METHOD FOR COOLING AND/OR SEPARATING ADHESIVELY BONDED COMPONENTS AND/OR REMOVING ADHESIVE RESIDUES FROM SURFACES AND JET APPARATUS HEREFOR

Abstract

In a cleaning method for removing adhesive residues from surfaces, in particular after separating an adhesive connection between adhesively joined partners, liquid carbon dioxide from a reservoir enters a jet, apparatus and is guided there through a first dosing unit into an expansion chamber wherein a cold-resistant liquid is then supplied to a mixture created in the expansion chamber from gaseous carbon dioxide and carbon dioxide particles and wherein the mixture, to which the cold-resistant liquid has been added, exits the jet apparatus via an outlet opening thereof. Furthermore, a jet apparatus removes adhesive residues from surfaces.

Claims

1. A cleaning method for removing adhesive residues from surfaces, in particular after the separation of an adhesive connection between joined partners (26), wherein liquid carbon dioxide passes from a supply to a jet device and is guided there through a first dosing unit (4) into an expansion chamber (2), wherein a cold-resistant liquid is then supplied to a mixture of gaseous carbon dioxide and carbon dioxide particles produced in the expansion chamber (2), and wherein the mixture mixed with the cold-resistant liquid then exits the jet device as a coolant via an outlet opening (18) of the jet device.

2. The method according to claim 1, wherein by means of the mixture comprising carbon dioxide and the cold-resistant liquid, by aligning the outlet opening (18) with the surface of at least one part of an adhesive connection and/or a baffle plate assigned to this surface, the adhesive connection of at least two parts of the adhesive connection is embrittled in such a manner by a charge of cold of -40° C. or lower and preferably about -70° C. that a mechanical separation of the parts is possible.

3. The method according to claim 2, wherein the parts of the adhesive connection are mechanically separated by a spatula and/or a vibration unit.

4. The method according to claim 1, wherein ethanol or isopropanol is supplied as the cold-resistant liquid or as the main component thereof.

5. The method according to claim 1, wherein a cooling head (21) is provided, the cooling head (21) covering at least one section of the adhesive connection to be separated in each case, the coolant is introduced between the cooling head (21) and the section (8) of the adhesive connection covered by the cooling head (21).

6. The method according to claim 5, wherein the cooling head (21) is pressed against the respective area (28) of the adhesive connection to be separated and largely seals off the coolant volume enclosed by the cooling head (21), the material of the cooling head (21) adapts elastically to the respective shape of the adhesively joined partners (26) and becomes less elastic by introducing the coolant into the area between the cooling head (21) and the adhesively joined partners (26) to be separated.

7. The method according to claim 5, wherein the adhesive connection to be separated as a whole cools down partially by successive displacement of the cooling head (21) relative to the adhesively joined partners (26) and the adhesive connection is partially separated one after the other.

8. The method according to claim 5, wherein remaining joints between the contact areas (23) of the cooling head (21) and the adhesively joined partners (26) are sealed by the effect of the escaping coolant.

9. A jet device comprising a supply unit (9) for liquid carbon dioxide, a first dosing unit (4) for the liquid carbon dioxide, an expansion chamber (2), an outlet opening (18) and a first line section (3), led to the outlet opening (18) realized as part of the expansion chamber (2), with an additional connection for a cold-resistant liquid as well as a second dosing unit (12) and a second line section (11) are provided for a cold-resistant liquid as a connection from the second dosing unit (12) to the expansion chamber (2) and/or to the first line section (3) of the expansion chamber (2).

10. The jet device according to claim 9, wherein the jet device provides a plastic jacket (10) or vacuum insulation at least in sections for thermal insulation.

11. The jet device according to claim 9, wherein the first line section (3) of the expansion chamber (2) is shaped divergently or has a constant cross-section.

12. The jet device according to claim 9, wherein the second line section (11) opens into the first line section (3) of the expansion chamber (2).

13. The jet device according to claim 9, wherein the expansion chamber (2) is provided as part of the dosing unit (4) and/or the first line section (3) is provided by means of a tubular base body (1) of the jet device and the outlet opening (18) is provided by means of a housing body (5).

14. The jet device according to claim 9, wherein the mixture of carbon dioxide and cold-resistant liquid exiting the jet device enters through a housing which adjoins the outlet opening (18) and which extends to the surface of the part to be separated and/or the contaminated surface of the part to be cleaned and is open and which has an opening for the removal of the mixture of carbon dioxide and cold-resistant liquid to which a discharge line is connected, which leads the mixture into the outside atmosphere or into a processing unit for further use and/or processing.

