Jaw crusher overload protection
Date：2019-07-31 14:57 Source：未知Views:
Jaw crusher working environment is bad, the work load is large, often because the material into uneven or hard can not be broken into the broken cavity and appear suddenly large overload risk.So the jaw has overload protection.
1. The method of breaking the elbow plate
Set the easy breaking point of bracket with low strength.That is, when the crusher appears overload, the elbow plate stress sensitive zone due to the rapid increase of stress to the limit and self-fracture, cut off power transmission, prevent machine damage.
Because the mechanical property of bracket (generally cast iron) fluctuates greatly and is limited by the calculation accuracy, the breaking point cannot be controlled precisely and quantitatively, and sometimes overload is not protected.
Moreover, even if the overload is protected, because the crusher is in an accident state, the equipment cannot operate before cleaning, disassembling and changing parts, and the process interruption delays production.
2. Flywheel moment limiting protection
Use spring friction clutch, hydraulic friction clutch or set safety pin.This method is widely used in simple pendulum jaw crusher.
Friction clutch, not only to ensure the transmission of normal working torque, but also to make the transmission torque does not exceed the allowable value.When the crushing cavity falls into the material barrier, the machine overloads and reaches the critical torque, and the flywheel slides freely on the shaft to protect the main parts.
But because the clutch friction factor is affected by external conditions (such as temperature, etc.), the reliability of its work is limited, and overload, still need to manually clear, stop repair, system recovery is more troublesome.
3. Hydraulic protection
Due to the above two overload protection methods have problems such as unreliable protection and the need to stop the machine in the accident state.Therefore, safe and reliable hydraulic protection device is more widely used.
Hydraulic overload protection device adopts oil pressure adjustment device to adjust the effective oil stroke of plunger type injection pump, and automatically adjust the oil injection amount according to the small amount of oil leakage in the hydraulic system.
In the working process of the equipment, through the rotation of the CAM device, the plunger injection pump is driven to supply high pressure oil to the system.The maximum crushing force allowed by the crusher is set by the adjusting nut of the oil pressure regulating device. When the oil pressure rises, the plunger compression spring in the oil pressure regulating device moves to the right, driving the plunger of the plunger injection pump to rotate counterclockwise, shortening the effective travel of the plunger to reduce the amount of oil filling and limiting the rise of the system oil pressure.On the contrary, when the oil pressure of the system decreases, increase the oil injection amount, prevent the oil pressure of the system from decreasing, and keep the oil pressure of the hydraulic system at the initial set pressure.
When jaw crusher crushing cavity into the broken objects, crushing force increases, the jaw crusher thrust plate role in the work on the hydraulic cylinder pressure is greater than the hydraulic cylinder thrust, provided by the work of the hydraulic cylinder of high pressure oil chamber of hydraulic transient, throttle valve action, system (hydraulic cylinder) drainage, limit the maximum thrust thrust plate (that is, the maximum crushing force) and protect the machine.