WHAT IS CNC MACHINES?

WHAT IS CNC MACHINES?

CNC MACHINES

Today, machines and machine tools for these machines are designed to reduce the need for agriculture and other human resources and to pass serial manufacturing, or fabrication. After the other machinery and automotive industries, it was necessary to be used in the production of agricultural machinery. The aim of these designers is to replace human power with faster, more reliable and more efficient instruments, as we have already mentioned. There have been no radical changes in these looms for many years. But there has been constant progress. Our age has been transformed into computer technology, has opened an era of metal cutting. This event is often called "Computer Aided Numerical Control". The short name is CNC. Such machine benches have jumped from other industry branches to the agricultural machinery industry, and the manufacturers have invested in these machines. In this respect, the agricultural machinery industry tended to approach the European standards and serial production of the machines was started. In this work, introduction of CNC, machine types and programming techniques will be mentioned.

HISTORY OF CNC MACHINES:

Numerical control idea II. At the end of World War II, A. B. D. was introduced for the production of complex aircraft parts that the air force needed. Because such parts could not be produced with the current production machines. PARSONS CORPORATION and MIT (Massachusetts Instute of Tecnology) have begun collaborative work to achieve this. In 1952, they first realized the first successful work in this area by equipping a CINCINNATTI-HYDROTEL milling machine with Numerical Control. Since then, many machine tool manufacturers have started to manufacture numerical control looms. The first priority was to use vacuum tubes, electric relays and complicated control interfaces on NC machine tools. However, they often had to be repaired and even renewed. Subsequently, miniature electronic tubes and monolithic circuits, which are more useful in NC machine tools, have begun to be used. Rapid developments in computer technology have affected numerical control systems. Nowadays, NC circuit boards have been developed with more advanced integrated circuit components, cheap and reliable hardware is used. It was possible to store programs in memory by using ROM (Read Only Memory) technology. As a result, these systematic developments pioneered the birth of the CNC (Computer Numerical Control). CNC then lathe, drill and so on. has begun to be widely used in machine tools.

CNC WHY?

The basic idea of ​​Computer Numerical Control is the number of machine tools, letters and so on. (MCU), which is executed by means of commands which are encoded in accordance with a certain logic, and which is able to program the part program of the machine control unit (MCU).

In addition to being able to maintain computerized control programs of the computer control unit, it is possible to stop the program at every step of the part production, to make the necessary changes in the program, to resume from the programmed location, and to store it in memory. For this reason, it is enough to load the control unit of the program once. Loan transfers of programs include perforated paper tapes (Punched Tapes), magnetic tapes (Magnetic Tapes) and so on. is carried out via data carriers.

CNC TOOLING MACHINES:

Numerical Control (NC), which will summarize CNC machine tools before CNC machine tools and explain them to CNC machines, is widely applied in all kinds of machine tools used in machining metal and other materials. Some of these looms are:

Lathe Machine (lathe Machine)
Milling Machine (Miling Machine)
Drilling Machine (Drilling Machine)
Hole Growing Machine (Boring Machining)
Grinding Machine

All NC machine tools have their own specific capacity, operational capabilities and a number of characteristic features. For this reason, no processing feature that the counter does not possess can not be done.

Since there is no memory in NC machine tools, block data are read and processed in such machines. During the manufacture of a workpiece, the machine control unit (Machine Control Unit) reads all the data in one block and performs the required operation operations on the loom. After the operations are completed, the next block is passed. This process continues until the end of the program in turn.

Part programs have different numerical and alphanumeric (alpha numeric) values ​​and meanings according to the place and arrangement on the standard paper ribbon.

The physical design and construction of the CNC machine tools are the same as the NC machines. However, a number of functional features that are practically possible and not economical to build on NC machine tools have been added to such machines.

These features are;

