What is a four column hydraulic press?
Four column hydraulic press is a kind of mechanical equipment that processes metal, plastic, rubber, wood, powder and other products by using the static pressure of hydraulic oil delivered by oil pump.
What is the working principle of the four column hydraulic press?
The hydraulic transmission system of four column hydraulic press is composed of power mechanism, control mechanism, executive mechanism, auxiliary mechanism and working medium.
The power mechanism usually uses the oil pump as the power mechanism, which is generally a product oil pump.
In order to meet the requirements of the movement speed of the actuator, one or more oil pumps shall be selected.
Gear pump for low pressure (oil pressure less than 2.5MP);
Vane pump for medium pressure (oil pressure less than 6.3MP);
Plunger pump for high pressure (oil pressure less than 32.0MP).
It is used for pressure processing and forming of various plastic materials, such as extrusion, bending, stretching of stainless steel plates and cold pressing of metal parts, and also for pressing of powder products, grinding wheels, bakelite and resin thermosetting products.
Working medium of four column hydraulic press
Evolution process of working medium
The hydraulic press uses water as the working medium at first, and then uses emulsion formed by adding a small amount of emulsified oil in water to increase lubricity and reduce corrosion.
In the late 19th century, oil presses with mineral oil as the working medium appeared.
The oil has good lubricity, corrosion resistance and moderate viscosity, which is conducive to improving the performance of the hydraulic press.
In the second half of the 20th century, a new type of water-based emulsion appeared. Its emulsification form is “water in oil”, rather than the original “oil in water”.
The external phase of the “water in oil” emulsion is oil, its lubricity and corrosion resistance are close to oil, and its oil content is small and it is not easy to burn.
But the price of water-based emulsion is expensive, which limits its popularization.
Function of working medium
The working medium used in the hydraulic press not only transfers pressure, but also ensures that the working parts of the machine are sensitive, reliable, long-life and less leakage.
Basic requirements for working medium
The basic requirements for working medium of hydraulic press are:
① Suitable fluidity and low compressibility to improve the efficiency of transmission;
② It can prevent rust and corrosion;
③ Good lubrication performance;
④ Easy to seal;
⑤ Oxidation resistance, stable performance, long-term work without deterioration.
What are the types of four column hydraulic presses?
Four column hydraulic press, also known as hydraulic press, is a machine driven by liquid pressure, which is made by Pascal’s law. There are many kinds.
Of course, the uses are also various according to needs. For example, there are two kinds of hydraulic presses and hydraulic presses according to the types of liquids that transmit pressure.
The total pressure produced by the hydraulic press is large, and it is often used for forging and stamping.
Forging hydraulic press is divided into die forging hydraulic press and free forging hydraulic press.
The die forging hydraulic press needs a mold, while the free forging hydraulic press does not need a mold.
Components of four column hydraulic press
The four column hydraulic press is composed of the main machine and the control mechanism.
The main part of the hydraulic press includes hydraulic cylinder, beam, column and liquid filling device.
The power mechanism is composed of oil tank, high-pressure pump, control system, motor, pressure valve, directional valve, etc.
The hydraulic press is suitable for the pressing process of plastic materials.
Such as powder product molding, plastic product molding, cold (hot) extrusion metal molding, sheet stretching and transverse pressing, bending, turning, correction and other processes.
The four column hydraulic press has independent power mechanism and electrical system.
It adopts button centralized control and can realize three operation modes: adjustment, manual and semi-automatic.
Structural form of four column hydraulic press
According to the direction of the force, there are two types of hydraulic presses: vertical and horizontal.
Most of the hydraulic presses are vertical and use liquid for extrusion, while the structural press is mostly horizontal.
According to the structural type, the hydraulic press has double column, four column, eight column, welded frame and multi-layer steel strip winding frame. The medium and small vertical hydraulic press also has C-frame type.
C-frame hydraulic press is open on three sides, easy to operate, but poor in rigidity.
The welded frame hydraulic press for stamping has good rigidity and is open in front and back but closed in the left and right.
