Tempo di lettura stimato: 9 minuto

Basic Knowledge

According to different transmission methods, the shearing machines are divided into mechanical transmission type and hydraulic transmission type. Shearing machines with a cutting thickness of less than 10mm are mostly mechanically driven, and those with a cutting thickness of more than 10mm are mostly hydraulically driven.

According to the orientation of the upper blade to the lower blade, the shearing machine can be divided into flat blade shearing and oblique blade shearing. When cutting with a flat blade, the sheet material touches the full length of the upper and lower cutting edges together, resulting in large shearing force, high power consumption, and large oscillation. However, the cutting quality is better, and the cut sheet is relatively straight without distortion. The transmission method of the flat-blade shearing machine is mostly mechanical transmission, which is mostly used for small shearing machines and thin plate cutting. Oblique blade cutting is a method of gradual shearing, so the instantaneous shearing scale is smaller than the width of the sheet. The cutting quality of the oblique blade is not as good as that of the flat blade, and there is distortion and deformation. However, the cutting force and energy consumption are smaller than flat-blade cutting, so it is used in large and medium-sized shearing machines.

The shear is divided into the linear type and swing type according to the movement method of its knife holder. The straight-line structure is relatively simple (it looks like a guillotine gate, so it is also called a guillotine shearing machine), and it is convenient to manufacture. The blade has a rectangular cross-section and all four sides can be used as blades, so it is more durable. The knife holder of the swing beam shear moves around a fixed point during cutting. The advantage is that the conflict and wear between the upper and lower cutting blades are small, the blade deformation is small, and the cutting accuracy is high. However, the swing tool post accepts positive and negative alternating torque during the cutting process, so the width of the tool post cannot be too large. Therefore, the pendulum structure is mainly used for shears with a plate thickness greater than 6mm and a plate width not greater than 4000mm.

Working Principle of Hydraulic Shearing Machines

After cutting, the shearing machine should be able to ensure the straightness and parallelism requirements of the cutting surface of the sheared sheet and minimize the distortion of the sheet to obtain high-quality workpieces. The upper blade of the shearing machine is fixed on the knife holder, and the lower blade is fixed on the workbench. There is a supporting ball installed on the workbench to prevent the sheet from being scratched when sliding on it. The back gauge is used for positioning the plate, and the position is adjusted by the motor. The pressing cylinder is used to compress the sheet to prevent the sheet from moving during cutting. The guardrail is a safety device to prevent work-related accidents. The return journey generally relies on nitrogen, which is fast and has little impact.

Working Principle of Mechanical Shearing Machines

The motor drives the flywheel shaft through the belt, and then drives the eccentric shaft through the clutch and gear reduction system, and then drives the upper tool post through the connecting rod to make it reciprocate up and down to perform cutting work. The cam at the left end of the eccentric drives the plunger of the pressing oil tank to return the pressure to the pressing foot and press the sheet before cutting. When returning, the presser foot is returned by spring force.

Precision Control Effect of Hydraulic Shearing Machines

The hydraulic shearing machine is a new type of shearing machine that is different from the ordinary shearing machine. Because of the numerical control, its operation is more streamlined, and the efficiency of the workers is further improved. Numerical control hydraulic shearing machine refers to the technology that realizes the motion control of one shearing machine or multiple shearing machines with digital instructions composed of numbers, characters, and symbols. CNC hydraulic shears generally use general-purpose or special-purpose computers to achieve digital program control, which usually controls mechanical quantities such as position, angle, and speed, and switches related to the direction of mechanical energy flow. The production of CNC hydraulic shearing machines relies on the emergence of data carriers and binary data operations.

Precision Control Effect of Mechanical Shearing Machines

For a long time, the technical improvement of mechanical shearing machines has been slow. Although some companies have made improvements to the adjustment of the blade gap of the mechanical shearing machine and achieved rapid adjustment, it still does more harm than good. It is easy to damage the machine tool and it will be eliminated in a short time. The mechanical shearing machine adopts a resistance key type clutch structure and an open gear transmission and adopts more advanced electrical appliances (footswitch, manual switch) for operation, low noise, easy operation, and maintenance. It adopts an all-steel welded structure, simple structure, easy operation, beautiful appearance, and low energy consumption.

Advantages And Disadvantages of Hydraulic Shearing Machine

1. Advantages

• The cutting force is large and the hydraulic overload protection reduces the damage to the machine tool.

• Equipped with electric back gauge, digital display, convenient and quick.

• The knife edge gap can be adjusted quickly, saving time and labor.

• When cutting the plate, the cutting of the plate is completed, and the upper knife frame automatically rises, which is not slower than the mechanical shearing machine.

• The integral steel plate welded structure has good strength, rigidity and vibration resistance. The two cylinders are fixed on the left and right columns. The working table is equipped with auxiliary knife holders to facilitate the micro adjustment of the blade. The working table is also equipped with a feeding ball and easy to operate.

• The stepless adjustment mechanism of blade gap adjustment can meet the cutting needs of different plate thicknesses and materials.

• The blade can be cut with four cutting edges, which prolongs the service life of the blade.

• The upper tool rest adopts an inwardly inclined structure, which is convenient for blanking and improves the precision of the parts.

• Adjusting the cutting stroke can not only improve the processing efficiency, but also realize the segmented cutting function.

• The number of cuts can be pre-set and automatically counted, which reduces the complicated inventory work.

• The use of an advanced integrated hydraulic system reduces pipeline installation and ensures a high degree of reliability and safety in the operation of the machine tool.

• The hydraulic pressure material mechanism is adopted. After the oil is supplied by a number of material pressure oil cylinders installed on the front support plate of the frame, the material pressure head is pressed down after overcoming the tension of the tension spring to compress the sheet material. After the shearing is completed, it is reset by the pulling force of the tension spring. The size of the pressing force increases with the increase of the thickness of the sheared plate

2. Disadvantages

• When cutting full mouth, the speed is slightly slower

• High price

Advantages And Disadvantages of Mechanical Shearing Machine

1. Advantages

• Fast cutting speed

• Good price

• Easy maintenance

• Two kinds of cast iron casting and steel plate welding, using pedal type, connected by pull rod and spring, work smoothly. Generally used in hardware, electrical appliances, color tiles and sheet cutting. Suitable for cold sheet metal and cold cutting.

2. Disadvantages

• During operation, the noise is loud.

• Can’t work at full load for a long time, let alone overload work, which will easily cause damage to machine tool parts

• There are too many wearing parts such as clutch parts, shaft sleeves, and brake bands.

• Knife edge clearance adjustment, machine tool maintenance is time-consuming and labor-intensive.