Shearing Machine Definition
The hold-down cylinder of the shearing machine is driven by the hydraulic system to press the steel plate, and the left and right oil cylinder to drive the blade up and down movement.
The upper blade on the blade carrier and the lower blade fixed on the blade holders adopt reasonable blade clearance. Shear force is applied to the metal sheet of various thickness and separate the sheet according to the size of the required fracture.
Shearing machine is widely used in all kinds of metal materials, to meet the various demand for direct shearing. It is mainly applied in steel manufacturing, shipbuilding, automobile, container manufacturing, and switch electrical appliances, machinery manufacturing, light industry etc.
Shearing Machine Classification
The shear plate machine can be divided into two categories: hydraulic shears and mechanical shears.
Due to the large energy consumption and excessive noise of mechanical shears, the hydraulic shearing machines are much more widely been used.
According to the blade carrier movement, the hydraulic shearing machine can be divided into:
hydraulic swing beam shears and hydraulic guillotine shears.
Various Types of Shearing Machine
- guillotine shear，plate shear
One blade one the shearing machine does the reciprocating linear motion relative to the other blade to realize sheet metal cutting purpose.
- hand guillotine shear，hand plate shear
- hydraulic guillotine shear，hydraulic plate shear
- pivot blade shear，swing beam shear
The upper blade carrier of the shears is swung around the pivot.
- hydraulic pivot blade shear，hydraulic swing beam shear
A hydraulic-driven swing beam shears.
- multi-strip slitter，coil slitting shear
Using multiple disc scissors to cut the coil into multiple strip with the required width.
- multiband slitter，sheet slitting shear
Using multiple disc scissors to cut the metal plate into multiple strip with the required width.
- nibbling machine
The plate is processed into any shape by step.
- circular shear，rotary shear
The shearing machine with a pair of rotary blades to cut plate in the straight line or curved line.
- universal ironworker for punch，bar and section shear
A machine with two functions of punching and cutting.
- universal ironworker for plate and section shear
A machine with two functions of metal plate punching and cutting.
- universal ironworker for punch，plate，bar and section shear
A machine with three functions including plate punch, plate shearing and section shearing.
- universal ironworker for punch，plate，bar and section shear，notching
A machine with four functions including plate punch, plate shearing, section shearing and notching.
- billet shear，section steel shear
Special shearing machine for steel section.
- bar shear
Special shearing machine for bar material.
- alligator shear
The upper blade of alligator shear is in scissor motion.
- reinforcing bar shear
Special shearing machine for reinforcing bar.
- precision bar shear
Special shearing machine for precise shearing bar.
- slab shear
Special shearing machine for slab.
- scrap shear
Special shearing machine for scrap steel.
- ingot shear
Special shearing machine for billet.
Main Structure and Function of Hydraulic Shears
1. Shearing machine frame
The frame is welded with steel plate, which includes the left, right board, worktable, clamp holder and fuel tank.
A hydraulic cylinder and sliding block guide support are installed on both sides of the rack, which is a pushup mechanism that can control the clearance of blades.
The hydraulic hold-down cylinder on the clamping device can tightly press the plate for shearing.
2. Blade holder
Fixed upper blade, connect with the hydraulic cylinder, do up and down straight movement, pass shear force, achieve the cutting purpose.
In addition, the backgauge mechanism is also fixed on the blade holder to realize the positioning of the shear plate size.
3. Shear blade
The upper and lower shear blades made of high standard steel can suitable for shearing steel from low carbon steel to stainless steel sheet, upper and lower blade has four interchangeable cutting knife, improve the service life of the blade.
4. Backgauge mechanism
Fixed on the blade holder, including the backgauge regulating motor, micro dynamic adjustment mechanism, backgauge lifting mechanism, the digital display device, transmission screw, guide bar, etc.
The movement of shearing machine backgauge is driven by the motor, and driven the running of backgauge stopper plate to realize cut-to-length cutting.
5. Fuel tank
The fuel tank is installed on the oil tank base behind the shearing machine, the left side of the tank is the hydraulic integrated valve block, hydraulic oil pump and main motor. The left side of the tank is equipped with an oil gauge and the hydraulic oil adding to the middle level of the gauge is ok.
