The structure and operating procedures of ordinary lathes

Ⅰ. Structural Analysis of Ordinary Lathes: Precision Systems Each Performing their own Duties

The structure of a common lathe may seem complex, but in fact, each component performs its own function and works closely together to complete the processing task. Its main components include the headstock, feed box, slide box, tool rest, tailstock, smooth screw, lead screw and bed.

(1) Spindle Box: The "Transfer Station" of Power

The headstock, also known as the headstock, is the power core of a common lathe. Its main task is to transfer the rotational motion transmitted by the main motor through a series of speed-changing mechanisms, enabling the main shaft to achieve the required forward and reverse rotation speeds at different speeds. Meanwhile, the spindle box will also distribute part of the power to the feed box to provide power support for the subsequent feed motion. As a key component of a lathe, the smoothness of the spindle's operation on the bearings directly affects the processing quality of the workpiece. Once the rotational accuracy of the spindle decreases, the value of the machine tool will also be greatly reduced.

(2) Feed Box: The "Conductor" of Feed Motion

The feed box, also known as the tool path box, is a key component that controls the feed motion. The feed box is equipped with a variable-speed mechanism for the feed motion. By adjusting these variable-speed mechanisms, the required feed rate or pitch can be obtained. Subsequently, the motion is transmitted to the tool rest through the smooth screw or lead screw, thereby achieving the cutting process.

(3) Lead Screw and Smooth Screw: The "Bridge" for Motion Transmission

The lead screw and the light screw are important components connecting the feed box and the slide box, responsible for transmitting the motion and power of the feed box to the slide box. Among them, the lead screw is specifically designed for turning various threads. When turning other surfaces of the workpiece, usually only the smooth screw is used, not the lead screw.

(4) Slide box: The "control room" for Tool Rest Movement The slide box is the control box for the feed movement of the lathe. It is equipped with a mechanism that converts the rotational motion of the lead screw and the smooth screw into the linear motion of the tool rest. Through the drive of the smooth bar, the longitudinal feed motion, lateral feed motion and rapid movement of the tool rest can be achieved. When the lead screw drives the tool rest to move longitudinally in a straight line, threads can be turned. (V) Tool Rest: The "Habitat" of Knives

(5)The tool rest component is composed of several layers of tool rests. Its function is to hold the tool and enable it to perform longitudinal, transverse or oblique feed movements to meet different processing requirements.

(6) Tailstock: A "good helper" for Workpieces

The main functions of the tailstock are twofold. One is to install the rear center for positioning and support, providing stable support for the workpiece. Second, drill bits, reamers and other hole processing tools can be installed to perform hole processing operations.

(7) Bed: The "Cornerstone" of the Lathe

The bed is the fundamental component of a common lathe. It supports all the main parts of the lathe, ensuring that these parts maintain accurate relative positions during operation and providing a stable foundation for the entire processing procedure.

Ⅱ. Operating Procedures for Ordinary Lathes: Ensuring Safety and Efficiency

The operation of ordinary lathes involves certain risks, so it is essential to strictly follow the operating procedures to ensure the safety of the operators and the quality of the processing.

(Ⅰ) Inspection before driving

1. Add appropriate lubricating grease according to the machine tool lubrication chart to ensure that all components are fully lubricated and reduce wear.

2. Carefully inspect all electrical facilities, handles, transmission parts, protective and limit devices to ensure they are complete, reliable, flexible and easy to use.

3. Set each gear handle to the zero position and check whether the tightness of the belt meets the requirements. Both too loose and too tight belts will affect the normal operation of the machine tool.

4. Metal objects must not be placed directly on the bed surface to avoid damaging the accuracy of the bed surface. The workpieces to be processed should be thoroughly cleaned of mud and sand to prevent them from falling into the drag plate and damaging the guide rails.

5. Before clamping the workpiece, an empty run test must be conducted. Only after confirming that everything is normal can the workpiece be installed for processing.

(Ⅱ) Operating Procedures

1.After installing the workpiece, start the lubricating oil pump first to make the oil pressure reach the specified value of the machine tool, and then start the machine tool.

