A press brake is a splendid machine. Yet, not a few errors may occur while applying it. Most errors are so widespread that they are subject to many preventative tactics.
These errors and failures are common and can be prevented.
These errors are common for all press brake machines:
Unclean state of press brakes. A widespread miscarriage by most of us is keeping the machine dirty in the workshop. Letting dirt pile up brings about extreme wearout of each gib and tool. Pieces might get scratched during formation because of dirt. Moreover, an electric problem or even system collapse may be caused by metal dirt penetrating into the controlling pavement.
In accordance with strict company policies, the machine and tools must be daily cleaned prior to performing the first setting-up. Remove residual oils to keep dust away from the equipment. Service life of a press brake gets extended, setting-up becomes simpler and quicker.
Disorder of rams.
This one is mostly miscomprehended in the system of press brakes. A press brake has a design of deviation restriction when working at a full load. Here the deviation is related with the ram bending upwards at the centeral part and the bed bending downwards at a full load. In case of load removal, beds and rams gain stable state.
Yet, if the bend loading appears excessively dense and the beds or rams are excessively sloping, they suggest constant failure at the equipment centeral part. Then bigger angles are formed in the middle of longer pieces compared to the tips. It is possible to prevent this when a careful bend loding is placed and adequate tonns are used whike making parts, as long as your bending press possesses controllable capacities.
Machine lubricating is one of the most crucial oversights. Each moveable part needs lubricating in accordance with your manufacturer`s recommendation. Each ram gib must be greased, if needed. Certain press brakes bear non-lubricated gibs, there are some with a lubrication fitting, some with handheld or automat greasing system. In case the gibways demand lubricating, failure to do this leads to their freezing or severe wearout. Then an expensive substitute will be inevitable.
Piston gibs need to be placed parellelly to prevent the ram twist-motioned operation. Unlevelled rams form improper pieces, at improper angles every gib acts as brakes, not allowing the rams to return the stroke tops with no increase of back pressures.
Extremely large gib gap.
The between-gib gap must correspond to the manufacturer`s recommendations. It may range from 0.001 to 0.002 inches. Yet, a gap above 0.006-0.008 may also be possible. In case of excessively little gap rams are held as brakes by gibs. If the gap is excessively large, rams float in the bend process, which effects adversely the breadth of flanges and bending consistence.
Wearout of tools. Improper tools can be a reason of unsuitable part formation.
Punch noses, die shoulder are exposed to waering. In case of overwork on the same area of the frame wearout occurs leading to unstable bending. Consult your suppliers to get appropriate tolerance specification, then realize weekly tool checking for tolerance. Tools are possible to remachine according to new requirements. This costs no more than new tools. The main thing is that tools, whether new or remachined, have to be firm and within 40-42 on Rockwell C Scale.
Part specification determines which tool is needed as long as your machine is consistent with the tools.
For instance, in case of banding radii more than sheet thickness and tolerances of angles within 1-2 degrees, air-bending by nearly all kinds of brakes is possible. This bending needs the minimum bend loading helping to defend the machine against being overloaded. Though, in case of radii the same as the sheet thickness and angles of 1-2 degrees, parts should be bottomed at 4 times as much tonnage as air bend.CNC brakes providing a precise repeatability of rams should realize bottom bending for little inner radius. It is crucial to entirely identify your machine type and make use of tools corresponding to its style. Applying unsuitable tools leads to improper part formation or the machine breakdown.
Precision of part formation depends on the proper alignment of punches and dies. The punch and die centers must appear upon the same level along the press brake length. Breadth of flanges is dependent on the alignment as well. The back gauge is placed at the die centeral part and the punch centeral part is determines the breadth of final flanges. Punch placement is stable, whereas die placement can be adjuasted to the centeral line of punches. Improper alignment occurs if dies or die rails move upon the frame.
Determining the necessary bend loading.
Knowing the necessary load for bending is crucial. Sheet thicknesses, metal types, bending length, applied tools determine the load. Being awre of the bend loading, it is possible to expend it on beds and escape damaging beds, rams and tools. Full load is not applicable for little parts.
Note that exceeding the specified tonns while bottom bending is possible. But this is not the case for air bend, for the equipment is capable of developing just the tonnage specified for the part formation. Every tool has got load limitation. Exceeding the limits causes tooling breakdown. Consulting your suppliers on tool limitation is the best thing to do.
Hydraulic press brake machines.
From time to time in case of the two-cylindered hydraulic press brake, rams drift downwards upon one or two tips if the press brake stops with its ram lifted and let at pressure with off power. The following situation may occur beacause of inner oil leakage in cylinders. Even if just one of the cylinders bears affect, rams drift far becoming unparalleled with beds.
Repalace the inner oil sealing to correct this leakage. Control the trouble of unalignment through setting a sheave beaneath the ram while the press brake is off. In case the leakage continues, the bend pressures reduce in affected cylinders. If leakage occurs on pistons, the outer seal has to be changed urgently.
Adjusting ram tonnage.
Certain hydraulic press brake machines do not bear controllable load features. In case they do, make use of them. The least load specified for a part bending is recommended for both tools and machines. It is possible not to overconcentrate loading reducing posibilities of ram and tool breakage. In case your press brake bears no controllable load system, consult manufacturers about availability of retrifitting units for the machine.
Insufficient changing of hydraulic oil.
Not changing hydraulic oil brings about risky situation. Oil may get polluted by dirt. If the brake runs at an excessive temperature for duarative periods, faults will occur connected with a valve, cylinder or some other block.
Check the oil at least yearly. Checking frequency depends on the machine functioning time. In case the press brake is used not so much, oil changing might not be compulsory. Consult lubrication specialists on this matter.
Mechanical press brake machines.
Contrary to hydraulic press brake machines mechanical ones may provide loading relatively greater compared to specified capacities at stroke bottoms. The excessive load can be twice or three times no more than the specified tonns.
The nominal tonnage is produced at the bottom and the excessive one is produced by the last motion of rams towards bottom. Note the position as well. The specified loading should not surpass the nominal tonnage. After the ram has passed a full circle, no overloading will exist near the stroke bottom.