Modern trends in the integration of combined machining have meant that grinding can also be carried out on lathes. When quality problems come to the fore, attention is always paid to the finishing process, which is called grinding - performing mechanical action in several passes to reduce initial errors. It is impossible to carry out finishing using a turning tool with the same quality as when using grinding heads due to the rounding of the cutting edge. Also, do not forget that vibration may occur on a lathe at small feeds, which will lead to errors. For this reason, even with the emergence of new materials that can withstand heavy impact for a long time and not change their shape, grinding remains the main method used to obtain a surface of a high class of roughness.
The production of rotating bodies on lathes has been carried out over the past several decades. As a rule, grinding was carried out using other equipment. This moment was determined by the following technological process:
Such a technological process determines an increase in costs due to the installation of a special machine for finishing processing. When creating a large batch of products, purchasing a grinding machine pays off, but in small-scale production, its purchase will lead to an increase in the cost of one product. A way out of the situation is the use of special grinding heads, which can also be used to obtain a surface with a high roughness class.
Grinding heads are a special design that is used to significantly expand the capabilities of a turning group machine. This mechanism conventionally refers to equipment. Design features include:
The design is quite simple. When considering it, it is worth paying attention to the type of frame. This is due to the fact that only a certain type of bed can be used instead of a tool holder for a certain model of lathe.
Using the equipment in question, steel and cast iron can undergo finishing on a lathe. In this case, it is possible to achieve the same roughness index as when using cylindrical grinding equipment. Model 200 differs from the considered power of the installed electric motor and the maximum diametrical dimensions of the installed circles. Similarly, the cost of producing parts can be reduced by increasing the versatility of the equipment used. At the same time, we note that the equipment is suitable for old and new turning equipment, as it has universal application.
Checking lathes for geometric and technological accuracy 
Preparing the foundation for lathes Dividing heads for milling machines
Wood sanders are one of the main production machines used in the woodworking industry. The equipment is intended for grinding wooden surfaces of blanks, parts of wooden structures and finished products made during the production process. Modern models presented in the catalog are powerful, compact and versatile devices capable of operating in long-term modes. Depending on the technical specifications, the mechanisms are capable of processing workpieces and products of any shape, including performing a number of other technological operations. This technique can be used to trim and grind the edges of finished products.
According to the nature of the operations performed and depending on production needs, all units can be divided into the following types:
surface grinding equipment, drum type;
units for internal and external grinding, installations for working with edges;
machines for external grinding of spherical and round surfaces, belt and disc-belt machines.
Each type of equipment is designed for a specific technological cycle. Changeover of mechanisms is carried out quickly and easily, thanks to a wide range of devices and equipment.
In the catalog you can see a wide variety of models, differing in size, compactness of the mechanism, and power of the electrical installation. The intended purpose of the mechanisms determines the location and type of installation. Large installations designed for mass production have a massive base and are installed on the floor. Small desktop-type products are intended for domestic use and work in workshops.
Most models are equipped with additional devices and devices that ensure grinding accuracy and compliance with the required dimensions. Angle stops, sanding belt or disc significantly increase the range of production use of this equipment. equipped with powerful asynchronous motors with high torque and shaft speed control devices.
Each machine is covered by warranty service, which significantly increases the operational life of the mechanisms. All machines comply with electrical safety standards and have the necessary compliance certificates.
Specialists from machine-building enterprises who attend foreign exhibitions of metalworking equipment are witnesses to the success of such a technical solution as the combination of several technological operations and even processes on one machine, and in various combinations. It seems that there are no operations left in production, even the most difficult to combine, that would not be combined in an attempt to increase the accuracy and productivity of processing by reducing the number of reinstallations.
This idea, which originated a long time ago and was actually implemented in 1992 by Emag, which presented an inverted vertical lathe at the METAV92 exhibition, became a real material force just a few years later. Proof of this is over 5,000 machines of this configuration, sold to various factories, mainly automobile and tractor ones. On its basis, it became possible to combine turning, predominantly hard turning, for difficult-to-cut steels and alloys with a hardness of over 45HRC, with abrasive processing, also for the first time in the world, carried out in 1998 by the same company Emag, but already together with the company Reinecker, which was part of it, on a machine Maud. VSC250DS (Fig. 1).
When the benefits are obvious
Since then, the advantages of this arrangement have become apparent to many other German, Swiss and Italian companies producing both lathes and grinding machines. For turning centers, they consist in the possibility of using dry and hard turning, and in some cases, grinding in one setup parts of small diameter (up to 400 mm, only the G 250 machine from Index has a processing diameter of 590 mm), but of a fairly large length. There are many such parts such as gears and various disks found in the automotive industry.
