1. Understand the purpose of the hydraulic press system, divide the schematic diagram of the hydraulic press system into three blocks in turn: actuators, power components, and control components, and then master the actions and requirements of the actuators according to the requirements of the host.

2. Find out the type, performance, relationship, and function of each hydraulic component. First, read hydraulic cylinders or hydraulic motors; then read and understand various control devices and variable mechanisms, and finally, read and master auxiliary devices. On this basis, the system is divided into a corresponding number of basic circuits according to the analysis of the work cycle and work performance requirements, and each circuit is found one by one on the hydraulic transmission schematic diagram.

3. According to the work cycle table, carefully analyze and write out the corresponding inlet oil and return oil flow routes for each action. In order to facilitate analysis, it is best to number each hydraulic component and each oil circuit in the hydraulic press system before analysis.

4. When reading the schematic diagram of the hydraulic press system, also pay attention to whether the main oil circuit and the control oil circuit are contradictory and whether they interfere with each other. On the basis of analyzing each action oil circuit, the action sequence table of an electromagnet and other conversion elements is listed.

The schematic diagram of the hydraulic press system is drawn with the graphic symbols of the hydraulic components. There are many kinds of hydraulic components, among which the control components are the most. The meaning of the graphic symbols of the control components is of great significance to the analysis and design of the hydraulic press system.

If drawings are the language of engineering, hydraulic press system schematics are the language of hydraulics. The hydraulic press system schematic diagram is a graphic that expresses the working principle of the hydraulic press system with prescribed lines and symbols in order to facilitate reading, analysis, design, and drawing. According to the regulations, the graphic symbols of hydraulic components only represent the function of the component, not the structure and parameters of the component, and are represented by the static state or zero states of the component.

The wide application of hydraulic technology in construction machinery and the rapid development of electromechanical-hydraulic integrated products. From the perspective of hydraulic technology, if you want to do a good job in the design, management, and maintenance of electromechanical-hydraulic integrated equipment, being able to understand the schematic diagram of the hydraulic press system has become a basic skill requirement.

1. Precautions for four-column hydraulic press

1) It is strictly forbidden to use the four-column hydraulic press with overload and performance.

2) When the four-column hydraulic press is working normally, it is strictly forbidden to start the lifting motor.

2. Emergency response and response to four-column hydraulic press operation accidents

1) It is strictly forbidden to use the oil cylinder over-stroke, and it is forbidden to process it when it shakes during pressurization or depressurization.

2) If the piston of the four-column hydraulic oil cylinder vibrates or the oil pump makes a sharp sound, the gas should be discharged.

3) It is strictly forbidden to arbitrarily adjust the regulating valve and pressure gauge of the four-column hydraulic press, and the pressure gauge should be calibrated regularly.

4) Keep the oil quality of the hydraulic oil, and the temperature of the working oil should not exceed 45℃. If there is an abnormality, it will stop.

The safe operation processes of the four-column hydraulic press machine are as follows:

1. Before working, the four-column hydraulic press machine should be run for 10 minutes in an empty stroke to confirm that the pressure of the hydraulic system is normal, and there are no abnormal phenomena such as jamming and overheating; the working slider can only start working after the movement is flexible.

2. The four-column hydraulic press must be in good lubrication conditions before it can enter normal operation.

3. For sheets of different thicknesses, it should be adjusted to an appropriate gap before leveling the sheets. During the leveling process, it is not allowed to rotate the pressing motor to press the sheets.

4. The working mechanism of the four-column hydraulic press should be coordinated with each other, and the operation should be flexible without abnormal noise or stuck phenomenon.

5. During the use of the four-column hydraulic press, the oil supply of each lubrication point should be checked frequently to ensure that the oil supply of each lubrication point is sufficient.

6. Clean all the sundries on the worktable, and polish the welds on the workpiece that may be in contact with the slider and the worktable.

7. During the operation of the four-column hydraulic press, it is absolutely not allowed to start the pressing and lifting device.

8. If abnormal noise, shock, vibration, or obstacles are found, it should be stopped immediately for inspection, and normal operation can only be resumed after the abnormality is eliminated.

9. You must concentrate on work and pay attention to (check, watch, listen) the operation of the four-column hydraulic press machine at any time.

The principle of the loss of load of the two-column hydraulic press is that due to the excessive energy stored in the hydraulic cylinder, the loss of load will occur once it is released. The following introduces the reasons and solutions for the loss of load of the two-column hydraulic press:

1. Releasing energy from the excess doorway: When the two-column hydraulic press suddenly starts to lose the load, it bypasses the local low-pressure liquid in the cylinder and releases it to increase the released energy.

2. Discharge energy for shock absorption: set a buffer pad at the lower part of the two-column hydraulic press. When the energy is almost used up, the buffer pad that is partially contacted when cut off is stopped, and the local energy is eliminated on the buffer pad.

3. Increase the storage of liquid elastic energy: the pad can be thickened between the task table and the lower part to make the task stroke of the static beam move upward, thereby increasing the height of the liquid column of the two-column hydraulic machine cylinder.

4. A movable pad is added between the cylinder piston and the static beam, that is, when the idle stroke of the two-column hydraulic press descends, the piston and the beam descend together. After contacting the workpiece, the piston returns to restore before pressurizing, and the auxiliary hydraulic pressure is at this time. The measure of the cylinder presses the movable pad between the piston and the stationary beam.