The part programs loaded in the workbench can be stored in the memory of the control unit, which is recalled several times.
There is a special power supply that feeds the machine control unit. Even if the energy of the counter is cut off, the data is stored.
The changes to be made on the part program are made easily and easily. The modified program is both operated and stored in memory in its final form.
Some routine operations are described in the program as cycles (Cycles) and are used where necessary. (Hole drilling, hole enlargement, rectangular pocket milling, graduated and conical turning, radius turning, etc.)
Operations that need to be repeated outside a loop on a workpiece are written once in the programming main program and are named Sub Program. During the execution of the main program, these subprograms are invoked where necessary and the operation is completed. An example of this is the ADANA writing program. Here a subprogram for the letter A is written. However, this program is applied at different X distances only by making coordinate descriptions. So the normal program is reduced by 40%.
When a program of a part is written, it is normally handled by the specific type and cutting edge. During the programming, some specific dimensional shifts have to be made taking into account the cutter diameter. However, with the ease of cutter compensation, these shifts are made by the CNC control unit during the operation of the program. If the used cutter is broken and no other cutter of the same diameter can be found, the different cutter allows the program to be continued from the place where the cutter is located. The control unit makes the necessary dimensional shifts according to the diameter of the new cutter.
Thanks to the computer, position changes achieve optimum values ​​in terms of speed and speed. As a result, ideal working conditions are ensured in CNC machine tools. As the diameter of the workpiece continuously changes in the turning operation, the number of revolutions must also change accordingly (Constant Surface Speed). The resultant surface quality and precision are good enough not to be compared to conventional machines (Conventional Machines).
The end result of using the computer in the CNC control unit has the advantage of communicating with many other computers and systems.
It is possible to simulate the part program graphically by means of the image unit (Visual Display Unit) before the part production.
Replacement of cutting tools is done without any manual intervention. Rotary turrets are used for this purpose.

ADVANTAGES OF CNC TOOL COUNTERS:

Some binding molds, gauges, etc. used in conventional benches. The time to set the counter is very short when compared to the elements.
Adjustment, measurement, control, manual movement, etc. the time losses caused by the reason are gone.
Because the human factor is not so effective in manufacturing, serial and precision manufacturing is possible.
Qualification does not need human needs.
Bench operations have a high sensitivity.
The working tempo of the counter is always high and the same.
All kinds of consumption (electricity, labor, materials, etc.) are reduced to a minimum.
All kinds of personal mistakes arising from the manufacturing operator have been removed.
Mold, gauge, template etc. The system is cheaper because it does not benefit from expensive elements.
Storage is needed less often.
Transition to parts manufacturing is faster.
The changes to be made on the part are only made in series in the relevant part of the program and not completely changed. For this reason, manufacturing with CNC machine tools has great flexibility.

DISADVANTAGES OF CNC TOOLING MACHINES:

As with any system, there are some disadvantages as well as the advantages of CNC workbenches and systems. These are;

A detailed manufacturing plan is required.
It requires an expensive investment.
The counter has a high hourly rate.
Compared to conventional benches, they require more rigorous use and maintenance.
Cutting speeds must be high and quality cutters must be used.
Periodical maintenance should be done regularly by specialist and authorized personnel.

CNC USING AREAS OF INDUSTRY:

Today, the part of the industry that we call machining is the most common form of CNC. The fact that today's CNC is born is also caused by the problems encountered in this area. When a three-axis milling machine was first started in 1952, it was perfect because it provided some sort of manufacturing problem for the day. These systems, which are applied to milling machines, are then turned, latched, It was also applied to machine tools. Almost every inland CNC manufactured today is used.

The main areas in which the CNC is used are;

Machining
Fabrication and welding.
Press forward
Inspection and inspection.
Assembly.
Movement of materials.

CNC TOOLING MACHINES:

A- CNC LATHE MACHINES:

Numerically controlled lathe machines generally have two basic axes, X and Z axis. Linear interpolation and circular interpolation are sufficient for many profile turning operations on such machine tools. In addition, the number of revolutions and cutter change, determination of the speed of progress, etc. functions.

CNC lathe machines with larger machining capacities may have more than 3 axes. The third axis can be the axis movement of the machine turret. Especially in industrial type CNC lathes, some design changes have been made in the structural details in order to increase the structural resistance of the machine, to make more precise manufacturing and to remove the chips from the cutting area.

CNC Milling benches are the most capable machines after machining centers in terms of the diversity of their operation capabilities. (Fig. B-2) Such benches have the ability to process 4-5 or more axes, at least 3. All variants of these machines are equipped with Continuous Paht Control. Automatic Tool Change Convenience is another feature. Tool Compensation provides great convenience especially in curved milling operations and molding.

Three dimensional (3 Dimension) workpieces are successfully processed with the ideal profile and optimum specification. The cutters used are hard metal and titanium-coated tips with a radius and high cutting speed. (Figure B-3)

C- CNC PROCESSING CENTERS:

Such CNC machines are equipped with point to point and continuous track control (CPC). Manufacture of workpieces having such complex and numerous operations is carried out in a context.

a- Horizontal machining center
b- Vertical machining center