Method of welding parts with different thickness out of dissimilar metals
SUBSTANCE: temporary beads 3 and 4 are made on thick 2 and thin 1 parts. The bead 3 height is by 3-4 times higher than thickness of part 1. Height of bead 4 is equal to height of bead 3. Bead 4 thickness is determined by equation S2=(1+Δ)·S1. Beads 3 and 4 contact surface is treated by ultrasound in ethyl alcohol. Parts 1 and 2 are secured in welding fixture. Butt joint gap and beads 3 and 4 shift at least 10% of part 1 thickness are ensured. Laser beam 5 is directed to butt joint of beads 3 and 4.
EFFECT: invention increases weld strength due to rational design of the temporary beads.
3 cl, 4 dwg
The invention relates to the field of welding production, in particular to the technology of welding parts of different thickness, made of dissimilar metals. The invention can be used in machine building, aircraft engineering, instrument making, nuclear energy and other industries.
The known method of laser welding of parts made of dissimilar metals (RF patent No. 2415739 on 10.04.2011, UK 26/40, UK 9/23, UK 33/00, the authors Zvezdin, V. V., Israfilov I. H., D. E. Veliev). The method consists in the fact that the plane of the butt joints of parts made of dissimilar metals perform inclined tangentially to the segment of the heat affected zone of the weld. Laser radiation is focused on a more refractory material at a distance from the butt of the plane. The angle of inclination of the plane of the butt joint and the focusing distance is calculated from the conditions of the absence of evaporation of the fusible material.
The disadvantage of this method due to the uneven heating of parts with different coefficient of thermal expansion is the tendency to accumulation of welding stresses and deformations. This can lead to reduction in the strength of welded joints.
As a prototype for the method was the selected method of arc welding with non-consumable electrode (patent RF №2458768 from 20.08.2012, VC/02, the authors Tregubov V. I., Zabolotiv V. M., Khabarov, A. N., Valery Gayevsky). In the method of manufacturing thin-walled axisymmetric welded construction with thick-walled hinged elements in a thick-walled tubular blanks of hinged elements in places of their welding technological form the ribs the thickness and width equal to the thickness of the tubular frame. Carry out preliminary Assembly, the assembled construction is fixed on the installation of welding in the welding fixture, fix each element of the potholder. Perform automatic welding in shielding gases.
The disadvantage of this method is the high probability of burn-through in thin-walled parts and rasplavlennyi with a thick-walled, which reduces the strength and violates the integrity of the weld. When welding workpieces of different thickness it occurs, as a rule, due to the greater thermal expansion of the metal thin edges, leading to local buckling and the emergence of a gap between the parts, a thin edge overheats burn-through is formed. In addition, the offset of the heat flux on the more massive the item is not always yields a high-quality weld as possible rasplavlennyi welded edges. Therefore, when welding raznoformnyh parts, to obtain a stable result, it is more expedient to consider �tykovoe flanged edges.
Disclosure of the invention
Task to be solved by the claimed invention is to provide a method of welding workpieces of different thickness made of dissimilar metals that produces a sealed permanent connections with a high quality weld.
Technical result achieved when solving this problem, is to increase the strength of the weld by performing rational design of technological clamps, ensuring uniform heating of the welded parts and the exception deformation of the weld.
For obtaining the specified technical result in the method of welding workpieces of different thickness in inert gases, including the formation of the technological pile on thick-walled parts, the Assembly of the parts in the welding fixture, tack, weld parts according to the invention form the technological pile on thin parts, with the height of the pile is 3-4 times greater than the thickness of the workpiece. Form the collar on thick pieces with a height equal to the height of the windrow thin-walled parts, thick-dependent reflection coefficient of the welded parts by the formula S2=(1+Δ)·S1where Δ=R2-R1, R1- the reflectance of a thick-walled parts, R2- reflectance thin-walled parts, S1- the thickness of the collar tone�istennoy details S2- thickness collar thick pieces. Weld parts made of dissimilar metals with a laser beam, wherein the laser beam is directed at the junction of clamps welded parts.
The totality of these essential features provides the technical result - uniform heating of welded parts and reduce overheating of thin-walled parts and deformation, as well as the exclusion of incomplete fusion and burn-through in the weld, thus enhancing the strength of the weld.
