Author: Site Editor Publish Time: 2024-03-16 Origin: Site
What is a hydraulic cylinder？
Hydraulic cylinder is the hydraulic energy into mechanical energy, do linear reciprocating motion (or swing motion) of the hydraulic actuator, its structure is simple, reliable. It is simple, reliable. When it is used to realize the reciprocating motion, it can eliminate the deceleration device, and there is no transmission gap, smooth movement, so it is widely used in the hydraulic system of various machinery. The output force of the hydraulic cylinder is proportional to the effective area of the piston and the pressure difference between the two sides;
Hydraulic cylinder is usually composed of rear end cover, cylinder barrel, piston rod, piston assembly, front end cover and other major parts, in order to prevent oil leakage to the outside of the hydraulic cylinder or leakage from the high-pressure chamber to the low-pressure chamber, there are sealing devices between the cylinder barrel and the end cover, piston and piston rod, piston and cylinder, piston rod and the front end cover, in the front end of the cover on the outside, but also equipped with dust-proofing devices, in order to prevent the piston from quickly back to the end of the stroke when it impacts the cylinder cover. In order to prevent the piston from hitting the cylinder head when it returns to the end of the stroke quickly, a buffer device is also installed at the end of the hydraulic cylinder, and sometimes an exhaust device is also required.
Cylinder assembly and piston assembly formed by the sealing cavity to withstand hydraulic pressure, therefore, the cylinder assembly should have sufficient strength, high surface accuracy and reliable sealing.
(1) flange connection, simple structure, easy processing, reliable connection, but the cylinder cylinder end is required to have sufficient wall thickness for the installation of bolts or screws, it is a commonly used form of connection.
2) half-ring connection, divided into the outer half-ring connection and the inner half-ring connection of the two connection forms, half-ring connection of good workmanship, reliable connection, compact structure, but weakened the cylinder strength. Half-ring connection is very common, commonly used in seamless steel cylinder barrel and end cap connection.
(3) threaded connection, external threaded connection and internal threaded connection of two kinds, which is characterized by small size, light weight, compact structure, but the end of the cylinder tube structure is complex, this form of connection is generally used for the requirements of the external dimensions of small, light weight occasions.
4) Tie rod type connection, simple structure, good workmanship, versatility, but the volume and weight of the end cap is large, the tie rod will stretch and become longer after the force, affecting the effect. It is only suitable for middle and low pressure hydraulic cylinders with small length.
(5) Welded connection, high strength, simple manufacturing, but welding is easy to cause deformation of the cylinder cylinder.
Standard double-acting: power stroke in two directions and used in most applications.
Single-acting cylinder: when only in one direction when the need for thrust, you can use a single-acting cylinder.
Double Rod Cylinder: Used when equal displacement is required on both sides of the piston, or when it is mechanically advantageous to connect a load to each end, and the additional end can be used to install cams to operate travel switches, etc.
Arrow Return Single Acting Cylinders: Usually limited to very small, short stroke cylinders used for holding and clamping. The length required to accommodate the return spring makes them a nuisance when a long stroke is required.
Plunger Type Single Acting Cylinders: Having only one fluid chamber, these types of cylinders are usually mounted vertically and the load reset causes the cylinder to retract, they are also known as "displacement cylinders" and are practical for long strokes.
Multi-stage telescopic cylinders: with up to 4 sets of briefs, the closing length is shorter than the standard cylinder, single or double acting, they are more expensive compared to the standard, usually used in the installation of small space but need a larger stroke of the occasions
Tandem cylinder: a tandem cylinder consists of two coaxially mounted cylinders, the pistons of the two cylinders are linked by a common piston rod, in the two cylinders before the installation of rod seals in order to make each cylinder can be double-acting, when the installation of the width or height restrictions, the tandem cylinder can increase the output force;
Duplex cylinder: a duplex cylinder is composed of two coaxial installation of the cylinder, the two pistons are not connected between the two cylinders to set up rod seals in order to make each cylinder can be double-acting, the two cylinders can be installed rod to piston (as shown in the figure) or back-to-back installation is usually used to provide three-position work
Hydraulic transmission principle - the fluid as the working quality, through the sealing volume changes to transfer the movement, through the internal pressure of the fluid to transfer power.
