K is the torque coefficient, K = 12d (P + Lsd2secA' + LwDw); (3) d is the nominal diameter of the thread, mm; P is the thread pitch, mm; Ls is the thread friction coefficient, check the literature <6>, on steel Ordinary threaded fasteners, Ls = 0.1 ~ 0.2 when no lubrication; d2 is the diameter of the thread, mm; A' is the thread flank angle; Lw is the friction coefficient of the bearing surface, check the literature <6> page 66, for the steel pair Steel contact, Lw ≈ 0.15 when there is no lubrication; Dw is the equivalent diameter of the bearing surface friction torque, mm.
The force of the 1 bolt when the bolt is connected to work. When working, the bolt is subjected to axial tension and residual preload. The total axial load F of the bolt is: F = F'f + Fc, and (4) Fc can be approximated as the centrifugal force generated when the rod and bolt assembly rotates. Fc=2mv2Dz, (5) where v is the linear velocity, v=PDn/(60×1000), m/s; m is the total mass of the rod and bolt assembly, kg; D is the diameter of the drum, mm; n is Roller speed, r/min; z is the number of bolts on each rod.
The residual preload force F'f is the pressure between the joints after the bolt is subjected to the axial tensile force Fc. It can be calculated as follows: <6>: F'f=Ff-CmCm+CbFc, (6) where CmCm+ Cb is the relative stiffness of the coupled member. The force of the coupled piece. The joint is subjected to the lateral force FH and the residual preload force F'f during operation. The lateral force FH is produced by the striking action of the rod on the material. This force acts on the rib, perpendicular to the axis of the bolt, and can be obtained by electrical measurement.
There are three failure modes of failure analysis and bolt connection between the rods: during installation, due to the tightening moment, the bolts are subjected to the combined action of tension and torsion, and excessive plastic deformation or fracture occurs; during operation, the bolts are axially affected. Excessive plastic deformation or fracture occurs in the pulling force; the sliding rod and the drum are relatively slipped under the lateral load.
Design calculation method The pre-tightening force Ff and the tightening torque Tf are determined by the force analysis of 1.1. It is known that there is a lateral load FH on the coupling member during operation, and the inertial force generated by the strut assembly also has a radial component, but Very small, ignored here. According to the condition that the joint surface does not produce slip, F'f≥KsFHLz, (7), Ks is the slip resistance coefficient, check the literature <6> page, Ks=1.1-1.3; L is the friction coefficient between the joint faces, Check the literature <6>, page 80 to 7, after taking L=0.10~0.16.F'f, the pre-tightening force Ff can be determined by the formula (6), and the tightening torque can be determined by the formula (1).
Strength during bolt operation The tensile force F of the bolt during design work can be determined by equations (4) and (5). To ensure that the bolt does not fail at this time, the following strength conditions should be met: R=4FPd2q≤ In the formula, d1 is the bolt diameter, mm; R is the bolt tensile stress, N/mm2; Allowable tensile stress for the bolt, N/mm2. This formula can be obtained: d1 ≥ 4FP (8) Strength check during bolt installation When the bolt is subjected to thread torque and pre-tightening force, it shall be checked according to GB/T16823.2-1997 <5>. The yielding fastening axial force Ffy is calculated according to GB/T16823.2-1997<5> (7) to calculate Ffy=RyAs1+32dAPn+Lsd2secA'2. (9) 156 Journal of Northwest Agricultural University, Vol. 28, Page 4, Ry is the yield limit of the bolt, N/mm2; As is the nominal stress cross-sectional area of ​​the thread, mm2; dA is the equivalent diameter of the nominal cross-sectional area of ​​the thread, mm, dA=4As/P. The strength condition to be satisfied is: S=Ffy/Ff≥ . (10) where S is the safety factor, S≥1.2; is the allowable safety factor.
Conclusion (1) The reasonable value of the tightening torque of the bolt connection between the threshing drum and the rod should be determined according to the conditions. (2) The diameter of the bolt between the drum and the rod can be designed to ensure that the bolt has sufficient strength during operation. (3) In order to ensure sufficient strength of the connecting bolt between the drum and the rod during installation, it should be checked according to GB/T16823.2-1997.
Wall spikes are just one of a number of types of anti climb security spike and whilst the name Wall Spike indicates that they are designed to be mounted on a wall (typically along the top edge), they can often also be found welded or otherwise fixed along the top of steel gates and robust fences.
![stainless wall spike]( "stainless wall spike")
Wall Spikes are a simple yet effective method of enhancing the security of an existing wall or security Fence . The wall spikes are easy to install and come in a variety of coatings or finishes.
Popular types of wall spikes include big type wall spikes and medium type wall spikes and small type wall spikes, with the spikes being manufactured from a range of materials including weather resistant plastics, steel and aluminum, among others.
Features:
materials: hot dipped galvanized, stainless steel, PVC coated plates.
Plate thickness: small type spikes with 1mm, and other wall spikes with 2.0mm.
Barb length: 64mm and 100mm
wall spike strips length 500mm to 2000mm
Metal anti climb spikes new specifications:
Base length :0.5 to 2 meter,
Spike height :100 to 140 mm.,
Base width:35 to 50 mm.,
Spikes pitch:70 to 90 mm.Wall Spike
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