In recent years, the development of the new energy vehicle market has continued to increase, and major automobile manufacturers now want to gain a place in the field of new energy vehicles. Although new energy vehicles are in full swing, real mass production vehicles are being realized. Enterprises are still relatively small, and a large number of enterprises are in the PPT stage.
The development of new energy vehicles is based on the manufacturing base laid by the traditional automobile manufacturing industry. However, the new new energy vehicles are different from the traditional automobile manufacturing processes, so many places cannot fully learn from the traditional automobile manufacturing process.
New energy vehicles are driven by electric energy. The cruising range is an important indicator for determining whether it can be oriented to the society. Under the current battery revolution, the mileage of new energy vehicles has changed a lot, but this is still not the ultimate, so in addition to the battery In addition to development, the weight of the car body is also a problem that is solved by various automobile product manufacturers. The traditional steel body can relatively reduce the total weight of the car in the case of changing the body design structure, but due to the steel material itself, this weight loss It does not achieve a very substantial income.
In order to meet the requirements of the front of the car body, the search for new lightweight materials has become a top priority, so the all-aluminum or steel-aluminum hybrid new energy car body was born. In fact, as early as the last century, Audi has already started the all-aluminum body. Development, its ASF space frame is used on the A8, R8 and other car bodies, the most impressive thing for us is the Audi A8 of the D4 version of 2010, the aluminum body rate of the body is as high as 90%.
The large-scale use of aluminum body in domestic independent brands started relatively late. A crucial issue to be considered in the design and development of all-aluminum body is the connection, which is different from the traditional steel body. It is well known that aluminum materials are compared with steel. Soft, many steel body connection technology is not suitable for aluminum body, so many aluminum material connection technology was born.
First, the wire threaded sleeve connection
Today I will introduce you to a connection technology for aluminum body---steel threaded sleeve connection.
The wire threaded sleeve is also known as the threaded wire sleeve, which is referred to as the wire sleeve. It is an insert developed to protect threaded holes in non-ferrous metals and is suitable for threaded connections. Screw in and fasten into the threaded hole of one of the connected parts to form a standard internal thread, into which the bolt (or screw) is screwed.
The spiral-shaped inner and outer concentric threaded coils are made of cold-rolled stainless steel wire, and the cross-section is rhombic. The shape is similar to a coil spring, and has high hardness and good surface roughness.
The installation of the wire screw sleeve is tapped and installed by a special tap and installation tool. The screw is set in the screw hole or the nut, which can reduce the uneven force of the thread and the impact vibration resistance, can improve the fatigue strength of the thread and reduce the thread. Wear and corrosion resistance to extend screw hole life.
Second, performance and use
Wire threaded sleeve performance
The wire thread insert is a new type of connection fastening technology, which can effectively improve the connection condition when the screw is connected, and greatly improve the reliability of the screw connection. The advantages are as follows:
1. The wire screw sleeve is applied in various low-strength materials, which can greatly improve the wear resistance of the screw connection and avoid the damage of the connecting thread.
2. Because the wire screw sleeve has certain elasticity, the load distribution on each circle of the thread can be made uniform, the pitch and the tooth shape deviation between the screw and the screw hole can be eliminated, and the vibration can be absorbed, thereby improving the connection strength and resistance of the thread. Fatigue strength.
3. The locking type wire screw sleeve can lock the screw in the threaded hole, and the screw is not loosened when subjected to impact vibration, which is better than the performance of the usual locking device.
4. Compared with the inlaid steel or copper bushing method, under the same strength conditions, the smaller size and higher strength screws can be selected, which can reduce the volume and reduce the weight.
5. The hardness of the wire screw sleeve is higher than that of the screw. Therefore, it is less worn during the process of connecting and disassembling with the screw and can be used repeatedly. According to relevant experimental research, the tensile strength of the wire screw sleeve is more than 7 times that of the screw, so the wire screw sleeve will not be damaged in the case of screw fracture.
