Structural Layout and Characteristics of CNC Lathes

CNC lathes are also composed of a spindle box, a tool holder, a feed transmission system, a bed, a hydraulic system, a cooling system, a lubrication system, etc., but the feed system of a CNC lathe is essentially different from that of a horizontal lathe in structure. The movement of the spindle of a horizontal lathe is transmitted to the tool holder through a hanging wheel frame, a feed box, and a slide box to achieve longitudinal and transverse feed movements, while CNC lathes use servo motors, which are transmitted to the slide plate and tool holder through a ball screw to achieve Z-direction (longitudinal) and Z-direction (transverse) feed movements. CNC lathes also have various threaded functions, and the motion connection between the spindle rotation and the tool holder movement is controlled by a CNC system. A pulse encoder is installed in the spindle box of a CNC lathe, and the movement of the spindle is transmitted to the pulse encoder through a synchronous toothed belt. When the spindle rotates, the pulse encoder sends a detection pulse signal to the CNC system, so that the rotation of the spindle motor and the cutting feed of the tool holder maintain the motion connection required for processing the thread, that is, when the thread is processed, the spindle rotates once and the tool holder moves the workpiece in the z direction by one lead.

The layout of the spindle, tailstock and other components of the CNC lathe relative to the bed is basically the same as that of the horizontal lathe, while the layout of the tool holder and guide rail has undergone a fundamental change. This is because the layout of the tool holder and guide rail directly affects the application function, structure and appearance of the CNC lathe. In addition, CNC lathes are equipped with closed protective equipment. Layout of bed and guide rail. There are 4 layouts of the relative position of the CNC lathe bed guide rail and the horizontal plane. The horizontal bed has good processability and is convenient for processing the guide rail surface. The horizontal bed equipped with a horizontally equipped knife can increase the movement speed of the tool holder, which can generally be used for the layout of large CNC lathes or small precision CNC lathes. However, the space under the horizontal bed is small, which makes chip removal difficult. From the perspective of structural dimensions, the horizontal placement of the tool holder makes the lateral dimension of the slide longer, thereby increasing the structural dimension in the width direction of the machine tool. The layout mode of the horizontal bed with an obliquely placed slide and equipped with an oblique guide rail protective cover, on the one hand, has the characteristics of good processability of the horizontal bed; on the other hand, the dimension of the machine tool in the width direction is smaller than that of the horizontal equipped slide, and the chip removal is convenient. The layout mode of the horizontal bed with an obliquely placed slide and the inclined bed equipped with an inclined slide is widely used by small and medium-sized CNC lathes. This is because these two layout modes are simple to remove chips, the chips will not accumulate on the guide rail, and it is also convenient to install an automatic chip conveyor; it is easy to operate and easy to install a manipulator to achieve single-machine automation; the machine tool occupies a small area, has a simple and beautiful appearance, and is easy to achieve closed protection.

The tool holder of the CNC lathe is an important part of the machine tool. The tool holder is used to clamp the cutting tool. Therefore, its structure directly affects the cutting power of the machine tool. To a certain extent, the structure and function of the tool holder reflect the planning and manufacturing level of the CNC lathe. With the continuous development of CNC lathes, the tool holder structure has been continuously innovated, but generally speaking, it can be roughly divided into two categories, namely, the row tool holder and the turret tool holder. Some turning centers also use automatic tool changing equipment with tool magazines. The row tool holder is generally used for small CNC lathes. Various tools are placed and clamped on a movable slide, and automatic positioning can be achieved when changing tools. The turret tool holder is also called a turret or a tool table, and has two structural forms: vertical and horizontal. It has a multi-tool position automatic positioning device, and the automatic tool change action of the machine tool is achieved through the rotation, indexing and positioning of the turret head. The turret tool holder should have accurate indexing, reliable positioning, high repeat positioning accuracy, fast indexing speed, and good clamping performance to ensure the high precision and high efficiency of the CNC lathe. Some turret tool holders can not only achieve automatic positioning, but also transmit power. At present, two-axis linkage lathes mostly use 12-station turret tool holders, and there are also 6-station, 8-station, and 10-station turret tool holders. There are two ways to arrange the turret tool holder on the machine tool: one is a turret tool holder for processing disc parts, whose rotary axis is perpendicular to the spindle; the other is a turret tool holder for processing shaft and disc parts, whose rotary axis is parallel to the spindle.

The bed of the four-axis CNC lathe is equipped with two independent slides and turret tool holders, so it is called a double-turret four-axis CNC lathe. During this period, the cutting feed of each tool holder is controlled separately, so the two tool holders can cut different parts of the same workpiece at the same time, which not only expands the processing scale but also improves the processing efficiency. The four-axis CNC lathe has a complex structure and needs to be equipped with a special CNC system to complete the control of the two independent tool holders. It is suitable for processing crankshafts, aircraft parts and other parts with complex shapes and large batches.