In the vertical four column free forging hydraulic press, the oil cylinder is fixed in the upper beam, the plunger is rigidly connected with the movable beam, which is guided by the column and moves up and down under the pressure of the working fluid.
There are worktables on the beam that can move back and forth.
The upper anvil and the lower anvil are respectively installed under the movable beam and on the working table.
The working force is borne by the frame composed of upper and lower beams and columns.
Large and medium-sized free forging hydraulic press driven by pump accumulator usually uses three working cylinders to obtain three-stage working force.
The working cylinder is also provided with a balance cylinder and a return cylinder that apply force upward.
Equipment characteristics of four column hydraulic press
The machine has an independent power mechanism and electrical system. It adopts button centralized control to realize three working modes: adjustment, manual and semi-automatic.
The working pressure and pressing speed of the machine, as well as the stroke and range of no-load fast descending and decelerating can be adjusted according to the process needs, and the ejection process can be completed.
There are three process modes, namely, ejection process and stretching process.
Each process has two kinds of process actions: constant pressure and constant stroke.
The constant pressure forming process has ejection delay and automatic return after pressing.
Independent power organization and electrical system, with button centralized control, can complete adjustment and semi-automatic operation methods.
Its mobile work platform is driven by a frequency conversion controller, and its electrical equipment is the world’s leading PLC programmable controller.
Through the innovation in the description and production of YH25-315D “T” type moving action platform, it is beneficial to improve the automation level of this series of hydraulic presses, improve the production power, and reduce the labor intensity of operators.
The liquid is used as the medium to transfer energy, and the advanced hydraulic circuit of the slave and master cylinder is adopted, with low oil temperature.
The idle travel speed is more than 10mm / s, the working speed is less than 20mm / s, the equipment is in standby, and the noise when the sliding speed moves up and down does not exceed 75db.
Four column and three plate structure is adopted.
The vertical accuracy of the movable plate is controlled by four precision guide sleeves, and the parallel accuracy of any point between the lower working face and the upper working face is less than 0.08mm.
What are the product advantages of four column hydraulic press?
There are many kinds of hydraulic presses in the market. Each type of hydraulic press is suitable for processing different parts and materials.
Now many large-scale material processing and metal material production are generally using four column hydraulic press, because it is economical and convenient.
So what are the product advantages of the four column hydraulic press?
1. Precision forming, small tolerance and high precision
The pressure of the four column hydraulic press is stable, the die wear is reduced, the products are precision formed under the precise numerical control, the forgings are less and no flash, the tolerance is small, and the accuracy is high.
It can realize less and no cutting processing, and no subsequent processing such as turning, milling and planing is required.
For example, the tooth shape of the cylindrical gear and the bevel gear can be directly formed and produced.
2. The human-machine interface is interactive
The motor is digitally controlled, and the user can input simple displacement and speed parameters to realize intelligent flexible process curve numerical control.
The user does not need to compile the process curve, which is extremely convenient to use.
3. High die life
Pressure numerical control, the mold will not be overloaded, worn and damaged.
4. High efficiency and energy saving
The four column hydraulic press has no clutch friction energy consumption, no flywheel idle energy consumption, and the high efficiency of the motor itself, which makes the servo press efficient and energy-saving.
5. High equipment reliability
The equipment of the four column hydraulic press has no wearing parts.
The motor rotor has neither windings nor conductors, nor permanent magnets.
It is stronger than the permanent magnet servo motor, solid and reliable, impact resistant.
The maintenance free equipment effectively saves maintenance personnel and maintenance man hours.
6. Intelligent mode adjustment
The body of the four column hydraulic press is equipped with a tonnage meter, which can adjust and test the mold under pressure control.
When the mold is adjusted slowly and close to the mold, it does not stop the machine.
It does not need to set special mold adjustment and test equipment and personnel, which saves the mold adjustment labor and man hours.
7. Intelligent automatic numerical control
The operation of the four column hydraulic press is controlled by high-speed computer intelligence, which can realize full automation without manual operation.