Use of wire thread inserts
1. Enhance the connection strength and improve the connection conditions. The wire screw sleeve is selected from low-strength materials such as aluminum and magnesium to avoid slipping and wrong teeth, and to obtain excellent connection performance.
2, resistant to wear. For frequently removed parts, the life of the thread can be greatly improved.
3. Increase the force surface. It is used for parts that require strong connection force and cannot increase the diameter of the screw hole.
4, anti-loose. Especially for occasions where spacecraft and other products require high insurance factor.
5, easy to repair. Insert the damaged screw hole into the wire screw sleeve and continue to use it after repair to avoid the possibility of damage to the workpiece.
Third, classification
The threading mechanism of the threaded threaded sleeve and the ordinary nut is basically the same. The direction of rotation is divided into left-handed and right-handed. The threaded sleeve is also coated with silver, cadmium, coloring, oxidation, etc., and the constituent materials are divided into three types:
　 1. Cr-Ni stainless steel material: It is usually used under mild conditions, aluminum alloy structure, sea water, chlorine-containing liquid, and increased corrosion resistance.
2. Copper alloy material: used when copper is required or when the rotating thread connection is frequently adjusted; it is used when it is required for conduction or self-lubrication.
3. High-temperature alloy materials: heat-resistant when the temperature is 500--750 °C; used for aerospace assembly technology, aircraft engines, internal combustion engine turbo compressors operating at 750 °C. Compared with the screw, the wire screw sleeve has a mounting handle to facilitate the installation of the screw sleeve.
Ordinary thread with Helicoil Free-Running Inserts Mark "FR"
Helicoil Screw Lock Inserts Mark "SL"
Fourth, the installation of wire screw sleeve
Special tools for wire screw sleeves are required for the installation of wire screw sleeves, mainly including special taps for wire screw sleeves, wire screw socket mounting wrenches, punching devices, unloading sleeves and wire threaded inserts.
Among them, the tap is used for processing the threaded bottom hole of the wire screw sleeve, the installation Wrench is used for the installation of the wire screw sleeve, the punch is used for the thrust of the tail handle, the unloader is used for the disassembly of the screw sleeve, and the bottom hole plug gauge is used. Inspection of the installation bottom hole.
Drilling
According to different specifications, select the corresponding standard drill bit drilling hole, the drilling depth is greater than or equal to the installation depth of the wire screw sleeve; be careful not to drill the hole into a taper, and do not fall into the chip. After drilling, the bore should not exceed 0.4 pitch depth, because excessive bore is not conducive to the screwing of the threaded sleeve.
2. Tapping
Tapping with wire taps marked with the specified thread size, the length of the tapping must exceed the length of the wire threaded sleeve, for the through hole, all tapping; the precision of the tapping determines the tolerance band of the final standard screw hole, use The tapping method and lubrication should be properly selected, and the blind hole tapping should be properly applied to prevent the tap from breaking.
After tapping, the threaded holes should be cleaned, usually with a compressed air spray gun. When blind holes are used, the long spray gun with radial holes should be used for cleaning from bottom to top. The threaded holes can also be cleaned by cleaning. When the precision of the threaded hole is high, the special wire screw bottom hole plug gauge is used for inspection.
3. Installation
In general, a manual installer is used for wire screw mounting. Insert the wire screw into the installation tool, insert the mounting handle into the guide groove and rotate the mounting tool handle to screw the wire screw into the screw hole and leave it with 0.25-0.75 turns of thread from the surface.
When installing a small amount of wire thread inserts and M14×2 or more coarse wire thread inserts, you can install them with a “T†type slotted or threaded head simple tool, and be careful not to apply a large axial force on the wire screw sleeve mounting handle. In case of "disorder". After the wire insert is installed, in order to check the standard internal thread hole accuracy level formed, the corresponding level plug gauge can be used for inspection.
4. Remove the handle
For the wire threaded sleeve with the broken groove, the mounting handle should be removed after screwing into the screw hole, and the tool for removing the handle is needed.