1, the power part - the mechanical energy of the prime mover is converted into the pressure energy of the fluid (hydraulic energy). For example: hydraulic pump
2, the implementation of the part - the hydraulic pump input fluid pressure can be converted to drive the mechanical energy of the working mechanism. For example: hydraulic cylinder hydraulic motor.
3, control part - used to control and regulate the fluid pressure, flow and flow direction. For example: pressure control valves, flow control valves and directional control valves.
4, auxiliary part - will be connected to the previous three parts, composed of a person system, oil storage, filtration, measurement and sealing and other roles. For example: piping and fittings, tanks, filters, accumulators, seals and control instruments.
The pressure exerted at any point on a certain volume of fluid can be transmitted in all directions with equal size. This means that when more than one hydraulic cylinder is used. Each cylinder will pull or push at its own speed, which depends on the pressure required to move the load.
In the case of hydraulic cylinders with the same load capacity range the cylinder carrying the smallest load will move first and the cylinder carrying the largest load will move last.
In order to synchronize the movement of the hydraulic cylinders so that the load is lifted at the same speed at any point, it is necessary to use control valves or synchronized lifting system components in the system.
In order to meet the different uses of various hosts, hydraulic cylinders have a variety of types
According to the oil supply direction, can be divided into single-acting cylinder and double-acting cylinder. Single-acting cylinder is only to the cylinder side of the input of high-pressure oil, relying on other external forces to make the piston reverse return. Double-acting cylinder is respectively to the cylinder on both sides of the input pressure oil. The forward and reverse movement of the piston are completed by hydraulic pressure according to the structure of the form, can be divided into piston cylinder, plunger cylinder, swing cylinder and telescopic sleeve cylinder. According to the form of piston rod, can be divided into single rod cylinder and double rod cylinder.
According to the special purpose of the cylinder, it can be divided into tandem cylinder, pressurized cylinder, speed increasing cylinder, stepping cylinder and so on. Such cylinders are not a simple cylinder, but with other cylinders and components combined into a cylinder, so from the structural point of view, such cylinders are also known as a combination of cylinders.
Differential principle of hydraulic cylinder, that is, both ends of the oil supply line at the same time, one end of the piston rod due to the role of the area is smaller than the other end, the use of differential principle of movement.
When the single rod piston cylinder two cavities at the same time into the pressure oil, due to the rodless cavity effective area of action is greater than the effective area of action of the rod cavity, so that the piston to the right of the force is greater than the force to the left, therefore, the piston moves to the right, the piston rod outward, and at the same time, and the rod cavity of the oil will be extruded, so that it flows into the rodless cavity, thus accelerating the speed of the piston rod to extend the speed of the connection, single rod hydraulic cylinders of this connection This connection of single rod hydraulic cylinder is called differential connection. Differential connection, the effective action area of the hydraulic cylinder is the cross-sectional area of the piston rod, the work of the sub-movement speed than the rodless cavity into the oil when the speed is large, while the output force is reduced.
Differential connection is not to increase the capacity of the hydraulic pump and power conditions, to achieve rapid movement of an effective method
Single rod hydraulic cylinder only has a piston rod at one end. It is a single piston hydraulic cylinder. Its two ends of the import and export oil port A and B can be through the pressure oil or return oil, in order to realize the two-way movement, so it is also known as double-action cylinder. When it is used to realize reciprocating motion, deceleration device can be dispensed with, and there is no transmission gap, smooth movement, so it is widely used in the hydraulic system of various machinery.
Features：
( 1) Rodless cavity into the oil, rod cavity back to the oil.
(2) rod cavity into the oil, rodless cavity back to the oil
(3) differential connection of a left and right two chambers connected, and all through the pressure oil single rod cylinder three comparisons, as shown below.
3、Single-rod piston cylinder
Single rod piston cylinder piston only one end with a piston rod, due to the single rod piston cylinder left, right two chambers of the effective area is not equal, so it is characterized by: when alternating into the cylinder two chambers of the fluid pressure household and flow Q constant, the piston cylinder in the left and right directions on the output of the thrust F is not equal, reciprocating motion speed mouth is not the same, and the larger the diameter of the piston rod, the greater this difference. However, respectively, when the cylinder is fixed and the piston rod is fixed, the movement range of their corresponding workbench is the same.
