How are lathes divided by structure?

There are many kinds of lathes, which can be divided into horizontal lathes, vertical lathes, turret lathes, CNC lathes and special lathes according to different structures and uses. Among all lathes, the horizontal lathe is the most widely used.

Figure 5-20 is the outline of an ordinary horizontal lathe, which is mainly composed of lathe bed, spindle box, feed box, polished rod, lead screw, slide box, tool rest, tailstock and bed legs.

Figure 5-20 CA6 140 Outline of Horizontal Lathe 1- Spindle Box; 2- tool rest; 3- tailstock; 4 beds; 5, 9- Bed legs; 6- naked strip; 7 lead screw; 8- carriage; 10- feed box; 11-the bed of the change gear mechanism (1). It is the basic part of lathe, which is used to connect the main parts and ensure the relative correct position between the parts. The guide rail on the lathe bed is used to guide the tool rest and tailstock to move correctly relative to the headstock.

(2) Spindle box. Built-in spindle and spindle speed change mechanism. The main shaft is a hollow structure, and the long rod can pass through the slender through hole. Usually for short parts, the three-jaw chuck connected to the front end of the spindle is used to clamp the workpiece, as shown in Figure 5-2 1. For slender shaft parts, a tip can be added to the lathe tailstock to improve the rigidity of the workpiece, as shown in Figure 5-22, or the spindle and tailstock of the lathe can be clamped back and forth with the tip, and the power is transmitted by the dial, as shown in Figure 5-23. For the machining of slender shaft workpieces, in order to prevent the workpiece from deforming under the action of cutting force and affecting the machining accuracy, a center frame or a tool rest is often used to improve the rigidity of the workpiece during the machining process, as shown in Figure 5-24. The motion of the motor is transmitted to the spindle box through V-belt transmission, and the spindle gets different rotational speeds through the speed change mechanism. The spindle drives the matching gear to rotate through the transmission gear and transmits the motion to the feed box.

Fig. 5-2 1 three-jaw chuck clamping workpiece

Figure 5-22 Clamping of Three-jaw Chuck and Tip

Figure 5-23 Clamping workpiece with two centers

Fig. 5-24 Application example of center bracket and heel bracket (3) feed box. Built-in speed change mechanism can change the feed speed according to the required feed or pitch adjustment.

(4) polished rod and screw. Transfer the motion of the feed box to the bracket. The lead screw is only used for turning threads, and the polished rod is used for automatic cutting of surfaces other than turning threads.

(5) carriage. It is the control box of lathe machining feed movement. It can convert the rotary motion of the polished rod into the longitudinal or transverse linear motion of the lathe tool, and can also drive the tool holder to rotate the thread by controlling the split nut through the lead screw.

(6) tool rest. Used to clamp the turning tool and make it move longitudinally, transversely or obliquely. It consists of a big carriage (also called a big carriage), a middle slide plate (also called a middle carriage and a horizontal carriage), a turntable, a small slide plate (also called a small carriage) and a square carriage, as shown in Figure 5-25. The big carriage is connected with the carriage box to drive the lathe tool to move longitudinally along the guide rail of the lathe bed. The middle slide plate moves laterally along the guide rail above the big carriage. The turntable is fastened with the middle sliding plate by bolts, and can rotate at any angle in the horizontal plane by loosening the nut. The small skateboard can move a short distance along the guide rail on the turntable. After rotating the turntable to a certain angle, the small skateboard can drive the lathe tool to move obliquely accordingly. The square tool rest is used for clamping turning tools, and four turning tools can be installed at the same time.

(7) tailstock. Its structure is shown in Figure 5-26, and it is installed on the lathe guide rail. Installing a center in the sleeve of the tailstock can be used to support the workpiece, and can also be used to install a drill and reamer to drill and ream the workpiece.

(8) Bed legs. Support the bed and connect with the foundation.

Figure 5-25 Composition of Tool Holder

Figure 5-26 Structure of Tailstock