Defina CN

1 – Defina CN

É uma técnica para dar instruções para a máquina no formato de um CÓDIGO que consiste de números, letras, pontuações e outros símbolos - a máquina responde esta informação codificada numa maneira precisa e ordenada para realizar várias funções de um processo específico.

_ O CÓDIGO de instruções é formado por BLOCOS de informações, que são grupos de comandos suficientes para permitir que a máquina realize uma operação individual

_ Cada BLOCO tem uma seqüência e é executado numa ordem numérica

_ Um conjunto de instruções forma um PROGRAMA NC

Os sistemas CN normalmente são utilizados para o cálculo do caminho da ferramenta, a partir da representação geométrica da peça disponível na forma computacional. Outra opção é a simulação final do programa, onde pode-se visualizar a usinagem. Com essas duas funções citadas é possível obter com boa precisão do tempo principal da operação, pois seu cálculo é determinístico, dependo dos movimentos da máquina

Os comandos de um programa CN são os responsáveis pelo acionamento de uma máquina CNC, informando todas as etapas de fabricação de uma determinada operação de uma peça . Uma linha de comando de um programa CN pode conter informações sobre o movimento da ferramenta (movimento rápido, interpolação, etc...), informações tecnológicas (velocidade, avanço, etc...), ou informações que acionam funções auxiliares (ligar refrigerante, eixo árvore, etc...). A obtenção dessas informações depende sobre tudo dos dados da peça a ser usinada, considerando-se as limitações da máquina, as características do CNC e da ferramenta .

2 – Defina CNC

Numerical control

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"CNC" redirects here. For other uses, see CNC (disambiguation).

The examples and perspective in this article may not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page. (May 2011)

A CNC Turning Center.

Siemens CNC panel.

Numerical control (NC) refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone. The first NC machines were built in the 1940s and 1950s, based on existing tools that were modified with motors that moved the controls to follow points fed into the system on punched tape. These early servomechanisms were rapidly augmented with analog and digital computers, creating the modern computer numerical control (CNC) machine tools that have revolutionized the machining processes.

In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine via a postprocessor, and then loaded into the CNC machines for production. Since any particular component might require the use of a number of different tools-drills, saws, etc., modern machines often combine multiple tools into a single "cell". In other cases, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the complex series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design.

Contents

[hide]

• 1 History

o 1.1 Earlier forms of automation

 1.1.1 Cams

 1.1.2 Tracer control

o 1.2 Servos and selsyns

o 1.3 Parsons and Sikorsky

o 1.4 Punch cards and first tries at NC

o 1.5 Enter MIT

o 1.6 MIT's machine

o 1.7 Proliferation of NC

o 1.8 CNC arrives

o 1.9 CAD meets CNC

o 1.10 Proliferation of CNC

o 1.11 DIY, hobby, and personal CNC

o 1.12 Today

• 2 Description

o 2.1 Tools with CNC variants

• 3 Tool / machine crashing

• 4 Numerical accuracy vs Equipment backlash

• 5 See also

• 6 Notes

• 7 References

• 8 Further reading

• 9 External links

[edit] History

[edit] Earlier forms of automation

[edit] Cams

The automation of machine tool control began in the 19th century with cams that "played" a machine tool in the way that cams had long been playing musical boxes or operating elaborate cuckoo clocks. Thomas Blanchard built his gun-stock-copying lathes (1820s–30s), and the work of people such as Christopher Miner Spencer developed the turret lathe into the screw machine (1870s). Cam-based automation had already reached a highly advanced state by World War I (1910s).

However, automation via cams is fundamentally different from numerical control because it cannot be abstractly programmed. Cams can encode information, but getting the information from the abstract level of an engineering drawing into the cam is a manual process that requires sculpting and/or machining and filing.

Various forms of abstractly programmable control had existed during the 19th century: those of the Jacquard loom, player pianos, and mechanical computers pioneered by Charles Babbage and others. These developments had the potential for convergence with the automation of machine tool control starting