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Six basic knowledge must be mastered to do a good job of ordinary lathe processing

Abstract: It is necessary to be proficient in the six aspects of ordinary lathe structure, transmission route, movement, processing range, data table and tools, in order to process qualified workpieces.

Ordinary lathe processing is the foundation of metal cutting processing. Through theoretical and practical training, it is necessary to have a deeper understanding and cognition from the following six aspects, and master the relevant operating techniques, in order to lay a solid foundation for CNC machine tool processing. The six aspects of knowledge are: the structure, transmission, movement, processing range, data tables, and tools of ordinary lathes. Let’s take the ordinary lathe CDE6140A x 1000 produced in Dalian as an example.

1. The structure of ordinary lathe
(1) Spindle box. It supports the spindle and drives the workpiece to rotate through fixtures such as three-jaw chucks; there are 4 handles on it, and the two handles cooperate to achieve 24 forward rotation speeds and 12 reverse rotation speeds.
(2) Hanging wheel box. There are 3 shafts and 4 gears in the box; replace these 4 gears and cooperate with the speed change mechanism of the feed box to expand the thread lead and the vertical and horizontal feed.
(3) Feed box. The speed change mechanism of the feed transmission system is transmitted to the slide box via a smooth rod or a lead screw (the two are mutually negated), and there are 4 handles on it.
(4) Slide box. Receive the movement transmitted by the light rod (or lead screw), and realize the vertical and horizontal movement of the turning tool through the handle and the quick-moving mechanism.
(5) Tool holder part. Bed saddles, middle slides, small slides and square tool rests, etc., complete longitudinal, lateral, oblique and curved motions.
(6) Tailstock. Install the guide rail of the bed, which is different from the saddle; after installation, the center supports longer workpieces; install drill chucks, taps or reamers for hole processing.
(7) Bed. Support and connect various parts of the lathe.
(8) The foot of the bed. Support the bed and install the various parts on the bed; adjust the lathe to be level and fix it through the pads and anchor bolts.
(9) Cooling system. The cooling pump sprays the cutting fluid to the cutting area through the cooling pipe and nozzle.

2. Transmission route

3. Travel
When turning on an ordinary lathe, the rotational movement of the workpiece is the main movement; the movement of the turning tool is the feed movement. The main movement speed is high, which consumes the main energy of the lathe; the feed movement speed is low, which ensures the continuous removal of excess material on the workpiece. During the turning movement, the machined surface, the transition surface and the surface to be machined will be formed on the workpiece. The linear speed of the selected point on the main cutting edge of the turning tool is the cutting speed Vc, the feed speed f of the tool movement, and the distance between the machined surface and the surface to be machined is the amount of the tool ap. These three are called the three elements of cutting. .

4. Processing range
Ordinary lathes mainly complete the processing of rotating bodies, specifically: shafts, sleeves, and disk workpieces. The processed parts are: outer cylindrical surface, inner cylindrical surface, end surface, outer conical surface, inner conical surface, inner groove, outer groove, cut off, end groove, inner thread, outer thread, worm, forming surface, etc. Must be matched with the corresponding three elements of cutting tools, measuring tools, processing methods and suitable cutting.

5. Data Table
Ordinary lathe processing is divided into continuous cutting processing and spiral processing. Longitudinal feed meter, 63 feeds are the first data table, the unit mm/r is adjusted through the headstock handle and the feed box handle. The feed is completed according to the table, and it is realized by the handle on the slide box. ; Transverse feed gauge, 63 feeds are the second data table, unit mm/r, adjust the fit through the headstock handle and the feed box handle, complete the feed according to the table, use the on the slide box Handle realization; the other 6 tables are: metric thread (or metric thread) lead table, inch thread lead table, modular thread lead table, diameter pitch thread lead table, enlarged metric thread lead table, plus Large modulus thread lead table; which type of thread to process is compared with the headstock handle and the feed box handle to select the corresponding table lead, and use the opening and closing nut on the slide box to realize thread processing.

6. Knives
The tools of ordinary lathes are divided into welding turning tools and cemented carbide indexable turning tools. According to their use, they are divided into: 90° turning tools, 75° turning tools, 45° turning tools, cutting tools, and grooving tools (outer groove and inner groove) Face groove), through-hole turning tools, blind hole turning tools, external thread turning tools, internal thread turning tools, forming turning tools, etc. What is important is the geometric elements of various turning tools, mainly the 8 angles of the turning tools. On the base plane Pr, there are three angles formed by the projection of the main cutting edge, the projection of the secondary cutting edge and the feed direction: the main deflection angle Kr, the secondary deflection angle Kr’, and the tool nose angle sr. The sum of the three is 180° ; 3 angles on the main orthogonal plane Po: rake angle yo, main back angle ao, wedge angle foot, these three angles are dihedral angles, the sum of the three is 90°; in the sub-orthogonal plane po ‘On the top, the included angle between the secondary back surface and the secondary cutting plane is the secondary relief angle ao’; in the main cutting plane Ps r, the included angle between the main cutting edge and the base surface is the edge inclination angle Xs. We must be well aware of the role of these eight angles, so that we can select or sharpen the workpiece that meets the processing requirements during processing.

A comprehensive understanding of the above 6 aspects of ordinary lathes, combined with process operations such as workpiece clamping, tool clamping, tool setting and trial cutting, will inevitably produce workpieces with qualified accuracy in high efficiency.

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