China Factory Manufacturer Wholesale Supplier DIN 7991 Hexagon Socket Countersunk Head Cap Bolt

Usage:

On the surface of the mounting hole on the connecting piece, a 90-degree conical round socket is processed, and the head of the flat machine screw is in this round socket, which is flush with the surface of the connecting piece. Flat machine screws are also used in some occasions with round head flat machine screws. This kind of screw is more beautiful and is used in places where the surface can allow a little protrusion.

The cone of the head of the countersunk head screw has a 90 ° cone angle. Usually, the apex angle of a newly purchased drill bit is 118 ° -120 °. Some untrained workers do not know this angle difference, and often use a 120 ° drill Reaming, which results in that the countersunk head screws are not strained when tightening the countersunk head screws, but a line at the bottom of the screw head, which is one of the reasons why the so-called countersunk screws cannot hold tight.

Precautions during use:
1.The taper of the reaming hole should be 90 °. To guarantee it, it is better to be less than 90 °, not more than 90 °. This is a key trick.
2.If the thickness of the sheet metal is less than the thickness of the head of the countersunk head screw, you can change the smaller screw, or rather expand the hole smaller than expand the hole so that the diameter of the bottom hole becomes larger and the part is not tight.
3. If there are multiple countersunk screw holes on the part, be more precise during machining. Once the drill is crooked, it is difficult to see the assembly, but it can be tightened as long as the error is small, because when the screw is not very tight Large (about no more than 8mm), when there is an error in the hole distance, the screw head will be deformed due to force when tightened, or it will be tightened.