below. The material has an operating temperature of -30 to 200°C, good wear resistance, and tensile strength ≥110MPa.

[0047]

[0048] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for molding a carburetor plunger using injection molding of a polymer material, characterized in that, The method includes: Step 1: Provide thermoplastic polymer material as raw material. This polymer material should maintain structural stability in an operating environment of -30℃ to 200℃, and its wear resistance should meet the working conditions of carburetor plunger. Its tensile strength should not be less than 110MPa. Step 2: The polymer material prepared in Step 1 is fed into the injection molding machine and melted and plasticized in the barrel temperature range of 240℃ to 260℃. Then, it is injected into the pre-prepared carburetor plunger mold cavity under pressure. After holding the pressure and cooling, the mold is opened to obtain the injection-molded blank of the carburetor plunger. The mold is designed as a multi-cavity structure, and multiple plunger blanks are produced simultaneously in one injection molding cycle. Step 3: Perform subsequent machining on the carburetor plunger injection molding blanks obtained in Step 2. The machining parts include turning, drilling or precision grinding on the end face, outer circle or guide part of the plunger, so as to finally form a finished carburetor plunger that meets the size and accuracy requirements of the design drawings.

2. The molding method for a polymer material injection-molded carburetor plunger according to claim 1, characterized in that, The multi-cavity structure described in step 2 has 6 or 8 cavities, which allows 6 or 8 plunger blanks to be produced simultaneously in one injection molding cycle.

3. The molding method for a polymer material injection-molded carburetor plunger according to claim 2, characterized in that, The machining process described in step 3 includes turning the end face of the plunger blank to a fixed length, precision grinding the outer circle to achieve the specified dimensional tolerances and surface finish, and drilling or milling the necessary guide parts.

4. The molding method for a polymer material injection-molded carburetor plunger according to claim 3, characterized in that, The density of the thermoplastic polymer material mentioned in step 1 is 1.3 g / cm³. 3 Up to 1.5g / cm 3 .

5. The molding method for a polymer material injection-molded carburetor plunger according to claim 4, characterized in that, The pressure holding and cooling described in step 2 has a holding pressure of 60MPa to 80MPa and a cooling time of 15 seconds to 30 seconds.

6. The molding method for a polymer material injection-molded carburetor plunger according to claim 5, characterized in that, The entire molding process, from raw materials to finished product, is completed within 6 hours.

7. The molding method for a polymer material injection-molded carburetor plunger according to claim 6, characterized in that, After obtaining the carburetor plunger in step 3, the finished product can be put into use directly without surface treatment.

8. The molding method for a polymer material injection-molded carburetor plunger according to claim 7, characterized in that, The carburetor plunger produced by steps (2) and (3) has a key dimensional tolerance controlled within ±0.05 mm to meet the assembly and use requirements of the carburetor.

9. The molding method for a polymer material injection-molded carburetor plunger according to claim 8, characterized in that, The thermoplastic polymer material described in step 1 has a friction coefficient of no more than 0.

3.

10. The molding method for a polymer material injection-molded carburetor plunger according to claim 9, characterized in that, The injection molding process in step 2 reduces the energy consumption per unit product by more than 60% compared to the traditional aluminum alloy melting-forging molding process.

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