What are the benefits of using four column hydraulic press?
Reduce quality and save materials
For typical parts such as automobile engine bracket and radiator bracket, hydroformed parts are 20% – 40% lighter than stamping parts, and for hollow stepped shaft parts, the weight can be reduced by 40% – 50%.
Reduce the number of parts and molds and reduce the cost of molds
Hydroforming parts usually only need one set of dies, while stamping parts mostly need multiple sets of dies.
The number of hydroformed engine carrier parts is reduced from 6 to 1, and the number of radiator bracket parts is reduced from 17 to 10.
It can reduce the welding amount of subsequent machining and assembly
Taking the radiator bracket as an example, the heat dissipation area was increased by 43%, the number of solder joints was reduced from 174 to 20, the number of processes was reduced from 13 to 6, and the productivity was increased by 66%.
Improve strength and stiffness, especially fatigue strength
For example, the rigidity of the hydraulically formed radiator bracket can be increased by 39% in the vertical direction and 50% in the horizontal direction.
Lower production cost
According to the statistical analysis of the applied hydroforming parts, the production cost of hydroforming parts is 15% – 20% lower than that of stamping parts, and the die cost is 20% – 30% lower.
Safe operation of four column hydraulic press
1. The hydraulic press operator must be trained and master the equipment performance and operation technology before independent operation.
2. Before operation, all sundries on the mold shall be cleaned and any dirt on the hydraulic press rod shall be wiped off.
3. The hydraulic press must be installed with power off. It is prohibited to collide with the start button, handle and foot on the foot switch.
4. Install and align the upper and lower molds, adjust the mold clearance, and do not allow one side to deviate from the center.
After confirming that the molds are fixed, press again.
5. Before the hydraulic press works, first start the equipment to idle for 5 minutes.
Meanwhile, check whether the oil level in the oil tank is sufficient, whether the sound of the oil pump is normal, and whether there is leakage in the hydraulic unit, pipes, joints and pistons.
6. Start the equipment for pressure test, check whether the pressure reaches the working pressure, whether the equipment operates normally and reliably, and whether there is leakage.
7. Adjust the working pressure, but it shall not exceed 90% of the rated pressure of the equipment.
Test a piece of work piece and then produce it after passing the inspection.
8. For different hydraulic press profiles and workpieces, during press fitting and calibration, the working pressure of the press, the number and time of pressing and holding pressure shall be adjusted at any time to ensure that the molds and workpieces are not damaged.
9. When the pressing plate of the machine body slides up and down, it is strictly prohibited to extend hands and heads into the working parts of the pressing plate and the mold.
10. It is forbidden to knock, stretch, weld, cut, bend and twist the work while applying pressure.
11. Smoking, welding, cutting and hot work are not allowed around the hydraulic press, and inflammable and explosive materials are not allowed to be stored. Take fire prevention measures.
12. After the hydraulic press is completed, the power supply shall be cut off, the hydraulic rod of the press shall be wiped clean, the lubricating oil shall be added, and the molds and workpieces shall be cleaned and placed neatly
Maintenance of four column hydraulic press
Common faults and maintenance methods of four column hydraulic press: often in the hydraulic transmission system, there are some relatively precise parts.
Although people feel that the hydraulic transmission of machinery is labor-saving and convenient, they also feel that it is easy to be damaged.
The main reason is that it is not clear about its working principle and structural characteristics, so it is not clear about its preventive maintenance methods
There are three basic “pathogenic” factors in the hydraulic system: pollution, overheating and entering air.
These three unfavourable factors have close internal relations. If any one of them occurs, another or more problems will arise.
It has been proved by practice that 75% of the “pathogenic” causes of the four column hydraulic press system are caused by these three factors.
1. The working oil deteriorates due to dirt;
3. Solution for entering the air: the cleaning and assembly of some main precision parts in the system should be carried out in a very clean room.
The room should have clean floors and closed doors and windows, and the temperature should be kept at about 20 ° C.
