Introduce in detail: the processing flow of injection molding parts of intelligent sweeper.
The processing flow of injection-molded parts of intelligent sweeper (such as fuselage shell, dust box assembly, roller bracket, internal structural parts, etc.) needs to be combined with the characteristics of "lightweight, high precision and impact resistance" of products and the standardized logic of injection molding production. The whole process can be divided into five stages: preliminary preparation, core injection molding, post-processing, quality inspection, packaging and warehousing, and each stage includes key process nodes. The specific flow is as follows:
First, the preparatory stage: laying the foundation for injection molding production (the core is "data conversion" and "material/mold readiness")
At this stage, it is necessary to complete the transformation from "design drawing" to "productive state" to ensure the stability and controllability of the subsequent injection molding process, which is the key premise to determine the product quality.
Product structure and mold design
Structural analysis and optimization: according to the functional requirements of the injection-molded parts of the intelligent sweeper (such as waterproof shell, wear-resistant dust box and load-bearing support), the 3D model design is completed by CAD (Computer Aided Design) software, and then the "mold flow analysis" is carried out by CAE (Computer Aided Engineering) software, which simulates the filling, pressure holding and cooling process of plastic melt in the mold and optimizes the structure (such as avoiding shrinkage marks caused by uneven wall thickness, increasing reinforcement)
Mold manufacturing: According to the optimized drawings, H13 (hot-working mold steel, suitable for mass production) or S136 (corrosion-resistant mold steel, suitable for transparent parts or parts requiring high surface quality) is selected to make the mold. The mold should include a cavity (corresponding to the shape of the product), a core, a cooling system (uniformly cooling to prevent the product from warping), an ejection mechanism (ejecting the product from the mold after injection molding), polishing (the shell needs mirror polishing, and the surface roughness Ra≤0.8μm), trial mold debugging (correcting the dimensional deviation of the mold to ensure that the product is consistent with the design).
Selection and pretreatment of raw materials
Material selection: common materials for injection molding parts of intelligent sweeper need matching functions:
Body shell/dust box: ABS (acrylonitrile butadiene styrene), which has both rigidity, toughness and impact resistance, and the surface is easy to be painted/electroplated; If lightweight is needed, ABS+PC (polycarbonate) alloy can be selected to enhance heat resistance (to avoid deformation caused by motor heating when the sweeper works).
Internal bracket/gear: POM (polyoxymethylene, commonly known as "Saigang"), which is wear-resistant and rigid and suitable for transmission structure; Or PA66 (nylon 66)+ glass fiber to enhance the bearing capacity.
Seal/soft rubber roller: TPE (Thermoplastic Elastomer), which is soft and aging-resistant, and can be integrated with hard rubber (such as ABS) by two-color injection molding.
Material pretreatment: plastic particles need to be dehydrated by a dryer (such as dehumidification dryer) (ABS water content should be ≤0.1%, PC water content should be ≤0.02%) to avoid bubbles and silver streaks after injection molding; If color matching is needed, color master batch should be added in proportion after drying (for example, adding black master batch to black dust box) and evenly mixed by mixer.
Second, the core injection stage: realize the transformation of "plastic melt → molded part" (the core is "precise temperature control" and "rhythm matching")
This stage is the core of injection molding. Plastic particles need to be converted into molded parts that meet the size requirements through injection molding machine and customized process parameters. Because of the multi-category and high precision of intelligent sweeper injection parts, the parameters need to be adjusted accordingly.
Equipment debugging and parameter setting
Selection of injection molding machine: select an injection molding machine with appropriate tonnage according to the product size (for example, 100-150T injection molding machine for small bracket and 300-500T injection molding machine for fuselage shell), and install a matching mold (aligned with the injection molding machine nozzle through the positioning ring); If two-color parts (such as soft rubber roller+hard rubber bracket) are involved, a two-color injection molding machine (double barrels and double nozzles) is needed.
