Cnc plasma cutter pdf

The purpose of trigger circuit is to generate high voltage and high frequency in order to ionize the gas. Microwave transformer steps up the main AC supply from V to V.

The frequency is increased by using LC circuit. A spark gap allows a resonant frequency of 2 MHz to be generated. Trigger frequency is designed using a coil with 3 turns each of 2 mm wire. The inductance of the coil is 8. To solve this problem, a Plasma unit in a shielding steel box is used to eliminate the electromagnetic wave as shown in figure 2.

When a command is sent from the computer to turn on Plasma, the control circuit turns on the contactor of power supply and relay of trigger circuit at the start of cutting. They are turned off when cutting is finished.

Plasma cutting is used to cut any kind of metal. It is proved the Plasma cutting is better than oxy acetylene which cannot cut all metals. Plasma is fourth state of matter, which is generated when applying positive charge on work piece and negative charge on electrode of Plasma head and passing compressed air. In this chapter also, the design stages of the Plasma arc part were detailed. These stages are: power circuit which converts AC voltage into DC voltage and handles the user safety, trigger circuit which ignites the Plasma torch by high voltage and high frequency, and control circuit which communicates the commands from the PC to the machine and this will be detailed in a separate chapter.

It is important to understand some mechanical structures such as linear motion system and linear bearing systems. It is also important to get to know some mechanical parts such as belts, bearing and gears. Autodesk Inventor, by Autodesk, is used in the mechanical design and simulation of the machine.

Support machine components. Guide the machine in a precise linear motion with minimal friction. Support lateral loads. An LM system is composed of some type of linear bearing and the linear bearing guides. The most famous types of bearings and guides are in figure 3. Rods and bushings system is selected for our machine because of it is high load capacity, low friction coefficient, good accuracy, low cost and easy maintenance.

The most popular drivers are: 1. Lead screw and nuts. Roller chain. Timing belts. Track and pinion. Timing belts are used to drive the X-axis and Y-axis while lead screw and nuts are used to drive Z-axis. Ball bearing: The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. Thrust bearing: they are designed to support a high axial load. Linear bearing: it is a bearing designed to provide free motion in one dimension. The types of bearing are shown in figure 3.

Figure 3. This machine contains five parts as shown in figure 3. Plasma head holder. Timing belts have many advantages: 1. No backlash. Good accuracy. Easy to replace. Low cost. The full Y-axis is shown in figure 3. Linear bearing holder: this part connects the linear bearing to Y-axis stands that will make motion to transfer from bearing to axis-stand.

Y-axis stands: there are two Y-axis stands the first is connected to two linear bearing holders as shown in figure 3. The second stand also constrains the axis motion as shown in figure 3. Y-axis Bridge: this part, shown in figure 3. This part connects X-axis to Y-axis.

Linear bearing holder: this part, shown in figure 3. X-axis stand: this part, shown in figure 3. The full Z-axis is shown in figure 3.

The advantages of using lead screw are: 1. Precise and accurate linear motion. Smooth, quiet, and low maintenance. Simple to design. The Z-axis is composed of the following parts: 1. Z-axis stand: this part, shown in figure 3. Thrust bearing: this part is used at the end of the lead screw. Its function is to hold the mass of the lead screw and fix it.

Z-axis Bridge: this part shown in figure 3. The bridge connects between a nut and linear bearing. This is the function of Plasma holder. The Z-axis moves down until Plasma head touches the work piece, then it is moves the Plasma head up until it touches the limit switch then Z-axis get up the required distance the complete part shown in figure 3.

It is stable and strong. The table was surrounded from all sides to avoid Plasma torch to get out. The table has two wings above the rods to protect it from dust and torch as shown in figure 3. The simulation results are listed below: 1.

Displacement : Maximum displacement in the machine is 0. Von Mises stress: Max Mises stress is Full details are shown figure 3. It is a good choice for strong machine. Timing belts and lead screw are as driver. This is a very accurate driver with no back lash. Autodesk Inventor is used to design CNC machine and make analysis. The results are very good as the machine is stable, robust and safe.

A stepper motor shown in figure 4. Every revolution of the stepper motor is divided into a discrete number of steps, in many cases steps, the motor's position can be controlled without any feedback mechanism, and we can control the speed of stepper motor by changing pulse frequency.

Figure 4. The rotation angle of the motor is proportional to the input pulse. The motor has full torque at standstill if the windings are energized. The stepper motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control [6].

Unipolar: in this type we use 5 wires from stepper motor, this type has more speed. Bipolar: in this type we use 4 wires from stepper motor, this type has more torque. Bipolar can be connected in two ways: Series connection and Parallel connection. Full step: Standard stepper motor has full steps per revolution of the motor shaft.

