Bending machine selection

Prospective buyers before the payment, the best start with the end use of the machine, known to occur in the torsion machine variables, such as parts of the bending radius of careful consideration of what to buy.
You have long realized that the companies should invest in a bending machine, and so is your responsibility to detail its specifications and recommended a new machine. This responsibility lightly, if properly selected, your production costs will rise, bending machine can not be expected to recover the cost. Therefore, there are several factors to be weighed in the decision-making.
Workpiece
The first important issue worth considering is the production of parts you want, point is to buy a table to complete the shortest processing tasks, the minimum tonnage of the machine.
Careful consideration of material grades and maximum processing thickness and length. If most of the work is the thickness of 16 gauge, the maximum length of 10 feet of low-carbon steel, then the free bending not more than 50 tons. However, if in a large number of die forming with bottom, and perhaps should consider a 150 tonnage machines.
Well, assuming the thickest material is 1 / 4 inch, 10-foot free bending of 165 tons, with bottom die bending (bending correction) at least 600 tons. If most of the work piece is 5 feet or less certain, almost half the tonnage, which greatly reduce cost of ownership. Part length to determine the specifications of the new machines is very important.
Scratch variable
You should also consider this machine torsion changes that may occur. In the same load, 10 feet machine table and change the slider appears flexible machine is 5 feet 4 times. That is, the shorter the machine requires less pad adjustment can produce qualified parts. Reduce the gasket to adjust it shorter preparation time.
Material Grade is also a key factor. Compared with the low-carbon steel, stainless steel, the load is usually required to increase by 50%, while most brands of soft aluminum reduction of 50%. You can always get from the press brake machine manufacturers tonnage table that appears in different thickness, different materials under each foot length of the estimated tonnage required.
Part of the bend radius
Then, to focus on the part of the bend radius.
A free-bending, the bending radius of the die opening of 0.156 times the distance. Bending process in a free, open die from the metal thickness should be 8 times. For example, use 1 / 2 inch away from the forming opening 16 gauge mild steel, the components of bending radius of about 0.078 inches. If the bend radius is almost as small as material thickness, to be carried out with bottom forming die. However, the die forming with bottom pressure ratio required for the free bending big four times.
If the bend radius of less than material thickness, to adopt the front-end radius less than the thickness of the punch and turned to stamping bending. This would require 10 times the pressure of the free bending.
The free bending, the punch and die by 85 ° or less than 85 ° machining (small something for the good). When this group of molds used, pay attention to the punch and the die bottom of the gap in stroke, as well as sufficient to compensate for springback of the material will remain around 90 ° bend over.
Typically, the free press brake bending mode to generate a new rebound angle ≤ 2 °, bending radius of the die opening distance equal to 0.156 times.
For bending with bottom die, die angle is generally 86 ~ 90 °. The bottom of the stroke, between the punch and die should be a little bigger than the gap thickness. Forming angle can be improved, as with bottom bending tonnage die larger (about 4 times the free bending), reducing the bending radius is usually caused by stress resilience.
Stamping die with bottom bending and bending the same, but the process has become the front-end punch needed bend radius, and stroke at the bottom of the punch and die clearance is less than material thickness. Since exert enough pressure (about 10 times free bending) force the front-end punch, contact materials, largely to avoid the rebound.
In order to select the minimum specifications of the tonnage, the best material thickness greater than the bending radius as intended, and as far as possible use of the free bending. Bending radius is large, often into pieces does not affect the quality of its future use.
Accuracy
Bending accuracy is a need to carefully consider the factors, it is this factor, the decision that you need to consider a manual or CNC bending machine bending machine. If the bending precision ± 1 ° and can not be changed, you must focus on the CNC machine.
CNC press brake ram repeatability is ± 0.0004 inches, forming a precise angle to be used such precision and good mold. Manual bending machine slider repeat accuracy ± 0.002 inches, and the use of appropriate conditions the mold will generally ± 2 ~ 3 ° of deviation. In addition, CNC bending machine to prepare for the rapid loading mode, when you need small quantities in many parts of the bending, this is considered an unquestionable reason.
Mold
Even if you have a shelf full of mold, do not think that these molds for the new machine to buy. To check the wear of each mold, method is to measure the front-end punch to the shoulder length and between the die shoulder length.
For the conventional mold, per foot deviation should be ± 0.001 inches, and the total length of the deviation is less than ± 0.005 Inch. As for grinding mold, per foot accuracy should be ± 0.0004 inches and no larger than the total accuracy of ± 0.002 Inch. Better to die used for fine grinding CNC bending machine, the conventional mold for manual bending machine.
Indeed, we are often guilty of just buying a new bending machine without buying a complete set of appropriate tooling errors.
Bending side
One factor often overlooked is the material before bending machine bending side.
Suppose along a 5 × 10-foot 10-gauge carbon steel bent 90 °, bending machine probably have to put 7.5 tons of additional pressure on the steel top up, and the operators must be 280 pounds to prepare for the whereabouts of straight edge . Manufacture of the parts may take several able-bodied workers and even a crane. Bending machine operator often bending the long side parts, but unaware of how strenuous their jobs.
There is a feeding device for care work in this workshop, which may be based on the new and old machines need to be improved. Use of the device, forming the long side parts only one operation.