1 The problem of the proposed method for the sealing of automotive window seals is usually the continuous roll forming of multiple pairs of rollers on a roller press line. Rolling production line is generally composed of four parts: the feeding system loosens the coil and continuously feeds the strip to the forming machine; the forming machine forms the cross-section of the rolled part, and the continuous roll passes through multiple pairs of rollers. Pressure (composed of two pairs of upper and lower rollers mounted on the horizontal roller shaft for each pair of rollers) finally forms the cross-sectional shape of the rolled piece; follow-up cutting system cuts the rolled piece to a given size; the collection system is in the production line Formed seals that are cut off are sent to the stocker in a timely manner without stopping the machine. The molding machine is the core part of the roller production line. The roller is the molding mold of the sealing strip. Its shape and dimensional accuracy are the key factors affecting the molding quality of the sealing strip. The sealing material of the middle window of a certain type of car is SPCC steel strip 155.5mm wide and 0.7mm thick, and is continuously rolled and formed on the imported rolling production line consisting of 36 pairs of rollers (partial rolling process semi-finished products and Finished shape). As the rollers need to be purchased from foreign countries after wear, the imported parts are expensive, thus increasing the production cost. In order to realize the localized manufacturing and repair of rollers, we have completed the design of roller products through the mapping and reverse calculation of rollers in the absence of spare parts drawings and data. Due to the complex shape of the roller profile (composed of multiple sections of straight lines and circular arcs) and the 72 roller shapes are all different (all in one piece production), the shape and dimensional accuracy are very demanding, and in addition the roller must be of high hardness. Die material manufacturing, so the roller cutting process is very difficult. 2 Roller Processing Plan Design The roller is a high-precision, high-hardness complex rotary body part. The complex profile rotary body can usually adopt profiling processing, numerical control processing, forming grinding and other processing technologies. Profiling is usually applied to the processing of large quantities of parts. Forming grinding requires the pre-preparation of a diamond electroplated dressing wheel that is consistent with the part profile, which is too costly for a single piece of small batch processing. Therefore, the single-piece machining of the complex profile roller is more reasonable with the numerical control processing method. The biggest difficulty in cutting high-hardness rollers is that ordinary carbide tools wear very quickly and cannot guarantee the quality of machining. This requires the use of polycrystalline cubic boron nitride (PCBN) tools. PCBN material is a binary superhard material artificially synthesized under high temperature and high pressure. Its hardness is second only to diamond, and its thermal stability is superior to that of diamond. PCBN tools have a relatively large chemical inertness to iron group metals, and are particularly suitable for processing heat-resistant, wear-resistant, and corrosion-resistant hard-to-handle materials (such as hardened high-speed steels, hardened alloy tool steels, die steels, etc.) above HRC45, HRC35 and above. Heat-resistant alloy, pearlite gray cast iron, etc. that are less than HRC30 but difficult to process with other inserts. The use of PCBN tools to car (镗, milling) on behalf of the grinding hard cutting, with high efficiency, good flexibility, low investment, simple process and so on. Through a comprehensive analysis of the processing requirements and the characteristics of the roller parts, PCBN tools and CNC machining, it is determined that the roller profile machining plan is: the outer cylindrical surface and the hole of the roller are processed by conventional technology; the roller profile part is used ordinary hard before heat treatment. The quality alloy tool performs rough machining and semi-finishing on the CNC lathe, and reserves a certain allowance; after quenching, the PCBN tool is used to perform surface finishing on a CNC lathe. 3 Roller CNC Machining Programming The NC machining programming is based on the process analysis of the machined parts, to determine the installation location of the parts, the relative movement of the tool with the size parameters, processing route (or processing sequence), process parameters And auxiliary operations and other processing information, and use standard numerical control code in accordance with the prescribed method and format written into a processing program, and then enter the processing program into the numerical control device, control the machine tool for automatic processing. CNC machining programming can be manual programming, automatic programming or image programming. Due to the complicated roller profile and single-piece processing, we use the U.S. UG