In order to make the thread size of the cold rolling process accurate and stable, higher precision requirements are imposed on the diameter size of the rolling stock. Therefore, most of the blank diameters that need to be cold-rolled are required to be precisely turned or ground. Otherwise, the size of the rolled thread is low in accuracy and the quality is unstable, and the cold rolling process is not easy to control. It is more difficult and sometimes the rollers are crushed, reducing the working life of tools and machine tools. The use of cold rolling threads and turning thread large-diameter superposition processing technology can better solve the above problems.
Figure 1 Hollow thin-walled parts to be rolled
1 Process Principles and Features The principle of the large-diameter superposition machining process of cold rolling and threading is to use a mandrel to support the inner hole of a hollow workpiece instead of using a support guide to support the workpiece when the ordinary thread rolling machine rolls the thread. , Or use other types of upper supports to support the rolled workpiece. In the lower part of the workpiece, the original support guide plate is equipped with a wide-blade plane forming turning tool. The turning tool can turn off any excess metal that has large diameters exceeding the standard requirements formed during the rolling process at any time. Because of this process, the large diameter of the thread is turned while the thread form is formed by the rolling process, so it is called the large-diameter superposition processing of the cold rolling thread and the turning thread. This process increases the process of turning a large diameter of a thread using a shaping tool compared to a process in which the thread is originally separately rolled. Because the diameter of the thread can be controlled by adjusting the position of the turning tool during the rolling of the thread, when the thread is rolled, the dimensional accuracy of the blank may not be as strict as the conventional rolling thread process. The diameter of the original thread rolling stock must be After the finishing process, the requirements of the rolling process can be ensured. When the overlap processing process is adopted, the blank diameter can only meet the requirements through rough machining (only the diameter of the blank before rolling is slightly increased by 0-0.3 mm), and the precision requirement can be From about IT9 to IT12. As shown in Figure 1 with hollow thin-walled parts of the shoulder, the actual diameter of the blank required for machining threads is d0=25.95-0.06mm. After adopting the rolling thread cutting technology, the actual process size is d0'=26.23-0.28. Mm. Thread turning large-diameter superposition machining process has the following characteristics: The diameter of the processed large-diameter thread is accurate and stable; The thread crest obtained after processing is trapezoidal, which is close to the crest of the theoretical tooth profile; Accuracy of the diameter size of the blank before thread rolling The requirements are reduced, the finishing process is reduced, the manufacturing difficulty is reduced, energy consumption and processing costs are reduced; the adjustment range of the use of ordinary rolling wire machine tools is expanded, a machine is realized, and the processing efficiency is improved. 2 Process equipment Figure 2 is a schematic diagram of a large-diameter superposition machining device for thread-turning threads with a hollow thin-walled part with shoulders.
1. Rolling wire 2. Square head eccentric shaft 3. Upper support frame 4. Support mandrel 5. Thread large-diameter tool 6. Tool holder body 7. Adjustment screw 8. Tool fastening screw Figure 2 Hollow thin-walled part rolling Wire turning large diameter overlap processing device
Thread Rolling Thread Rolling Thread Large Diameter Coincidence Processing Process Device is refitted on common rolling wire machine tools. Its structure is simple, easy to modify, and the workload is not large. The thread rolling part of the device still maintains the basic structure of the rolling thread part of the original machine tool, that is, it consists of a fixed roller and an active roller. The fixed roller refers to the roller wheel installed on the fixed spindle of the thread rolling machine. When the thread is rolled, it only performs rotary motion; the movable roller refers to the thread rolling wheel installed on the active spindle of the thread rolling machine. When rolling the thread, In addition to the rotary motion, it also moves with the machine's movable carriage (driven by a cam or hydraulic cylinder) for feeding, retreating or intermittent movement perpendicular to the axis direction. When the movable roller is fed to the left, the workpiece is rolled; when retracting to the right and stopping, the workpiece can be loaded and unloaded. The upper supporting part of the upper-diameter superposition processing device of the upper supporting part of the rolling thread cutting mainly includes the supporting mandrel, the support frame, the eccentric shaft and the bearing and the like (see FIG. 2 ). The upper support part was restructured and assembled on the original rolling wire machine tool. When rolling the thread, the mandrel for supporting the workpiece is mounted in two single-row tapered roller bearing holes in the lower part of the support frame to ensure that the mandrel rotates flexibly. The support mandrel supports hollow thin-walled parts for determining the center height and axial position of the part. The upper part of the support frame is fixed with a square head eccentric shaft on the connecting plate of the rolling machine tool. The support frame and the square head eccentric shaft are assembled by sliding fit. The support frame is centered on the eccentric shaft of the square head and can be freely oscillated. By adjusting the axial position of the eccentric shaft of the square head, the center height of the support frame together with the lower support mandrel can be adjusted, and the center height of the rolled part can be adjusted. Turning device As shown in FIG. 2 , while the hollow thin-walled part is being processed by thread rolling, a large-edged turning tool on the turning device is used to turn the large-diameter thread. The turning device is composed of a tool holder body, a turning tool, a tool fastening screw, a tool adjusting screw, and the like, and is installed at the base position of the original support guide plate of the rolling wire machine tool. In order to adapt to the rolling of different specifications of the threaded parts, to obtain accurate thread diameter, the distance from the tool to the workpiece centerline can be adjusted. When adjusting the tool distance, first loosen the tool fastening screw, and then twist the T-shaped adjustment screw embedded in the turning tool to raise or lower the flat turning tool, change the distance from the tool edge to the workpiece centerline, and control the workpiece thread. Large diameter size. The position of the base of a thread rolling machine with a tool holder can be adjusted to the left or right so that the front of the flat turning tool maintains a horizontal distance H from the center line of the workpiece, thus obtaining the turning angle g of the turning tool. 3 Operation points Before processing, first select the required rolling wheel, supporting mandrel, and flat car according to the parameters such as the thread size of the hollow thin-walled part to be machined, the length of the rolling thread part, and the size of the part hole, etc., and the processing requirements. Knife and thread measuring tools, etc., and correctly install the rolling wheel, the supporting mandrel, and the turning tool according to the installation adjustment requirements. Then according to the characteristics of the workpiece and processing requirements, select the rolling amount of the rolling machine, spindle speed, feed speed and rolling cycle. Start the machine and check whether the machine parts are running normally and the machine enters the automatic cycle processing state. After the preparation and adjustment work is completed, when the center distance between the two roller positions of the thread rolling machine is the largest, the machined parts are mounted on the supporting mandrel. At this point the machine has entered the automatic cycle process, the active roller feed, push the workpiece and with the supporting mandrel and bracket swing to the fixed roller at the same time, when the rolling thread, turning thread large diameter, voltage regulator plastic to reach the preset processing time After that, the activity wheel returns to its original position and stops. At this point, the operator can remove the workpiece, check the thread size and parts quality is stable, normal, according to the existing quality problems and defects, can analyze the cause of the search, continue to adjust the machine, eliminate all kinds of abnormal factors, continue rolling processing . After the part diameter is qualified, stable and normal, the machining operation can be automatically cycled.
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