What is the difference among the three concepts of bolt, screw and screw?
Last week we introduced some of the most commonly used parts in castor installation: bolts, screws and screws. Today we will continue with the next part of the knowledge.
The washer is used between the supporting surface of bolts, screws and nuts and the supporting surface of the workpiece to prevent loosening and reduce the stress of the supporting surface.
a) Flat washer: used to overcome the uneven supporting surface of the workpiece and increase the stress area of the supporting surface;
b) spring (elastic) washer: spring washer by elasticity and diagonal friction to prevent the loosening of fasteners, widely used in the connection of often disassembly. The inner tooth elastic washer and outer tooth elastic washer have a lot of sharp elastic warping teeth on the circumference, which can prevent the loosening of fasteners by piercing them on the supporting surface. The inner tooth elastic washer is used under the screw head with smaller head size; Elastic washers with external teeth are mostly used under bolt heads and nuts. The elastic washer with teeth is smaller than the ordinary spring washer, and the fastener is stressed evenly and reliable to prevent loosening, but it is not suitable for the usual disassembly;
c) Stop washer: there are inner tooth lock washer, outer tooth lock washer, single ear stop washer, double ear stop washer and stop washer for round nuts, etc. Single ear and double ear stop washers allow the nut to be tightened at any position to be locked, but the fastener should be near the edge of the appropriate;
d) Inclined washer: In order to adapt to the slope of the working supporting surface, the inclined washer can be used. Square inclined washer used to channel steel, I-beam flange and other inclined surface pad flat, so that the nut support surface is perpendicular to the nail rod, to avoid the screw screw by bending force when tightening the nut.
8, retaining ring
The retaining ring is mainly used to position, lock or stop the parts in the shaft or hole.
a) Elastic retaining ring: the elastic retaining ring for shaft and hole is stuck in the shaft slot or hole slot for rolling bearing to load back and back. In addition, there are open retaining rings for shaft, which are mainly used to be stuck in the shaft slot for part positioning, but cannot bear axial force;
b) Wire retaining ring: wire retaining ring for hole (shaft) and wire locking ring. The steel wire retaining ring is installed in the shaft groove or hole groove for parts positioning can also bear a certain axial force;
c) Locking retaining ring for shaft parts: retaining ring with cone pin locking and retaining ring with screw locking are mainly used to prevent axial movement of parts on the shaft.
d) Shaft end retaining ring: shaft end retaining ring tightened with screws and shaft end retaining ring tightened with bolts is mainly used to lock the parts fixed at the shaft end.
Pins are commonly used for positioning, but also for joining or locking parts, and as overload cutting elements in safety devices.
a) Cylindrical pin: Cylindrical pin is mainly used for fixing parts on shaft, transferring power, or as positioning element. Cylindrical pins have different diameter tolerances and can be used for different fit requirements. The cylindrical pin is generally fixed in the hole by interference, so it is not suitable to remove more;
b) Taper pin: Taper pin has 1:50 taper, easy to install cross-eye, but also can ensure self-locking, generally used as a positioning element and connecting element, mostly used in places requiring regular disassembly. Taper pins and tail taper pins with internal thread for holes that are not perforated or where pins are difficult to pin out. The tail taper pin is driven into the hole and the rear end can be opened to prevent the pin itself from slipping out of the hole.
The pin holes of cylindrical pins and various cone pins generally need to be reamed. After repeated assembly and disassembly, the positioning accuracy and connection fastening will be reduced, and only a small load can be transmitted. Elastic cylindrical pin itself has elasticity, installed in the hole to hold tension, not easy to loose, convenient disassembly, and does not affect the nature of the pin hole does not need to hinge. Pin with hole and pin shaft, both for hinge joints;
c) Cotter pins: Cotter pins are the anti-loose devices that connect the parts. When used, cotter pins are inserted into the pin holes of nuts, bolts with pin holes or other connecting parts, and then the feet are separated.
One end of the rivet has a head, and the rod has no thread. When used, the rod is inserted into the hole of the connecting piece, and then the end of the rod is riveted to play the role of connection or fastening.
a) Hot forged rivets: generally large size, mostly used in locomotives, ships and boilers, etc., usually through hot forging to make the head shape;
b) Cold heading forming rivet: the general diameter specification is 16mm, usually through cold heading to make the head shape;
c) Hollow and semi-hollow rivets: hollow rivets are used to connect plastic, leather, wood, canvas and other non-metallic parts where the shear force is not large.
11. Connection pair
A coupling is a screw or bolt or a combination of tapping screws and washers. Washer installed after screw, must be able to turn freely on the screw (or bolt) without falling off. Mainly plays the role of fastening or tightening.
It mainly includes welding nails and other contents.
The selection principle of twelve kinds of varieties
(1) Considering the efficiency of processing and assembly, in the same machinery or engineering, the use of fasteners should be minimized;
(2) From the economic consideration, should give priority to the selection of commercial fastener varieties.
(3) According to the expected use requirements of fasteners, according to the type, mechanical properties, accuracy and thread and other aspects to determine the selection of varieties.