4 categories of CNC lathe processing
4 common classifications for CNC lathe machining
CNC lathe processing is a high-tech processing method for machining precision metal parts. At present, there are many kinds of CNC lathes, which can be classified according to various different principles. Let's take a look at the four common classifications of CNC lathe processing.
1. Classification by process use
(1) General CNC lathe processing. This kind of CNC lathe processing is the same as the traditional general-purpose lathe processing. There are CNC machining methods such as turning, milling, boring, drilling, grinding machines, etc. The machining possibilities of this type of CNC lathe are similar to those of general-purpose machine tools. The difference is that it can be processed. Parts with complex shapes.
(2) CNC CNC lathe processing. This type of CNC lathe processing is developed on the basis of general CNC lathe processing. It is a CNC lathe with automatic tool changer installed on a general CNC lathe with a tool magazine (capable of holding more than 10-100 tools) and automatic tool changer (also known as multi-step CNC lathe or boring and milling). Class machining centers, customarily referred to as machining centers, make CNC lathe machining further moving toward automation and efficiency.
(3) Multi-axis CNC lathe processing. Some complex-shaped parts cannot be machined with a three-coordinate CNC lathe, such as propellers, aircraft curved surface parts, etc., requiring more than three coordinates of the combined motion to machine the desired shape. Then there is a multi-coordinate CNC lathe machining, which is characterized by a large number of axes controlled by the numerical control device and a complicated lathe structure. The number of coordinate axes usually depends on the machining process requirements of the machined parts.
2. Classification according to the movement track of CNC numerical control lathe
(1) Point control CNC lathe processing. The numerical control device for such CNC lathe machining can only control the moving parts of the lathe to move accurately from one position to another, that is, only the coordinate value of the end point of the stroke is controlled, and no cutting process is performed during the movement, as between the two related points. The speed and route of movement depends on productivity. In order to have the highest possible productivity based on accurate positioning, the movement between the two related points is first to move quickly to a new position, and then to a speed of 1-3, so that it slowly approaches the positioning point, Guarantee its positioning accuracy.
(2) Point linear control CNC lathe processing. When machining such a CNC lathe, it is necessary to control not only the position between the two related points but also the moving speed and route between the two related points. The route is generally composed of straight segments parallel to each axis. The difference between it and the point-controlled CNC lathe machining is that when the moving parts of the lathe move, it can be cut in the direction of one coordinate axis (usually cutting along a 45° oblique line, but not along a straight line of any slope). And its auxiliary function is more than the numerical control lathe of point control, for example, to increase the spindle speed control, cycle feed machining, tool selection and other functions.
(3) Contour control CNC lathe processing. This type of CNC lathe machining control unit can continuously control two or more axes at the same time. The machining not only controls the starting point and the end point, but also controls the speed and position of each point in the whole machining process, so that the CNC lathe can process complex shaped parts that meet the requirements of the drawings. Its auxiliary functions are also relatively complete.
3. Classification according to the control method of the servo system
(1) Open loop control CNC lathe processing. In open loop control, there is no detection feedback device for CNC lathe machining. The flow of the signal from the numerical control device is one-way, so there is no system stability problem. It is also because of the one-way flow of the signal that it does not test the actual position of the moving parts of the CNC lathe, so the machining accuracy of the CNC lathe is not high, and its accuracy mainly depends on the performance of the servo system. The working process is as follows: The input data is distributed by the numerical control device to distribute the command pulse, and the controlled worktable is moved by the servo mechanism (the servo element is often a stepping motor).
(2) Closed-loop control CNC lathe processing. Since the open loop control accuracy does not meet the requirements of precision CNC lathes and large CNC lathes, it is necessary to detect its actual working position. To this end, a detection feedback device is added to the open-loop control CNC lathe to detect the movement of the CNC lathe during processing. The position of the component is matched to the position required by the numerical control device in order to achieve high machining accuracy.
(3) Open-loop compensation type CNC lathe processing. The characteristics of the open-loop control CNC lathe processing and the closed-loop control CNC lathe processing are selectively concentrated, and a hybrid control scheme can be formed. Large CNC lathe machining requires high feed rates and return speeds, and requires considerable precision. If only full-closed control is used, the CNC lathe drive chain and the workbench are all placed in the control link. The factors are very complicated, although the installation and commissioning are often difficult. In order to avoid these contradictions, a hybrid control method can be adopted.
4, according to numerical control device classification
(1) Hard-wire CNC lathe machining (called ordinary CNC, NC). The functions of input, interpolation, and control of such numerical control systems are realized by devices such as integrated circuits or discrete components. In general, CNC lathes have different control circuits, so the versatility of the system is poor. Because it is composed entirely of hardware, the function and flexibility are also poor. Such systems were widely used before the 1970s.
(2) Soft wire CNC lathe processing (also known as computer numerical control or microcomputer numerical control, namely CNC or MNC). Such systems use medium, large-scale and ultra-large-scale integrated circuits to form a CNC device, or a microcomputer and a dedicated integrated chip. The main numerical control functions are almost entirely realized by software. For different CNC lathes, only different software needs to be compiled. It can be implemented, and the hardware is almost universal. Therefore, it is flexible and adaptable, and it is also convenient for mass production. The modular software and hardware improve the quality and reliability of the system. Therefore, modern CNC lathes use CNC devices.
to sum up
The above are four common classifications of CNC lathe machining that must be understood when performing CNC lathe processing. Only by understanding the classification of these CNC lathes can we select a suitable CNC lathe for machining according to the shape requirements of the machined parts.