Essentially one digital pulse from the driver is equivalent to one step. Half step: Half step simply means that the step motor is divided to two steps that mean the motor that have step by revolution will be rotating at steps per revolution. In this mode, one winding is energized and then two windings are energized alternately, causing the rotor to rotate at half of the distance, or 0. Microstepping: microstepping is a relatively new stepper motor technology that controls the current in the motor winding to a degree that further subdivides the number of positions between poles.

Microstepping is typically used in applications that require accurate positioning and smoother motion over a wide range of speeds like our machine. Two sine waves in quadrature 90 degrees out of phase form the ideal current drive.

If the two stepper coils follow the current waveforms shown in figure 4. In fact, the "step" usually associated with stepper motors will disappear [7].

As one coil increases in current the other decreases, the rotor advances smoothly and torque output is continuous at any given position. The motor shaft advances smoothly during the entire cycle as shown in figure 4. Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, and toys.

PWM signal shown in figure 4. Every rising edge in step input makes the motor move one step. The control circuit schematic shown in figure 4. We need positive and negative voltages when driving the motor and this is the function of H-Bridge. H-Bridge provides positive and negative output voltages as shown in figure 4. The power circuit schematic is shown in figure 4. After the circuit is built in Proteus as shown in figure 4. The stepper motor is brushless and synchronous electric motor.

Control circuit is designed to control stepper motor motion depending on steps and direction input. Control circuit is required to control stepper motor in high accuracy on CNC. So, microstepping part is utilized. The purpose of microstepping is to make the motion of stepper motor smoother and more accurate. The stepper motor accuracy is 0. To drive the motor we use l dual full bridge to control of the motor at high power. A CNC control board is connected to the PC through a parallel port to control the machine using computer software.

In this chapter, many concepts are explained: parallel port, G-code, Mach3 application and how to convert an image to G-code. Figure 5. Somewhat of a generic, catch-all type of term for CNC programming language. Very few machines adhere to this standard today. There are as many variations as there are manufacturers. G-code example: 1. G00 Rapid positioning 2. G01 Linear interpolation 3. G02 CW circular interpolation 4.

G03 CCW circular interpolation 5. G20 Programming in inches 6. G21 Programming in mm 7. It is very flexible program designed to control machines such as milling machines, lathes, Plasma cutters, and routers.

Mach3 and its parallel port driver communicate with the machine hardware through one or optionally two parallel ports. Mach3 generates step and direction signals to perform the steps defined by a G-Code program and sends them to the port [8]. The limit switch stops this motion if the axis reaches the end of machine. The reading of caliber is written to Mach3 calibration, and then Mach3 makes correction for speed and acceleration for stepper motor.

Finally another command is sent to y-axis to move 50 mm. The actual value is measured to be To sum up, in order to cut an image using the CNC machine. After explaining every part of Plasma CNC machine and knowing it is importance and function on the system.

Now we discuss the results and recommendations. First test for Plasma unit is to cut iron as shown in figure 6. The result is good and satisfying. Figure 6. CNC controller circuit shown in figure 6. CNC controller part testing with small stepper motor and get high accuracy, high torque and good performance.

The controller board shown in figure 6. The CNC machine shown in figure 6. Some picture is load to mach3 to test the machine accurate the pictures drown by CNC machine shown in figure 6. Now test the machine by making some art drawing from PC to real world the first shape shown in figure 6. Second shape is the same of first one put in the circular shape the image shape shown in figure 6. The gear is designed by Autodesk inventor as shown in figure 6.

The accurate of machine is very high because the maximum error is 0. The other part is the shape contains a lot of shape such as arc, chamfer, teethes, oblong and circle as shown in figure 6. Also we faced problem in advance for that some of mechanical and electrical parts, which were bought from abroad. Because of Plasma CNC Machine is new on industrial world and its research still going and facing hardly to get the research of it, at the time there is no application for it on Middle East for it.

Finally we can design this new system, at high accuracy despite the difficulties. We look forward to enter new improvement to Plasma CNC Machine, increasing the cutting thickness and cutting speed. We look on producing this Machine to improve the industrial area. Wikipedia [online]. Plasma-cutter [online]. CNCrouter source [online]. Pitruzzello, G. It moves each axis at its max speed until its vector is achieved. We provides online technical support, it can be by phone, email or skype; machine tutorials in English language will be provided with machine.

Damage caused by abuse, or neglect is not included in the warranty. Acts of God, fire and etc. The easily damaged parts such as cutters, belts and etc will not enjoy the warranty. You are advised to order some easily damaged parts for maintenance purpose in future. Jackie Oversea Market Dept. Millions discover their favorite reads on issuu every month. Give your content the digital home it deserves. Get it to any device in seconds.

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