Compared with other CNC machine tools, CNC hobbing machine technology is more complicated and starts late, but its technology has a high starting point and rapid development. In recent years, high-level full CNC CNC gear hobbing machines have become the mainstream in the international market. The domestic hobbing machine has a complete range of products. The maximum modulus of cylindrical gear hobbing machine can be more than 6mm, but it is reasonable to use gears with a modulus of more than 3mm. The production of medium and small modulus gears is not only inaccurate, but also in performance. The price ratio is lacking. In the fierce market competition, enterprises engaged in small gear processing urgently need new equipment with low cost, high efficiency, high processing precision and stable quality to arm themselves. The price of CNC hobbing machines imported from abroad is usually about 400,000 US dollars. Domestic small and medium-sized enterprises are generally unacceptable. Therefore, research and development of a medium and small modulus economical multi-function CNC gear hobbing machine is of great significance. The CNC gear hobbing machine we developed has a machining accuracy of IT7, a maximum machining diameter of 80mm, a maximum machining modulus of 3mm, and a tool rotation speed of 400~2000r/min. The minimum number of machining teeth is 3, which meets the above requirements. 2 overall design and mechanical layout 6. bed 7. workbench 8. motor 9. work box 10. motor machine outline diagram The bed is a plate welded structure, with a shaft moving rail, and a y-axis moving pair. There is a cooling box inside and the entire cooling system is inside the bed. The flow rate of the cooling system is 15. The spindle system consists of a rotary slide, a column and a cutter box. The swinging skateboard is connected to the bed to achieve y-axis movement. The upper part is a support surface for adjusting the rotation angle of the column. The column is located at the upper part of the rotary slide, which can adjust the P angle. As the support of the cutter shaft housing, there is a z-axis guide. The cutter shaft box drives the ball wire through the servo motor to drive the movement in the z-axis direction, that is, to achieve radial feed or to realize the action of allowing the knife and retracting. A spindle is mounted in the knife shaft box. The spindle is driven by a servo motor to achieve the main motion of the machine. The shaft box and the column have z-axis detection devices. : Li Qing (1974-)) Female, Assistant Professor, professional direction in mechanical manufacturing and automation. A11,. A, the workbench is matched with the bed rail, and the servo motor is driven by the ball screw to realize the X-axis movement. There is an X-axis detection device with the bed. The upper part is equipped with a workpiece box and a top support frame. The workpiece box is a workpiece positioning and mounting component, and the servo motor is connected to the drive pair to drive the workpiece spindle, and cooperates with the b-axis and the X-axis to realize the hobbing. At the rear, there is a pneumatic clamping device (special accessory). The front part is a workpiece holder (clamping according to the workpiece design, and the clamping device is provided according to user requirements). The top support frame can be moved, locked and top positioned along the X axis. These actions are all manual. 2.2 Multi-function machining movement distribution The b-axis is connected to the hob spindle, and the tool holder structure is fixed on the spindle box. The spindle taper taper is 7:24. This tool holder can also be equipped with a milling cutter. The b-axis can also be connected directly to the boring bar. The machine tool can be processed according to the needs of users. The a, b and x axes are used as the numerical control linkage axis, the z axis is used for the CNC feed axis, the P axis is used to adjust the tool angle, the u and v axes are used for the tip clamping workpiece, and the function of the four-axis three-link CNC hobbing machine can be realized. . The b-axis is equipped with a milling cutter. The a, x, and z axes are used to realize the feed motion of the machine tool. The y, P, u, and v axes are used for manual adjustment. At this time, the machine tool can realize the function of the CNC spline shaft milling machine. The b-axis is equipped with a milling cutter or a boring tool. The x, y, and z axes are used to realize the feed motion. The a-axis is used to mount the workpiece digital control. This machine can complete the CNC boring and milling machine function. 2.3 Determination of the accuracy of the CNC system and the selection of the motor The commonly used hobbing methods are the radial one-axis hobbing method and the diagonal hobbing method. The gears processed by the diagonal hobbing method have good tooth profile accuracy, good surface roughness, uniform tool wear and high durability, but at least a four-axis CNC system is required. From an economic point of view, we design a four-axis three-link CNC system to achieve radial-axis rolling. The hobbing machine processes the workpiece through continuous development, and the control precision of each shaft speed is high. Therefore, the resolution of the control system we designed is 0.001mm, and the AC servo motor is selected as the driving device. 