Structure analysis of European version of jaw crusher (3)
The structure of the jaw crusher is relatively simple, mainly composed of a frame, a working mechanism, a transmission mechanism, a regulating device, a safety device and a lubrication system. Take the 900mm×1200mm simple pendulum jaw crusher as an example to briefly introduce its structure.
5. Safety device
Large objects such as mechanical parts and iron blocks enter the crushing cavity, or the crushing cavity is blocked by materials near the discharge port, etc., which will cause overload of the jaw crusher. At this time, the force on the machine increases sharply, therefore, a safety device must be installed to prevent accidental damage to the crusher. The commonly used safety devices are as follows.
(1) Thrust plate doubles as a safety device
When designing parts, the thrust plate is designed to be broken first when overloaded to protect other parts of the equipment from damage. The thrust plate 13 in the above figure 1 is not only a connecting rod for transmitting force, but also a safety part of the crusher. The thrust plate is generally made of cast iron, and drilled or cut grooves in the middle to reduce its cross-sectional area. The thrust plate can also be combined (Figure 5). The connecting elements such as rivets are made of brittle materials. They are first sheared when overloaded. This kind of safety device is very simple, but the disadvantage is that the handling after an accident is more complicated and the downtime is long.
(2) Overload protection transfer arm
The JC type jaw crusher introduced later (Figure 7), its overload protection adopts the form of overload protection force transmission arm. The device mainly relies on a leaf spring to connect the belt wheel and the main shaft of the crusher, and the torque transmitted is realized by adjusting the shim as needed.
When the overload occurs, the leaf spring is disengaged from the pulley, the pulley is idling on the main shaft, and the main shaft stops rotating, and can be quickly reset when the overload is eliminated. The feature of the device is that it does not damage any parts, and the insurance has high sensitivity, safety and reliability.
(3) Hydraulic connecting rod as safety device
In Figure 4 above, a hydraulic cylinder and piston are connected to the connecting rod. The hydraulic cylinder is connected with the upper part of the connecting rod, and the piston is connected with the lower part of the connecting rod. During normal operation, the hydraulic cylinder is filled with pressure oil, and the piston and the hydraulic cylinder are equivalent to a part of the integral connecting rod. When overloaded, the pulling force acting on the connecting rod increases sharply, causing the oil pressure in the lower oil chamber of the hydraulic cylinder to increase.
When the oil pressure exceeds the pressure specified by the high-pressure relief valve of the combination valve, the pressure oil is discharged through the high-pressure relief valve, the piston and thrust plate stop moving, and the movable jaw stops swinging, thus playing a safety role. When the overload is eliminated, the hydraulic pump motor is started to replenish oil in the lower oil chamber of the connecting rod hydraulic cylinder, and the crusher can continue to work.
(4) Hydraulic friction clutch
The 1200mm×1500mm segment-start simple pendulum type jaw crusher manufactured in my country is equipped with hydraulic friction clutches at both ends of its eccentric shaft (Figure 6). When the crusher is overloaded, the overcurrent relay activates the hydraulic pump motor through the delay relay to separate the clutch and cut off the main motor at the same time, thereby playing a safety role.
The belt wheel and flywheel of the crusher are connected with the eccentric shaft by a friction clutch. The friction clutch is controlled by the hydraulic system. When starting, the hydraulic pump motor is first activated, so that the pressure oil enters the right side (that is, the pulley side) or the left side (that is, the flywheel side) of the plunger through the central through hole of the plunger, and pushes the plunger to compress the spring of the friction plate of the friction clutch. The friction plate is separated, so that the eccentric shaft is disconnected from the belt wheel or flywheel. At this time, the motor can be turned on and the pulley can be rotated.
Then through the electromagnetic reversing valve, the friction clutch between the pulley and the eccentric shaft is closed, and the eccentric shaft and the connecting rod start to move. Subsequently, the friction clutch between the eccentric shaft and the flywheel is closed to make the flywheel rotate. The crusher is started in three stages according to the above sequence.
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