Before Assembly of the contact surface clamps can be subjected to ultrasonic treatment in ethanol. This clean weldable surface from contamination, and thus exclude the influence of adsorbed atoms of the external environment on the quality of the weld. Contaminant-free weld quality is improved.
The Assembly can run with the assumption of a gap in the junction and offsets the height of the welded clamps not exceeding 10% of the thickness of thin-walled parts. At the same time provide intimate contact of the welded clamps eliminates the formation of air cavities between the piles, which can cause burn-through of thin-walled collar detail. The absence of gaps improves the quality of the weld.
To ensure the possibility of welding of dissimilar metals, including in an inert environment, it is necessary to consider their thermophysical and physico-chemical�economic characteristics.
To connect thin-walled and thick-walled parts, it is advisable to use the method of welding with minimum heat input laser or pulsed laser welding.
This method allows to obtain a reliable connection of dissimilar metals only maintaining the specified parameters ledge. Moreover, the geometrical dimensions of the clamps matched with thermal properties of the connected metals.
Brief description of the drawing figures
Fig.1 shows a cross section of the welded parts made with technological piles.
Fig.2 shows the connection of the parts before welding.
Fig.3 shows a cross section of a welded joint M1+12X18H10T.
Fig.4 shows a cross section of a welded joint NP2+12X18H10T.
Embodiments of the invention
As a material of thin-walled parts used copper marks M1 GOST 1173-2006 and Nickel NP2 GOST 2170-73.
Material thick pieces - stainless steel 12X18H10T of GOST 4986-79.
Thus, in this paper, the authors examine the welding of parts of different thicknesses from dissimilar metals in the following combination: M1+12X18H10T and NP2+12X18H10T.
Fig.1 shows a thin-walled part 1 and the thick-walled part 2, which made technological piles 3 and 4. In this embodiment, the welding geometries�e the dimensions of the welded parts 1 and 2 are very small, a therefore, for experimental validation of the proposed welded structure as an example, consider the pulsed laser welding.
The thickness of the collar 4 of the workpiece 2 is determined by the formula: S2=(1+Δ)·S1where Δ=R2-R1, R1- reflectance parts 2, R2- reflectance parts 1, S1- the thickness of the collar 3 details 1, S2- the thickness of the collar 4 of the workpiece 2. The reflection coefficient of copper details 1 is R2=0,91, part of the energy of the laser beam 5 is reflected by the surface of the part 1. Thus less energy is absorbed laser beam 5 of the collar 3 and it is less heated. The reflection coefficient of stainless steel is less than copper, Therefore, the collar 4 absorbs more energy than the collar 3. Therefore, for uniform heating of the clamps 3 and 4, it is necessary that the thickness of the collar 4 was greater than the thickness of the collar 3. Therefore, in order to ensure uniform melting of the clamps 3 and 4 welded parts 1 and 2, consider the reflection coefficients of the welded parts 1 and 2.
Pulsed laser welding raznoformnyh parts 1 and 2 is as follows. Form technology the collar 3 with a height of 3-4 times greater than the thickness of the workpiece 1. Form the collar 4 by a height equal to the height of the collar 3, the thickness-dependent reflection coefficient of the welded parts 1 and 2 by the formula S2=(1+Δ)·S1.
�if the thickness of the S 2collar 4 details 2 less than the thickness S1collar 3 details 1, this leads to uneven heating of parts 1 and 2 during welding, therefore, the lack of mutual melting of the clamps 3 and 4 and the formation of weld seams 6 and 7 of unstable quality.
If the height of the collar 3 details 1 less than 3-4 thickness of the workpiece 1, the material of the cap 3 is insufficient to form a nominal weld section 6 and are formed by incomplete fusion or undercuts, which may degrade the quality of the weld 6. If the height of the collar 3 parts 1 more than 3-4 thickness of the workpiece 1, then there is an incomplete fusion of the collar 3 with the distortion of the shape of the weld seam 6, as formed by the excess material for forming a welded seam 6.
The shape of the collar 4 is because it is necessary to reduce thermal impact on the workpiece 2 during welding and to provide more uniform heating of the clamps 3 and 4.