When the through hole is broken, the wire screw sleeve mounting handle should be broken. Generally, the punching device is used to align the mounting handle, and it can be removed by punching with a hammer of about 200g. For the coarse threaded wire screw sleeve of M18×2.5 and M14×1.25 The above fine threaded wire screw sleeve can be broken by bending the mounting handle up and down with a needle nose Pliers. Then remove the broken mounting handle from the screw hole.
Note: If you use the automatic punch, you only need to use the punch of the automatic punch to punch the wire handle of the bottom hole with a suitable force to break the mounting handle.
5. Disassembly
Insert the tip end of the detacher into the hole of the threaded sleeve and firmly press the handle to rotate it counterclockwise to remove the threaded nut.
After the wire screw sleeve is installed, the threaded hole tolerance band depends on the manufacturing tolerance of the wire screw sleeve surface and the thread tolerance band of the wire screw sleeve mounting hole. The former is controlled by the wire thread sleeve manufacturer, and the latter mainly depends on the wire screw sleeve mounting hole attack. The precision of the wire is usually 6H grade. When the precision is high, it can reach the tolerance zone of 5H and 4H. The standard thread standard is 2B and 3B. The bottom hole thread can be tested with the appropriate level of plug gauge.
Tight lock ring structure
Five advantages
As a kind of screw sleeve fastener, the threaded threaded sleeve has obvious advantages compared with the normal thread:
1. Extend the service life: Since the wire screw sleeve is made of stainless steel and has high hardness, the thread life of the soft base member is increased by tens to hundreds of times; the strength is increased, and the tripping and the disorder are avoided. occur.
2, enhanced thread connection strength: applied to soft low-strength alloy materials such as aluminum and magnesium, can effectively enhance the joint strength of the thread, the ordinary internal thread of the aluminum profile, the maximum tensile strength is 1394N, and the inside of the pre-installed wire screw sleeve Thread with a minimum tensile strength of 2100 N.
3. Increase the force surface: It can be used for thin body parts that require strong connection without increasing the diameter of the screw hole.
4, improve the connection conditions, increase the bearing capacity and fatigue strength of the threaded connection: Since the wire screw sleeve is an elastic fastener, the use of the wire screw sleeve can eliminate the pitch and the tooth shape deviation between the screw and the screw hole, so that the load is evenly distributed. , thereby improving the load bearing capacity and fatigue strength of the threaded connection.
5, anti-rust death: the characteristics of the wire screw sleeve material and its surface is extremely smooth, used in harsh environments such as humidity, corrosion, etc., will not rust the mating substrate, avoiding the expensive replacement due to the rust of the threaded hole Loss of the matrix. It can be used in chemical, aviation, military equipment and other places where high insurance factor is required.
6. Abrasion resistance, heat resistance and corrosion resistance: Due to the extremely high surface finish of the wire screw sleeve, it can effectively reduce the friction between the internal and external threads, and the material itself has the characteristics of high temperature resistance and corrosion resistance. It can be used in parts that are frequently disassembled and installed, and in screw holes that are often rotated to extend its service life.
7. Anti-vibration and anti-loose: The special structure of the locking type screw sleeve can lock the screw in the screw hole in the strong vibration and impact environment, and will not loosen, and its locking performance is better than other locking devices. It can be used in instrumentation, precision and precious power equipment, as well as aerospace, aviation, military equipment and other occasions requiring high insurance factor.
8, easy to repair: In the case of thread processing errors or repair of damaged internal thread, the use of wire screw sleeve can make the base back to life, and can use the original screws, which is fast and economical. For simple examples, such as diesel engine body, textile components, various aluminum parts, lathe turrets, etc. will be scrapped due to a screw hole damage, as long as it is tapped again, the screw sleeve is installed, and the scrap pieces are brought back to life.
9. Conversion: The use of wire thread inserts for metric â†â†’ inch system â†â†’ international standard threaded hole conversion, very convenient, fast, economical and practical, suitable for any import and export products.
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