What is the principle of a pipe bender?

Pipe benders are indispensable in industrial production.So,what is the principle of a pipe bender?

The principle of a pipe bender is mainly based on the coordinated operation of the hydraulic system and the numerical control(NC)system.Specifically,the working principle of a 3D NC pipe bender is to control the movement of the piston in the hydraulic cylinder through the NC system,thereby achieving the bending of metal pipes.

During the operation,a pipe bender consists of several key components,including the frame,worktable,hydraulic system,control system,and clamps.These components work together to ensure the stability and accuracy of the pipe during the bending process.

In addition,the pipe bending process involves the functions of several key components,such as the die,clamp die,guide die,mandrel,and wrinkle plate.Among them,the die is the core component and serves as the center of rotation for the pipe during bending;the clamp die is used to hold the pipe in place;the guide die,together with the wrinkle plate,provides auxiliary support during bending;the mandrel provides internal support during the bending process to prevent deformation and collapse of the pipe.

In summary,the pipe bender achieves efficient and accurate bending of metal pipes by driving the movement of the hydraulic cylinder piston with the hydraulic system,combined with precise control from the NC system and the coordinated operation of various mechanical components.

The hydraulic system of a pipe bender mainly consists of components such as a hydraulic pump,solenoid valve,and hydraulic cylinder to achieve the bending operation of the pipe.The specific working principle is as follows:

• Hydraulic Pump:The hydraulic pump is the power source of the hydraulic system,responsible for converting mechanical energy into hydraulic energy.Once the hydraulic pump is started,hydraulic oil is pumped into the system.
• Solenoid Valve:The solenoid valve is used to control the direction and flow rate of the hydraulic oil.In the initial state,all solenoids are de-energized.The hydraulic oil output by the plunger pump is unloaded through a 4-way,2-position solenoid valve,and all actuator pistons are in the retracted position.
• Hydraulic Cylinder:The hydraulic cylinder is the actuator,responsible for pushing the pipe to perform the bending operation.Depending on the working conditions,the actual pressure,flow rate,and power of the hydraulic cylinder at various stages of the working cycle need to be calculated and adjusted.
• Unloading Circuit:The unloading circuit consists of a relief valve and a 4-way,2-position solenoid valve.When the hydraulic pump is started,the 4-way,2-position solenoid valve is in the unloading state by default,and all the output of the hydraulic pump is returned to the oil tank through the solenoid valve.
• Control Scheme Design:The design of the hydraulic system needs to consider load analysis and the selection of control algorithms to ensure the efficient and reliable operation of the system.

The numerical control(NC)system plays a crucial role in a pipe bender,primarily responsible for controlling the movement of the hydraulic cylinder piston.Specifically,the NC system controls the movement of the hydraulic cylinder piston in the following ways:

• Parameter Setting and Command Output:Before using an NC pipe bender,it is necessary to set some key parameters through the NC system,such as bending angle,bending radius,and bending method.After these parameters are set,the NC system generates corresponding control commands based on this information.
• Hydraulic Transmission and Synchronous Control:Pipe benders typically use hydraulic transmission technology.The ram part consists of the ram,hydraulic cylinder,and mechanical stop fine-tuning structure.The left and right hydraulic cylinders are fixed on the frame,and the piston(rod)drives the ram to move up and down through hydraulic pressure.The NC system controls the amount of oil entering the cylinder by adjusting the opening size of the synchronous valve,thereby achieving synchronous operation of the ram and ensuring that the worktable remains parallel.
• Solenoid Valve and Oil Flow Control:The NC system can also use solenoid valves to control the flow of oil,thereby enabling the piston to move to the required position.This control method is simple and convenient and has a high degree of precision.
• Human-Machine Interaction and Real-Time Monitoring:The NC system also includes a touch screen and other human-machine interaction interfaces to facilitate interaction between the operator and the machine.In addition,the NC system can monitor the working state of the machine in real time and adjust the control strategy according to the actual situation to ensure the quality of the workpiece and production efficiency.

