Hydraulic press application & features
It can also be engaged in the calibration, press and press forming of metal products.
The hydraulic press has an independent power organization and electrical system and uses the button common control. The working is controlled by PLC programmable controller, and can be adjusted and semi-automatic operation.
This hydraulic press working pressure, pressing speed, travel range can be adjusted according to technology needs.
Hydraulic press structure overview
This hydraulic press machine consists of the master motor and control mechanism, integrated together through pipelines and electric devices.
The main motor includes: machine frame, master cylinder, stroke limiting device etc.
The control mechanism includes: hydraulic pump station (power system), electric cabinet.
The structure and functions of above-mentioned parts are as follows:
The hydraulic press machine frame
Machine frame mainly consists of beam, workbench, hydraulic pad, and slider, and vertical columns, and tight nut.
And the regulation nut, four basic columns, upper beam and workbench are tightly fixed on its ends through locking nuts with slider on its center.
The accuracy is adjusted by regulation nut and locking nut fixed on the beam.
The slider and piston rod of master cylinder are connected by locking nuts and relies on four columns for oriented up and down movement, slider and movable workbench all are equipped with T channel, which is convenient for die installation.
Master cylinder is fastened on the upper beam through cylinder shoulders and large locking nuts.
Piston bottom ends connection adopts flange, screw and slider, piston heads are made from cast iron and equipped with reverse sealing ring outside and “O” shape sealing ring inside to form two oil chambers.
The cylinder opening is equipped with sealing rings as well and fastened by flanges to ensure the sealing of lower chambers.
The up side and lower side of flange are also equipped with a sealing ring.
The hydraulic pad is installed in the workbench, fixed with top cylinder by locking nut, making up and down movement; the structure of top cylinder is same with that of master cylinder.
The electric cabinet can be moved randomly and with buttons, time relay and auto switch on the surface.
Stroke limiting device
Strike limiting device is located on the right side of the machine, consisting of bracket, ram, limit switch etc, slider can be adjusted by adjusting the ram position.
Hydraulic pump station (power system)
Hydraulic pump station consists of the oil tank, high-pressure pump, motor, and cartridge valve etc, welded tank with filter screen inside.
Hydraulic system theory
Hydraulic system theory sees as attached drawing-hydro theory drawing- and action sequence list, here now we take semi-auto working cycle as an example to demonstrate the hydraulic theory:
First, connect with power, press down SB3、SB5 to start the motor.
At present, due to all electric valves still be on idle states, the oil flowing out from high-pressure pump will re-flow back to the oil tank, the system is on no-load cycling circulation state.
With both hands press down the SB6、SB7, at the time, solenoids YA1、YA5 will be powered on, and oil coming from high-pressure pump flows into the upper chamber of master pump, YA5 powered on will make valve 11 connect together with P and B, A and T, oil in the lower chamber will flow back to oil tank through valve 11 and slider on no-supporting state will quickly move downward due to its self weight.
At this time, oil in the pump is incompetent to supplement the upper chamber of the master cylinder and form negative pressure which will suck the oil-infusing valve open, making oil in oil-supplying drum infuse into master cylinder upper chamber heavily.
Therefore slider will quickly run down.
When the slider run down and approaching SQ2 switch, the switch will release signals for continuing power YA1, and cut off YA5, then the oil must overcome supporting valve pressure before return back to oil tank, and lower chamber forming reverse pressure reducing the descending speed, therefore, slider cannot decent relying on its self weight and slow down.
When slider run down and touch the workpieces and the system pressure increase up to prescribed pressure in pressure gauge SPI, the system will give out the signal to discharge solenoid, the pump will enter into no-load circulation state, time relay KT1 connected and enter into press-holding time-delay condition.
When time-delay increases up to pre-setting time, delay contacts KT1 release signal to power YA2 and YA6, and low-pressure valve adjusts the system oil and generates pressure, and the system will be on the low-pressure state, meanwhile pump oil will open the unloading valve on infusing valve, unloading the high-pressure oil in the upper chamber.
During the time, put through the time relay KT2 and begin time-delay unloading.
When KT2 pre-setting time for pressure relief comes to end, KT2 give out the signal for charging YA2 and cutting off YA6.then all oil from the pump will flow into the master cylinder lower chamber to increase the backstroke pressure. Upper chamber oil flows back to infusing drum through the master valve of infusing valve to drive slider back.
