Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/02—Lapping machines or devices; Accessories designed for working surfaces of revolution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B31/00—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor
  • B24B31/10—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor involving other means for tumbling of work
  • B24B31/116—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor involving other means for tumbling of work using plastically deformable grinding compound, moved relatively to the workpiece under the influence of pressure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B33/00—Honing machines or devices; Accessories therefor
  • B24B33/02—Honing machines or devices; Accessories therefor designed for working internal surfaces of revolution, e.g. of cylindrical or conical shapes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B57/00—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/02—Polishing compositions containing abrasives or grinding agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1454—Abrasive powders, suspensions and pastes for polishing
  • C09K3/1481—Pastes, optionally in the form of blocks or sticks

Definitions

• the invention relates to an uncovering compound, to an uncovering process and to an uncovering apparatus, in particular for uncovering surfaces, such as for example cylinder bearing surfaces, made from material with pronounced Si primary crystals.
• the automotive engineering sector is nowadays making increased use of materials which, on account of improved materials properties, allow the service lives of the components made from such materials to be significantly extended yet nevertheless allow components which are as lightweight as possible to be realized.
• engine constructors are making more and more use of lightweight aluminum materials, these aluminum materials containing additions, for example in order to enable cylinder bore surfaces in crankcases made from aluminum materials of this type to be made as wear-free as possible, which would not be feasible using pure aluminum, on account of it being a relatively soft material.
• Materials which are preferably used for these surfaces of cylinder bores or cylinder bearing surfaces are known, for example, under the names Locasil, Silitec, SAE 390 or as hypereutectic aluminum. These materials may include pronounced Si primary crystals embedded in the aluminum material, ensuring the required strength of these materials.
• silicon carbide grains are already being used as uncovering materials, but only extremely coarse-grained particles with particle sizes of over 5 ⁇ m in oil-based lapping pastes are used.
• the object of the present invention is to provide an uncovering compound, an uncovering process and an uncovering apparatus which allow the maximum possible process reliability under large-series conditions combined, at the same time, with low manufacturing costs, while at the same time rounding the edges of the Si primary crystals which are to be uncovered in the material to be machined and allowing the abraded or fragmented parts of the Si primary crystals to be completely removed from the machined surface, while also producing an improved residual base roughness of the machined surface in order to improve oil adhesion and free-running properties on surfaces of this type.
• the object of the present invention is achieved by an uncovering compound, a process and an apparatus.
• the uncovering compound according to the invention in particular for uncovering cylinder bearing surfaces made from material with pronounced Si primary crystals, according to the invention includes an uncovering material which is embedded in a visco-elastic plastic carrier compound. Embedding this uncovering material in a visco-elastic plastic carrier compound on the one hand allows a good uncovering action to be achieved under large-series manufacturing conditions, and on the other hand allows the uncovered, partially abraded Si primary crystals or parts of these Si primary crystals to be completely removed in a simple way from the region of the surface to be machined, i.e. in particular from the region of the cylinder bearing surface which is to be uncovered.
• the uncovering material according to the invention may consist of silicon carbide grains which have a grain size in the range from 4 ⁇ m to 1 ⁇ m. In this case, these grain sizes may preferably have size distributions which are closely distributed around a given mean.
• the selection according to the invention of silicon carbide grains with a relatively small grain size in the range according to the invention makes it possible in a particularly simple way to release the soft aluminum matrix between the Si primary crystals of the corresponding crystal structure which are to be uncovered and on average have a particle size of 8 ⁇ m and to remove the soft aluminum skins which are located above the hard, wear-resistant Si primary crystals of the materials to be uncovered.
• ceramic fibers it is also possible for ceramic fibers to be used as uncovering material instead of or in combination with the silicon carbide grains according to the invention, in which case these ceramic fibers may particularly preferably consist of Al 2 O 3 . These fibers have a particularly good adhesion in the visco-elastic plastic carrier compound of the uncovering compound which is provided in accordance with the invention.
• the uncovering compound contains organic admixtures of cellulose, preferably of wood and/or sisal fibers, forming up to 60% by volume of the uncovering compound.
• organic admixtures on the one hand are particularly successful at binding loose aluminum microchips, and on account of their branched surface improve the accumulation of aluminum at the uncovering compound, thereby increasing the ability of the uncovering compound to hold aluminum and any oil residues from the previous machining steps, and also offer the option of being floated out using washing water.
• the uncovering compound may also contain organic binders forming up to 40% by volume, in which case these organic binders may particularly preferably be provided in the form of natural waxes.
• the uncovering compound according to the invention may preferably contain admixtures of starch flours forming up to 20% by volume of the uncovering compound and/or admixtures of natural animal and/or vegetable fats forming up to 40% by volume of the uncovering compound.
• a preferred embodiment of the uncovering compound according to the invention may also contain admixtures of resins forming up to 20% by volume of the uncovering compound.
• the abovementioned admixtures may, for example, precipitate or flocculate at relatively high temperatures in a washing process, so that they can be recycled.