The die,clamp die,guide die,mandrel,and wrinkle plate in a pipe bender each have different functions and roles,as described below:

The die plays a very important role in the pipe bending process.It ensures that the pipe does not deform or get damaged during bending.Different diameters and thicknesses of metal pipes require different specifications of dies to ensure the accuracy and effect of the bending.

The clamp die is used to hold the pipe in the correct position for bending.Together with the die,it ensures the stability of the pipe during the bending process.

The guide die serves a guiding and supporting role during the pipe bending process.It rotates around the die with the pipe,helping to complete the bending function.

The main function of the mandrel is to support the inner wall of the pipe's bending radius to prevent deformation.The mandrel comes in various forms,such as cylindrical mandrels,universal single,double,or multi-ball head mandrels,etc.The mandrel prevents the pipe from flattening during bending and allows bending without wrinkles or kinks.Additionally,the position of the mandrel has an important impact on springback.If the mandrel is positioned far from the cutting point and is in a rearward position,it will not sufficiently stretch the pipe on the outer side of the bend,resulting in significant springback.

The wrinkle plate prevents the pipe from wrinkling and flattening during the bending process.By increasing the support in this area,the pipe wall thickens evenly after contraction,avoiding the formation of wrinkles.

Ensuring the stability and accuracy of the pipe during the bending process requires a comprehensive consideration of several aspects,including mechanical structure,control system,material quality,and process specifications.Here are detailed measures:

The pipe bender should have a stable mechanical structure and an accurate control system to ensure stability and precision during the machining process.Mechanical equipment can precisely control the applied force and bending angle,thereby providing higher precision and stability in pipe bending.

The material used for pipe bending must be qualified and free from defects such as deformation or cracks.Using highly polished lubricating oil and appropriate pad-type chamfering molds can reduce friction and wear,ensuring smooth contact between the pipe and the mold.

All pipe bends must be processed in accordance with relevant standards and regulations,such as the span and spacing meeting the specification requirements.In addition,the technical specifications have strict regulations on the ellipticity of the pipe bend to ensure the quality of the pipe bend.

Use measuring tools such as calipers and micrometers to check whether the dimensions of the pipe meet the requirements,ensuring the precision of length,diameter,and other dimensions.When adjusting the pipe bending mold,attention should be paid to precise adjustment of areas with special requirements.

Adding two support points based on three-point bending can make the bending process more stable and smooth.This method can improve the stability of the pipe bending process to a certain extent.

For pipe systems involving fluid flow,fluid-structure interaction analysis can be used to study the vibration stability of the pipe,and the pipe design and maintenance guidance can be optimized based on the analysis results.

The operating procedure of a pipe bender can be divided into the following steps:

• Pipe Shape Standardization:During design and pipe layout,avoid large arcs,arbitrary curves,compound bends,and arcs greater than 180 degrees.These factors not only make the tooling cumbersome but also are limited by the size of the pipe bender machine,affecting mechanized and automated production.
• Standardization of Bending Radius:Ensure that the radius of the pipe being bent meets the standard requirements to guarantee processing quality and efficiency.
• Loading and Fixing:Place the pipe to be bent into the corresponding mold and secure it.Select the appropriate die head according to the outer diameter of the pipe to be bent,fit it onto the plunger,align the slots of the two rollers with the die head,then place it into the corresponding size of the flower plate hole,cover with the upper flower plate,and insert the pipe to be bent into the slot.
• Machine Start-Up:Press the main power switch and wait for the computer to start up normally,then press the start button on the control panel.The machine will automatically perform the start-up operation.After the NC pipe bender completes its self-inspection,processing can begin.
• Bending Formation:In the mandrel bending method,ensure that the mandrel head or mandrel does not obstruct when the bending arm returns to prevent the mandrel head or rod from being bent or broken by the sheet metal.When reaching the specified temperature,push the handle to the desired angle to complete the bending process.
• Mold Release and Pipe Removal:After bending is completed,release the mold and remove the pipe,allowing the mold to return to its original position.
• Cutting Operation:In the cutting operation area,cut the pipe to the desired length.
• Post-Work Procedures:After completing the above steps,perform necessary cleaning and maintenance to ensure the equipment remains in good working condition.