When backstroke approaching near SQ1 prescribed position, the system will give out signals to discharge YA2 and stop back stroke. Meanwhile, YA3 will be charged, system flow into the lower chamber of the top cylinder, its pressure can be adjusted by the overflow valve, and realize automatically kick-out the workpieces until touch the SQ5.
When press down the SB13 button, the YA4 and YA6 will be charged, P and A of valve will be connected, T and B connection will open 20b valve, and enter into upper chamber of top cylinder, realizing top cylinder retreat action, YA6 charged can decrease the oil pressure in the lower chamber of the master cylinder, making preparation for next working cycle.
Come here, a complete circulation has been finished.
Electric system overview
Brief introduction of hydraulic press
The hydraulic press machine suits for 380V、50Hz power, control circuit voltage is 220V supplying by the transformer.
The hydraulic press is equipped with a dedicated electric cabinet which can be placed randomly; on the door: switch, control buttons and signal lamps, in the cabinet, are the various controllers, such as power switch, programmable controller, thermal relay, AV contractor, time relay, transformer and intermediate relay and so on.
According to the pressing technology requirements, the machine can be classified into two kinds of manipulation ways: manual and semi-automation, mainly used to adjust the machine and die and carry out slider down, backstroke, ejecting and retreat piston etc, pressing corresponding buttons to start its action, releasing for stop working.
Under the semi-auto condition, once pressing forming can be done only by pressing the”work” button.
Technical parameters for driving device and electrics
The hydraulic press pump uses the three-phase squirrel-cage asynchronous motor, its model and specification as follows:
Y180L-6 22KW ~380V 1470rpm two sets
Solenoid directional control valve of the machine hydraulic system is driven by the wet-type electromagnet, the number of the electromagnet is 16, the operating voltage is DC 24V.
Main technical parameters displayed on electrical data tag are as follows:
- Total power: 44kW
- Voltage: ~380V
- Phase No: 3
- Frequency: 50Hz
- Rated Current of general fuse: 100A
- Protection Rate: IP54
Stroke signaling components
Each limit switch functions:
- SQ1—Slider backstroke limit switch
- SQ2—signl switch of slider backstroke
- SQ3—limit switch of the limiter
- SQ4—upper limit switch on the hydraulic pad
- SQ5—lower limit switch on the hydraulic pad
Electric operation method
Brief introduction of current technology procedures:
First initiate the motor, the rotating direction of motor shall be consistent with pump direction, otherwise, the system cannot work, even breakdown.
- Initial position: use inching action to make the slider back to extreme position, then the SQ1 limit switch begin to work and eject the piston to the low position and trigger the SQ5 limit switch;
- Operation procedures:
First turn the SA1 switch to “semi-auto” position.
Properly adjust the limit SQ1-SQ10，SP1-SP2 limit switch according to the technical requirements.
After completing the aforementioned steps, press down the “both hand pressing” button, then the machine begins to work according to the prescribed processing procedure until finishing the following actions:
- SQ1 signaling, slider quickly run down
- SQ2 signaling, slider slowly run down
- SP1 signaling, slider prolongs pressure-holding time.
- KT1 signaling, slider pressure relief
- KT2 signaling, slider backstroke
By to now, a complete semi-auto circulation action has been finished, other actions implement need to press corresponding buttons.
- “Emergency stop”: when the machine encounters some emergency needing stop all work immediately, can press down the SB1 button, and the machine will stop working at once.
- “Emergency stroke”: when the machine encounters some emergency, the slider need return stroke at once, can press down the SB1 button, then the machine will stop working immediately.
- Cut off power: when need to use the machine, the first step you need do is to turn the rotary switch to “turn on power” position, when finish work, turn the rotary switch to “turn off power” position.
Electric interlocking and electric protection device
6.1 The master circuit shall adopt automatic switch for short circuit protection, the motor shall use thermal overheat relay in case of overload protection; control circuit adopts small-sized high breaking circuit breaker in case of circuit short.
6.2 Photoelectric alarm: the hydraulic press is equipped with photoelectric protection program, users can prepare photoelectric protector, its interface: 220V power, wire No. “0，12”; Hold-open signal wire No. “60，84”.