3 software functions of numerical control system The software functions of numerical control system are mainly divided into two categories of management and control (see details). From the user's point of view, the software's editing function allows input, deletion, modification and search of data; input machine and tool parameters; set coordinate system; control function to achieve speed control, direction control, displacement control; manual, automatic, back of the machine Zero and reset adjustment; terminal function handles the machine's emergency stop, limit, raster zero and servo alarm. In addition to the above basic functions, we have also designed the automatic programming and trajectory simulation software for hobbing. This software was developed with Visual Basic under the Windows operating system. In the automatic programming part, after the user inputs the required workpiece parameters, tool parameters and cutting parameters, a G code file for processing the involute cylindrical gear can be generated, and the contents of the file can be displayed and modified. The simulation part through the theoretical simulation, the automatic programming of the meshing rail 4 and the design of the trajectory simulation software, we take the hobbing helical gear as an example to illustrate the realization of automatic programming and simulation software. The CNC gear hobbing machine processes the workpiece through the forming motion of the hob and the tooth blank and the feed motion of the hob. When the hob turns a turn, the blank must be rotated through n/z. The helical gear has a certain lead (T). When the tooth blank rotates one turn, the additional rotation between the hob and the blank is fx/T. Therefore, when the direction of the helix of the hob and the gear is the same, when the hob turns z/n, the blank should be rotated by 1+fx/T. When the hob and the helical direction of the gear are opposite, when the hob turns z/n, the blank should be rotated by 1 fx/T. When the direction of rotation of the gear is the same as the direction of rotation of the hob, the mounting angle of the hob is small, the hob cutting time and the tooth load are small, the tool life is long, and the machine tool vibration is small. So, we chose to roll in the same direction. The cutting amount of the hobbing mainly refers to the cutting speed, the axial feed amount and the cutting depth. When the modulus of the gear is less than 3 mm, it is generally completed. In order to meet the user's processing requirements for special gear materials and special gear precision, we have also programmed two passes. At this time, the first machining depth is equal to 0.65 times the total machining allowance, and the second machining depth is equal to 0.35 times the total machining allowance (Liebherr CNC gear hobbing machine operation manual). The cutting speed and axial feed are directly related to the accuracy, roughness and machining efficiency of the gear. It also affects the service life of the hob and the rigidity of the machine tool, workpiece and tool system. The modulus, number of teeth, material and precision requirements of the workpiece. Related, the situation is more complicated. Therefore, we provide some values ​​mentioned in the manual to the user in the form of a database, and use the actual cutting time (tm) to compare the expected cutting time to roughly check the cutting amount. L2=3m.tan((32+y.)-A trace simulation and code imitation Li's projection line is the involute iaf compared with the theoretical involute, judging the feed rate of gHouse. f workpiece (mm/r) Z—the number of hob heads; the distance from the center of the hobbing to the end face of the hob; the centroid of the heart workpiece, the angle of the helix, the angle of the helix of the hob, and the adjustment parameter of the angle of the blade, usually the G code file generated by the automatic programming part of 35 (mm). The code can be checked by the display program function and can also be checked by the trajectory simulation function. In the trajectory simulation section, we chose two planes, one for the XOZ coordinate plane (see) and the other for the normal plane of the workpiece tooth profile (see ). Before the hob is in contact with the workpiece, the simulation with the XOZ coordinate plane clearly shows the relative motion of the tool and the workpiece. During the machining process, part of the tooth profile of the gear in the normal plane of the tooth profile of the workpiece. In this plane, we also used the actual cutting base section to calculate the cutting condition compared with the calculated base section. The theoretical simulation is based on the involute polar coordinate equation: when the parameters of the machined gear are known, the parameters of the base circle radius, the root circle radius, the tip circle radius, the base section and other parameters are determined, and the theory of the gear tooth profile is gradually Open the line to draw. The meshing trajectory simulation is based on the principle of the forming method, showing the cutting trajectory in the normal plane of the tooth profile. The hob is a whole. If the movement path of a certain point on the cutting edge meets the requirements, the movement of the hob meets the requirements. Hobbing is performed in accordance with the gear and rack meshing principle. It is known by analysis that the most effective cutting trajectory at each point on the cutting edge of the hob is linear along the axis of the hob. Therefore, in the normal plane of the tooth profile of the workpiece, we skillfully select the trajectory of a point on the main cutting edge of the hob that is tangent to the base circle to verify the motion of the entire hob and convert the rotational motion of the hob into Linear motion to simplify the simulation process. Aiming at the demand of the domestic market, this paper proposes a medium and small modulus economical multi-function CNC gear hobbing machine, and discusses the mechanical layout, motion distribution, numerical control system and motor selection of the hobbing machine. It has been proved by many parties that it is feasible. The automatic programming and simulation software expands the functions of the CNC system and enriches the CNC machine tool simulation operation software system. The software interface is friendly and beautiful, the code is safe and stable, and has strong versatility. The effect is good. (Finish) Solenoid Cartridge Valve Guangdong Heidler Technology Co., Ltd , https://www.hyhemit.com
September 26, 2024