CNC lathe on metal - characteristics and models

Huge technological opportunities for the production of quality metal parts, characterized by high accuracy of their geometric parameters, provides a modern CNC lathe. Such machines, produced by domestic, as well as foreign manufacturers, are characterized by high efficiency and exceptional reliability.

CNC lathe with turret on 12 positions

Design features of machines

CNC lathes, which are used today in many manufacturing plants, Is modern equipment, that allows to carry out processing of details from metal, characterized by high accuracy. This is ensured by the following design features of such equipment:

• there are almost no gaps in the transmission devices of the drive of such machines;
• all load-bearing elements, components and mechanisms, included in the design of the CNC lathe have high rigidity;
• kinematic equipment circuits are specially designed in this way, to keep them to a minimum, and to keep the number of manual gears to a minimum, which make them up;
• special signaling devices are provided in the design of turning units, who are responsible for feedback;
• such devices are characterized by increased resistance to vibration loads, necessarily arise in the course of their work;
• hydraulic, as well as other parts of the turning equipment are preheated by special systems before starting work, which minimizes the risk of thermal deformation during processing.

Guides are installed on CNC lathes, characterized by increased wear resistance and low coefficient of friction, which is very important to ensure high accuracy of metal turning. Due to these characteristics of the guides of the unit reduces the level of inconsistency in its control system, and all moving mechanisms move according to the set parameters with the maximum accuracy.

Lathe guide units, where rolling elements are provided, as which rollers are mainly used, designed and manufactured as follows, that at work at high speeds and at their intensive heating the coefficient of friction in them remained invariable.

Hardened guide rails of the TRENS-SE-520 machine

Naturally, lathe guides, on which processing of details from metal is carried out at high speeds, should be characterized by increased rigidity. This requirement is met due to this, that the guides are pre-tensioned, which is performed using special regulatory mechanisms. To reduce the friction forces in the guide units of the caliper of the unit and its frame, working on the principle of sliding, they are made on the basis of pairs of materials: wear-resistant quality plastic (usually, fluoroplastic) plus cast iron or steel.

Guides of lathes, equipped with CNC systems, can be located in the horizontal, vertical or inclined planes. Depending on this, the models of units belong to a certain category.

To ensure high rigidity of the bearing elements of CNC turning equipment, they are made in a box shape with mandatory transverse and longitudinal inner ribs. For the manufacture of these elements using casting and welding technologies. If earlier for performance of bearing elements of lathes on metal used only pig-iron or steel, now many foreign manufacturers make columns, beds, as well as sledges of such units made of concrete with the addition of polymers or artificial granite, which gives them high rigidity and increased resistance to vibration loads.

The most important element of any metal cutting equipment, including the turning group, there is a spindle assembly, experiences significant loads during operation. That is why all the base and landing surfaces of such a node, as well as his neck, should be characterized by increased wear resistance. Bearings, which are installed node supports, ensure the accuracy of its rotation, they are subject to increased requirements as they are durable.

Front headstock with machine gun SN-500

On lathes, equipped with a CNC system, spindle assembly is characterized by a more complex design.

This is due to the fact, that in this element set a number of additional: clamping mechanisms for working devices, operating in automatic mode, indicators, responsible for self-diagnostics of equipment and for adaptive control over the processing process. On lathes of this category spindle unit (along the axis of its rotation) can be located horizontally, as well as in the vertical plane.

Marking of turning equipment with CNC

The system of automated control of lathes can be organized according to three main schemes.

Contour

This scheme involves programming the trajectory of movement (curvilinear including) working tool and control over the correctness of this procedure.

Positional

When implementing such a scheme, the coordinates of the points are programmed, in which the working tool should appear after performance of certain technological operation.

Adaptive

This scheme involves a combination of the principles of the previous two.

On marking of domestic turning equipment, equipped with CNC, it is quite simple to determine the category of such a device.