In addition, processing productivity is increased, since the allowance for grinding after turning can be increased to several hundredths of a millimeter (in reality it usually reaches several tenths), and its accuracy, which is ultimately determined by grinding. To date, such combined machines are produced by several companies, mainly German, whose main field of activity is, as shown in Table 1, the production of not only turning centers (Emag, Index, Weisser), but also grinding machines (Junker, Buderus Schleifmaschinen, Schaudt Mikrosa BWF). Their cost varies widely and is determined, first of all, by the layout, design and configuration.
The EMO 2003 exhibition showed that interest in combined machines for hard turning and grinding is growing. Along with the companies Emag, Index, Weisser, Buderus, Schaudt Mikrosa BWF, which previously exhibited machines for combined turning and grinding, similar products were demonstrated by other manufacturers of machine tool equipment. For example, the Tacchella company (Italy) showed a prototype of the Concept cylindrical grinding machine, equipped with an 8-position turret with fixed tools (Fig. 2), and the Meccanodora company (Italy) showed a serial Futura machine for hard turning and milling, as well as external and internal grinding transmission parts. The Stratos M, first shown by Schaudt Mikrosa BWF at the EMO 2001 exhibition, was additionally equipped with an 8-position turret.
Combined processing
For parts passing through a turning-grinding center, for example, electric motor shafts, in most cases it is not necessary to grind all surfaces - mainly only the supporting ones or the most worn ones. For the rest, turning is quite enough. In such cases, when tight dimensional tolerances and high surface quality are required only in certain areas of the part, the use of lathes with grinding capabilities is fully justified, especially since processing on them occurs in one setup. If the workpiece has many steps, most of which are subject to grinding, then it must be processed on a grinding machine with the ability to turn.
Thus, processing is carried out on a grinding machine if:
A lathe is used for processing when:
Many parts have both requirements, so combining grinding with hard turning on one machine increases its flexibility and allows each operation to be optimized.
Design features of the machines
An analysis of the machines presented in Table 1 shows that the vast majority of them have a vertical layout, which for relatively short parts (with a diameter greater than the length), usually subjected to turning and grinding, turned out to be more effective than a horizontal one. Processing of fairly long shafts (from 600 mm for the Emag HSC250DS model to 1400 mm for the Index G250 model) remains an exception and is carried out only on horizontal machines. In addition, most machines, in order to increase their efficiency, are equipped with conveyors for feeding workpieces and removing finished parts from the working area. One of the means of increasing the rigidity of machines subjected to increased loads during combined processing is the use (for machines from Emag, Schaudt BWF Mikrosa and some others) of polymer concrete frames that have good damping properties, as well as (for machines from Buderus) frames made of natural granite.
Almost all machines are equipped as standard with more than one grinding spindle in order to be able to carry out both external and internal machining. In this case, the straightening mechanism is built directly into the machine. Note that almost all companies offer linear motors as options, not only along the longitudinal axis, along which maximum movement occurs, but also along the transverse one. This means that the productivity of such machines can be further improved. 
Of course, lathe manufacturers such as Emag and Index and grinding machine manufacturers such as Junker, with the common goal of providing high flexibility, productivity and machining efficiency when choosing an approach to the design of their equipment that combines hard turning with grinding or vice versa - are guided by various considerations. As a rule, this design is made in such a way that the machine, in addition to turning and grinding, has the ability to perform other operations, if necessary.
So, the machine mod. Index's V300 has an inverted vertical spindle design (inspired by Emag) and is designed to handle a wide range of workpieces of any type (castings, forgings, etc.). Their loading and unloading is done automatically. Thanks to the modular design, the machine, which is equipped with a large number of tool heads and blocks that can be combined in any order (Fig. 3), designed to perform various operations of turning, drilling and grinding, can work in both small- and medium-scale production. During the processing process, the spindle moves the workpiece, bringing it to various tool blocks installed on the bed, which carry out the specified operations of turning, drilling, external and internal grinding. To perform combined hard turning and grinding, a turret with stationary and rotating tools is mounted on the frame. The external grinding unit uses grinding wheels with a diameter of 400 mm and a width of 40 mm made of traditional and super-hard materials, such as CBN, rotating at a frequency of up to 6000 rpm from a 7.5 kW drive. They are edited automatically. The unit has a built-in electromagnetic grinding wheel balancing system. Internal grinding is carried out with wheels made of the same materials, but mounted on mandrels with a HSK32 cone to obtain maximum precision and rigidity of the grinding spindle. The high-frequency spindle for their rotation has a power of 2 to 15 kW and is designed for a rotation speed in the range of 45,000-100,000 rpm. Additional operations on this machine can be performed using a diode laser built into the production process to harden the outer surfaces, as well as the ends and individual areas on the inner surfaces, on the workpiece clamped in the spindle chuck. An additional operation is also rolling, performed on a mod machine. CNC 435 from Buderus.