Before assembling the surface of the contact clamps 3 and 4 is subjected to ultrasonic treatment in ethanol. Welded parts 1 and 2 installed in a special Assembly and welding fixture, provide tight contact surfaces of the clamps 3 and 4 thus, as shown in Fig.2. With the gap and the displacement of the welded clamps 3 and 4 does not exceed 10% of the thickness of the workpiece 1. Assembly and welding fixture provides unhindered access of the laser beam 5 and�itogo gas in the weld zone. For protection during welding of weld seams 6, 7 (Fig.3 and 4) by oxidation using an inert gas. Next, the laser beam 5 is directed to the junction of clamps 3, 4 and perform tack detail 1 detail 2 separate points in several places, equidistant from each other. Tack perform on the same mode, which then carry out the welding.
Welding is done on the joint parts 1 and 2. In the process of interaction of the laser beam 5 with welded clamps 3 and 4 produce heating thereof and further melting. The difference of thermophysical properties and reflection coefficients of the laser beam 5 is compensated by the form of the clamps 3, 4 and their geometric dimensions. As a result the weld seams 6 and 7 are formed with a uniform reflow of technological clamps 3 and 4 welded parts 1 and 2.
As shown in Fig.3, the weld metal 6 thick, free of defects. In the weld 6 is a mutual melting of the copper collar 3 and the stainless steel collar 4.
As shown in Fig.4, a more stable weld formation 7 is observed when connecting the Nickel collar 3 with stainless steel collar 4. A characteristic feature of the microstructure of the weld 7 is dendritic or, in other words, the cast structure. In the HAZ the compound has an austenitic structure. The boundaries of austenite grains coincide with the boundaries of the primary crystals. All� seam 7 due to the high stability of the austenitic structure of the secondary crystallization is not observed, after solidification of the weld bath is fixed to the primary structure. Consequently, the weld metal 7 has a more homogeneous structure, is not observed the appearance of internal stresses, which contribute to the development of microcracks and, as a rule, the air-tightness of the seam 7.
Practice has shown that, in compliance with the requirements for Assembly of parts 1, 2 and maintaining the necessary geometric dimensions of clamps 3, 4, welds 6, 7 are of the highest quality.
Thus, the implementation of the cap 3 on the parts 1 and implementation of the cap 4 for details 2 not only improves the stability of the quality of welding seams 6 and 7, but also to ensure the tightness. As a result of the experiments it was confirmed that during pulsed laser welding of parts 1 and 2 different thicknesses of different metals mutual melting of the clamps 3 and 4. With welded seams 6 and 7 are sealed, have no external and internal defects and defects of the microstructure.
Most effective looks using the proposed method in the power nodes of designs for critical applications where high demands are placed on the tightness of welded joints. That is, where the design there is a need to combine parts of different thickness, made �W of dissimilar metals, and increased requirements to the geometry of the product, in General, and to the quality of the welds, in particular.
The proposed design of the welded connection provides the technical effect consists in increasing the quality of welded joints.
In General, the considered embodiment of the invention can be implemented on current hardware using available materials. It shows that it works and confirms the industrial applicability.
1. The method of welding workpieces of different thicknesses of different metals in inert gases, including the formation of the technological pile on thick-walled parts, the Assembly of the parts in the welding fixture, tack and weld parts, characterized in that the technological form of a shoulder on thin-walled parts with a height of collar 3 - 4 times longer than its thickness, and the collar on thick pieces are formed with a height equal to the height of the windrow thin parts, and the thickness is selected depending on the reflection coefficient of the welded parts by the formula S2=(1+Δ)·S1where Δ=R2-R1, R1- the reflectance of a thick-walled parts, R2- reflectance thin-walled parts, S1- the thickness of the thin-walled collar detail, S2- thickness collar thick pieces, in this case, the�m parts are welded by a laser beam, which is sent to the junction mentioned ledge.
2. The method of welding parts according to claim 1, characterized in that before Assembly of the contact surface ledge is subjected to ultrasonic treatment in ethanol.
3. The method of welding parts according to claim 1, characterized in that the Assembly is performed with the gap in the joint and the relative displacement of the welded clamps for height not exceeding 10% of the thickness of thin-walled parts.