• the abovementioned admixtures can be used to crosslink the uncovering compound to make it tacky.
• the abovementioned admixtures can contribute to allowing the uncovering compound according to the invention to be used in processes in which the surface to be machined is still contaminated by oil contamination on account of previous machining steps yet nevertheless allow uncovering to take place without a prior washing step, which can further improve the processing properties in particular when an uncovering compound of this type according to the invention is used in large-series manufacturing.
• the abovementioned admixtures can additionally increase the viscosity of the uncovering compound and possibly impart further pasty properties to it, with the result that the complete removal of any abraded Si primary crystals or of parts of these Si primary crystals can also be further improved.
• the visco-elastic plastic carrier compound used in the uncovering compound according to the invention may be any suitable visco-elastic plastic carrier compound material.
• An embodiment of the uncovering compound according to the invention which is made recyclable is particularly preferred. Recyclability can advantageously result in accordance with the recycling steps recited below as described in connection with the process according to the invention.
• the process according to the invention for surface-machining a workpiece, in particular for uncovering cylinder bearing surfaces made from material with pronounced Si primary crystals, in particular using uncovering compound comprises the following steps:
• the uncovering process according to the invention in particular achieves better or targeted residual base roughnesses of the surfaces to be machined, with the result that, on account of the deepening of score marks following the precision-turning machining by the visco-elastic uncovering, it is possible to achieve higher reserves of oil films which can adhere to the surface machined by the process according to the invention, and therefore improved running properties.
• New running properties are also implemented in targeted fashion in a lower region of the cylinder bearing surface, which is not touched by the piston rings but is touched by the piston skirt. These running properties are made possible by targeted setting of the oil retention volume by way of the surface roughness or higher score mark depths.
• Cross-channels which are produced by precision-honing, by contrast, predominantly on account of the use of cutting grain which machines in a stationary position (and forms part of the honing brick) and also with defined, helical movements being implemented by controlling the rotational speed and stroke reversal of the honing tool, generally have rectilinear surface pattern/score structures.
• the visco-elastic uncovering according to the invention produces different ratios, which are not steady-state, of different material-removal characteristics at the surface, with the result that, on the contrary, a wavy flow structure is created.
• the uncovering process according to the invention also allows the score marks which were formed by the previous turning operation to be leveled and reduced, which likewise leads to improved running properties on surfaces machined in this way.
• the process according to the invention is relatively simple to employ, with its reduced number of process steps, a particularly high process reliability under large-series conditions is also possible combined, at the same time, with low manufacturing costs.
• An embodiment of the process according to the invention in which the uncovering step is divided into at least two or more uncovering steps using different uncovering compounds is particularly preferred.
• first of all the roughnesses of the surfaces to be machined can be reduced by relatively coarse-grain uncovering compound, with the surfaces to be machined being macroscopically smoothed, and then the roughness of the machined surface can be improved by using a further, more fine-grained uncovering compound, during which step it is possible to set roughnesses which are in a range above 0.1 ⁇ m, since in the roughness range below 0.1 ⁇ m there is a potential risk of a break in the oil film if smooth-running oils are used as lubricant on a correspondingly machined surface.
• a recycling step is provided, in which case, after the uncovering has been carried out, an aqueous treatment of the used uncovering compound or—if the uncovering is carried out in more than one step—of the used uncovering compounds is used to recycle this/these uncovering compound(s) by adding sodium hydroxide solution thereto and the constituents of the uncovering compound(s) are separated, preferably cellulose constituents, fats and lightweight floating constituents and the heavier uncovering material are separated, by settling and screening.
• the aqueous treatment is particularly preferable for the aqueous treatment to be carried out by adding 4.5% strength sodium hydroxide solution to the used uncovering compound(s) and drying and then composting the cellulose constituents. Fats and readily floating constituents can be scooped out and returned. The heavy silicon carbide constituents, which preferably form the uncovering material, will fall to the bottom of a settling tank provided and can then be removed from the tank in a controlled way and used for a fresh uncovering compound after they have been treated, screened and returned. Any suspended particles which may be present in the aqueous-treated used uncovering compound can be removed from the production process using conventional filter technology.
• the process water of the aqueous treatment which is slightly basic on account of the addition of sodium hydroxide solution, can also be fed in a controlled way to any further acidic industrial wastewater which may be present in order to neutralize them, allowing the environmental compatibility of the process according to the invention to be further improved.
• the apparatus according to the invention for surface-machining, in particular for uncovering cylinder bearing surfaces made from material with pronounced Si primary crystals, in particular for carrying out the process, and in particular using uncovering compound includes the following components:
• At least one storage chamber for holding uncovering compound
• controllable elastic flat slides which can be matched to the contour of the workpiece to be machined
• At least one helical swirl stage for supplying the uncovering compound
