As we all know, the internal thread formed by aluminum and its alloys has poor wear resistance. After the bolts are disassembled several times, the teeth are almost polished, resulting in slipping, which causes the entire substrate to be scrapped in severe cases. However, aluminum and its alloys have excellent heat dissipation and electrical conductivity, and have high strength and low specific gravity. In many cases, they cannot be replaced by other materials, such as automobile engines, aero engines, and radiators.
Is there a good way to use aluminum and its alloy materials while overcoming the easy wear of the internal threads formed by it? Have! That is to insert a wire thread insert in aluminum and its alloys.
Wire Thread Insert, also known as thread sleeve, threaded sheath, thread sleeve, or wire sleeve, screw sleeve, is a new type of internal thread fastener. It is a spring-like spiral coil made of high-strength, high-precision, smooth-cut cold-rolled diamond-shaped stainless steel wire, which is a concentric body of internal and external threads. It is especially suitable for internal threads formed of soft materials such as aluminum and its alloys to improve wear resistance. The accuracy of the metric (M) internal thread formed by the wire screw sleeve is usually 6H, the precision is 4H when the precision is high, and the precision of the US uniform thread (UN) is 2B or 3B.
The outer diameter of the free-form steel threaded sleeve is larger than the diameter of the special threaded bottom hole of the steel threaded sleeve to be loaded. When assembling, the steel threaded sleeve is subjected to the torsion force through the threaded guide ring of the mounting wrench, so that the diameter is reduced and the screw thread is screwed into the threaded sleeve. Special threaded bottom hole. After loading, the wire screw sleeve expands to the periphery, so that it is fixed in the bottom hole of the thread to form a reliable standard internal thread, which does not rotate with the rotation of the bolt screwed into it.
The specific use is as follows:
First, drilling
Use the appropriate drill diameter (depending on the thread size, the wire screw manufacturer will provide you with the specific drilling size). Drilling holes with a drilling depth greater than (during blind holes) or equal to (through holes) aluminum and its alloy bases must be installed with wire snails. The depth of the threaded hole of the sleeve; be careful not to tap the hole into a taper. It is not advisable to use a bit that is heavily worn. Do not drop the chip into a place that may cause damage. After drilling, the burr-like boring hole is allowed. The boring should not exceed 0.4P depth. The diameter is the diameter of the internal thread of the installed wire screw sleeve, and the chamfer is 120°±2°.
Second, tapping
Tapping with a wire screw special tap (ST tap) marked with the specified thread size, the length of the tapping must exceed the length of the wire screw sleeve installation, for the through hole, all tapping is required; the precision of the tapping determines the final standard internal thread For the tolerance zone of the hole, the user should select the tapping method and lubrication appropriately. After tapping the wire, the threaded holes must be cleaned. For some important products, the accuracy of the internal thread must be checked with a special plug gauge for the screw sleeve.
Third, the assembly
The wire screw sleeve can be coated with a small amount of oil or without any substance before being screwed into the aluminum and its alloy matrix.
The installation of the wire threaded sleeve is usually installed by a sleeve type manual installation wrench (optional electric or pneumatic wrench can be used when the quantity is large). The specific operation process is as follows:
The first step is to withdraw the mandrel of the socket wrench and place the wire thread sleeve from the sleeve slot (slot upward) into the sleeve.
The second step is to prevent the wire screw sleeve from moving, insert the mandrel, and rotate the mandrel until the mandrel slot catches the mounting handle of the wire screw sleeve (if it is a T-shaped head, no need to rotate, you can directly use the front end of the mounting wrench mandrel The groove is caught by the mounting handle of the wire screw sleeve).
In the third step, turn the mandrel, screw the wire screw into the guide sleeve of the sleeve installation tool, and pre-shrink the end of the wire screw sleeve with the guide sleeve so that it is flush with the end face of the guide sleeve (do not let the threaded screw sleeve The end of the sleeve comes out).
In the fourth step, the mounting wrench with the wire threaded sleeve is aligned with the threaded hole of the base body, and the mandrel is rotated in the direction of the thread until the wire screw sleeve is screwed into the threaded hole of the base body. During the rotation of the mandrel, the torsion force of the wire screw sleeve may be too large. At this time, it is only necessary to rotate the sleeve in the reverse thread direction (the wrench mandrel does not move) to be alleviated.
Step 5 After the wire screw sleeve reaches the required assembly depth, turn the mandrel in the reverse thread direction until the thread mandrel is released from the wire nut (if the T-head is used, the mandrel can be directly extracted).
Fourth, remove the mounting handle
Remove the mounting handle immediately after installation of the wire nut with the broken groove. The purpose of the mounting handle is to avoid interference when the bolt or screw enters the threaded hole of the threaded sleeve or the damage of the mounting handle during product use. For the blind hole, when the threaded hole formed is deep enough and the bolt end does not reach the position of the mounting handle, the mounting handle can be omitted, and the prepared wire screw sleeve can also be opened and broken.
The operation to remove the mounting handle is as follows:
1. Insert the special screw thread inserter into the threaded hole of the assembled wire screw sleeve, and use the punch of the punch to withstand the mounting handle of the wire screw sleeve.
2. Use a hammer of about 200g to strike the ram to remove the mounting handle. The magnitude and direction of the striking force should be accurate, so that the mounting handle can be completely detached.
3. Use a pliers or tweezers to remove the broken mounting handle to avoid future problems.
When it is found that the installation of the threaded screw is wrong or the screw hole of the installed wire screw is unqualified, the installation will affect the normal use of the bolt, or the previously installed wire screw sleeve, resulting in wear and tear due to the long time of use. For other reasons, it will affect the normal use of the internal thread formed by the wire screw sleeve, and the wire screw sleeve needs to be taken out.
The method of taking out is as follows:
Use a bladed shovel to vertically insert into the threaded hole formed by the wire screw sleeve, and then gently tap it with a hoe, apply an axial force to make the edge of the detacher sleeve firmly hold the wire screw sleeve, and then reverse Unscrew the wire screw sleeve in the direction of the thread. The removed wire screw sleeve can no longer be used.
After the wire screw sleeve is removed, a new wire screw is reinserted, and the threaded hole is replaced.
Concerned about surprises
Label: wire threaded sleeve--reinforced aluminum and its alloy internal thread wear resistance
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