The subject of the invention is a unit for surface treatment of top layers, especially of metal, which is used for the treatment of top layers of working surfaces of machine parts, and especially for placement of coatings of micro- and nanometric solid greases in the unevenness of the surfaces of extrusion punches and on sliding guides of machine tools.

The surface treatment of surfaces using the method of plastic microdeformation (burnishing) is divided into static burnishing and dynamic burnishing, depending on the method of applying pressure. The method described in the claim fits in the category of dynamic methods, in which the method of exerting tool pressure on the processed item is variable as a result of kinetic energy.

The methods closest to the described method include ball burnishing, shot blasting and hammering. Characteristic for this group of burnishing methods is the discontinuous, short-term contact of the tool with the surface of a treated item. The resulting traces of the tool operation are separate areas. The dynamic methods are based on probabilistic distribution of imprints of the operational tool in the form of balls, shot etc., on the treated surface, which does not guarantee a uniform micro-deformation of the surface and the distribution of deformations. Therefore, these methods require such an amount of traces, so that the overall area of the projection over the treated surface was at least equal to the area of the surface. In order to achieve a specified depth of hardening multiple overlapping traces are required, as measured by the number of strikes over a surface of area. The above methods of burnishing are characterised by unrestrained kinematics, which adversely influences the geometry of treated objects. This results in:

- lack of ability to directly reduce geometric errors, with the exception of changes to the coarseness,

- condition of the top layer is significantly more varied in comparison to static methods,

- smoothness of the surface is usually lower than before the burnishing process

- danger of damage to the surface by crumbling of working elements in the ball burnishing and shot blasting method.

Also, the method of hammering is characterised by limited kinematics, which limits its use to parts, the surface of which is composed of regular shapes,

The essence of the invention, which is a unit for surface treatment of top layers, especially of metal, in the form of an element driving a ram, hitting the treated surface with a reciprocating movement, consists of the ram being a hammer with a ball-shaped working area, connected with a piezoelectric actuator, which is driven by a high frequency voltage generator with a frequency changeable within the range of 10 Hz to 1000 Hz and a relative movement of the hammer in relation to the treated material along the acting line within the range of 0.05 to 5.0 mm.

The use of the solution presented in the invention enables the control over the dynamics of the strikes of the piezoelectric actuator, which enables the control of the amount of energy of the hammer which produces microdeformations of the top layer, guaranteeing the hardening which does not exceed the limiting values of plastic deformation of crystallites. The essential feature of this solution is a uniform distribution of treatment traces on the treated surface which results from the synchronised movement of the treated item (feed) and the working tool powered by a PE actuator controlled by the frequency generator (strike frequency, amount of provided energy). This synchronisation enables a permanent distance between the imprints and the depth of the imprint. The advantage of the solution when compared to previous solutions is that it guarantees a uniform distribution of imprints over a unit of surface of the product, which translates into a uniform placement of foreign objects over the treated surface. Additionally, uniform microdeformations of the surface cause compressive stresses in the top layer, and thus, it improves mechanical properties (including fatigue strength, hardness), tribiological properties (by increasing the abrasion resistance) and geometric properties (improving the smoothness and precision of construction).

Additionally, during the hammering process it is possible to control the value of local deformation over the treated surface, and thus, to control the mechanical properties which vary over different fragments of the treated surface.

Through the use of the presented solution it is possible to control the plastic deformation of the top layer of working surfaces of machine parts which improve their mechanical, structural and tribological properties, and increase their smoothness and precision, which as a result extends the operational period of these parts and advantageously influences the natural environment. This method, as distinguished from the typical hammering methods enables the improvement of the surface smoothness.

The proposed solution is relatively easy to be used in numeric control systems.

The examples of the use of the solution in accordance with the invention:

- burnishing of the working surfaces of machine parts,.

- improving the smoothness of the working surfaces of machine parts

- controlling the properties of burnished working surfaces of machine parts, with varying of the deformation values of the top layer

The subject of the invention, in an example, but not limiting, implementation was presented in diagrams of the figure,

Piezoelectric actuator 1 is mounted at a set distance to the treated surface. To the end of the piezoelectric actuator I a hammer 2 is attached - a tool with a ball-shaped end acting on the treated surface. The drive of the piezoelectric actuator is provided by a high frequency voltage generator which ensures its reciprocal movement with a set frequency within the range of 10 to 1000 Hz and the input function curve characteristic. These parameters allow the control of the energy of the hammer strike over the treated surface. The treated object 3 moves in a direction perpendicular to the direction of movement of the hammer 2. As a result of the strike of the hammer 2 the deformation of the top layer of the treated material 4, with the scale between individual strikes of the hammer within the limits of 0.01 to 5.0 mm.

Initially compressed piezoelectric material, subjected to electric current, lengthens in proportion to the amount of the applied voltage.

The speed of lengthening depends directly on the speed of voltage increase. The acceleration in an amount of thousands of gees can thus be obtained. This is a feature which was used in dynamic applications, such as used in the invention.

The frequency and strength of hits of the ram attached to the piezoelectric element depends on the current voltage, intensity and frequency and on the inertia of the mechanical system of the ram. The control of these parameters enables the adaptation of the character of the strikes to the requirements of the process.