SUBSTANCE: aluminium steel joint is obtained by fusion welding of a transient two-layered aluminium steel-element with elements from the same materials by fillet welds. Welding is performed with incomplete penetration of each of the layers of the transient element. Legs of the welds adjacent to the transient two-layered element are at least 1.5 and not more than 2.0 of its thickness on the side of the aluminium layer and at least 1.0 and not more than 1.5 of its thickness on the side of the steel layer, and the weld leg adjacent to the aluminium element being welded is within 1.0 to 1.5 of the value of the weld leg adjacent to the aluminium layer of the transient element.
EFFECT: method allows excluding the formation of delaminations at the boundary of the layers of the aluminium-steel element and provides the achievement of fatigue strength and operating reliability of weld joints.
2 dwg, 1 ex, 2 tbl
SUBSTANCE: first, a shell with an outside end thickening of a cylindrical shape and a spherical bottom of a variable cross section is made of an O-bar of high-strength steel like SP-28 or VP-30 of a rolled plate. A reinforced throat is made from carbon steel 35. The thickness of a weld edge of the throat is chosen in the ratio of 2:1 to the thickness of the shell weld edge. The structure is assembled in a welding and assembly device with a removable pad so that the coincidence of axes and an annular manufacturing clearance at the butt, which is equal to 0.10…0.16 of the thickness of the shell weld edge, is provided. Gas-shielded welding is performed.
EFFECT: invention provides the quality of the weld joint from dissimilar steels and the uniform strength of the weld joint.
7 cl, 10 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to production of large-sized structures of molybdenum and its alloys, for example, at welding of shells of high-temperature gas-static muffle shields. Structure sheet edges are trimmed and formed. T-like copper insert is fitted between trimmed edges to the clearance there between to comply with leg depth. Trimmed edges are welded together by electron beam at incomplete penetration over the height. Welding is performed by repeated heating of non-penetrated trimmed edges with filling of said clearance with said copper insert.
EFFECT: decreased brittleness of the structure.
3 dwg, 2 tbl
FIELD: process engineering.
SUBSTANCE: invention relates to welding of overlap joints and can be used in power production, motor production, ship and railway car building. Power supply is connected. Plasma-forming protective gas is fed. Arc is excited at top element to penetrate both elements. Note here that top element features higher density that that of lower element metal. Depths of top and bottom elements are related as 1:3. Note also that elements are assembled to overlap by at least tem depths of bottom element while welding time is set (2…4)δ seconds where δ is total depth of the elements, mm.
EFFECT: reliable weld.
SUBSTANCE: device for making stents comprises a core and a sleeve. The core has a rigid and substantially cylindrical outer surface. The sleeve surrounds the core and has a variable inner diameter. The sleeve has a rest inner diameter. The core has an outer diameter. The rest inner diameter is less than the outer diameter. That provides extending the sleeve when fitting the core, and substantially placing it back to the inner rest diameter after the core is removed. According to the second version of the device for making the stents, the sleeve has a variable rest diameter and a working diameter. The working diameter is less than the rest diameter. The sleeve surrounds the core and contacts thereto, when the sleeve obtains the rest diameter. An auxiliary unit for making the stents comprises the sleeve having the inner diameter and configured to extend from the rest diameter to the working diameter after applying the expansive force. The working diameter is more than the rest diameter, which the sleeve has at rest. The sleeve is configured to place back to the rest diameter after the expansive force is removed from there. A method for making the stent by means of the device for making the stents according to the first version providing contacting the sleeve to the core for fastening the sleeve on the core. That is followed by contacting the sleeve to a metal relief sheet. The above sheet is then wrapped about the device, and the sheet ends are welded up to form the stent.
EFFECT: invention provides the protection of the upper surface of the stent during the making process.
30 cl, 9 dwg
FIELD: machine building.
SUBSTANCE: welding method consists in two-sided simultaneous fusion of opposite sides of a joint. The parts being welded are installed in a horizontal plane. Grooving with bevels and noses of 8-12 mm is carried out. One welding electrode is installed at each side of the joint, the said electrodes are shifted in respect to each other in longitudinal direction. The distance between the electrodes is chosen as equal to 1.0-1.5 of the weld pool length of the front arc. Powers of the welding arcs are regulated separately at each electrode. The travel speeds of the welding electrodes and the arcs are equal. Welding in overhead position is carried out on the side of the edge nose by means of a non-consumable electrode which is set ahead in respect to the direction of the welding path. The speed and power of a welding arc are chosen so that to provide for 25-35% penetration from the nose of the bevelled welded edges. Flat-position welding is carried out on the side of the edge nose by a consumable electrode. The power of a welding arc at flat-position welding is chosen so that to provide for 85-75% penetration from the nose. The diameter of the consumable electrode is chosen so that to provide for maximal filling of grooving cross section.
