First, the bender rebound control – no mandrel when the rebound is very strong. This should be considered when selecting the bending mold. Depending on the bending radius, rebound will make the tube back 2 to 10 degrees, may also increase the bending radius of the tube. The smaller the bend radius, the smaller the springback. Rebound is influenced by the position and pressure of the die. This method produces different radii for the same bending die. And the position of the mandrel can cause great rebound, which will reduce the angle of bending and may also increase the radius. When the radius is increased, the mandrel should be advanced (toward the cut point). There is no ready-made formula for adjusting the mandrel setting. Obviously, when the rebound angle is greater than 3 degrees, the mandrel is too far back and the pipe bending radius will be greater than the bending die.
Second, the bender mandrel too close to the front – mandrel too close to the front has several consequences. There will be a bulge at the end of the outside cut point of the bend, and there will be a depression at the beginning of the inside cut point of the bend. These deformations are exemplified on one tube. However, they do not always occur simultaneously due to differences in mandrel shape and bend radius. Feel free to use the insertion mandrel, the length of the clamping die should be at least three times the diameter of the tube.
Third, the bender mandrel is too far back – mandrel slightly forward, the front does not produce wrinkles but begins to produce at the back of the cut point. Mandrel position is still not far enough forward to produce the necessary pressure on the inside to shrink the material. And when the bent tube is removed from the bender die, there is a large wrinkle. So it is necessary to advance the mandrel again until the material will not be squeezed between the mandrel and the bending die.
Fourth, pick up the pump also known as bubble pump, back to the pump, usually due to the outlet valve steel ball can not be properly reset, you can extend the role of the rod, so that when there is pressure on the plunger pump, the handle seat with a Lang head tap a few times to make the valve ball reset.
Fifth, large and small pump oil suction is not enough, is due to the strainer inside the screen with garbage or insufficient oil caused by unscrewing the elbow mold parts, clean the net body with gasoline and fill the oil.
Sixth, the top of the top rod oil leakage, which is mainly due to damage to the top of the piston rod seal, you can replace the 14 × 2.4 O-ring seal, so it should be okay.
Seven, the die mounting hole cracking, generally due to the die item out when there is lateral load, such as: bent workpiece re-bending position is not put right, etc., you can check the two support wheel position is symmetrical, support wheel and workpiece fit at the oil, put the second bending position.