15. The jet device according to claim 9, wherein a cooling head (21) is provided, the cooling head (21) covering at least a section of the adhesive connection to be separated in each case, wherein a coolant with the carbon dioxide and the cold-resistant liquid can be introduced between the cooling head (21) and the section of the adhesive connection covered by the cooling head (21).

16. The jet device according to claim 15, wherein the basic shape of the cooling head (21), preferably by means of additive manufacturing processes, is adjustable to the respective shape and/or geometry of the adhesively joined partners (26) in the area of the respective adhesive connection to be separated.

17. (canceled)

18. The jet device according to claim 15, wherein the cooling head (21) shows a material which, at normal ambient temperature, can be elastically deformed and adapted to the shape of the adhesively joined partners (26) in the area of the respectively covered adhesive joint, the material of the cooling head (21) retains its respective shape when the adhesive joint cools, preferably solidifies inelastically.

19. (canceled)

20. The jet device according to claim 15, wherein the cooling head (21) partially cools the complete adhesive connection to be separated by successive displacement relative to the adhesively joined partners (26) and the adhesive connection can be partially separated one after the other.

21. (canceled)

22. The jet device according to claim 15, wherein the cooling head (21) has a separating device with which the adhesively joined partners (26) can be separated by applying a mechanical force, preferably a force introduced in a pulsed manner, in the region of the cooled adhesive surface.

23-24. (canceled)

25. The jet device according to claim 15, wherein the material of the cooling head (21) comprises, at least in sections, plastic materials with a glass transition range between -50° C. and -78° C., preferably silicone rubber and/or styrene-butadiene rubber and/or polybutadiene.

26. The jet device according to claim 15, wherein the material of the cooling head (21) comprises metallic materials, at least in sections, which are formed in the form of a bellows (22) or similar to corrugated pipes or flexible hoses.

27. A method of using the jet device according to claim 9 for embrittling adhesive surfaces for the purpose of separating and/or removing contamination such as adhesive residues from a surface by means of a cleaning method, wherein liquid carbon dioxide passes from a supply to the jet device and is guided there through a first dosing unit (4) into an expansion chamber (2), wherein a cold-resistant liquid is then supplied to a mixture of gaseous carbon dioxide and carbon dioxide particles produced in the expansion chamber (2), and wherein the mixture mixed with the cold-resistant liquid then exits the jet device as a coolant via an outlet opening (18) of the jet device.

Description

[0037] Show it:

[0038] FIG. 1 - shows a partial sectional view of a jet device according to the invention,

[0039] FIG. 2 - is a schematic representation of a cleaning arrangement with the jet device according to FIG. 1,

[0040] FIG. 3 - shows a schematic, isometric representation of a cooling head as an optional part of the device according to the invention with an elastic, bellows-like basic structure and connections for the supply of a coolant into the interior of the cooling head,

[0041] FIG. 4 - shows the cooling head according to FIG. 3 in three plane views,

[0042] FIG. 5 - shows a first application of the cooling head according to FIG. 3 on a plane adhesive surface for cooling the adhesive as part of a separation of the adhesive joint partners before and after placing the cooling head on the adhesive joint partners in the undeformed state and in the compressed state,

[0043] FIG. 6 - shows a further application of the cooling head according to FIG. 3 with blow-out openings arranged on the bellows-like lamellae and a curved contact surface on the adhesive joint partners, and

[0044] FIGS. 7 to 9 - applications of a straight-shaped cooling head according to FIG. 3 on a flat adhesive surface (FIG. 7), a sloping-shaped cooling head on a sloping adhesive surface (FIG. 8) and a rounded-shaped cooling head on a rounded adhesive surface (FIG. 9)

[0045] FIG. 1 shows a partial sectional representation of a jet device according to the invention. The jet device according to the invention comprises as essential components a tubular base body 1, a housing body 5, which surrounds the outer surface of the base body 1 in sections and provides an outlet opening 18, a feed unit 9 for the liquid carbon dioxide and a first dosing unit 4, via which the feed unit 9 is connected to the base body 1. Also provided are a second dosing unit 12 for the cold-resistant liquid and a line section 11 associated with the second dosing unit 12 for the cold-resistant liquid.

[0046] The first dosing unit 4 and the base body 1 of the jet device together provide an expansion chamber 2 which is formed in sections by a first line section 3 which has a cylindrical, convergent and/or divergent cross section.