Multifunctional machines—the most successful type of blade machining equipment currently in many respects—are not particularly new to the abrasive industry. Using grinding wheels, built-in, for example, into the magazines of some milling machining centers, semi-finishing and finishing machining of complex surfaces of parts made of difficult-to-machine materials, such as turbine blades, has long been performed. The main technological advantages of such centers - reducing the amount of necessary equipment and, accordingly, the required production space and number of operators, the ability to transfer finished parts directly to assembly - are also preserved for multifunctional grinding-based machines. However, this equipment for combined grinding and turning has a number of differences and advantages. It should be noted, in particular, the significant predominance of grinding operations over turning, milling and drilling, the mandatory cooling of the working area, and the presence in some cases of a wheel changing mechanism during grinding. It is also necessary to consider as an advantage that when performing lathe, milling, thread-cutting and other blade operations on grinding machines, greater accuracy is achieved than when performing them on lathes and/or milling machines, because grinding machines that are converted into multifunctional ones initially have more higher accuracy than, for example, in turning machines, which are given the ability to grind. Such machines are produced by the Swiss company Magerle and the German company Junker. 
The modular MMS machine (Fig. 4), first shown by Magerle at the EMO2003 exhibition, has a symmetrical portal design, which, together with ball screws along the coordinate axes, ensures its static and dynamic rigidity and thermal stability. Movements along three coordinate axes (500x250x200 mm) through these gears are performed by the table, which allows you to install horizontal, vertical or inclined grinding heads on the machine and manually or automatically load it from four sides. At the exhibition, in particular, a version of the machine was shown with a vertical motor spindle with a power of 30 kW and a built-in tool changer (five grinding wheels with a diameter of 300 mm, a width of 60 mm and a weight of no more than 20 kg, or 20 wheels with a diameter of no more than 130 mm), produced in 3 seconds. The rotation speed of the circles is recommended within 1000-8000 min -1. The HSK-A-100 spindle cone can also accommodate cutters, drills and other blade tools, which, when combined with a two-axis dividing head and a satellite changer, allows the processing of small pump blades, turbine blades and other complex parts. This is facilitated by the ability to supply coolant through the center of the spindle at a pressure of 80 bar.
A prototype of the Concept multifunctional machine, which was also shown for the first time at this exhibition by the Italian company Tacchella Macchine, is a combination of a conventional cylindrical grinding machine with an eight-position turret in which stationary tools are installed. Two large-diameter circles made of CBN are rotated on the machine 180 degrees relative to each other and can be rotated in turn into the working area. The machine bed is made in the form of a rigid ribbed cast iron casting. Movements along the X and Z axes can be performed using linear motors or ball screws. Hydrostatic guides are used to move the working parts. The disadvantages of this machine include the fact that it does not have separate working areas for turning and grinding. In the future, apparently, rotating tools will also be installed in the turret, which will expand the technological capabilities of the machine, and the number of turrets can be increased to two.
On the Hardpoint 300 series machine of modular design from Junker with an inclined bed, hardened and non-hardened parts such as rotation bodies with a diameter of 80 mm and the same length (Fig. 5) in addition to grinding and honing with wheels and CBN heads can be used for turning, drilling and reaming in one setup , as well as cutting threads and removing burrs. The machine is implemented in four versions with a number of spindles from two to four, in which up to four parts can be processed simultaneously with or without transmission from one spindle to another. The machine is controlled along six coordinate axes from the Sinumerik 840D CNC device. The machine can be loaded manually or automatically.
High performance machine mod. CNC235 from Buderus Scheiftechnik (Fig. 6) is achieved by installing two spindles on it, allowing external and internal grinding (with special heads) and hard turning (with separate cutters or a turret) of workpieces with a diameter and length of up to 150 mm, as well as a belt conveyor. 
Multifunctional machines designed for hard turning and grinding of heat-treated workpieces are in fairly high demand among consumers abroad and are gradually beginning to penetrate into Russia. There is information about the installation of one such machine (by Buderus) at the Volgoburmash plant. Two machines mod. Stratos M was delivered to VAZ in 2004. At the same time, 60 such machines are already operating in Europe, the USA and Southeast Asia. The reason for such a sharp difference is the insufficient level of development of most sectors of our industry and the insufficient efficiency of such complex and expensive equipment in our economic conditions, and, consequently, the minimal demand for it. Therefore, in the near future one should not expect the appearance of a large number of machines for dry turning and grinding at Russian factories, except perhaps at individual enterprises in the automotive industry and several enterprises producing equipment for the oil and gas industry.