1. Operation requirements of four-column hydraulic press

The operator should be familiar with the performance, structure, process principle, and control system operation method of the four-column hydraulic press, and can only work after passing the training and assessment.

Operators should wear work clothes, safety helmets, and protective gloves. Female workers should put their braids in the hat, and should not wear skirts, slippers, or high heels.

2. Inspection before the operation of the four-column hydraulic press

Before starting and stopping the four-column hydraulic press, all buttons of the electric control system must be placed in their original positions; check whether each operating handle (button) and each connecting part are loosely fastened and whether the performance is reliable; Whether obstacles, limit devices and safety protection devices are in good condition.

Check whether the lubricating points and refueling places of the four-column hydraulic press are adequately supplied with oil; check whether the electronic control system is in good condition and whether the grounding is proper; all fastening connections must not be loose, and whether the limit devices and safety protection devices are perfect; Lubricated parts are fully lubricated.

3. Select the appropriate equipment process parameters according to the processing drawings (specifically according to the production process card) and set them.

The 4-post hydraulic press is a kind of mechanical equipment that uses the static pressure of hydraulic oil delivered by an oil pump to process metal, plastic, rubber, wood, powder, and other products. Its principle is to use Pascal's law to make use of liquid pressure transmission machinery, there are many types.

The 4-post hydraulic press is composed of the main engine, electric control mechanism, and hydraulic system. The main engine part includes the fuselage, the main cylinder, the ejector cylinder, and the liquid filling device; the power mechanism is composed of a fuel tank, a high-pressure pump, a low-pressure control system, an electric motor, and various pressure valves and directional valves; the electrical device operates in accordance with the provisions of the hydraulic system Program, select the specified working mode, and complete the specified process action cycle under the instruction of the signal; under the control of the electrical device, the power mechanism realizes the conversion, adjustment, and transmission of energy through pumps, oil cylinders, and various hydraulic valves.

The working pressure, pressing speed, no-load fast descending speed, and decelerating ascending speed of the 4-post hydraulic press can be adjusted according to the needs of the process. The press can complete three process modes: ejection process, without ejection process, and stretching process. It is commonly used in the pressing process and press forming processes, such as forging, stamping, cold extrusion, straightening, bending, flanging, sheet drawing, powder metallurgy, press fitting, etc.

Servo press machines usually refer to presses driven and controlled by servo motors, including metal forging servo presses and dedicated servo presses for the refractory industry.

So, what to consider when selecting a servo press machine? 

1. First of all, the accuracy of the servo press. Accuracy refers to how accurately the pressure and position stop at a specific point. It is related to the resolution of the driver, the resolution of the pressure transmitter, the accuracy of the servo motor and the response speed of the reaction equipment.

2. The structure of the servo press machine. The common structures are four-column, single-column, C frame, horizontal, H frame-type, etc. So, the selection of the structure needs to be based on the product size and structure.

3. The functions of the servo press machine. The servo press is widely used in forging, stamping, assembling, assembling, pressing, forming, flanging, shallow drawing, etc. Different functions often have different structures, so you need to choose the appropriate servo press according to your own situation.

How to solve the displacement problem of the servo hydraulic press? The abnormality of the servo hydraulic press is generally reflected in the following three aspects: sensor, amplifier unit and system setting failure.

1. Check the system settings of the servo hydraulic press.

If the display screen in the workstation shows that the stroke of the actuator is different from which under normal conditions, there is maybe a problem with the settings, and the system needs to be reset.

2. Check the servo hydraulic press sensor. 

If the sensor signal is normal, disconnect the feedback signal of the sensor, after repeating several times, the feedback data of the sensor is measured as a linear change line, and the sensor is judged.

3. Check the servo hydraulic press amplifier unit. 

After eliminating the fault of the sensor, it is now necessary to check whether the amplifier unit is normal. First, disconnect the output signal of the amplifier unit system. Remove the output wiring, add a DC input signal to the amplifier unit through the workstation, and then measure the amplifier, after several repetitions, the output signal of the amplifier unit changes linearly to determine whether the amplifier unit is normal.

The CNC hydraulic press body includes the upper beam, the slider, the table, the column, the tightening nut and the adjusting nut. The upper beam and the table are fixed frames composed of uprights and fastening nuts. The precision of the machine is adjusted by adjusting the nut and the tightening nut fixed on the upper end; the sliding block and the master cylinder piston are connected by the flange and the screw and move up and down by the four columns.

The plunger cylinder of the CNC hydraulic press is fixed by screws between the cylinder body and the upper beam. There is a filling valve at the tail of the master cylinder, a plunger is set in the master cylinder, and a two-way combined seal is adopted to ensure that the oil cylinder does not leak under high pressure.

The hydraulic system of CNC hydraulic press is composed of valve body, piston, main spool, unloading spool, etc. When the slider falls rapidly, the extracted oil cannot be supplied to the upper chamber of the master cylinder in time, resulting in negative pressure, so that the main valve sucks, a large amount of oil into the upper chamber of the master cylinder. In the reverse direction, the main spool is opened by the controlled oil, and a large amount of oil in the main cylinder returns to the filling cylinder.

The ejector cylinder of the CNC hydraulic press is installed on the base, the worktable and the lower top plate are arranged on the top, and the T-shaped groove is arranged on the worktable, and its size is the same as that of the slider.