6. Clearance adjustment device
The best shear force can be achieved according to the gap between the upper and lower blades of the shear material and the plate thickness, which can protect the life of the blade and guarantee the product quality.
Rule of adjustment: generally adjust the gap of 10% of the thickness of the cut material.
7. The front supporter
There is also a side retaining device attached to the work table, which is designed to ensure that the shear plate is perpendicular to both sides.
8. Finger protection plate
The finger protection plate of the shearing machine is installed on the machine clamp holder, which is mainly used to control the safe distance of the fingers. In order to ensure the safe distance of the finger, the position of the finger protection plate must meet the mechanical safety standard.
Safe distance for fingers protection
Note: The above dimensions are in accordance with mechanical safety standards.
- When placing the plate in the backstop block, the finger should not be placed between the plate and the shearing machine table, in case the plate is pressed against the finger during the pressing process.
- When the backgauge block is not in the position, the plate should not be pushed through the finger protection plate to avoid scratching the finger.
9. Hold down cylinder
In order to prevent the moving of the plate during the cutting process, the hold-down cylinder is adopted to press the plate firmly.
10. The electric system of shearing machine
The function of electric system mainly includes start oil pump motor drive oil pump to provide the driving force for hydraulic shears, supply control power; The control circuit is mainly connecting the solenoid valve and oil pressure based on operation instructions to drive the knife carrier up and down movement to achieve the shearing purpose.
At the same time, the electric control the stroke of the blade, the back and forth movement, to lighten the alignment line, increase and reduce the gap, and adjust the shear angle.
11. The hydraulic system of shearing machine
It consists of the main oil pump, hydraulic system, hydraulic cylinder, pressure cylinder, hydraulic pipe, etc.
Hydraulic oil pump provides shearing pressure for hydraulic equipment.
The hydraulic system mainly controls the system pressure and hydraulic oil direction.
The hydraulic cylinder is used to drive blade holder movement to achieve plate shearing function.
The hold-down cylinder is mainly pressing the workpiece to ensure the precision of the workpiece.
The Operation of Hydraulic Shearing Machine
- Pre-operation preparation
- clean the oil on the surface of each shearing machine component, and notice that the ball valve should be in the open position;
- lubricate the lubricating parts;
- add N32-N46 thickened hydraulic oil to the tank (the oil must be filtered);
- machine grounding, switching on the power supply, checking the coordination of each electrical activity;
- before starting, especially if the accumulator needs to be re-inflated, it must check the position of the ball head.
- Operation of hydraulic shears
- (1) start the machine to run a certain number of cycles, and make sure that various thickness of the plate is cut (from thin to thick) under normal conditions for testing purpose.
- (2) open the pressure gauge switch when cutting, observe the oil pressure value, if there is abnormal, adjust the overflow valve to make it meet the requirements;
- (3) adjust blade clearance to a suitable position according to the plate thickness
- (4) transfer the plate to the work table;
- (5) adjust the backgauge to the proper position according to the size of the cutting sheet
- (6) push the plate to make the plate contact with the backgauge plate, and set the shear size;
- (7) step down the foot switch to shear the steel plate;
- (8) repeat (4)- (6) to cut off the next sheet;
- (9) after cutting a piece of steel plate, replace it with a duplicate (4)-(8) processing;
- (10) turn off the power when the work is finished, and carry out daily maintenance of the equipment (according to the daily maintenance of the shearing equipment);
17 Shearing Machine Safe Operation Rule
- The operator must be familiar with the general structure and performance of the shearing equipment.
- The operator must master use and maintenance standard of the shearing equipment.
- Lubricate the shearing machine according to lubrication provisions, check the oil quantity, oil quality, and cover the oil cup.
- Aligning cutting blade before the operation. The blade clearance shall be determined according to the thickness of the shear plate, generally between 5 ~ 7% of the thickness of the cutting sheet. Each clearance adjustment applies the hand to rotate the flywheel to make the upper and lower blade reciprocate once, and check the clearance with the feeler gauge.
- According to the requirement of the shearing workpiece, loosen the anchor bolt, adjust the position of the retaining plate, and strengthen it. The shearing machine should be run 2 ~ 3 times before work, make sure the lubrication is good, and the operation can be done without exception.