Key parameter setting: Set core parameters according to material characteristics and product structure, taking ABS shell as an example:
Barrel temperature: 220-240℃ in the front section (near the nozzle), 210-230℃ in the middle section and 190-210℃ in the back section (near the hopper) (to ensure that ABS is fully melted and does not decompose);
Injection pressure: 60-80MPa (avoid flash caused by excessive pressure or insufficient filling caused by insufficient pressure);
Holding pressure/time: 60%-80% of injection pressure, and holding time is 5-10 seconds (to supplement melt shrinkage and ensure product size stability);
Cooling time: 15-20 seconds (according to the wall thickness adjustment, the cooling should be extended when the wall thickness is more than 3mm to prevent deformation after demoulding);
Speed of mold opening and closing: Close the mold at a low speed (to avoid mold collision), and open the mold first quickly and then slowly (to take out the product quickly and avoid mold sticking).
Automatic injection molding production (combined with manipulator)
Process connection: adopt customized manipulator of injection molding machine (such as side-hanging manipulator) to form "linkage cycle" with injection molding machine;
The injection molding machine closes the mold → the charging barrel heats the molten plastic → the injected melt enters the mold cavity → the pressure is maintained → cooling;
The mold is opened in place → the manipulator extends into the mold (through customized fixtures, such as vacuum suction cups to hold the shell and mechanical claws to hold the bracket);
The manipulator takes out the molded part and cleans the residual waste (such as gate material) in the mold synchronously;
The manipulator places the molded part on the conveyor belt or directly transfers it to the subsequent gate shearing station;
The injection molding machine closes the mold and enters the next production cycle (a single cycle is usually 15-30 seconds, which is adjusted according to the product size).
Advantages: Compared with manual picking, the manipulator can realize 24-hour continuous production, and the positioning accuracy is within ±0.1mm, avoiding the safety risk caused by manual contact with high-temperature molds and reducing the defective products caused by picking deviation.
Third, the post-processing stage: optimizing the product appearance and function (the core is "removing defects" and "strengthening functions")
The injection parts of intelligent sweeper need to be post-treated to meet the requirements of "beautiful appearance and assembly adaptation", and the post-treatment process of different types of parts is different.
Gate/flash removal
Gate removal: after molding, the injection molded parts will have gates (channels for melt to enter the cavity), which need to be removed manually (small parts) or by automatic equipment (such as punching machine and laser cutting machine); For example, the side gate of the fuselage shell can be trimmed with a special tool to ensure that the cut is flat (to avoid sticking during assembly).
Flash cleaning: If the pressure is too high during injection molding or the mold clamping is not tight, flash will occur at the product edge, which needs to be polished with sandpaper (detail number is more than 800#) or through a freezing trimming machine (using low temperature to make flash brittle and high-speed shot blasting to remove it), especially suitable for TPE soft rubber parts (manual polishing is easy to deform).
Surface treatment (as required)
Spray painting/silk screen printing: The fuselage shell needs to be beautiful and wear-resistant, and usually spray painting (such as matte black and metallic color), first spray primer (to enhance adhesion), then spray topcoat, and finally dry (80-100℃ for 30 minutes); If it is necessary to print logo or operation logo, screen printing process (printing ink on the surface through screen printing, drying and curing) is adopted.
Electroplating: Some decorative parts of high-end sweepers (such as buttons and frames) adopt electroplating process (such as chromium plating and nickel plating), and a metal coating is formed on the ABS surface through electrolysis to improve the texture and corrosion resistance (ABS parts need to be "roughened and activated" first to ensure the adhesion of the coating).
Ultrasonic welding: if the product is an assembled structure (such as the upper cover and the lower cover of the dust box), ultrasonic welding (melting the plastic on the contact surface through high-frequency vibration and bonding after cooling) is lighter than screw connection and has better sealing performance (preventing dust leakage).
Assembly pretreatment
Drilling/tapping: some structural parts (such as roller bracket) need to be provided with mounting holes, which are accurately drilled by CNC drilling machine (hole diameter tolerance is ±0.05mm). If screws need to be installed, subsequent tapping (internal thread processing) is required.
Stress relief treatment: There may be internal stress in the injection-molded parts with thick wall (such as fuselage base) after cooling, so it is necessary to "anneal" (put the products in an oven, keep the temperature at 80-90℃ for 1-2 hours, and slowly cool) to avoid cracking caused by stress release in later use.
