1. Overview of Crank Shear Machine

A Crank Shear Machine is a type of mechanical shearing equipment that uses a crank mechanism to drive the upper blade for cutting metal materials, billets, or rolled products.
It converts the rotational motion of the motor into a reciprocating linear motion of the shearing blade through a crank and connecting rod system, achieving precise and efficient cutting operations.

Crank shear machines are widely used in steel Rolling Mills, metal forming lines, and plate processing industries, especially in the hot and cold rolling of steel where continuous and rapid cutting is required.
Because of their high cutting speed, stable operation, and reliable accuracy, crank shears are indispensable equipment in modern metallurgical and steel processing plants.

The machine is typically installed after rolling mills or before cooling beds to cut continuous bars, plates, or billets into specified lengths according to production needs.

2. Working Principle

The crank shear machine operates based on the crank–connecting rod mechanism.
When the main motor drives the flywheel, torque is transmitted to the crankshaft through a clutch.
As the crank rotates, it drives the connecting rod, which converts the rotational motion into linear reciprocating motion of the moving blade frame.

During each crank rotation, the upper blade moves down to shear the material and then returns to its initial position.
The cutting stroke and timing can be adjusted by changing the crank radius, stroke length, or synchronization with the material feeding system.

The working process includes:

1. Acceleration and Power Transmission (motor → flywheel → clutch → crankshaft).

2. Crank Rotation and Linkage Motion (crank → connecting rod → sliding frame).

3. Cutting Action (upper and lower blades shear the moving material).

4. Return Stroke (spring or inertia brings the mechanism back).

This mechanism allows continuous cyclic operation, suitable for high-speed shearing in rolling production lines.

3. Structural Composition

A typical crank shear machine consists of the following main components:

1. Main Frame:
   Rigid welded steel structure supporting all moving parts and ensuring alignment accuracy.

2. Crankshaft and Connecting Rod System:
   Converts rotary motion into reciprocating motion, the core of the cutting mechanism.

3. Upper and Lower Blades:
   Made of high-speed or alloy tool steel, arranged at an optimal shear angle to minimize deformation.

4. Flywheel and Clutch Assembly:
   The flywheel stores kinetic energy; the clutch controls engagement for continuous or intermittent cutting.

5. Main Drive Motor:
   Provides rotational power to the crankshaft, often driven by variable-frequency control for speed adjustment.

6. Lubrication and Cooling System:
   Reduces friction, dissipates heat, and extends component life.

7. Control System:
   Includes sensors, PLC control, and synchronization with rolling speed for precision shearing.

8. Foundation and Safety Guards:
   Ensures vibration isolation, stability, and operator protection.

4. Performance Characteristics

1. High Efficiency:
   Continuous and rapid cutting with synchronized operation to the rolling line.

2. Precision Cutting:
   Crank mechanism ensures consistent stroke length and cutting accuracy.

3. Energy Saving:
   Flywheel energy storage reduces peak motor load.

4. Durability:
   High-strength components withstand heavy cyclic stress.

5. Low Noise and Smooth Operation:
   Balanced mechanical design and dynamic alignment.

6. Easy Maintenance:
   Modular design enables quick replacement of blades and bearings.

7. Automation Compatibility:
   Can integrate with automatic measurement and control systems.

5. Classification

Crank shear machines can be classified as follows:

1. By Function:

• Front-end shear: Cuts before rolling for head/tail trimming.

• Flying Shear type: Continuous cutting on moving billets.

• Fixed shear: Stationary cutting for stop-and-cut operation.

2. By Drive Mode:

• Mechanical drive (crank type): Traditional design using gears and flywheels.

• Hydraulic-assisted crank shear: Combined drive for smoother operation.

3. By Application Material:

• Bar shear, billet shear, plate shear, and strip shear machines.

6. Application Fields

• Steel Rolling Lines: For head and tail cutting or dividing long billets.

• Metal Plate Production: Used for trimming and length cutting.

• Automotive Industry: Pre-cutting of steel sheets for stamping.

• Shipbuilding and Construction: Cutting of heavy plates and beams.

• Rebar and Wire Rod Production: Continuous shearing in high-speed lines.

7. Maintenance and Operation

1. Regularly inspect crankshaft bearings and lubrication levels.

2. Replace worn blades promptly to maintain cutting quality.

3. Monitor vibration, noise, and oil temperature during operation.

4. Ensure synchronization between shear and line speed.

5. Conduct dynamic balancing after long-term use.

Conclusion

The Crank Shear Machine is a critical piece of equipment in metal processing and rolling industries.
Its mechanical simplicity, high reliability, and efficient cutting capability make it ideal for continuous production environments.
With the advancement of automation, servo technology, and intelligent control, modern crank shear machines are evolving toward higher precision, efficiency, and digital integration, supporting the transformation of traditional steel manufacturing into smart production systems.