Brake press
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<reference/>colophon title: Press brake productivity Guide Publisher: Wila b.v. copyrights same second edition 2003.</ref>
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A press brake is a machine, used for industrial purposes, mainly for the bending of sheet metal products.
Ever since man discovered the boundless possibilities of metals, there has been a demand for forming techniques to transform these materials into the desired products. This initially brought casting and forging, as well as hammering of sheet metal components. The first sheet mill was not seen until the end of the seventeenth century, after the industrial revolution had gained momentum. This represented the careful beginnings of today's sheet metal industry. Next to presses, press brakes were gradually seen. At first these were Mechanical models with fly wheels, but today they are almost solely hydraulic models with hydraulic pumps and cylinders. To an increasing degree, the machines are computerized; the software controlled proportional valves ensure precise movement and equally precise bend angles. The first steps have now been taken towards automatic tool changing, and the Universal Press Brake Concept by Wila would seem to be the beginning of the next revolution.
Until the first half of 20 century, the world's industrially produced, mainly mechanical presses because of the relatively low cost of production, ease of performance, reliability of operation. However, mechanical press, in spite of these advantages are significant drawbacks associated primarily with increased demands of operating these machines. These disadvantages of mechanical presses include: a large mass, high power consumption, high levels of noise and vibration, hard adjusting, the high level of danger of injury to the motor operating the press, low quality of manufactured products.
Pneumatic press brakes took small area in the field of sheet metal, because of their limitations, mainly due to the efforts of a small, and the requirements for leading the compressed air line that puts the narrow scope of their application. Pneumatic presses are used, mainly in industrial sites, where the production process does not require great effort, but hydraulic or mechanical press used inappropriate because of their higher cost.
Since the second half of the 20 th century, in connection with the development of technologies, as well as for reasons of the higher requirements of enterprises that manufacture products from sheet metal, is beginning to dominate the production of hydraulic presses, which have several advantages compared with mechanical and pneumatic presses. These advantages are: high quality of manufactured products, high reliability, a much lower level of the risk of injury of staff, low energy consumption. Further development of technology has enabled the introduction of new systems of governance and security, which has several new features: a graphical user interface with the possibility of automatically calculating the bending sequence of operations, the job step program, the protection of the operator control device, a laser line protects tool from pressure overload, the possibility of electronic adjust the speed of progress of cross-beams, the use of additional hardware, operating synchronously with the process of bending - the front of the workpiece support, the sensor monitoring the received angle of bending and other improvements.
Scope of work press brake - ensuring the necessary effort and travel cross - a rigid steel beam on which the necessary tools, depending on the desired manufactured products and flexible regime. Progress of the beam is controlled by linear displacement sensors are generally of two that control the left and right side cross, to ensure uniformity of pace and the synchronization of traffic. As an additional equipment installed on the press brake, as a rule, the emphasis is back, with the possibility of programming of its position, depending on the desired size of leg.
No less important part of the press is a security system, which serves primarily to protect staff from injury, and as a support function - limiting travel in the violation of certain manufacturing operations. System security is a set of hardware and software that process the signals from different devices, the control necessary process. The most important is the laser device is the lack of control of foreign object (the hand of the operator) in the working zone of the machine. To control the laser beams are used, forming the plane of the upper tool, at a distance of about 3-5 mm below it. If the cross traffic from entering the hands of the operator occurs in the working area, laser beams, or one of them would be crossed, and the system will give the command to immediately stop the movement.
Typically, the algorithm works hydraulic press brake is as follows: 1. Travers is at Top Dead Center (TDC). The notion of TDC is conditional, because it originally comes from the construction of connecting rods, crank mechanism, which is used in mechanical presses. Hydraulic presses are able to adjust the status of the upper cross-beams, but this provision is also referred to as top dead center. 2. At the time of pressing the pedal or button two-handed control yoke begins movement down to a certain speed. This speed is usually higher than the speed of direct bending process, so that movement is happening to a certain point of switching speed and speed is called «free fall». This is also a conditional term, because in reality, no drop traverses does not happen, because the hydraulic system through the regulation, the rate is fixed in a certain range. 3. Having reached the point of switching speeds, the system control shifts to a lower speed, called the working speed. In point of switching speeds are also synchronize the movement left and right hand cross, which compared the testimony with linear displacement sensors and signals are given for the required adjustment to the hardware management - servo to adjust the rate of delivery of oil in the working-cylinder machine. 4. After a change of speeds, there is further movement traverses to the bottom dead center (as a rule, it is possible to adjust / programming), reaching the bottom dead center occurs extract under pressure. This is the time required for distribution to the entire length of the workpiece, because this factor affects the quality of manufactured products. 5. After the end of time, shutter speed, you need to release part of the effort. To this end, cross-arm rises up to the required size at a slower speed. This process is called decompression. 6. After the end of decompression, yoke reaches the top dead center. 7. The machine will come in motion after another pushing the pedal or button two-handed control.