Double rod piston cylinder at both ends of the rod diameter is usually equal, so the effective area of action at both ends of the piston is also equal. When the two cavities of the cylinder were alternately input the same flow and pressure of the fluid, the piston produced on the maximum thrust and speed of movement are also equal. However, respectively, when the cylinder fixed and the piston rod fixed, the corresponding range of motion of their workbench is different from the structure of the double rod cylinder and double rod hydraulic cylinder structure is similar to its graphic symbols are the same.
Double rod hydraulic cylinder is the piston on both sides of the piston rod of the hydraulic cylinder, generally two-way hydraulic drive, can realize the reciprocating motion at the same speed.
Features：
(1) rodless cavity into the oil, rod cavity back to the oil
(2) rod cavity into the oil, rodless cavity back to the oil
(3) Differential connection between the left and right chambers is connected, and all through the pressure oil.
Gas-liquid booster cylinder is also known as gas-liquid booster cylinder is generally referred to as booster cylinder.
Pneumatic-hydraulic booster cylinder is a combination of the advantages of cylinders and cylinders and improve the design, hydraulic oil and compressed air is strictly isolated, the piston rod in the cylinder after contact with the workpiece is automatically started, fast action, and more stable pneumatic transmission, the cylinder device is simple, easy to adjust the force, under the same conditions to achieve the high force of the hydraulic press, low energy consumption, soft landing does not damage the molds, easy to install and special booster cylinder can be installed in 360 degrees at any angle, taking up little space. Installation is easy and the special booster cylinder can be installed at any angle of 360 degrees, occupies little space, has fewer faults and no temperature rise trouble, has a long service life and low noise, and other core features. Booster cylinders use general air pressure that can reach the high output of hydraulic cylinders, without the need for hydraulic units.
Booster cylinders can be generally divided into: pre-pressure type booster cylinder, direct pressure type booster cylinder, stroke adjustable booster cylinder, increase the return tension booster cylinder, compact parallel type booster cylinder, mini type booster cylinder, fast type booster cylinder, oil and gas isolation type booster cylinder.
The working frequency of the booster cylinder, according to different strokes and cylinder diameter is generally in the 10 ~ 70 times / minute Operation mode: double-action operation speed force range: 1 ~ 100 tons Application range: embossing marking, bending profiles, mold punching, punching and cutting.
Enjoyment:50~1000mm/s steel, profile welding, extrusion molding, flattening and straightening, riveting and forging, rectification of gold, tight assembly, riveting connections, metal stamping.
Telescopic hydraulic cylinder is a longer working stroke can be obtained with a multi-stage sleeve-shaped piston rod of the hydraulic cylinder, telescopic hydraulic cylinder, also known as multi-stage hydraulic cylinder. Telescopic hydraulic cylinder is a set of two or more piston hydraulic cylinder, the piston rod of the former piston cylinder is the cylinder barrel of the latter piston cylinder.
When the pressure oil enters from the rodless chamber, the cylinder with the largest effective area of the piston starts to extend, and when the line reaches the end, the cylinder with the second largest effective area of the piston starts to extend. Telescopic hydraulic outstretched order is from large to small outstretched in turn, you can get a long working stroke outstretched cylinder barrel effective area is smaller, the faster the outstretched speed. Therefore, the outstretched speed has slow to fast, the corresponding hydraulic thrust from large to small, this thrust, speed change rule, is suitable for a variety of automatic loading and unloading machinery on the thrust and speed requirements. The order of retraction is generally from small to large sequential retraction, the axial length of the retraction is shorter, occupies less space, compact structure. Commonly used in engineering machinery and other
Other traveling machinery, such as cranes, dump trucks and other hydraulic systems.
Plunger cylinder is a structural form of hydraulic cylinder single plunger cylinder can only realize a direction of movement, reverse to rely on external forces, as shown in Figure A. With two plunger cylinder combination, as shown in Figure B, but also with pressure oil to achieve reciprocating motion. The piston cylinder is guided by the guide sleeve on the cylinder head, so the inner wall of the cylinder barrel does not need to be finished. It is especially suitable for long stroke applications. In addition, there are radial piston cylinders and axial piston cylinders.