- It is forbidden to using the percussion method to loosen the backgauge device or adjust the clearance of the blade. When adjusting the clearance of guide rail and blade clearance, the shearing machine should be stopped before carried out the adjustment. It is forbidden to hand in the cut area or to pick up or catch the materials during the operation.
- The blade must be sharp and should be sharpened or replaced in time for damage or wear or delay.
- When cutting the plate with different thickness and materials, the pressure of clamp spring and blade clearance should be adjusted properly, to prevent spring breakage or damage the blade edge.
- It is forbidden to cut steel bar with the hydraulic shearing machine, Other items must not be placed on the workbench so as not to get into the blade and damage it.
- It is prohibited for the operator to leave or to hold the equipment operation under others’ watch.
- Pay close attention to the clamping mechanism and clutch and brake for abnormal failure; during shearing the operator should be concentrated, if detection abnormal phenomenon of the shearing machine, the operator should stop shears immediately, cut off power, inform concerned personnel to repair.
- Before leaving work, should cut off the power, wipe off the equipment, make a check record.
- It is forbidden to cut excessively long and thick plate, not to shear the high-speed steel, tool steel and cast iron.
- The clutch should be off before starting, and the motor should not start with the load.
- Before starting, test the empty cutting, after everything works well, then start cutting operation.
- It is forbidden to cut explosive articles, rods, overthin workpieces and non-metal materials.
- Notice whether the pull rod fails, whether the fastening screw is strong. The finger cannot enter the blade mouth when feeding. It is strictly forbidden to cut two workpiece by two operators at the same time. No standers behind the shearing machine.
Matters Needing Attention for Shearing Machine Operation
（1）Check the gap between the blade frequently and adjust the gap according to the thickness of different materials;
（2）The blade must be kept sharp, and the cut surface is not allowed to have a scar, gas cut seam and protruding burr;
（3）When adjusting the machine, it must be stopped to avoid personal and machine accidents;
（4）If found abnormal noise or oil tank overheating phenomenon during operation, should immediately stop the shearing machine to check, the highest temperature of oil tank cannot exceed 60 ℃;
（5）Do not cut strips to avoid damage to the machine. The cutting size of the most narrow sheet shall not be less than 40mm;
（6）Note: the shearing thickness of the plate shears refers to the material of Q235 steel plate (shear strength 450 Mpa), the thickness of the plate tensile strength increases, the maximum cutting thickness decreases. For the hydraulic shearing machine with the maximum cutting thickness of 16 mm, the shearing thickness of Q345 plate is 13 mm, while for 8 mm cutting capability of Q235 steel plate, for Q345 plate the thickness is 6 mm.
Hydraulic Shearing Machine Blade
** Shearing machine blade material
Standard blade hardness
These blades can cut ordinary cold rolling plate and most of the stainless steel plates.
When cutting mass stainless steel or hard materials, the raw edges may be generated when cutting. In this case, we can provide the optional blade for 6.5/10mm shears, hardness HRC 56/57.
You can also check out the detailed 8 Commonly Used Materials of Hydraulic Shears Blade
** Shearing machine blade angle adjustment
Blade angle and clearance calculation depend on the standard material. The gas cabinet has a diagram to adjust the data at any time to get better shear results.
For example, sometimes increasing “tilt angle” to reduce the cutting edge. But it may be deformed when cutting the strip. Sometimes reducing the “tilt angle” can reduce the deformation, but may produce burrs.
** Minimum cutting width for hydraulic shears
The width of the shearing strip should not be less than three times the thickness of the plate without requiring precise shearing.
In the precision shear, the width of the shear material should not be less than 6 times the thickness of the plate in case of distortion or bending.
The greater the width of the shear material, the smaller the deformation.
** Shearing accuracy of hydraulic cutting machine
When inspecting the shear quality, the data of the shear 2mm ordinary cold rolling plate are as follows:
- When setting X = 100mm, the parallelism allowance of the specimen is 0.15mm in any 1000mm length.
- When setting X = 100mm, the straightness of the specimen is 0.25mm in any 1000mm length.
- The repeat positioning accuracy of X-axis is 0.02 mm.
- The length of the specimen can be plate shearing width.