Fourth, the quality inspection stage: to ensure that the products meet the standards (the core is "full dimension inspection" and "batch screening")
The injection parts of intelligent sweeper need to pass strict inspection to avoid unqualified products from flowing into the assembly process. The inspection content covers three dimensions: "size, appearance and performance".
Dimensional accuracy detection
First piece inspection: Before each batch of production, the first molded part is extracted, inspected by caliper (measuring length and thickness), micrometer (measuring wall thickness with accuracy of 0.001mm) and projector (measuring complex structural dimensions, such as hole position coordinates), and compared with the tolerance requirements of design drawings (such as shell length and width tolerance of ±0.2mm and assembly hole position tolerance of ±0.1mm), and the batch can be started only after it is qualified.
Batch sampling: For every 100-200 pieces produced, 5-10 pieces are randomly selected, and full-size detection is carried out with a three-coordinate measuring instrument (high precision detection, accuracy of ±0.005mm) to ensure the stability of batch production.
Appearance and defect detection
Manual visual inspection: under a well-lit inspection platform (illuminance ≥800lux), check whether there are any defects such as bubbles, silver wires, shrinkage marks, scratches, chromatic aberration, etc. on the product surface (for example, bubbles with a diameter of > ＞0.5mm are not allowed on the shell surface, and the scratch length is ≤2mm).
Automatic inspection: in mass production, visual inspection equipment (such as industrial camera+AI algorithm) is used to automatically identify appearance defects, and the inspection speed can reach 100-200 pieces/minute, which is more efficient than manual work and avoids missing inspection (especially suitable for small structural parts).
Performance test (key parts)
Impact resistance test: the fuselage shell needs to be tested by falling ball impact (for example, 1kg steel ball falls from 1m height, and the shell is not cracked) to ensure that the sweeper is not easily damaged during collision.
Wear resistance test: the inner wall of the dust box needs to be tested by a wear resistance tester (loaded with 500g weight and rubbed for 1000 times), and there is no obvious scratch on the surface to prevent dust leakage caused by dust wear.
Sealing test: After the dust box is assembled, introduce compressed air (pressure 50kPa) and put it into water to observe whether it bubbles, so as to ensure no air leakage (to avoid dust overflow when the sweeper works).
5. Packaging and warehousing stage: ensuring transportation and warehousing safety (the core is "protection" and "traceability")
Qualified injection molded parts should be packaged in a standardized way to avoid damage during transportation, and at the same time, it is convenient for subsequent assembly workshops to collect them.
Classified packaging
Single protection: easy-to-scratch appearance parts (such as fuselage shell) need to be sheathed in PE protective film or bubble bag; Small structural parts (such as screw posts and buckles) shall be put into the anti-static tray (to avoid electrostatic adsorption of dust).
Batch packaging: put a single protected piece into a paper box or plastic turnover box, which is separated by foam partitions (to prevent collision), and the product name, model, quantity, production date and batch number are marked outside the box (to facilitate traceability).
Storage management
Storage conditions: Store in a ventilated and dry warehouse (temperature 20-30℃, humidity 40%-60%), avoid direct sunlight (to prevent plastic aging) and keep away from heat sources (to prevent deformation).
Inventory registration: record the warehousing information (batch, quantity and quality inspection results) through ERP system, and issue the goods in batches when the goods are collected in subsequent assembly workshops, so as to ensure "first in first out" (to avoid material performance degradation caused by long-term inventory).
summary
The processing flow of injection-molded parts of intelligent sweeper is the whole chain control of "design → material → injection molding → post-treatment → inspection → warehousing", and the core lies in the accurate matching of molds and parameters in the early stage (ensuring molding stability), the efficient connection of automatic production in the middle stage (improving productivity) and the strict control of full-dimensional inspection in the later stage (ensuring quality). At the same time, it is necessary to adjust the process details according to the functional requirements of different injection parts (such as appearance parts, structural parts and sealing parts), and finally meet the overall requirements of "lightweight, durability and assembly accuracy" of the intelligent sweeper.
