Thread is a common connection method in mechanical engineering. As a basic and necessary element in mechanical design, the majority of designers must thoroughly study and master the thread, not only to correctly and reasonably select the thread, but also to understand Thread processing methods and processes to solve problems that may be encountered in production.
The main processing methods of thread are: Thread cutting: generally refers to the method of machining threads on a workpiece by using a forming tool or an abrasive tool, mainly including turning, milling, tapping, threading, grinding, grinding and cyclone cutting. When turning, milling and grinding threads, the machine's drive chain ensures that the turning tool, milling cutter or grinding wheel can accurately and evenly move a lead along the workpiece axis. During tapping or threading, the tool (taper or die) rotates relative to the workpiece and guides the tool (or workpiece) for axial movement by the previously formed threaded groove. Thread rolling: A method of machining a workpiece by plastically deforming the workpiece with a forming rolling die.
1. Introduction to rolling
Rolling is not a metal cutting process compared to cutting methods. It does not form the desired profile by removing the metal, but forms a thread according to the mirror image of the roller drawing die, which is a non-cutting thread forming process. When rolling the thread, the roller mold presses the base material to press the thread shape into the workpiece blank. As the roller misaligns the material that will form the root, the material will flow out of the root from the radial and axial directions, and the shape of the roller will form a thread shape in the workpiece blank. The figure below shows the microstructural changes of the material of the rolling thread and the cutting thread.
Rolling is mainly used for the machining of external threads. Before processing, the diameter of the blank should be approximately equal to the median diameter of the thread. For higher precision threads, the choice of blank diameter should be determined based on material performance calculations and process tests. Unqualified threads will be machined beyond or below the proper diameter. If the outer diameter of the blank is too small, it will not flow completely into the roller mold; if the blank is too large, unnecessary pressure will be applied to the roller and the roller frame, which may cause damage to the thread rolling equipment. Most of the rolling threads are 60° angled threads, and the rollers used have sharper tips, usually with a rounded edge to facilitate penetration of the material. 30° on each side of the tooth ensures the force required to flow the material in a controlled and predetermined manner in the axial and radial directions. The figure below shows the thread rolling wheel.
2, rolling method
Depending on the rolling die, the thread rolling can be divided into two types: twisting and rolling.
Two threaded teeth are arranged in a staggered 1/2 pitch, the static plate is fixed, and the moving plate is parallel to the reciprocating linear motion of the static plate. When the workpiece is fed between the two plates, the moving plate advances to press the workpiece, and the surface thereof is plastically deformed into a thread. The wire is machined on a reeling machine or on an automatic lathe with an automatic opening and closing thread rolling head. It is suitable for mass production of standard external fasteners and other threaded couplings. The efficiency is quite high, up to 50 per minute. . The outer diameter of the thread processed by this method is generally not more than 25 mm and the length is not more than 100 mm.
Rolling is divided into three types according to the feeding method:
The axial threaded roller moves from the end of the tail center of the turning center and moves along the centerline of the workpiece blank to form a thread. Typical axial roller processing ranges from 1.5 to 228 mm in diameter.
The axial rollers are usually mounted in one of the turning center turret pockets. Three passes (or up to six) of rollers can be fed to the blank in one pass and activated by the rotation of the workpiece blank. The arrangement of the rollers allows the blank to pass, thus forming a thread that is longer than the width of the roller. Some of the threads starting on these rollers are progressive, like taps or broaches, and can be machined until the shoulder or other workpiece features, but the life of the rollers may be affected by additional stress.
Concerned about surprises
Label: Fastener Knowledge: Understanding the Processing Methods and Processes of Threads
Previous: Detailed processing characteristics and manufacturing techniques of stainless steel fasteners Next: What are the benefits of using hydraulic bolt stretching tools?
Poly Diallyl Dimethyl Ammonium Chloride
Polydadmac For Oil Industry,Polydadmac For Textile Industry,Polydadmac For Papermaking Industry,Good Use Polydadmac
ZHEJIANG XINHAITIAN BIO-TECHNOLOGY CO.,LTD. , https://www.dadmacxht.com