[0047] In the expansion chamber 2, the liquid carbon dioxide expands and gaseous carbon dioxide and carbon dioxide particles are formed. The carbon dioxide mixture passes through the first line section 3 to the housing body 5 of the jet device and leaves it through the outlet opening 18 formed on the housing body 5.

[0048] The second line section 11, which is used to supply the cold-resistant liquid, opens into the divergently shaped part of the first line section 3. The cold-resistant liquid is therefore added to the carbon dioxide mixture shortly before it exits the jet device.

[0049] The quantity of the cold-resistant liquid can be set via the second metering unit 12 if it is not already contained in the liquid gas. In particular, the second dosing unit 12 can be designed in such a way that a cross section is completely blocked and the addition of the cold-resistant liquid is dispensed with.

[0050] An annular gap 14 is formed between the base body 1 and the housing body 5 of the jet device. Bores 6 provided on the housing body 5 are assigned to the annular gap 14 distributed in the circumferential direction. Ambient air can either be sucked in via the bores 6 or another propellant gas, for example compressed air, can be added. By supplying the ambient air, the jet geometry of the exiting jet can be influenced and excessive cooling of the housing body 1 can be counteracted. The supply of the propellant gas can also affect the geometry of the jet and counteract a cooling of the housing body 1. In addition, the emerging jet can be accelerated by the propellant gas, with the result that the cleaning effect is improved once again.

[0051] In the present case, the jet device provides a plastic jacket 10 on the base body 1, which is used for thermal insulation. Alternatively, for example, vacuum insulation can be provided.

[0052] FIG. 2 shows a schematic representation of a cleaning arrangement with the jet device according to FIG. 1. Here, a carbon dioxide tank 16 is connected to a supply hose 7 of the supply unit 9, via which the liquid carbon dioxide is made available. The supply hose 7 is connected to the first dosing unit 4 of the jet device via a screw connection 8.

[0053] Instead of the carbon dioxide tank 16, for example, a riser tube bottle or a bundle of bottles can be provided for storing the carbon dioxide.

[0054] Furthermore, a pressure bottle 17 in which the cold-resistant liquid is provided is connected to the second dosing unit 12 via a supply line 15. Instead of the pressure bottle 17, for example, a tank with a pump for the cold-resistant liquid can be provided.

[0055] To clean a surface that is not shown and to remove adhesive residues, a valve of the first dosing unit 4 is usually completely closed first. A valve of the second dosing unit 12 is also completely closed. A closure (not shown) of the CO.sub.2 tank 16 is then opened. The first dosing unit 4 is then set in such a way that the desired ratio of gaseous carbon dioxide and carbon dioxide particles is provided. Typically, the adjustment will be such that about 40 to 60% solid carbon dioxide particles are provided and that 250 to 350 litres of gaseous carbon dioxide are produced from one kilogram of liquid carbon dioxide. Furthermore, by opening the second dosing unit 12, the cold-resistant liquid can then be added to the carbon dioxide mixture.

[0056] A cooling head 26 may be provided as part of the apparatus of the present invention. FIGS. 3 and 4 show schematically a cooling head formed here by way of example from segments 22 in the form of bellows, which is used for local cooling of at least sections 28 of the adhesively joined partners 26 to be separated, so that these adhesively joined partners 26 can be separated from one another with lower mechanical forces. For this purpose, by the effect of the coolant, which is conducted from a coolant reservoir (not shown) by means of fluid-tight connections to connections 25 in connection pieces 24 on the cooling head 21 and from there into the hood-like interior of the cooling head 21, which is surrounded by the cooling head 21, the adhesively joined partners 26 and the adhesive between the adhesively joined surfaces is thus cooled in such a way that the glass transition temperature of the adhesive is undershot. In this cooled state, the strength of the adhesive connection below the cooling head 21 is significantly reduced to such an extent that the adhesive connection is destroyed even by small, for example sudden, loads on the adhesively joined partners 26 and the adhesive joint partners 26 can be detached from one another at least locally.

