There are many specifications of CNC machine tools and classification methods are different. Generally, depending on the function and the structure, press below 4 principles are classified
1. Classification of the movement control trajectory of the machine tool
⑴ Control of the controlled CNC machine requires that the control component of the control machine from one point to another specific positioning. not relevant. In order to obtain a rapid and precise positioning, the movement of the displacement between two points generally moves quickly, then slowly approaches the positioning point to ensure the positioning accuracy, as shown in the figure below, which is the trajectory of Movement controlled by points.
Machine-tools with points control functions include CNC drilling machines, CNC and CNC Punch milling machines. With the development of CNC technology and the decrease in the price of CNC systems, CNC systems which are simply controlled by points control are rare.
机 Right control CNC Machine Tool Control Machine Tools CNC is also called parallel control CNC machine. points, but but, but, but, the route (trajectory), but but ,,,,,,, contact details of the machine tool, which means that there is only one axis of coordinates controlled at the same time (that is to say that it is not necessary to have a computer function of ‘Interpolation in the CNC system). Its machine tools with linear control functions mainly include relatively simple CNC towers, CNC milling machines, CNC grinding machines, etc. The CNC system of this machine tool is also called a linear control CNC system. Likewise, CNC machine tools simply used in linear control are rare.
机 Control CNC CNC Machine Tool
CNC control machines Control Control are also called continuous control of CNC machines. In order to respond to the relative movement trajectory of the contour of the tool to meet the requirements of the part processing outline, movement control and speed control of each coordinate movement must be coordinated with precise the proportional relationship specified. Therefore, in this type of control method, the CNC device is necessary to have an interpolation computer function. The SO-SALLED interpolation is the basic data entered according to the program (such as the coordinate of the end point of the line, the coordinates of the final point of the arc, and the coordinates of the round heart or the radius). At the same time, the impulse controls the axis controller on each axis of coordinates according to the results of the calculation, thus controlling the linked displacement of each axis of coordinates and the outline of the requirements. Treatment of the contour control trajectory. This type of machine tools mainly includes CNC towers, CNC milling machines, CNC cutting machine ice cream, treatment centers, etc. The corresponding CNC system is called the CNC system for control of the outline.
① Lighting in two axes: it is mainly used for the curve of the rotary surface of the treatment of the CNC tour or the treatment curve of the CNC machine.
② Two-Axis and Half Links: it is mainly used for controlling machine tools above the three axes.
③ Liaison link with three axes: generally divided into two categories, one is the three linear coordinate trees of X / Y / Z, and even more for CNC milling machines, treatment centers, etc. The other is that in addition to controlling the two straight coordinates in X / Y / Z at the same time, it also controls the axis of rotation coordinates around one of the outline coordinates. For example, in addition to the two trees of linear coordinates of vertical axis (axis Z) and horizontal (axis X), it must also control the bond of the pin (axis C) around the Z axis at the same time.
④ Four axes line: at the same time, control X / Y / Z three linear coordinates with an axis of rotary coordinates.
⑤ Five -axis link: with the exception of the simultaneous control of X / Y / Z, the coordinates axis of the three coordinates of the nursery line. At the same time, the two coordinated trees in A, B and C, which are turned around these trees of straight coordinates, to form a two -axis link at the same time. space. For example, the control tool is controlled at the same time around the X axis and the Y axis, so that the tool still maintains and the surface of the treated outline of the treated surface in the direction of its point cutting to ensure the softness of the softness of the curved surface treatment, improve treatment accuracy and treatment of treatment and treatment efficiency, reduce the roughness of the treatment surface.
two, Classified by Servro Control
机 The machine tools training driver such as CNC machines is open, that is to say that there is no detection feedback device. Changed whenever the instruction pulse signal is modified. The output of the Power Instructions signal by the CNC system controls the drive circuit through the pulse dispenser. Therefore, the largest characteristic of this control method is practical control, simple structure and cheap price. The flow of the instruction signal emitted by the CNC system is unidirectional, so there is no problem of stability of the control system. The first CNC machines used this control method, but the failure rate was relatively high. Especially in our country, CNC NC systems and the many reconstructions of the old equipment adopt this control method. In addition, this control method can be configured with a single chip micro-computer or a single card machine as a CNC device to reduce the price of the whole system.
床 The driver of the CNC machines supply reader such as closed control machines works according to a closed feedback control method. Back. part to eliminate the movement error. The installation site of the position feedback detection element is different from the feedback device used, and it is divided into two control methods: Full-Closed and Semi-Clos.
three, Classification according to the functional level of the CNC system
① Completely closed control Its location feedback device uses a linear movement detection element (currently the raster rule is generally used), which is installed in the machine’s seat parts part, that is to say that online displacement Right of the machine-tool coordinates can be directly detected. Comment, the entire mechanical engine transmission chain to the saddle of the tool-tool can be eliminated. However, because in the entire control cycle, the friction characteristics, the rigidity and the gaps of many mechanical transmission bonds are non -linear, and the dynamic response time of the entire mechanical transmission chain is very large compared to at electrical response time. This brings great difficulties to the stability correction of the entire closed system, and the design and adjustment of the system are also quite complicated.
② Semi-fermized control As the figure shows, position feedback uses corner detection elements (currently the coder is mainly used) and is directly installed on the servomotor or the end of the screw. Since most mechanical transmission links are not included in the closed system circuit of the system, it is called to obtain more stable control characteristics. Mechanical transmission errors such as screws cannot be corrected at any time by feedback, but fixed compensation methods of the software can be used to improve their accuracy appropriately. Currently, most CNC machine tools use semi-closed control methods
(3) Hybrid control CNC tools concentrate the characteristics of the above control method, which can form a hybrid control diagram. As mentioned earlier, due to the good stability, low cost and poor precision of the opening control method and poor precision, the stability of the complete closed loop is bad, therefore to compensate for each other To meet the control requirements of certain machine tools, hybrid control must be adopted. Use more than two ways: more type of loop compensation and semi-closed loop compensation type
Four, Classification according to the functional level of the CNC system
Depending on the functional level of the CNC system, the CNC system is generally divided into three categories: low, medium and high. This classification method is used more in my country. The limits of the three low, medium and high equipment are relative, and the division standards will be different at different periods. In terms of current development level, according to certain functions and indicators, various types of CNC systems can be divided into three categories: low, medium and high. Among them, the high environment and gradation are generally called CNC Full-Feriaux or standard CNC.
⑴ Metal cutting classes refer to CNC machine tools which use various cutting processes such as car, milling, collision, hinge, drilling, grinding and planing. It can be divided into two following categories.
① Ordinary CNC machines such as CNC towers, CNC milling machines, CNC grinding machines, etc.
② The main characteristic of the treatment center is that the tool library with an automatic knife change mechanism is once. After loading, by automatic replacement of various tools, processing various strike processes (car), hinges, forests and attack threads on each room treatment surface on the same machine, such as (construction / milling) central central treatment, transfer centers, drilling centers, etc.
The metal molding class refers to CNC machine tools with compression, punching, press, pull, shoot, etc., and CNC pressure machines commonly used, CNC folding machines, CNC folding machines, compressors CNC rotary, etc.
(3) Special treatment categories include CNC Electro-Spark cutting machines, CNC electro molding machines, CNC flame cutting machines, CNC laser machining machines, etc.
类 The measurement and drawing categories mainly include measuring instruments with three coordinates, CNC -To -Kife instruments, CNC drawers, etc.
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