This article is about the rules and techniques for controlling a lathe. Your safety depends on compliance with the rules for working on a lathe. A confident lathe control technique affects the quality of the product and the productivity of controlled work. If your goal is to learn more about it, follow the guide.
Step 1. Checking the lathe before starting
Before starting the lathe, tolerance control must be carried out, namely:
During shift work in production, the shifter who hands over the lathe to you is obliged to report the problems noticed in it (orally, in writing, or by phone). The absence of comments implies that the lathe is in good condition.
In production, the repair service is engaged in troubleshooting the lathe. The machine operator only has to inform them of the occurrence of a malfunction.
Before connecting the lathe machine to the power supply, make sure:
- That there is no warning on the machine, such as (do not turn on the lathe in repair)
- Covers, doors, hatches that cover the main parts, and lathe mechanisms must be closed.
- The control knobs for the spindle feeds, and the uterine nut must be in the neutral position.
- The cooling supply is off, and the liquid supply nozzles are directed downwards.
- RPMs and feed steps are set to what you want them to be when the spindle starts up.
- The part you installed to be processed must be securely fastened.
- The floor near the lathe should be clean, and there should be no unnecessary objects under your feet.
- Turner’s clothing should be neat (no hanging flaps).
- Do not forget the key in the chuck (always take care to remove the key from the chuck).
Having completed the tolerance control: we turn on the main switch of the lathe, and additional switches, if any. Next is the lubrication of the lathe.
Step 2. Spindle control
Before starting the spindle or main engine, be sure to make sure that the rotating elements on it, in particular the chuck, will not be obstructed by rotation from the stationary parts of the machine. A particular danger when starting the spindle at high speeds is thin bar stock protruding beyond its limits.
This also applies to parts of large diameters with a significant overhang from the cartridge and the center of the tailstock not pressed from the other end.
As already mentioned in the first lesson “The device of the lathe”, the spindle speed settings are made by setting the switches and levers on its nodes to a certain position according to the table located on the machine.
Step 3. Lathe Feed Control
Manual control of the feed of the machine means the feed of the tool for small lengths (during processing, settings, eyeliners).
It control allows you to quickly lead, interrupt and resume feed, as well as instantly change its speed (depending on changing conditions and processing situations). Manual feed in the longitudinal direction is driven by a handwheel with or without a horizontal handle. Turning the flywheel counterclockwise moves the caliper to the left, and clockwise to the right.
The longitudinal movement of the caliper on the lathe is carried out by means of a rack and pinion gear. Such gears have backlashes or gaps in the contacts of parts and their mechanisms.
Step 4. Managing mechanical feeds
Mechanical feeds are driven by a drive shaft, and they are controlled by a 4-position switch handle. The direction of movement of the switch handle corresponds to the direction of movement of the tool on the caliper.
Before turning on the mechanical feed in any direction, you need to visually make sure that there are no obstacles at all points of the caliper from other parts of the machine, especially rotating ones. A frequent oversight of beginner turners is an attempt to bring the caliper closer to the chuck with the sled shifted to the right, which leads to a collision. Therefore, the free movement of the caliper should be checked in advance.
Step 5. Accelerated lathe feed
On machines with rapid feed, the following requirements must be observed:
- To prevent accidental pressing of the rapid feed button, the feed selector lever must be operated by applying a hand from the side, but not from above.
- Before starting the rapid feed, you need to make sure that there are no obstacles to advance at any points on the support, including the tool, in the direction where you want to feed.
- Rapid traverse cannot be used for short movements, especially when approaching rotating elements.
- Heavy calipers of medium machine tools have inertia, which is enhanced by accelerated feed by its drive mechanism.
There are combined feeds of lathes (by type of drive, by directions). Such lathes are used for processing irresponsible cones (irrelevant chamfers) and shaped surfaces.
For threading, the caliper is fed by closing the mother nut with the lead screw. Turning the mother nut on and off is done with a separate lever. The spindle and lead screw rotate synchronously regardless of the set thread pitch. Changing the direction of rotation of the spindle leads to a change in the direction of movement of the caliper. Also, changing the spindle speed leads to a change in the speed of movement of the caliper.
Lathe tailstock control
Fixation by the tailstock of the lathe is carried out by a lever, as the working stroke of which increases the clamping force. When machining with heavy loads, requiring a better fixation of the tailstock, the impact on the lever should be vigorous. It is important not to confuse the resistance of the lever when clamping with its hard stop at the end of the stroke.
In the process of work, any turner will sooner or later have to face unforeseen situations when working on a lathe.
Possible situations when working on a lathe:
- Spontaneous stop of the lathe during operation, during a power outage or mechanical failure;
- Collision of rotating elements with caliper elements;
- Turning the part in the chuck;
- Pulling the part out of the clamping fixtures of the lathe;
Lathe malfunctions can be expressed in extraneous noise, the smell of burning electrical wiring, etc.
So, what is a lathe?
A lathe is, among other things, a shaper, cutter, sander, and deformer. It takes attachments for specialty jobs and creates results precise enough to be used in other pieces of machinery.