software for automatic image programming. CNC machining tools, machining path planning, cutting amount, etc. are input by human-computer interaction. The programming content mainly includes: Process plan on the CNC lathe with ordinary hard alloy tool roughing and semi-finishing roller profile (prepared finishing allowance) → quenching heat treatment → CNCN lathe with a PCBN tool finishing roller Profile. Tooling roller roughing and semi-finishing (before heat treatment) using VHB2525 hard alloy tool; finishing (hardened after heat treatment) using PCB markings ISO labelled VBMW160402, VBMW160404, the basic tool model can be left-biased Right-handed PVVB2525 uses left- or right-handed PVHBR/L2525M-16 for special part processing. In NC programming, the selection of the tool declination angle and the auxiliary declination angle should ensure that no interference occurs during NC machining, and the tool can be adjusted on the machine tool during machining. Although the tool parameters selected during programming are not necessarily the optimal parameters, the tool's versatility and machining accuracy should be guaranteed. When the cutting parameters are rough and semi-finished with carbide tools, the cutting parameters are: cutting depth ap=1mm, cutting speed v=150m/min, and feed rate 120mm/min. When finishing with PCBN tool, the cutting parameters are: cutting depth ap=0.2-0.3mm, cutting speed v=110m/min, feed rate f=0.1mm/r, feed speed 50mm/min, dry cutting. The wear standard of PCBN tool during finishing is VB=0.3mm. After the tool is reground, the tool position and parameters must be re-determined, and the machining program must be reprogrammed accordingly. After the process parameters of the tool processing path are determined, it is necessary to plan the NC machining path of the tool. Because there are a total of 36 pairs of 72 rollers in the full set of rollers, the shape of the profile is very complex, and even some cutters are difficult to reach. Therefore, for ease of manufacturing, the roller profile can be decomposed into several parts and the tool path can be planned accordingly. Taking the 27th pair of rollers as an example, the sealing strip machining design curve and the top and bottom roller rolling state simulation. Its upper and lower roller profiles can be divided into two parts. Due to the complex shape of the roller, it is difficult to fully express it with a machining trajectory, so different machining trajectories can be used separately or in combination for different roller shapes. The 27th pair of rollers can be used for the three machining trajectories of the right-hand part of the upper surface. According to the equidistant offset trajectory of the final contour, this toolpath is stable and with high precision; the ZIG-ZAG parallel machining trajectory is characterized by a short processing program; the insertion of the machining trajectory (similar to the cutting process) is suitable for various Groove processing, but the tool processing rigidity is poor. Depending on the shape of the specific part, different machining trajectories can be applied separately or in combination. For the 27th pair of rollers on the right side of the upper part of the profile, the final determination of rough machining using the processing trajectory, finishing processing is to use contour processing trajectory. 4 Roller NC machining simulation is to verify the feasibility of NC machining program and avoid machine tool collision or tool interference during the machining process. CNC machining simulation must be performed after the CNC machining program is completed. Machining simulation methods can be simulated on the CNC machine tool after programming or after programming. The simulation display function or the air-run function can be used when performing the machining simulation on the numerical control machine tool. When using the display simulation, input the machining program, and then call the graphical simulation display function to carefully observe the tool movement path and check whether the tool and workpiece (or fixture) collide. When using air running simulation, input the machining program, install the tool (or workpiece), and then press the “Dry Run” button (DRY button). At this time, the spindle does not rotate, and the worktable automatically runs according to the processing program path. Verify that the tool path is correct and check for collisions. However, it should be noted that the tool and the workpiece cannot be installed at the same time or collision will occur. After the programming is finished, the machining simulation on the CNC machine tool takes up the machining time of the machine tool. When programming is used, the simulation does not have this problem. The processing practice shows that the use of high-performance PCBN tools for numerical control of the roller seal roller of the automotive window seal can ensure the processing quality, reduce the processing cost, significantly shorten the development cycle of the roller, and effectively realize the local manufacture and repair of the roller.
Shenyang Zhongda Huanxin Refrigeration Technology Co., Ltd.
