Hydraulic Tube Bending Machine for Workshops

Posted on Apr 15, 2021

Hydraulic Tube Bending Machine

Since no swing arm or pressure die mechanism hangs below the plane of the bending die, the mainframe of the bender is put in place and should sit directly under the ram and support it. This way, all bending forces – exerted by the spindle and exerted by the pressure die – are directly "distributed" in a single, compact, heavy-duty tubular beam. The hydraulic tube bending machines also have the largest spindle and bearing diameters, the largest spread between the bearings, and the shortest distance from the die to the upper spindle bearing - all to ensure the greatest possible rigidity.

What Is a Hydraulic Bending Machine?

A hydraulic tube bending machine, or a hydraulic Tube bender,  is a single axis bender – It is hydraulically driven(not CNC). With the right bending tools, they have the power, accuracy, and stiffness to produce wrinkle-free bends with minimal ovality and thinning of tube and pipe walls made of various metals and alloys.

Bending machines are designed and built according to the latest machine tool standards, including JIC. Their capacities are referred to as Sch. Pipe 80 - this is not a thin-walled pipe, the section modules of which can only be half the size. Standard capacities are: 3 ", 4", 6 ", 8" IPS (60.3, 88.9, 114.3, 168.2, 219mm) and larger.

Benders are more durable and versatile than traditional swing-arm benders. Since no swing arm or pressure die mechanism hangs below the plane of the bending die, the mainframe of the bender is put in place and should sit directly under the ram and support it. This way, all bending forces – exerted by the spindle and exerted by the pressure die – are directly "distributed" in a single, compact, heavy-duty tubular beam. The hydraulic tube bending machines also have the largest spindle and bearing diameters, the largest spread between the bearings, and the shortest distance from the die to the upper spindle bearing - all to ensure the greatest possible rigidity.
 

Components of Hydraulic Bending Machine

The main components included in the standard of the single-axis bender are the mainframe, mandrel table, mandrel puller, mandrel, hydraulic control system, and top clamp.

By mounting the hydraulic clamping mechanism on the rotating flexible die itself, the conventional swingarm has been eliminated. This system has many advantages. Built-in clamp alignment in mating mounting surfaces of the clamp mechanism and bend die to assure that no vertical or horizontal clamp set-up adjustment is required. Therefore tool changing is faster and easier.

The clamp opens upwards, eliminating interferences in the forward feed of the curved workpiece. The potential collision between the clamp and the withdrawable workpiece is a major disadvantage of conventional swing arm benders. This problem is usually solved by the use of a cam or cable type drop-down clamping mechanism or by a separately rotatable coaxial swing arm and main shaft. Both are complex, compromise "amendments". an overhead clamp system eliminates this problem.

The clamping forces are independent – they are not transmitted through the die holder, spindle, or any other part of the machine. Thus, there is never any tilt of the die due to the clamping forces. No overhead beam is required for the top clamp as there is no die deflection for bending due to clamp pressure even when bending the heaviest or most "critical" workpieces.

Tooling remains correctly positioned as the bending die pivots horizontally throughout the bend.
Limited maintenance of machines and tools. There are no rocker arm slips or pivot links to cut or break, and less stress and tooling wear. Top mounting is safer. The dangerous "pinch point" between the rocker arm and die arm is gone.

Moreover, the operator has direct control of the clamping forces. They are easy to read on the pressure gauge and easily set with the relief valve, ensuring consistent and accurate settings. (The knee-type gripper mechanisms generate unreadable and necessarily excessive forces in their top dead center, prior to closing). The Mandrel Retrieval Unit includes both centerline radius adjustment and lead screw tangential adjustment - a major improvement over the old method of screwing in and out the mandrel on the mandrel. Motorized centerline radius adjustment is optional.
 

:: Read More: Introduction to Square Tube Bending Machine

The Mandrel System

The mandrel beam includes a mandrel extraction cylinder and pipe supports. The basic bender is completed by a mandrel beam assembly, without any design compromises. The standard 20 '(6.1m) load length is also not limited by the length of the main bending beam and does not require an extended frame or other modifications.

Motorized adjustment of the center axis radius of the mandrel assembly during setup is optional on Series 1000 Benders. The 20 '(6.1m) mandrel load length ensures that the entire length of the pipe can be loaded in one continuous motion without feeding the coupler. Longer load lengths are available.

The tangential adjustment of the mandrel is accomplished by a lead screw on the mandrel extractor cylinder – an improvement over the traditional method of screwing in and out the mandrel at the end of the mandrel.
 

Optional Pressure Support

Unlike other benders, the stamping and assist systems on some series benders are not "add-ons". The booster cylinder is integrated into the pressure die support head – parallel to the centerline of the workpiece, where it should be so as not to cause any asymmetric loads. The massive die guides on large bending machines can withstand the loads exerted by the booster system. Both the side dies to assist pressure/boost pressure can be adjusted from the control console with reference gauges.
 

Bending with a Pressure Die

Bending with a pressure die requires the use of a controlled pressure applied to the die. This reduces tool resistance and helps control part thinning. However, since the pressure die is not clamped onto the workpiece, the overall support force is limited by the coefficient of friction between the pressure die and the tube. Die bending is not the same as power bending.

Support bending involves a continuous pressure force applied directly to the workpiece through the support clamp. To achieve the maximum booster effect, the booster cylinder and its mounting system must be able to exert a sufficient load of a workpiece close to the yield point. In the Booster system, the support clamp is mounted directly to the rear of the pressure die, ensuring the continuous strengthening of the workpiece column under heavy load. A sequence of four preselected boost pressures is automatically applied when predetermined bend points are reached.

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