6.3 All electric equipment shall be equipped with special grounding devices for safety.
Electric components list of the hydraulic press:
|QF1||Small high-breaking circuit breaker||DZ47-63||1||3P30A|
|QF2||Small high-breaking circuit breaker||DZ47-63||1||2P3A|
|QF3||Small high-breaking circuit breaker||DZ47-63||1||1P3A|
|QF4，5||Small high-breaking circuit breaker||DZ47-63||2||1P1A|
|QF6，7||Small high-breaking circuit breaker||DZ47-63||2||1P6A|
|YA1-19||Electromagnet||17||Follow with hydraulic|
|HL1||Signal lamp||LAY7-XD/25||1||~6V White|
|HL4，5||Signal lamp||LAY7-XD/21||2||~6Vd Red|
Installation and testing of hydraulic press
When the hydraulic press machine unloaded on the destination first carefully wipe away the antirust oil. Pay attention to gravity center selection when hanging, and put protection pad on contact position, avoiding use thin sheet for loading in case of damaging the meters and components.
The hydraulic press shall be installed on the concrete foundation, the foundation design sees attaching a drawing, as for other waterproof measures and safety lighting device etc shall be designed by the user according to actual conditions.
Hydraulic press installation steps as follows:
- First, put the hydraulic pad in the workbench, and then put the movable workbench on the workbench. Inset the columns into the four holes on slider and workbench, then install the power mechanism and electric cabinet and make level, finally, use foundation screws fasten on the ground.
- Hang and put the master cylinder and upper beam into the column during the period, block the piston of the master cylinder to prevent the piston falling down and have an accident when finish installing work, screw up the nut, and remove the fastener.
- Connect the pipeline, electric circuit, stroke limit device etc according to outline drawing, hydraulic theory drawing, electric theory drawing etc, infuse suitable amount oil into the clean tank, recommended oil amount is approx.1200L
- Twist open the oil valve of the pump, infuse oil to full to eliminate the air in the pump, and loose the handle of the pressure-adjusting valve( safety valve), by to now, almost all machine testing preparation have put into place.
- Power on and start the motor, its turning direction shall be in line with the specification, otherwise, exchange the power connectors, then officially start the motor, let the oil pump run without the load.
- Turn the switch to “adjustment” position, press down the button SB8, let the master piston run down, the piston head must properly lead into the positioning hole of slider, then install the connecting nut between piston and slider and leave 3-5mm gap to connecting flange, adjust the pressure valve to increase the pressure in master cylinder up to 5MPa,fasten the connecting nut with wrench on pressure-holding condition.
- Press down SB9 button to let the slider backstroke, put two pressure-test plate on the workbench, the center of the plate shall be under the piston rod; testing plate size f320x650（mm）,top and bottom shall parallel, parallelism error shall less than 0.02/500mm,and the plate shall can bear 500T or more pressure, then adjust parallelism and verticality between slider and workbench, finally, fix the upper beam and fastening nut.
- Testing under loading condition
- See hydraulic theory drawing, adjust the back valve pressure until the slider will not slip on any position, and also notice that the pressure shall not be too large, the upper chamber pressure of master cylinder less than 1MPa is preferable when slowly run down.
- Pressure range shall be controlled within 5MPa-25MPa, namely, divided into three times from 80t to 500t.
