Machining large modulus, hard tooth surface, wide tooth surface and high-precision screw umbrella has been a problem that has plagued the industrial gear industry for many years. Before the emergence of general-purpose machining centers, the only way to process this kind of gear was to use a special screw umbrella machining machine, and because this large-modulus and high-precision gear contains high profits, special machine tool manufacturers do not sell this kind of gear to the outside world.
This kind of gear machining machine tool, but only sells gears, which makes users unable to process such gears by themselves and can only rely on imports.
As the machinery industry becomes more and more heavy-duty, the manufacturing bottleneck brought by the machining of large-modulus and high-precision spiral bevel gears has become more and more prominent, forcing people to consider new machining methods. Therefore, general 5-axis machining is adopted. This method of centering large-modulus and high-precision screw umbrellas came into being.
At the Beijing International Machine Tool Exhibition held from April 6 to 11, 2009, a pair of helical bevel gears machined by the Mikron five-axis universal machining center appeared on the booth of the Swiss GF AgieCharmilles Group, which attracted many Attention gear users. The pair of gears are hard-toothed gears, and the contact area after rolling inspection is ideal. Under the linear speed of 21.5m/s, the noise of the gears is lower than 67db, which indicates that the gears have good meshing characteristics and precision.
As we all know, machining high-precision workpieces on a machining center requires a series of related technologies, the most critical and core of which are machine tool manufacturing technology and CAM software technology. Only with the support of high-precision machine tools and high-quality CAM software, High-precision parts can be machined efficiently.
For a long time, the Swiss GF AgieCharmilles Group is an internationally renowned machine tool manufacturer for producing high-precision and high-rigidity Mikron five-axis machine tools. The Mikron HPM1850U five-axis machining center produced by it adopts many advanced machine tools. technology.
This five-axis machining center applies direct drive technology to its swing axis (B axis) and rotary axis (C axis). The swing speed of the B axis can reach 20r/min; the C axis can reach 30r/min. Not only that, hydraulic clamping is adopted on the B/C axis, so that the B/C axis can obtain great rigidity during the machining process, which is especially important in the machining of gears. In addition, due to the long machining time of gears, the thermal stability of the machine is more critical. The Mikron HPM1850U machine is equipped with APS (Advanced Process Control System) and ITC (Intelligent Thermal Compensation System), which makes this machine tool with excellent thermal stability. Therefore, it can ensure the machining accuracy of gears, making it possible to process high-precision large-modulus helical bevel gears on a general-purpose five-axis machining center.
The project partner, the developer of the screw umbrella CAM software, Professor Wang Xiaochun of Beijing Jiaotong University, is one of the most prestigious gear experts in the world. The problem of third-order parameters, the English monograph published by him has become a classic work in the gear industry, and he has high attainments in CAM and CNC. The snail umbrella CAM software includes the following features:
1.Gear Pair Design With High Strength And High Machinability
Due to the flexibility of the tool path arrangement on the machining center, the tooth line curvature can be selected according to the optimal tooth bending strength without being restricted by the size series of the cutter head. Similarly, the relative position between the production surfaces of the tooth surfaces on the left and right sides can also not be constrained by the relative positions of the inner and outer cutter teeth on the cutter head, and can be adjusted automatically through appropriate adjustments to achieve the desired accuracy of the large and small wheels. The width of the tooth top and groove bottom is basically the same on the whole tooth surface width, so a large root fillet radius can be used, the machined gear has a thick tooth top, and allows the use of a larger diameter tool for high efficiency and high efficiency. Precision gear machining.
Taking a pair of 31:32, modulus 36, and tooth surface width of 270 as an example, if the traditional Gleason or national standard design method is used, the width of the groove bottom of the small wheel is only 12mm, and the tooth depth exceeds 70mm, which is very difficult to process. The root fillet radius can only be about 6mm. With the new design concept, the width of the groove bottom of the large and small wheels reaches more than 20mm, and the maximum tooth depth is reduced to 66mm, which greatly improves the machinability, and also avoids the back shrinkage of the tooth top. At the same time, the root fillet radius Can reach more than 10mm.
The design module also includes two types of tooth profiles: equal-height teeth and micro-shrinking teeth, which users can choose flexibly according to their needs. The software package also supports the machining of spiral bevels with shaft extensions for the use of guide bearings to reduce volume and improve the performance of bearings and gear pairs.
2.Good Assemblability
It can meet the requirements of normal assembly along the axis of the small wheel, which can simplify the assembly process and improve the assembly efficiency in many occasions. Since the tooth line curvature is relatively uniform, even if the gear pair with a large transmission ratio is assembled along the axis of the pinion, the phenomenon of jamming will generally not occur.
3.Perfect Tooth Surface Contact Area And Noise Control
No small adjustment is required to manufacture the screw umbrella, and the ideal tooth surface contact area can be processed at one time, basically achieving silent operation. This software package has a function module for automatically optimizing the contact area of the tooth surface. Without any manual intervention, it can automatically adjust the contact area of the tooth surface to the ideal position and shape within a few seconds, and ensure that the processed gear pair is basically silent. run. Therefore, the spiral bevel gear pair manufactured by this software package does not require minor adjustments or rolling inspection, and can be shipped or assembled directly after machining.
4.Supports A Full Range Of CNC Machine Layouts
With complete post-machining functions, it supports all machine tool layouts. A post-machining module that supports the layout of a full range of 5-axis and 6-axis 5-axis machine tools is embedded in each CAM module. The user can easily define the type of machine tool used through the human-machine interface, and the software will automatically generate a suitable machine tool. the G code.
5.Powerful And Complete
Features Design, Strength Analysis (CAE), Contact Area Optimization, Contact Area Analysis (TCA), Machining Methods (CAM) to support different types of tools (end mills and high-efficiency face milling cutters), flank measurement and error analysis And tooth surface mesh data generation function, powerful and complete.
6.Software Structure For Fools
The software package is easy to learn and easy to use, and it is a fool-like software package. Except for some of the most basic gear parameters that need to be provided by the operator, the rest of the parameters are either determined automatically by the system through optimization or expert library, or the system gives suggested values, which are input by the user after rounding. Therefore, as long as the operator has some basic knowledge of the machining and debugging of the screw umbrella and the cutting amount of the tool on the machining center, he can initially master it in half a day, and can use it proficiently in two days.
7.Ensure High-Precision Gears Are CNC Machined
This software does not require the user to build a 3D solid model by himself, and the software automatically generates the tool position path data points, thus avoiding the loss of precision caused by the CAD/CAM model conversion process, so that under the same hardware conditions as the machine tool and the tool, it can be processed. higher precision gears.