Alphanumeric designation, standing at the end of the marking, just points to that, according to which system in this machine numerical program control is organized:

• F1 - machines, in which the work tool moves at predetermined coordinates, at the same time digital indication is provided in them;
• F2 - models, where the movement of the tool is realized according to the positional scheme;
• F3 - turning equipment, in which the contour scheme of control of the movement of the tool is implemented;
• F4 - models of CNC lathes with adaptive (universal) management systems.

Marking of CNC lathes

In the marking of some models of lathes with CNC can be found alphanumeric designation C1-C5, which speaks for itself, that such equipment has special technological capabilities. In particular, models, in the marking of which there are symbols C1 and C2, have a low feed limit and a small range of their regulation. And here are the units, marked with C3 symbols, C4 and C5T, vice versa, have the increased range of giving and differ in wide possibilities on their regulation.

Due to its advanced capabilities of the machine model, in whose marking there are symbols C4 and C5, can be used to efficiently perform many technological operations, example, cutting external and internal threads, processing of preparations, having a cylindrical, conical and shaped shape, including stepped. It is worth noting, that can be processed on such mills as external, and internal surfaces, differing in complexity of the configuration.

Features of machine tool programming

To use lathes, equipped with a CNC system, was most effective, it is necessary to carefully develop the technological process of processing, and compile a program, which will control the operation of the equipment. In addressing these issues, a number of important parameters need to be considered: the need to link equipment coordinate systems, the location of the workpiece and the starting position of the working tool with its subsequent movements, which he must automatically perform in the process.

The principle of numerical software control of a lathe

When compiling a program for such a machine is taken into account, that the working tool moves along the coordinate axes of the workpiece, which is stationary. What is important, it moves in the rectilinear direction of the axes, parallel axes of the workpiece.

The essence of programming a separate technological operation, performed on such a machine, is, that a computer program describes the route, which must pass the cutting tool, to form a part with specified geometric parameters.

The following algorithm is followed when compiling such a program.

• The technological process is divided into three stages: draft, finishing and finishing. To increase productivity and reduce their complexity, roughing and finishing operations are trying to combine.
• To minimize errors in fixing and basing the workpiece, its technological and design bases are combined according to certain rules.
• It is desirable to complete turning of a detail with the minimum quantity of its installations.
• It is necessary to follow a rational approach to the processing of workpieces. It assumes, example, turning parts of cylindrical and conical workpieces with low rigidity only after that, how the processing of their plots is performed, characterized by sufficient rigidity.

In the technological process, which involves the use of lathes for machining, equipped with CNC, a separate operation means processing, which is performed on one machine. In this case, such operations can be divided into separate transitions, are divided into independent passages.

Transitions, which can perform a lathe, equipped with CNC, are divided into positional, elementary, instrumental and auxiliary.

There are certain rules for developing sequence programs with the workpiece, adhering to which you can ensure the high quality of the finished product. In accordance with these rules, the following parameters are set in the computer program for the lathe: number of transitions and passes, total number of installations, type of processing, which is subjected to procurement, the number of cutting elements and their sizes. If the technical capabilities of the equipment allow, then all tools are desirable, who participate in the work, place in one tool holder.

SAUTER turret for CNC lathe

But not always tool holders of the unit allow to establish in them all elements, involved in processing. In such cases, not very rare, in the control program provide for the suspension of work, which is required to replace the tool. in addition, when using such machines, you can break the machining process into several parts, so as not to stop it to replace the tool. Most models of lathes with CNC systems are equipped with tool holders, in which you can fix a limited set of cutting tools. In most cases, tools are used to operate such devices, equipped with multifaceted cutting inserts. To quickly put it in order, if the cutting edge is worn, just turn the plate and continue working.

Among the most common tools, which are equipped with CNC lathes, the following can be noted: for boring - cutters, cutting plates which are welded or fixed mechanically; for threading - triangular prefabricated cutters; for processing of openings and performance of undercutting - rhombic cutters with hard-alloy plates. All tools are installed in the tool holder in that sequence, in which they participate in the processing. The starting point, specified in the computer control program, there is a rounding at the top of the cutter or its top.

