When the thread is placed vertically along the axis, it can be seen that the thread has a certain inclination angle. If the left side is higher than the right side, it is left-handed thread. When the right side is higher than the left side, it is a right-handed thread.
Right-handed thread: according to the right-handed rule, the right hand clenches the fist, the thumb of the right hand points to the movement direction of the spiral piece, and the other four fingers point to the rotation direction of the spiral piece.
Tightening right-handed screws (especially screws) is suitable for the physiological characteristics of right-handed force, so it is implemented as a standard specification. Common screws and bolts are all right-handed if not explained.
Left-handed thread: it conforms to the left-handed rule and the method is similar to the right-handed rule. Make a fist with your left hand, the thumb of your left hand points to the movement direction of the spiral blade, and the other four fingers point to the rotation direction of the spiral blade.
Extended data
The invention relates to a processing method for obtaining the plastic deformation of a threaded workpiece by forming a rolling die. Wire rolling is generally carried out on a wire rolling machine. The thread rolling machine is carried out on an automatic lathe with an automatic thread rolling head, which is suitable for mass production of external threads of standard fasteners and other threaded connectors.
Generally, the outer diameter of the rolled thread is not more than 25mm, the length is not more than 100mm, the thread accuracy can reach Grade 2 (GB 197-63), and the diameter of the blank used is roughly equal to the middle diameter of the processed thread.
Generally, the internal thread cannot be processed by rolling, but for soft workpieces (the maximum diameter can reach about 30 mm), the internal thread can be cold extruded by slotless extrusion tap, and the working principle is similar to tapping.
The torque required for cold extrusion of internal thread is about 1 times that required for tapping, and the machining accuracy and surface quality are slightly higher than tapping.
Rolling thread requires that the hardness of workpiece material should not exceed HRC40；; It requires high dimensional accuracy of the blank; The precision and hardness of the rolling die are also high, and it is difficult to manufacture the die; Not suitable for asymmetrical thread of hobbing.
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