Other common maintenance:
1. L-HL32 / GB1118-89 hydraulic oil, N32 / GB3141 can be used when the temperature is lower than 20 ° C, and N46 / GB3141 can be used when the temperature is higher than 30 ° C.
32 # and 46 # anti-wear hydraulic oil are recommended for working oil, and the oil temperature is within the range of 15-60 ℃.
2. The oil can only be added to the oil tank after strict filtration by the oil industry.
3. The working oil shall be replaced once a year, and the first replacement time shall not exceed three months;
4. The sliding block shall be regularly injected with lubricating oil, and the external surface of the column shall be kept clean. The oil shall be sprayed before each operation.
5. Under the nominal pressure of 500t, the maximum allowable eccentricity of concentrated load is 40mm.
Excessive eccentricity is easy to cause column strain or other undesirable phenomena.
6. Calibrate and check the pressure gauge once every six months;
7. If the machine is not used for a long time, the surface of each processing plant shall be cleaned and coated with anti rust oil.
1. How to select hydraulic oil for four column hydraulic press?
After determining some characteristics of the oil used, such as viscosity, density, vapor pressure, air dissolution rate, bulk modulus, anti combustion, temperature boundary, pressure boundary, lubricity and compatibility, and selecting or equipping hydraulic oil according to certain requirements, all questions that cannot be regarded as the working medium of the hydraulic system have been solved.
In fact, improper use will still change the properties of the oil.
For example, it is generally thought that the viscosity of the oil at a certain temperature and pressure is a certain value, regardless of the activity.
In fact, the viscosity of the oil will be significantly reduced after it is excessively sheared.
2. To ensure the stability of the four column hydraulic press, under the condition of using hydraulic oil
As for the hydraulic oil used for a long time, oxidation and thermal stability are the factors that determine the temperature boundary.
Therefore, the hydraulic oil shall be stored, transferred and filled at a temperature lower than its initial oxidation temperature for a long time.
In the process of storage, transfer and filling, the oil shall be prevented from being polluted.
The oil shall be sampled and inspected regularly, and the regular oil change criteria shall be established.
The oil storage in the oil tank shall be sufficient to facilitate the heat dissipation of the hydraulic system and adhere to the sealing of the system.
Once there is a leak, it should be cleaned up immediately.
Troubleshooting of four column hydraulic press
Common faults and protection methods of four column hydraulic press: often in the hydraulic transmission system, there are some relatively fine parts.
Although people feel that the hydraulic transmission of machinery is labor-saving and convenient, they also feel that it is easy to be damaged.
The reason is that we don’t understand its operating principle and structural characteristics, and then we don’t know how to prevent and protect it.
The hydraulic system has three fundamental “pathogenic” factors: pollution, overheating and air entry.
These three unfavourable factors have close internal relations. If any question is presented, one or more other questions will occur.
Practice has proved that 75% of the hydraulic system is “pathogenic”.
The electrical wiring is not firm or connected incorrectly
Troubleshooting: check the circuit according to the electrical diagram.
Troubleshooting for insufficient oil filling in the oil tank: add oil to the oil level.
Sliding block crawling
Air accumulated in the system or oil inlet of the pump
Troubleshooting: check the oil suction pipe, and then run up and down several times and pressurize.
Improper accuracy adjustment or lack of oil on the column
Troubleshooting: readjust the accuracy and add oil on the surface of the column.
Downward with pressure
- Excessive support pressure
Troubleshooting: adjust the pilot valve and use the pressure no more than 1MPa.
- Sliding block slides seriously after stop
Cylinder port (or piston) seal ring leaks oil
Troubleshooting: check the sealing ring and replace it if damaged.
- Pilot valve preset pressure is too small
Troubleshooting: adjust the pressure value
- Poor sealing of cartridge valve port
Troubleshooting: check valve port and re fit
- The pointer of the pressure gauge swings badly
There is air in the oil passage of the pressure gauge.