- Specimen tensile strength σb≤450 mpa.
** Shearing machine blade assembly
Upper blade installation:
First mount blade, bolt M12*40 screw on the upper blade, temporarily not bolt the screw at the two ends. Resist the upper blade with a stick, tighten the installed M12*40 screw in turn when the surface of the upper blade is fully pressed with the contact surface of the slider. Drop down the slider, turn off the pump motor, and install the M12*40 screw on both ends of the blade, tightening the screw. The tightening torque of the blade screw is 35N/M.
Lower blade installation:
Start the oil pump first and make the slider rise to the dead point, when the oil pump is turned off, load the blade and twist the hexagon screw of M12*45 (Don’t twist it too tightly for the time being). Press the blade with a stick to make the blade close to the bottom of the work table, screw the M12*45 screw in turn according to requirement.
** Adjustment of blade clearance
The blade clearance directly influences the quality of the shear surface and the life of the blade.
1. Too small blade clearance
Generally, the standard clearance between upper and lower blade is 0.02mm, which is equivalent to the thickness of a normal A4 paper.
In the installation process, by using the shearing machine to cut paper is the most commonly used method for adjusting blade clearance.
If the blade clearance been adjusted to small:
- The cutting edge of the blade is under too much force, which will damage the cutting edge directly and make the cutting edge not sharp.
- Affected by other factors, the dislocation of the upper and lower blade lead to upper blade cut lower blade, which causes the cutting edge of the blade to crack. This situation is very easy to hurt the operators.
2. Too big blade clearance
This is also a mistake that non-professionals make when installing blades. In order to prevent the blade of the shearing machine to hit each other, they simply enlarge the gap, in fact, this is not correct.
Usually, if the blade of the cutter blade is too large:
— The size of the plate which is cut off by the shearing machine is not accurate. Besides, there will be a lot of metal burrs on the cutting edge, especially for cutting thin sheet metal materials.
— The sheet metal will be nipped by the upper and lower blade and it is very difficult to take it out. This will not only wear out the blade but may also lead to the shearing machine stop. However, this condition will not be obvious for cutting thick plate.
After long use of the shears, the gap between blades needs to be adjusted.
Generally, we recommend setting the blade clearance around 10% of the metal sheet thickness.
The lower blade is fixed on the hydraulic shearing machine, and the blade clearance can only take the lower blade as the baseline to adjust the upper blade to achieve the ideal blade clearance.
The minimum clearance should be adjusted between 0.05-0.1 mm.
Such as range at the ends of the blade clearance, can be adjusted by adjusting the pole (see below figure), (loosen the lock nut at the bottom of regulating lever, turn the adjusting lever until clearance is equal on both ends of the upper and lower blade, twist lock nut).
If the clearance between lower blade does not conform to the requirements, can be adjusted by referring to the following figure, to adjust allen screw M16*60 and M12 * 65 to adjust the blade gap between the blade, in order to make the parallelism allowance of the upper and lower blade within 0.05 mm.
Of course, to get the ideal blade clearance, the M12*65 and M16*60 inner hexagon screw must be adjusted repeatedly.
Working Principle of Hydraulic Shearing Machine
As we put at the beginning of the post, the sheet metal shearing is realized by upper and lower blade movement driven by hydraulic system.
In order to fully understand the working theory of hydraulic shearing machine, you can refer to Hydraulic Guillotine Shears V.S Swing Beam Shears
Maintenance of Hydraulic Shears
The daily maintenance of the shears includes daily lubrication, tank cleaning and cleaning of the shearing machine.
1. Safety instructions
- When any maintenance is carried out on the shearing machine, the machine must be cut off.
- The power must be switched on for 20 seconds before the capacitor and the servo amplifier discharge completely.
- When the hydraulic parts work, the slider may move, and the following matters must be noted:
1> shall not be placed arms or feet between the upper and lower blades;
2> before removing the valve:
- Shut off pump
- Lower the slider to the oil cylinder without oil
- If can’t lower the slider, pad with a wooden block, pay attention to the pressure within the system due to movement of the slider valve removal.