Vladimir Potapov
Magazine "Equipment: market, supply, prices", No. 07, July 2004.
The processing of steel products can consist of several stages, differing in the technological scheme and the equipment used. To give a product or workpiece its final shape, metal grinding machines are used. Despite their design differences, they have almost the same functions and parameters.
The grinding process is necessary to form the final dimensions and roughness parameters of the part. During this work, using abrasive materials, layers of metal are gradually removed from the workpiece.
Additionally, performing this procedure will allow you to get rid of minor defects, improve the appearance of the product and increase its anti-corrosion properties. Grinding is the gradual removal of a thin layer of chips by contact of the material with an abrasive tool. The cutting rotation of the tool is the main movement in the equipment. The treatment can be performed at the periphery of the abrasive component or at its end.
Depending on the configuration of the workpiece and the required grinding parameters, the following processing methods are distinguished:
To perform each type of work, it is necessary to select the right equipment and its characteristics. The selection parameters are productivity, degree of automation and functionality of the machine. Also, special attention is paid to abrasives, with the help of which layers of material are removed. They must have the required grain size and have a large enough area for contact with the workpiece.
Some models of metal grinding machines are designed to perform several types of processing. But at the same time they are characterized by high cost and complexity of operation.
These machines are designed to perform longitudinal and plunge grinding of metal workpieces of various shapes. They are characterized by high accuracy of the operation. To increase this indicator, it is recommended to select models with an electronic control unit.
Structurally, the equipment consists of two work tables. On the main (horizontal) part, the part is fixed in the centers (chuck) for further rotation. The vertical table contains a spindle head with an installed abrasive wheel. It can be controlled manually or using a CNC unit.
Stages of operation of an internal grinding machine.
Depending on the characteristics of the equipment, it can be used for rough or fine grinding. In the second case, the best option would be to use models with an automatic feed system. In this case, the determining parameter will be the rotation speed of the abrasive wheel.
The defining parameters of the machine are restrictions on the size and weight of the workpiece. Thanks to the wide range of settings, equipment of this class can perform all types of grinding.
Changing the location of the abrasive wheel depends on the machine model. In some of them, it can shift not only in the vertical plane, but also in the horizontal. This significantly expands the range of applications.
They are designed for processing the inside of workpieces with through or blind holes. The main difference from the models described above is the immobility of the workpiece relative to the abrasive. This metal grinding machine is used for processing engine cylinders and similar structures.
Processing occurs due to a movable spindle on which the disk is installed. It transmits to the abrasive not only rotational, but also translational motion. Thanks to this, the internal edges of the workpiece are polished.
Depending on the design and required complexity of grinding, equipment of this type is conventionally divided into the following groups:
Internal grinding machines are used for grinding massive products. Thanks to their design and wide functionality, they can perform all types of processing, including final finishing of the internal surface.
Special technical characteristics are the maximum processing length, restrictions on the outer diameter of the workpiece and the values of the maximum and minimum rotation angle of the abrasive in conical products.
One of the problems in operating internal grinding machines is the timely removal of waste from the abrasive area. For this purpose, magnetic devices and special filters are used. Without them, it will be impossible to achieve the desired roughness indicator.
The final grinding stage is best done using special honing equipment. Its design is in many ways similar to internal grinding models. The difference is that the workpiece is not mounted on a special device. The spindle is also longer for more thorough grinding.
To fully perform its functions, nozzles with different configurations and abrasive grain sizes can be installed on the spindle. Processing of the workpiece is performed manually or using an automated system. In the first case, the spindle can move relative to its axis. The automatic mode provides mechanisms for maximum finishing of the workpiece surface.
To select the optimal model, it is necessary to take into account the following design nuances:
A blank mounted on a spindle is used as a processing tool. Its design provides connectors for attaching abrasive bars of various configurations.
To achieve optimal results during the honing process, liquid is supplied to the treatment area. It performs several functions: it prevents heating of the surface and removes abrasive particles that have broken off from the bars.
The operating principle of these machines is based on the transmission of torque from the drive wheel to the workpiece. It is not attached rigidly in the centers. The degree of pressure applied to the working abrasive is controlled by adjusting the position of the driving wheel.
Most often, an abrasive tape is used as a processing material. It is installed on the surface of the working circle. This operating principle allows you to quickly reconfigure the equipment to activate another mode.
Advantages of using centerless grinding units:
Such equipment is equipped with an automated function control complex. This is a necessary measure, since it is almost impossible to achieve a good finish grinding result using manual mechanisms for this method.
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