What kind of material is it made of?

Time：

2021-07-07 10:28

A few days ago, when I saw a video introducing Made in China 2025, I always followed the operation instructions when screwing in a screw. When screwing in a screw, I first screwed in three turns and then retreated half a turn. In order to prevent loosening, the screw should be tightened. Why do we have to retreat half a turn each time, and when we use the tap to manually tap, it will also pass back a quarter of a turn, why?
This is because the screw is in deformation after tightening, especially under high temperature or vibration, the deformation will occur under such continuous pressure for a long time, and the strength of the screw will be greatly reduced or invalid after deformation. Retracting half a circle is to restore the elasticity of the screw, so that the screw will not deform under various pressure or environmental changes, so that the screw can withstand high strength pressure.
When tapping, the tap will also turn back half a circle to cut off the chip discharge, so as to prevent the chip discharge blockage from affecting tapping.
The tap is a tool for processing internal threads. Its function is tapping. For small internal threads, the tap is almost the only tool for processing. It has simple structure and is convenient to use. It can be used for manual processing with the tap holder, and can also be used for processing products on machine tools. It is widely used in production,
Type and working principle of tap
According to shape, it can be divided into straight groove tap, spiral groove tap, screw point tap and extrusion tap.
Straight groove tap is the most commonly used tap. The product is made of high hardness materials such as high speed steel and hard alloy. It is used as a tool for thread processing of common lathes and drilling machines. The cutting speed is relatively slow. The long handle is used for through-hole and the short handle is used for through-hole.
The chip removal groove of the spiral groove tap is spiral. It has left and right spiral grooves. The chips in operation will be directly discharged from the spiral groove. It has the advantages of long service life, high efficiency, low cost, and stable chip cutting. The common ones are right rotation of 15 ° and 42 °. The larger the rotation angle, the better the chip removal performance, and is suitable for processing the thread without holes.

The screw tap is also called the tip tap. When machining the thread, the chip is discharged forward. It is suitable for through-hole thread and deep thread processing. It has the characteristics of fast cutting speed, stable size and clear tooth pattern.

Extrusion tap is a tool that uses the principle of metal extrusion deformation to process internal threads, also known as screw tap. Extrusion tap is a chip-free processing process, suitable for processing materials with low strength, such as aluminum alloy. The thread surface extruded by the tap is smooth, wear-resistant, and high strength. It is widely used in the electronic and plastic industries.
Tap structure and size
The working part of the tap consists of a cutting part and a calibration part. The former is responsible for cutting, while the latter is responsible for complex calibration of the size and shape of the thread. The groove is used for chip removal, the handle is used for torque transmission, and the square head is used for positioning with the machine tool.
Tap specifications include metric tap and English tap, for example, metric tap M8 * 1.2, where M is the code of triangular thread, 8 represents the diameter of tap, and 1.2 represents the pitch of tap, in mm. For example, the inch tap 5/16-18, in which the tap diameter is 5/16 inch, and the rear 18 represents 18 threads in 1 inch.
Tap manufacturing
The common materials of the tap are various high-speed steel and cemented carbide. Its hardness depends on different materials, including ordinary high-speed steel: 62~64HRC, cobalt-containing high-speed steel: 67~68HRC, and cemented carbide: 69~79HRC.
The manufacturing process of the tap with such high hardness is completed by the machine tool, which can not only achieve the processing accuracy, but also improve the processing speed. The main part of the thread of the tap is processed by the grinder, and the tap tooth is grinded by the grinding wheel on the grinder. The processed tap needs to be quenched at high temperature, so that the tap can have a high hardness.
threading die
The die is a processing tool for processing or correcting external threads. The working principle of the die is the same as that of the tap, both of which are metal cutting or extrusion molding.
It is equivalent to a round nut with high hardness. The material is made of alloy tool steel or high-speed steel. The cutting tooth with taper of the die plays a cutting role. Several holes around it are used for chip removal. There is a deep groove on the die and four pits on the side. These are used for positioning and fastening the die. A die holder is also used to hold the die, which plays a role in transmitting torque. Different die holders should be used for dies with different outer diameters.
Technological process: blank → forging → annealing → machining → quenching → inspection → tempering → cleaning → inspection → blackening → inspection - packaging.

Use of tap die
Clean up the chips in the chip removal groove and thread before each use, check that there are chamfers on the machined parts, and select appropriate tap dies according to the diameter of the processed products.
During processing, the tap die and the machined part shall be kept vertical. During operation, the force shall be uniform. The force shall be applied in sequence and often reversed to cut off the chips for discharge. When encountering resistance during processing, the tap die shall be withdrawn in time to discharge the chips. During processing, coolant shall be added according to different materials. The tap is also divided into head taps, two taps and three taps. The head tap is the first to attack the shape of the thread, and then the two taps and three taps are tapped in a more precise sequence
When it comes to tap tapping, the most troublesome thing is that the tap broke in a snap during tapping. I believe that many small partners have experienced it, and it is also a headache. It is no big deal to break a tap. The key is that it is broken in the workpiece. If the product is not good, it can still be scrapped, and it also wastes time. So the broken wire removal technology veterans also show their own abilities. They have to tap slowly, weld the nut and try to screw it out, and the broken wire section has a slot to screw it out, Electric spark, corrosion solution, acetylene flame burning, broken wire extractor, direct drilling on the machine bed and so on. As long as you can get it out, it is a good way. There are many people who scrap the product, including you

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