- No operation shall be performed on the shearing machine that has not improved safety protection
2.Shearing machine lubrication
The shearing machine is lubricated by week (or every 40 hours). Use the calcium base grease, and the grease gun is injected into each lubrication point. The lubrication points are shown below：
|1||Ball screw, nut and screw end bearing||Calcium base grease|
|2||Guide rail and slide guide base||Calcium base grease|
|3||Sliding block guide rail||Calcium base grease|
|4||Guide rail and clearance adjustment screw and nut||Calcium base grease|
3. The hydraulic oil and calcium base grease
The shears are recommended to use the following hydraulic oil:
|GULF||HARMONY 46 AW|
|TBXACO||RANDO OIL 46|
|MOBIL OIL||MOBIL DTE 25|
4. Change hydraulic oil
Hydraulic oil should be replaced after 2000 hours operating for the first time, later replace the oil after every two years or 4000 hours work.
- Prior to removal of the tank cover and access to the tubing, the area must be cleaned to prevent contamination.
- Draining the hydraulic oil when the hydraulic oil is warm, and the slider is at the upper dead point.
- Clean the inside of the tank with the clean cloth and suitable solvent
- Replace oil filters
- Replace the new hydraulic oil
- Before the shearing machine is reworked, starting oil pump to circulate the hydraulic oil for about an hour.
5. Shearing machine maintenance procedures
In order to ensure the reliable operation of this shearing machine, the following procedures must be paid attention to.
This procedure is graphically represented.
The following listed time is based on the 5 days per week, working 8 hours a day.
|Item||The attention points||Period|
|Whole body||Brush the dust and dirt on the machine, gently oil the blade||weekly|
|Backgauge support bearing||Gun lubrication||weekly|
|Backgauge ball screw||Gun lubrication||weekly|
|Slider guide rail||Check the derrick adjustment||3 month|
|Check backgauge positioning||If the position error of the backstop blocks exceeds + 0.1mm, please reset||3 month|
|Hydraulic parts and systems||Check the tank oil level. If you need to replace the new oil, change the filter to 20um||weekly|
|Drain the old oil and add the new oil||12 months for the 1st time|
|Check all valves, hydraulic system, tubing and connectors to prevent leakage, blockage and replacement when necessary.||3 month|
|Check cleanness of the import and export filters||3 month|
|Foot switch||Check foot switch pedal, in case of deformation, breakage, etc||monthly|
|Electrical control equipment||Check the limit switches in the electric cabinet, and the wear and burn must be replaced in time||3 month|
|Shears||Observe wear and abnormality of air metal shears||3 month|
|Finger protector||Check the sheet shears protection device to prevent the finger from entering the dangerous area||monthly|
Hydraulic Shearing Machine Troubleshooting
Shearing Machine Model
For swing beam shears, the manufactures usually name it QC12K/Y, while for guillotine shears, QC11K/Y is adopted.
Hydraulic Shearing Machine Instruction Manual
You can click below link to view both the instruction manual for swing beam shears as well as guillotine shears.
Hydraulic Shearing Machine Drawing
** Hydraulic shears circuit diagram
** Hydraulic schematic diagram
1. The slider up and down movement
When the oil of the main oil line into three-position four-way directional control valve S6, S6Y1A get the electric. The oil enters into S6B via S6P, open one-way valve S8, and oil enter the lower chamber of the right cylinder(The left and right cylinder is connected in series), make the oil fluid from the right tank into the lower chamber of the left cylinder. The oil in the upper chamber of left cylinder enter S6A and enter S6T, to make the slider go up.
If S6Y1 get electric, the oil will enter S6A via S6), then enter into the upper chamber of the left cylinder, then enter the upper chamber of the right cylinder. The oil will overcome the pressure of back pressure valve S7 to enter S6T via S6B, then back oil tank, to make the slider go down.
2. Shear angle adjustment
If there is no set value in the shear angle of the shearing machine, the sliding block cannot operate up and down. Therefore, the shear angle must be in the state of controller setting.
The adjustment of shearing angles is as follows:
When the oil into three-position four-way directional control valve S2, and Y2A get electric, then oil will enter S2B via S2P, open hydraulic control single way valve S3, enter lower chamber of left cylinder and upper chamber of right cylinder cause the upper chamber of the left oil cylinder cannot form a circuit, so the left oil cylinder does not move. When the oil in the lower chamber of right cylinder back to oil tank via S6T, back pressure valve S7 and S6B valve, the cutting angle becomes small.