Troubleshooting: loosen the connector to bleed when pressing up.
- Mechanical vibration of pipeline
Troubleshooting: check whether the pipeline is loose, and if it is loose, clamp it firmly.
- Pressure gauge damaged
Troubleshooting: replace the pressure gauge.
- At high speed, the travel speed is not enough and the upward pressure is slow.
Pressure compensation variable pump flow is too small.
Troubleshooting: adjust according to the requirements of the oil pump.
- Worn or burned pump
Troubleshooting: if the oil output from the oil drain of the oil pump is greater than 4L / min, it should be removed for maintenance.
- Oil leakage in the system
Troubleshooting: check the corresponding links of each part.
- The valve ports involved in sealing are not tightly sealed or the pipeline leaks oil.
Troubleshooting: check whether the sealing fastener of the corresponding valve is damaged, and replace it if damaged.
Repair and weld the leaking pipeline and check whether the pressure commissioning is normal.
- The sealing ring in the master cylinder is damaged.
Troubleshooting: replace the sealing ring.
The above introduction only gives a general description of the general situation.
After the fault is found in the actual use process, the reason shall be analyzed first and then troubleshooting shall be conducted one by one.
How to buy four column hydraulic press?
In China, due to the variety of hydraulic press models, as well as the different stiffness, accuracy and use methods, it is suggested that the buyer should make reasonable selection according to the nature of the production process, batch, mold conditions, accuracy requirements, etc.
The four column hydraulic press is widely used in industrial production. It is not easy to buy a high cost-effective hydraulic press.
For many friends who often use and operate the four column hydraulic press, it is not so easy to buy a suitable equipment.
It is suggested that the purchasing partners should determine the purchase specifications according to the actual needs, and generally follow the following principles:
1. You need to select the appropriate model and equipment according to your own needs.
① Before purchasing, you should know what shape and raw materials you need to press, what the output requirements are, and whether there are special requirements for the four column hydraulic press, and then ask the manufacturer to provide the appropriate model.
② When selecting the four column hydraulic press, the pressure should be sufficient, not only to improve the service life of the equipment, but also for the long-term development in the future. The nominal pressure must be greater than the actual working pressure.
③ The output of the four column hydraulic press is not only related to the model, but also to the hydraulic system of the equipment. There should be a fast system.
④ The stroke of the four column hydraulic press shall meet the required size of the molded product, and the molded product can be easily taken out of the mold.
2. Select the appropriate manufacturer
The quality of four column hydraulic press not only affects the service life, but also affects the production efficiency.
After determining the equipment model, we should contact several more companies to learn about their hydraulic press prices, parameters, delivery methods and other information.
After that, we should go to the processing factory for on-the-spot investigation to investigate the production scale, actual processing capacity and the company’s technical strength, so as to determine the quality of the produced equipment.
(1) Whether the appearance design of the four column hydraulic press is reasonable, whether the painting is uniform and smooth, and whether the appearance is smooth and free of pitting is better.
(2) During the equipment test run, check whether there is abnormal noise and mechanical vibration.
During the test run, test the pressure effect of the four column hydraulic press and whether the operation is flexible.
3. Understand the manufacturer’s after-sales service
Many people don’t understand the four column hydraulic press very well. Installation and commissioning are also very important.
It is the key to the performance and efficiency of the equipment.
Don’t give up after-sales service because of the pursuit of low price, and don’t think that after-sales service is included because of the high price of the equipment. It should be included in the contract as a clause.
When you decide to purchase a hydraulic press, in addition to evaluating the factors mentioned above, you should also provide the press supplier with your requirements on the performance of the press in as detail as possible, including safety, maintainability, installation cycle and cost.
The key points for the manufacturer are: production cycle, budget, mold design, workpiece structure, number of mold changes, external dimensions of the press, and the purpose of the project.
The development of science and technology shows that in order to make a correct and wise choice, you must keep close contact with and communicate with different hydraulic machinery manufacturers.
Only in this way can we correctly select a high-quality hydraulic press.