1. First remove the broken screw broken surface of the sludge center 铳 the center of the cross-section 铳 dead and then drill mounted on a diameter of 6-8 mm diameter drill hole in the center of the cross-section, note that the hole must be drilled. After the hole is drilled, the small bit is removed and replaced with a 16 mm diameter drill bit to continue expanding and drilling the broken bolt hole.
　　2. To take the diameter of 3.2 mm below the electrode with small and medium current in the broken bolt hole from the inside to the outside of the surfacing welding start the site to take off the entire length of the half of the bolt can be started when the arc welding should not be too long So as not to burn the outer wall of the bolt burned.Oil surfacing to break the bolt after the end face of a diameter of 14-16 mm high 8-10 mm cylinder.
　　3. After surfacing with a hand hammer to hammer its end face so that the bolt along the axial direction of the broken bolt due to the previous heat generated by the arc and the subsequent cooling coupled with vibration at this time will make the bolt and the body thread Loose between.
　　4. Careful observation When you find a trace amount of rust after tapping leakage from the fracture can take M18 nut sets in the welding of stigma and the two welding.
　　5. After soldering cool cold hot with a wrench set nut on the nut back and forth around the twist can also move back and forth while using a small hammer percussion nut end face so that the bolt can be removed.
　　6. Remove the broken bolt with a suitable tap to re-threading the rack to remove rust and other debris in the hole.
Testing method
Screw surface inspection is divided into two kinds, one is the production of the screw before the test after no plating, the other is the test after the screw plating, that is to say after the screw is hard, the screw surface treatment after the test. Screw before the production of good after plating, we have the size of the screw, tolerance and other aspects of the test. Have you met the national standards or customer requirements? After the screw surface treatment, we electroplated screws for testing, the main test of the color plating and there is no bad screws and so on. In this way, when we send the screwdriver to the customer, the customer can pass the check when receiving the goods. After the screw test:
First, the appearance of quality requirements
The appearance of the screw test is from the appearance, plating and other aspects of testing.
Second, the thickness of the screw coating inspection
　　1, measuring method
The amount of micrometer, vernier caliper, plug gauge and so on.
　　2, magnetic method
Magnetic method to measure the coating thickness is the non-destructive measurement of the non-magnetic coating on the magnetic substrate by the magnetic thickness gauge.
　　3, microscopy
Microscopy method known as the metallographic method, which is to be eroded fasteners on a microscope with a micrometer eyepiece zoom microscope to measure the thickness of the coating on the cross section.
　　4, timing flow method
Chronograph flow method is used to make the coating dissolved solution flow injection in the local surface of the coating, according to the partial coating is dissolved in the time required to calculate the coating thickness. There are coating trickle, anodic dissolution coulometry.
Third, the screw coating adhesion test
There are many ways to evaluate the adhesion of the coating to the base metal, usually the following.
　　1, friction and polishing test; 2, file method test; 3, scratch method; 4, bending test; 5, thermal shock test;
Fourth, corrosion-resistant screw coating inspection
Coating corrosion resistance test methods are: atmospheric exposure test; neutral salt spray test (NSS test); acetate spray test (ASS test), copper accelerated acetate spray test (CASS test); and corrosion paste corrosion test (CORR test) and solution drip corrosion test; immersion test, between the immersion corrosion test and so on.