On the contrary, if Y2B get electric, the oil will enter S2A via S2P, open single way valve S4, and enter lower chamber of right oil cylinder. The oil in the upper chamber of the right cylinder can only enter hydraulic control single way valve S3 (At this point, the S3 valve is in the open state), oil enter S2T via S2B, the shearing angle turns big.
The relationship between shear angle and shear force:
|Mild Steel (mm)||6||8||10||13||13||13||13||16||16||20|
|Stainless Steel (mm)||3||4||6||8||8||8||8||10||10||12|
|Shear Force (KN)||132||220||430||730||620||620||650||730||850||1270|
|Shear Angle Adjustment (°)||0.5-2.5||0.5-2.5||0.5-2||0.5-2||0.5-2.5||0.5-2.5||0.5-2||0.5-3||0.5-2.5||0.5-3|
3. The work of hold-down cylinder
When the oil enter directional control valve S9 via clamping proportional control valve S10 (Its proportional pressure is controlled by electrical ark pressure adjusting switch), when S9 get electric, the oil will enter S9A via S9P, then enter the upper chamber of clamping device, press the clamping piston down to form compression, when S9 lose electric, the clamping piston will be press upward via clamp’s built-in spring, which forces the oil in upper chamber of clamping cylinder enter S9T via S9 valve, the clamping device is reset.
** Hydraulic shearing machine structure drawing
List of vulnerable parts of the hydraulic shearing machine
Hydraulic Guillotine Shears V.S Swing Beam Shears
You can check out one old post to learn the difference between hydraulic guillotine shears and swing beam shears.
Under the leadership of sheet metal workshop director, learning to abide by the regulations of the company, obey leadership arrangement, staff solidarity, positive efforts, acting on saving, do good work, to produce qualified products.
- Responsible for daily routine maintenance, check, repair, adjust and tighten the shears, and keep records.
- Be familiar with the safety technical operation procedures of the work, and strictly follow the safety technology and operating procedures.
- Master the normal operation method of the shearing machine, can accurately judge the abnormal situation of the machine, and take emergency measures timely and correctly.
- Operate strictly according to the operating rules, the equipment can be started when the working environment is normal.
- Check whether the oil storage tank is sufficient, and check valve and pipeline after starting the oil pump, and the pressure should meet the requirements.
- Observe the resistance of the blade movement and start cutting when the test is normal. It is strictly prohibited to start suddenly.
- It is not allowed to cut the laminated sheet material, not to trim the edges of the plate with burrs, and it is forbidden to shear the narrow plates and short materials that can’t press tightly.
- The clearance between the blades shall be adjusted according to the thickness of the sheet, but shall not be greater than 1/30 of the thickness of the plate.
- The blade should be fastened firmly, and the upper and lower blade shall be kept parallel to prevent accidents.
- The edge of the blade should be kept sharp. If the edge of the blade becomes dull or cracked, the blade should be repaired and replaced in time.
- When shearing, the pressure material shall be firmly pressed on the plate, and shall not be cut under pressure.
- The hydraulic valve is not allowed to adjust by yourself.
- It is forbidden to use the shearing machine for super length and super thickness, and it is not allowed to shear the steel, high carbon steel, alloy tool steel, cast iron and brittleness material.
- Frequently check whether the fastening screw is loose.
- Do not operate the shearing machine alone. It shall be coordinated by two people to deliver the material, control the dimension accuracy and materials taking, and confirm that the one person shall be unified in the command.
- Adjust the clearance of the shearing machine according to the thickness of the shear plate. It is not allowed to cut two different specifications and different materials.
- The fingers of the operator should stay at least 200mm away from the scissor shears mouth and leave the compression device.
- For the cutting thickness of the hydraulic swing beam shears, it shall be determined according to the curve diagram of the relationship between plate limit strength and plate thickness.
- No other items should be placed on the workbench.
- The cleaning must be carried out after stopping the shearing machine.
- After adjusting the blade (alignment), run the shearing machine in empty for the test.
- Before leaving work, should pile up the finished product, clear the field, cut off the power, lock the switch box.