• a circulation system having a pump unit for delivering the uncovering compound from the at least one storage chamber into the at least one rotating uncovering mandrel, and having at least one return passage in the at least one uncovering mandrel for returning the used uncovering compound, and having at least one collection vessel for collecting the returned used uncovering compound.
• the controllable elastic flat slides of the uncovering apparatus according to the invention may preferably consist of fluororubber, in which case the controllable elastic flat slides allow the apparatus according to the invention to be adapted to different internal diameters/displacements of cylinder surfaces which are to be uncovered by machining.
• the helical swirl stage for supplying the uncovering compound may also have a groove-like recess and be configured similar to a screw thread.
• the pump unit of the circulation system of the uncovering apparatus according to the invention is used to pass the uncovering compound through the circulation system from the storage vessel and to transfer it into the rotating uncovering mandrel to produce a primary pressure and also to pass the used uncovering compound in the at least one return passage and to transfer the used uncovering compound into the collection vessel.
• the uncovering apparatus on the one hand offers increased process reliability for the uncovering operation under large-series manufacturing conditions, since it can be of very simple design, while at the same time it allows complete removal of the materials produced during the uncovering operation, resulting in particularly successful surface machining, which also leads to a better residual base roughness of the machined surfaces.
• the latter includes a hollow cylinder which is integrated in the circulation system and can be controlled in such a way that it presses the uncovering compound, which is located between the hollow cylinder and that surface of a workpiece to be machined which is to be uncovered, onto that surface of the workpiece to be machined which is to be uncovered, in particular the inner wall of a cylinder, with a controllable prestressing pressure, the hollow cylinder preferably having at least one further return passage for returning the used uncovering compound.
• the uncovering compound can be guided along a predetermined machining direction for the workpiece, in particular along the longitudinal direction of a cylinder bore of a cylinder to be machined, preferably through chambers in the at least one rotating uncovering mandrel.
• This oriented guidance of the uncovering compound along, for example, a cylinder bore serves to avoid what is known as shadow formation, which would lead to uneven removal of material around the Si crystals to be uncovered in the workpiece material, and therefore to a deterioration in the surface properties of the uncovered material.
• the apparatus according to the invention prefferably includes a magazine feed system, it being possible for the uncovering compound to be held in tablet form in the at least one storage chamber and/or for the used uncovering compound to be ejected by an automated ejector system. This allows particularly improved usability of an uncovering apparatus according to the invention equipped in this way in particular under large-series conditions.
• a plurality of uncovering compounds which can be stored in different storage chambers, can be used in the apparatus according to the invention, in which case it is also possible to provide different controllable elastic flat slides, different or a plurality of helical swirl stages and if appropriate a plurality of different feed lines in the circulation system provided according to the invention for the respective different uncovering compounds. It is also possible to provide a plurality of rotating uncovering mandrels for the various uncovering compounds. However, if a plurality of uncovering compounds which can be used are provided in a correspondingly configured uncovering apparatus (cf. above), according to the invention it is advantageous to provide just one collection vessel for the returned used different uncovering compounds, so that these uncovering compounds can be treated or recycled jointly.
• a center rest or a tube blank can be placed onto a cylinder opening before the at least one rotating uncovering mandrel is introduced into the cylinder.
• the apparatus according to the invention can preferably be used to achieve a material-removal volume of at least 0.1 cm 3 and, when uncovering to an uncovering depth in the range from 0.15 ⁇ m to 0.8 ⁇ m, a material-removal volume of approx. 0.01 cm 3 per cylinder bore.
• the ratio of a holding volume for the uncovering compound in at least one rotating uncovering mandrel to a material-removal volume of material to be uncovered is in the range from 1:20 to 1:100, preferably of 1:50.
• a separating membrane arranged in front of the uncovering mandrel for sealing off the workpiece to be machined from overflowing uncovering compound, it being possible for this overflowing uncovering compound to be returned from the corresponding region of the separating membrane, in particular into the collection vessel.
• the apparatus according to the invention as a whole or preferably at least partially can be set in micro-oscillation.
• a shaking movement can be at least partially superimposed on the apparatus according to the invention.
• Apparatuses which impart the shaking movement used may, for example, be eccentric apparatuses which are known per se and are not described in more detail at this point, for the sake of simplicity.
• the uncovering apparatus according to the invention in accordance with a preferred embodiment, also includes a float device, a settling device and a screening device.
• the present invention offers an uncovering compound which is improved compared to the prior art, an improved uncovering process and an improved uncovering apparatus.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Geometry (AREA)
• Materials Engineering (AREA)
• Processing Of Solid Wastes (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Polishing Bodies And Polishing Tools (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=33441293

Family Applications (1)

Country Status (5)

Citations (7)

Family Cites Families (13)

• 2003
  • 2003-05-24 DE DE10323743A patent/DE10323743B4/de not_active Expired - Fee Related
• 2004
  • 2004-04-22 WO PCT/EP2004/004269 patent/WO2004103640A1/de active IP Right Grant
  • 2004-04-22 JP JP2006529696A patent/JP2007533782A/ja not_active Withdrawn
  • 2004-04-22 DE DE502004001748T patent/DE502004001748D1/de not_active Expired - Lifetime
  • 2004-04-22 US US10/559,166 patent/US20060229001A1/en not_active Abandoned
  • 2004-04-22 EP EP04728795A patent/EP1626838B1/de not_active Expired - Fee Related

Patent Citations (9)

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