2.When adjusting the exchange gear frame, the power supply must be cut off. After adjustment, all bolts must be tightened, the wrench should be removed in time, and the workpiece should be disconnected for a test run to ensure safety.

3.After loading and unloading the workpieces, the chuck wrench and the floating objects of the workpieces should be removed immediately to prevent accidents during the operation of the machine tool.

4. According to the processing requirements, adjust the tailstock, rocker, etc. of the machine tool to the appropriate positions and tighten or clamp them.

5. The workpiece, cutting tool and fixture must be firmly clamped. The floating power device must extend the guide part into the workpiece before starting the machine tool.

6. When using a center rest or tool rest, the center must be properly adjusted, and there should be good lubrication and support contact surfaces to ensure the stability of the processing.

When processing long materials, the protruding part behind the spindle should not be too long. If it is too long, a material support frame should be installed and a danger sign should be hung to prevent safety accidents.

8. When entering the workpiece, the tool should approach it slowly to avoid impact. The speed of the drag board moving back and forth should be uniform. When changing tools, the tool and the workpiece must be kept at an appropriate distance to prevent collision.

9. The turning tool for cutting must be tightened. The overhang length of the turning tool generally should not exceed 2.5 times the thickness of the tool to ensure the stability of the cutting.

10.When processing eccentric parts, there must be appropriate counterweights to balance the center of gravity of the chuck, and the vehicle speed should be appropriate to prevent excessive vibration of the machine tool due to eccentricity.

11. For workpieces that extend beyond the machine body, protective measures must be taken to prevent them from being thrown out and injuring people.

12. Tool setting adjustment must be slow. When the tool tip is 40 to 60 millimeters away from the workpiece processing area, manual or working feed should be used instead. Rapid feed and direct cutting are not allowed to avoid damaging the tool or the workpiece.

13.When polishing the workpiece with a file, the tool rest should be retracted to a safe position. The operator should face the chuck, with the right hand in front and the left hand behind. Workpieces with keyways or square holes on the surface are prohibited from being processed with files to prevent danger.

14.When polishing the outer circle of a workpiece with sandpaper, the operator should follow the posture specified above, holding both ends of the sandpaper with both hands for polishing. Do not use your fingers to hold the sandpaper to grind the inner hole to avoid injury.

15.When the tool feed is automatic, the small tool rest should be adjusted to be level with the base to prevent the base from hitting the chuck.

16.When cutting large or heavy parts or materials, sufficient machining allowance should be left to prevent the workpiece from falling and getting damaged during the cutting process.

(Ⅲ) Parking operation

1.After processing is completed, cut off the power supply first and then remove the workpiece.

2. Lower all the handles to the zero position, count the tools and equipment, and clean the machine tool and its surrounding environment.

3. Check the condition of all protective devices to ensure they are intact and ready for the next use.

(Ⅳ) Precautions during operation

1. Non-staff members are strictly prohibited from operating the machine tool to prevent safety accidents caused by misoperation.

2. It is strictly prohibited to touch the cutting tools, rotating parts of the machine tool or rotating workpieces during the operation of the machine tool to avoid being caught and injured.

3. Do not use the emergency stop button at will. In case of an emergency, after using this button to stop the machine, it should be rechecked according to the regulations before starting the machine tool. Only after confirming that there are no errors can it be started again.

4. It is not allowed to move the guide rail surface, lead screw, smooth rod, etc. of the machine bed. Unless otherwise specified, it is strictly forbidden to operate the handle with feet instead of hands to avoid damaging the machine tool components or causing accidents.

5. For parts with sand holes, shrinkage cavities or keyways on the inner wall, it is not allowed to use a triangular scraper to cut the inner hole to prevent the tool from breaking and injuring people.

6. The pressure of the compressed air or liquid for pneumatic or hydraulic chucks must reach the specified value before they can be used to ensure the clamping force of the chucks.

7.When turning slender workpieces, if the overhang in front of the headstock exceeds four times the diameter, it should be supported by a center rest, a center rest or a tool rest as per the process requirements. When extending behind the head of the bed, protective devices and warning signs should be added to ensure safety.