EFFECT: reduction of expenditures on additional material at welding and improvement of welding efficiency.
SUBSTANCE: proposed method comprises making of backing of allowance of one of the parts. Said backing is removed at machining after butt welding at vertical position of the beam. Backing depth and width equal 0.25-0.35 and 0.10-0.15 of butt depth, accordingly. Mark 0.004-0.006 of butt depth is made on back of backing opposite the butt to evaluate visually the absence of bridging by smelting rate.
EFFECT: high-quality weld.
SUBSTANCE: this method comprises machining of edges to make the skews over pipe or sheet with 2-3 mm circular transition to plating layer and nose from plating layer in the form of rectangular ledge. Skew of edges over pipe or sheets to nose is broken at angles of 1-2 and 4-8 degrees. Nose from plating layer is 2.5-3.5 mm high and 3.4-4.7 mm long. In compliance with second version, method comprises machining of edges to produce skew with nose over pipe or sheet and bore with skew on plating layer side to depth larger than thickness of the latter. Skew of edges over pipe or sheet to nose features angle of 1-2 degrees. Nose is shaped to rectangular ledge and is 1.8-2.3 mm high and 3.2-5.2 mm long while bore features skew angle of 52-57 degrees.
EFFECT: lower material input, simplified design of welding set, higher quality of weld.
3 cl, 2 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to welding, particularly, to preparation of part edges for at welding of butt joint. Dual-sided skews and edge blunting are made for making of double-welded butt joint. Said skews are asymmetric over the part depth with smaller skew-to-larger skew ratio of 0.2-0.6 at total height of skews not exceeding of 50% of welded parts depth. Smaller skew is arranged on welding side at overhead position.
EFFECT: lower input of welding materials, faster preparation of weld edges.
FIELD: mechanical engineering.
SUBSTANCE: invention relates to a method of butt joining of different materials, providing uniform distribution of stresses in a composite structure at extension-compression. Essence: an inclination angle of materials to be jointed relative to the horizontal axis is specified for each pair of materials to be jointed, wherein the inclination line of the parts to be jointed depends on mechanical properties of the materials.
EFFECT: as a result of joining of the materials in accordance with the described procedure, the stress state in the built-up structure is homogeneous.
3 cl, 5 dwg, 2 ex
SUBSTANCE: device to manufacture items by layer-by-layer laser agglomeration of powders contains tanks for powder and powder surpluses, located between them module for item forming including table with drive of its vertical movement, device for powder supply to the table from powder tank, and powder discharge to power surpluses tank, optical laser system for agglomeration of the powder nozzles installed above the table for air or inert gas supply on the powder layer, and gas intake installed under the table with possibility of connection with vacuum system. The table is made gas permeable and is equipped with installed on its top surface of the refractory gas permeable plate intended for powder layer arrangement on its surface and agglomeration.
EFFECT: improved quality of obtained items.
FIELD: machine building.
SUBSTANCE: module comprises a guide belt, a movable orbital carriage mounted on the guide belt and able of travelling along it. The carriage includes a longitudinal movement drive and a moving device consisting of a carrying roller system and a gear wheel. A joint monitoring sensor, a welding wire reeling device and a handler are installed on the carriage. The handler consists of two mutually perpendicular linear guides with motors, which can move in respect to each other. The transverse linear guide is equipped by a laser welding head, a wire feeding unit, an arc welding torch, a video camera and a controller.
EFFECT: invention allows for the increase of productivity and efficiency of welding process for fixed ring pipe joints and for the improvement of welded joint quality.
3 cl, 3 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to low-inertia robot for laser cutting of flat sheets. Robot comprises support appliance (15) for laser cutting head (14) displacing in axes X and Y. Said support appliance is provided with two sliding units (5, 6) actuated by independent drives (7, 8). They serve for their displacement in axis Y to vary their mutual spacing while bars (9, 10) intended for swivelling said sliding units (5, 6) with laser cutting head (14).