CNC lathe DMTG model CKE6150Z

Drives and auxiliary devices

Different types of electric motors are used in low and high power CNC lathes, which serve as the drive for the main movement. In the first case, DC motors are mainly used, in the second - variable. Domestic producers, producing machines of this category, equip them with asynchronous electric motors with four poles, which are able to work smoothly even in the most difficult conditions: in the presence of oil particles in the ambient atmosphere, metal dust and fine shavings. Not afraid of such electric motors and critical overloads, which they successfully tolerate.

D250x550 CNC table lathe drive mechanism

Synchronous and asynchronous electric motors are used to drive the feed mechanism of CNC lathes, but most often use the first type of engine, equipped with feedback indicators, brake elements, as well as magnets, made of rare earth chemical elements. Digital converters are used in the electrical circuit of lathes to control such motors.

In that case, if an asynchronous motor is installed on the equipment, to control them you need a frequency converter, assembled on microprocessors. When using such electric motors, a special programmer is installed on the machines, equipped with a graphic or digital type screen.

Trens lathe control panel

On lathes, controlled by computer programs, be sure to install accessories, which include:

• loading mechanisms;
• mechanisms, providing a clamp of preparation;
• lubricating devices;
• devices, designed for chip cleaning, which is formed during processing;
• mechanisms, designed for quick tool changes.

Unlike similar devices, used on conventional machines, these devices are characterized by high performance and reliability.

The most popular models of machines

One of the most popular models of the lathe, equipped with a CNC system, which is actively used by domestic manufacturers, is 16A20F3. As a control system on such machines the system Electronics НЦ-31 or 2Р-22 is established. On machines of this model the frequency-regulated motor of asynchronous type is established, automatic head on 6-12 positions, spindle assembly with three speeds of rotation, drive and sensor, which are used for threading.

The lathe of the 16A20F3 series, designed for semi-automatic processing of metal parts

Another popular model is the MK6713S5 machine, belonging to the category of high-precision cartridge equipment. In the design of this lathe should be distinguished cross-shaped caliper and spindle, in the holder of which you can lock six tools at once. Using this lathe, equipped with CNC system, you can effectively perform the following work on the metal: cut a thread, sharpen and grind workpieces, to carry out processing of details of disk type.

Presented on the domestic market and similar lathes of foreign models to the most popular of which are the following.

TRENS SBL300 CNC - CNC turning equipment of two-spindle type. The machine of this model differs in wide functionality, in addition to standard turning operations on metal, on it it is possible to carry out processing of various shafts, flanges, details of complex configuration, perform milling operations. The spindle assembly of this machine is equipped with radial thrust bearings, which allows you to work on it at high speeds and get products, of high quality. Software control of the machine involves rigid binding of its coordinate system to the geometry of the cutting tool using a special adjustment system, working on the contact circuit. Due to this, there is no need for a clear orientation of the working tool relative to the workpiece.

ROXM counter spindle, mounted on TRENS lathes

Vturn-V760 - a machine with a vertical arrangement of the spindle assembly, as constructive features of which the following are allocated: eight-position working head, twelve-inch hydraulic cartridge, device for removing chips of conveyor type, automated lubricated mechanism, cutter holders of different types. in addition, the machine can be equipped with additional technological devices, significantly expand its functionality. For ease of management, which is provided by the Fanuc 0i-T system, the lathe of this model is equipped with the color monitor of graphic type.

Spindle and turret tool head of the Vturn-760 vertical lathe

LS360 CNC (manufacturer MetalMaster) - lathe, the frame of which is located in an inclined plane. On the machine of this model, where the Siemens 808D control system is installed, it is possible to process details, made of ordinary and stainless steel, copper and aluminum alloys. Among the design features of this unit is a reliable hydraulic system from the Japanese company Yuken, eight-position working head, pulse lubrication system, operating in automatic mode.

Naturally, products of other foreign manufacturers are widely represented on the domestic market, among which everyone will be able to choose exactly that lathe, which will satisfy him in all respects.