Generally speaking, it refers to the methods of machining threads on workpieces with forming tools or abrasives, mainly including turning, milling, tapping, tapping, grinding, grinding, cyclone cutting and so on. When turning, milling and grinding threads, the transmission chain of the machine tool ensures that the turning tool, milling cutter or grinding wheel moves a lead accurately and evenly along the axial direction of the workpiece every time the workpiece rotates. When tapping or tapping, the cutter (tap or die) moves relative to the workpiece, and the cutter (or workpiece) is guided by the pre-formed thread groove for axial movement.
thread rolling
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 rolling 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 diameters of all blanks are 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 30mm), 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.
The advantages of wire rolling are: the surface roughness is less than that of turning, milling and grinding; Due to cold working hardening, the strength and hardness of the rolled thread surface can be improved; High material utilization rate; The productivity is twice as high as that of cutting, and it is easy to realize automation; The rolling die has long service life. However, 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.
According to the different rolling dies, rolling threads can be divided into thread rolling and thread rolling.
What are the tooth types of threads? 1. The most commonly used tooth type is triangle, and the angles of the tooth type are mostly 55 and 60; Common thread, also known as universal thread, is the largest number of threaded parts.
2. Trapezoidal thread: widely used for fastening connection of various transmission and large-size parts, commonly used for transmission screw, lead screw, tool rest lead screw, etc.
3. Sawtooth thread: used for force transmission and positioning in one direction, such as the screw of rolling mill, screw press, hydraulic press and crane hook. At present, there are 3/30, 3/45, 7/45, 0/45 flank angle serrated threads.
4. Rectangular threads: screws used for force transmission or conduction, such as jacks and small presses. At present, it is only used for mechanical parts with high transmission efficiency, also known as rectangular thread, and there is no national standard.
5. Threads are divided into fine threads, sealing pipe threads and short threads.
What kinds of common threads1.00mm1.25mm1.50mm1.75mm 2.50mm?
What kinds of tools are there for turning trapezoidal threads? This problem is considered from the following aspects:
1. Tool head structure (refers to the structure of cutting part and clamping part of the tool): 1) integration, that is, the cutting part and clamping part are integrated, and the cutting angle is not adjustable; 2) adjustable, that is, the cutting part and the clamping part are adjustable.
2. Clamping part: 1) elastic guide rod, 2) rigid guide rod;
3. Geometric angle of cutting part: 1) hand grinding, 2) forming tool.
4. Tool material: It depends on the processed material and process route. Taboo: Do not use YT cemented carbide when processing stainless steel materials. If you want to use cemented carbide in rough machining and finishing, it is best to use YW cemented carbide with good versatility.
Finally, it is suggested to use manual sharpening, adjustable angle, elastic arbor and high-speed steel cutter, separate rough and fine turning tools, and fully pour coolant by cutting method.
I hope it helps you.
What are the commonly used thread tooth types? Explain the characteristics and uses of various lines. Thread profile mainly includes triangular thread (that is, common thread), trapezoidal thread, rectangular thread and circular arc thread.
Triangular thread:
Triangular thread is the most common thread, so it is sometimes called ordinary thread, which mainly includes the following types: English thread, metric taper thread, special fine thread, transition thread, interference thread, short thread, MJ thread, small thread, 60 taper pipe thread and 60 pitch.
Rectangular thread:
Rectangular thread has high efficiency and is mainly used for transmission. Its cross section is rectangular, but it is difficult to center the internal and external threads because it is not easy to grind, so it is often replaced by trapezoidal threads.
Trapezoidal thread:
The cross section of trapezoidal thread is isosceles trapezoid, and the tooth angle is 30. Compared with rectangular thread, the transmission efficiency is slightly lower, but it has good manufacturability, high root strength and good alignment.
Sawtooth thread:
The working edge of serrated thread teeth is close to rectangular straight edge, which is mostly used to bear unidirectional axial force. There are two main types of teeth: (3, 30) and 45.
Round thread:
Its cross section is semicircular, which is mainly used for transmission. At present, it is widely used in rolling screw. Compared with rectangular thread, it has good manufacturability, high thread efficiency and good neutrality. At present, rectangular thread and trapezoidal thread have been replaced in many places, but they are rarely used in places with low transmission requirements because of their complicated processing and high cost.
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