The cost of production will rise when a folding machine is chosen improperly, and the bending machine cannot expect to recoup its costs. Therefore, several factors must be weighed in the decision.
1. The workpiece
The first important thing to consider is the part you want to produce, the main point is to buy a machine that can complete the processing tasks with the shortest working table and the smallest tonnage.
We should carefully consider the material number and the thickness and length of the maximum machining. If the bulk of the work is a low carbon steel with a thickness of 16 gauge and a maximum length of 10 feet, the free bending force does not need to be greater than 50 tons. However, if you are engaged in a large number of bottom-die forming, you may want to consider a 150-ton machine.
Well, let's assume the thickest material is 1/4 inch, a 10 feet free bend requires 165 tons, while a bottom-concave mold bend (corrected bending) requires at least 600 tons. If the bulk of the workpiece is 5 feet or less, the tonnage is nearly halved, thereby it will greatly reduce the acquisition cost. The length of the parts is very important to determine the specification of the new machine.
2. Folding and bending
Under the same load, the 10-foot-machine table and slider appear to be four times as big as five feet. That is to say, shorter machines require fewer spacer adjustments to produce qualified parts. Reducing the pad adjustment reduces the preparation time. Material number is also a key factor. Compared with low carbon steel, the load of stainless steel usually increases by about 50%, while the majority of soft aluminium is reduced by about 50%. You can always get a ton of machines from the bending machine manufacturer, which shows the amount of tonnage required per foot in different thicknesses and materials.
3. Bending radius of folding parts
When free bending is adopted, the bending radius is 0.156 times of the opening distance of the concave mold. In the process of free bending, the opening distance of the concave should be 8 times of the thickness of the metal material. For example, the bending radius of the part is about 0.078 inches when using 1/2-inch opening to form 16 gauge low carbon steel. If the bending radius is similar to the thickness of the material, it must be formed. However, the pressure required for the die forming is about four times greater than that of free bending.
If the bending radius is less than the thickness of the material, it is necessary to use the convex mold of the front circular Angle less than the thickness of the material and turn to the pressure printing bending method. In this case, you need 10 times the pressure of free bending.
In terms of free bending, convex die and concave die according to the 85 ° or less than 85 ° processing (smaller). When using this set of mold, we must pay attention to the punch and die in the gap at the bottom of the stroke, and compensate the springback and keep the material around 90 ° of flexion. Usually, the springback free bending die bending machine produced in the new angle is less than 2 degrees, the bending radius is equal to 0.156 times of the die opening distance.
For a bottom bending die, the die Angle generally is 86 ~ 86 °. At the bottom of the stroke, there should be a gap slightly greater than the thickness of the material. The forming Angle has been improved because the bending of the bottom concave modulus is larger (about 4 times that of free bending), and the stress of springback is usually caused by reducing the radius of the bending radius.
The bending of the embossing is the same as that of the bottom concave mold, but the front end of the convex mould becomes the required bending radius, and the gap between the concave die of the bottom end of the stroke is less than the thickness of the material. By applying enough pressure (about 10 times the free curve), this forces the front-end contact material to basically avoid the rebound.
In order to choose the lowest tonnage specification, it is better to plan for bending radius greater than the thickness of the material, and adopt free bending method as far as possible. When the bending radius is larger, it often does not affect the quality of the parts and their future use.
4. The folding accuracy
The bending precision requirement is a factor that requires careful consideration. It is this factor that determines whether you need to consider a CNC bending machine or manual bending machine.
The double precision of the sliding block of CNC bending machine is plus or minus 0.0004 inches. The precision of the forming precision and the good mould are used. The folding accuracy of the manual bending machine is ± 0.002 inches, and under the condition of using the suitable mold, the deviation of " ±2~3 " will occur in general. In addition, CNC bending machine is ready for fast loading, which is an indisputable reason when you need to bend many small batch parts.
5. The folding mold
Even if you have a shelf full of molds, we should not think these moulds are suitable for new machines. The wear of each die must be checked by measuring the length of the front of the punch to the shoulder length and the shoulder length of the die. For conventional molds, the deviation should be about plus or minus 0.001 inches per foot, and the total length deviation is not greater than plus or minus 0.005 inches. As for the fine grinding mould, the accuracy of each foot should be plus or minus 0.0004 inches, and the total precision must not be greater than or minus 0.002 inches. It is best to use the grinding mould for CNC bending machine, and conventional die for manual bending machine.
6. Folding the length of bending parts
It is assumed that when a 5 * 10 foot 10-gauge low carbon steel plate is bent 90 degrees, the bender must approximately apply additional 7.5 tons of pressure to push the steel plate up, and the operator must be ready for the 280-pound straight edge. It may take several able-bodied workers or even a crane to make the parts.The operator of the bender often needs to bend the long side parts, but don't realize how much they have to work.
There is a kind of feeding device suitable for this kind of workshop, which can be improved according to the needs of the new or old machine. If you use the device, you need only one person to operate the long side parts.
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