Common faults and troubleshooting solutions
|1||Action failure||1. Electric connecting wire become loose or connecting wrong||1. Inspect the electric|
|2. Control oil tank pressure is insufficient||2. Properly increase the oil pressure up to 1.5MPa|
|3.Oil volume too little||3. Add more oil|
|2||Slider crawl||1. Some air accumulated in the system or pump suck air||1. Inspect whether some air come into the oil pipe, then move times and increase pressure|
|2. Improper accuracy adjustment or vertical column lacks oil||2. Add some oil into the vertical column, readjusting the accuracy|
|3||Slider holds some pressure when slowly run down||Bearing pressure too large||Adjusting back valve to fully release pressure in the upper chamber, Max. pressure shall less than 1 MPa|
|4||Slider slips heavily when stopping the machine||1. Sealing ring on the cylinder mouth leakage||1. Inspec the cylinder brim, if leaks, replace it|
|2. Pressure is too small or leakage||2. Adjust the pressure and check the cylinder brim|
|5||Pressure gauge pointer swing heavily||1. There is some air in the oil pipe of the pressure gauge||1. Slightly loose the connector to release air when increase pressure|
|2. Pipeline mechanical vibration||2. Firmly fasten the pipeline|
|3. The pressure gauge has been broke down||3. Exchange the pressure gauge|
|6||High-pressure stroke speed is not enough, increase pressure slow||1. The flow of high-pressure is too small||1. Adjust according to the pump instruction, and eccentric can adjust to 5 steps when 25MPa|
|2. Pump wears or burns||2. If oil back mouth is heavily damaged, dismount for inspect|
|3. System inter leakage heavily||3. First, inspect whether the infusing valve has been closed, then inspect other components respectively|
|7||Pressure relief is too quick under the pressure-holding condition||1. Valve mouth concerned pressure holding is not fully sealed or pipeline leakage||1. Inspect the infusing valve, and pressure holding& relief condition|
|2. The sealing rings are damaged||2. Replace new sealing rings|
All aforementioned faults only can sum up the common faults, and just for your reference, as for actual faults meet daily use, first analyze the possible reasons, then shoot the problems one by one.
Maintenance & safety operation rules
Rightly use the hydraulic press machine; seriously abide by maintenance and safety operation rules is the premise for prolonging the service life and safety production.
Therefore, familiar with the machine structural performance and operation procedure shall take priority over all other considerations, furthermore, here we offer some tips for maintenance and safety operation based on the general condition for user reference.
- we recommend adopts N46 hydraulic oil, if, machine oil or turbine oil shall be subject to the temperature, when the room temperature is less than 20°C, 20# machine oil or 22# turbine oil are acceptable, when the room temperature is higher than 30°C, 30# or 40# machine oil are acceptable, and the oil temperature shall be controlled within 15°C~60°
- Oil must be strictly filtered before infused into the oil tank.
- Working oil shall be replaced every year; the first replace interval time shall not exceed three months.
- Regularly infuse some lubricating oil on the slider, the exposed surfaces of column and piston shall keep clean, and infused with machine oil each time before working.
- Acceptable eccentricity is 75mm under concentrated load nominal pressure of 500t;
- Inspect and calibrate the pressure gauge per half year.
- If the hydraulic press has lied idle for a long time, all machined surfaces shall be clean and coated with anti-rust oil.
Safety operation rules of hydraulic press
- Operators who are unfamiliar with the hydraulic press structural properties or operation procedure cannot start the hydraulic press without permission.
- All overhaul and die-adjustment work shall not be done during working.
- If any severe leakage or abnormal situation occur, such as unreliable action, noise too large, or vibration etc, shall stop the machine and analyses the reasons any machine with faults cannot be put into use.
- Exceeding the maximum eccentricity distance and maximum load use is forbidden.
- Exceeding the maximum stroke is forbidden, the closed height of the die shall be not less than 500mm
- Electric grounding device must be reliable and solid.
Vulnerable components list of hydraulic press
Vulnerable components of the master motor, master cylinder and top cylinder.
|Part Name||Drawing No.& Code||Component Name||Material||Quantity||Remarks|
|Master Motor||Guide Sleeve||HT200||8||Attached drawings|
|Master cylinder||TDM-YA320||Sealing ring||PU||3|
|D320x5.7||“O” shaped ring||Oil resistant rubber||2||GB1235-76|
|D220x5.7||“O” shaped ring||Oil resistant rubber||2||GB1235-76|
|Piston head||HT200||1||Attached drawings|
|Cylinder brim guide sleeve||HT200||1||Attached drawings|
|Cylinder||D140x3.1||“O” shaped ring||Oil resistant rubber||2×4||GB1235-76|
|D70x3.1||“O” shaped ring||Oil resistant rubber||2×4||GB1235-76|
|Cylinder guide sleeve||HT200||1×4||Attached drawing|
|Piston head||HT200||1×4||Attached drawing|
Hydraulic Press Diagram
Fig 10. Hydraulic Press Guide Bushing
Fig 11. Hydraulic Press Guide Ring