EFFECT: higher quality of cutting.
4 cl, 8 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to protection of steam turbine blades against erosion. Proposed process comprises application of protective coating on the blade. Coating is applied by laser surfacing. Laser head is displaced at the rate of linear interpolation Vi not over 0.05 m/s at laser radiation power making 800-1200 W.
EFFECT: hardened ply of 1/3 length of the blade root at sufficient aerodynamics.
FIELD: process engineering.
SUBSTANCE: invention relates to repair of turbine blades. Proposed process comprises preparation of blade surface. Coating is applied with the help of laser radiation with simultaneous feed of additive powder to melt belt. At hard-facing, radiation power P is varied from 300 to 2500 W, and/or as radiation source feed rate V from 0.1-0.01 m/s, and/or amount of powder fed from 3 to 15 g/min.
EFFECT: accelerated process, higher hard-facing quality.
FIELD: process engineering.
SUBSTANCE: invention relates to welding of metal wires. Welding is performed with the help of laser source to make the weld, in fact, not extending beyond the wire radial cross-section. Prior to welding, at least one of wires to be welded together is subjected to annealing in hot gas flow and/or, in welding, produced weld point is subjected to annealing by hot gas flow.
EFFECT: high-quality weld without further machining.
20 cl, 5 dwg
SUBSTANCE: powder composition mixture for laser build-up on the metal base includes powders of titanium and silicone carbide with particles size 20-100 mcm at the following ratio of components, parts by weight: titanium - 5-7; silicon carbide - 3-6. Titanium powder particles can be in form of spheres.
EFFECT: assurance of uniform distribution of hard inclusions over volume of coating due to synthesis of the titanium carbide, resulting in improvement of the coating quality, namely its hardness and wear resistance.
2 cl, 1 tbl
FIELD: physics, optics.
SUBSTANCE: invention relates to the technology of making complex holes using a laser beam, particularly a through hole for film cooling of a turbine component. At the first step, the internal part (7) of the hole (1) is made from the surface (12) to the opposite internal surface (13) of the substrate (4) using a laser (22) located in a first angular position (1) and simultaneously making a diffuser (10) part. The diffuser (10) residue (16, 18, 28) is removed at the next second and third steps. At the second step, the angular position of the laser (22) is changed to a position (II), different from angular position (I), and the laser is moved to the angular position (II) until the lateral side (17a) of the diffuser (10) is open and part of the volume (18) of the residue (16, 18, 28) remains. At the third step the angular position of the laser is changed from the angular position (II) at the second step so as to remove said residue (18). The angle in the angular positions (I, II, III) is defined as the angle between the middle line of the laser beam (25) and the surface (12) around the film cooling hole (1).
EFFECT: using a laser in three different angular positions relative to the processed substrate significantly simplifies the making of complex holes in the substrate.
13 cl, 12 dwg
SUBSTANCE: processed surface is prepared by cleaning, washing and abrasive flow machining. That is followed by laser clad deposit of a powder material in an inert gas medium. The powder material is presented by titanium and silicon carbide particles 20-100 mcm in size in mass ratio 6:4 or 6:5. The deposit process is performed at laser power 4÷5 kWt, laser beam travel speed 500÷700 mm/min and power consumption 9.6÷11.9 g/min.
EFFECT: invention enables the defect-free wear-resistance coating with high adhesion to the substrate and minimum effect thereon.
2 tbl, 1 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to light industry and can be used for production of equipment intended for cutting of articles of high mechanical strength. Proposed device comprises load bearing case with drive incorporating transfer mechanism designed to revolve the disc of abrasive mechanism. Said case is connected with laser device to transmit laser beam to transmission waveguide. Transmission waveguide end output part is aligned with working waveguide ends part located at preset distance from each other. Working waveguide outer end part is located at abrasive disc lateral generatrix. Working waveguide inner end part is located at circular ledge composed at abrasive disc lateral side.
EFFECT: higher cutting rate irrespective of strength properties of metals.
FIELD: systems for cleaning rigid surfaces.
SUBSTANCE: in order to improve quality of cleaning, surface is irradiated by means of space-modulated beam of laser irradiation.
EFFECT: improved quality of cleaning surfaces.
1 cl, 2 dwg