[0057] In order to be able to carry out this cooling with the least possible loss of coolant, the coolant is fed into the interior of the cooling head 21 and the solid particles of the carbon dioxide typically change into the gaseous state, whereupon a large amount of cold is released inside of the cooling head 21 and acts on the adhesively joined partners 26 arranged on the cooling head 21 and the section 28 of the adhesive layer. As a result, the adhesive between the adhesively joined partners 26 becomes brittle and the adhesively joined partners 26 can be separated from one another much more easily, for example by means of hammer blows or other mechanical effects. If the adhesively joined areas of the adhesively joined partners 26 are larger than the dimensions of the contact surfaces 23 of the cooling head 21, the cooling head 21 can be displaced or repositioned relative to the adhesively joined partners 26 and the process of cooling and separating is repeated and the entire bonded connection between the adhesively joined partners 26 are gradually separated. Due to the brittle fracture behaviour of the adhesive in the cooled state, a material-friendly removal is made possible, since the joint partners 26 are not damaged. A repair bond or rebonding is thus made possible.

[0058] With the device according to the invention, it is possible to partially cool adhesive connections within a few seconds to a temperature below -70° C. and to separate them manually with little effort. For this purpose, an advantageously flexible cooling head 12 in the basic form of a bellows 22 is used, which is made, for example, from elastomeric materials that have brittle properties below their glass transition temperature, and for example can be made from silicone rubber and/or styrene-butadiene rubber and/or polybutadiene or the materials TPU or TPE. This also makes it possible to deep-freeze curved geometries. The cooling head 21 can, for example, be attached to ferromagnetic, adhesively joined partners 26 by means of attached magnets or pressed by the worker using a thermally decoupled handle (not shown here) to the region 28 of the adhesively joined partners 26 to be cooled. The carbon dioxide CO.sub.2 or nitrogen emerging from the coolant reservoir fills the cooling head 21 and thus carries out a cooling of the contact surface 28 under the cooling head 21. The temperature in the cooling head 21 can be monitored in an integrated manner via a thermocouple (not shown). One or more vent openings 27 can be provided on the cooling head 21 for pressure equalization.

[0059] As an addition, it is also possible to digitally record the area 28 of the adhesively joined partners 26 to be removed via a scanning process and to generate one or more individual cooling heads 21 from the resulting 3D model using an additive manufacturing process, for example. Likewise, the force required for separating can be applied by a suitable mechanical or motorized mechanism (chisel or similar).

[0060] A further possibility for designing the cooling head 21 would be the use of metallic materials which are constructed in the form of a bellows 22 or analogous to corrugated pipes or flexible hoses.

[0061] With the invention, industrial as well as repair shops, especially in the automotive sector, can dismantle and/or clean adhesive joints as required with very little effort. This results in both monetary (reduction in working hours) and ergonomic (less physical stress on the worker) advantages. In addition, the invention can be used wherever adhesive bonds have to be removed, in particular non-destructively, for example in the railway industry, the aircraft industry, mechanical engineering, electronics and the plastics industry: The adhesive connection of components has meanwhile gained immense importance. Particularly suitable adhesives are cross-linked adhesives, which react to cold exposure with embrittlement and/or hardening, for example epoxy resins, polyurethane adhesives and/or acrylate adhesives.

[0062] A simple adaptation of the shape of the cooling head 21 is also advantageous, in which, for example, the bellows-like sections 22 of the cooling head 21 and/or the contact surface 23 of the cooling head 21 on the adhesively joined partners 26 and the sealing elements present there are made of an elastic material that adapts elastically to the shape of the sections 28 to be separated of the adhesively joined partners 26. For example, elastically deformable materials such as TPU, TPE or other elastomeric materials can be used for this. It is advantageous here if these materials themselves have glass transition temperatures below which they reversibly lose their elasticity and exhibit brittle properties. This can be used to also temporarily harden these materials under the influence of the coolant, which is introduced into the cooling head 21 anyway to embrittle the adhesives of the adhesive joint, and thus retain their geometry achieved by pressing against the shape of the adhesively joined partners 26. As a result, the deformed state of the bellows-like sections 22 of the cooling head 21, as can be seen, for example, in FIG. 6 can be retained and the cooling head 21 no longer has to be pressed against the adhesively joined partners 26 against the elasticity of the bellows-like sections 22 of the cooling head 21. As a result, on the one hand, the worker is relieved when operating the cooling head 21 and the sealing effect between the cooling head 21 and the adhesively joined partners 26 is improved.

[0063] Furthermore, as can be seen in FIGS. 7 to 9, the basic shape of the cooling head 21 can be adapted to the shape of the adhesively joined partners 26 in the region 28 of the adhesively joined surfaces to be separated, for example by placing an inclined cooling head 21 on an inclined bonding surface 26 (FIG. 8) or a rounded cooling head 21 is adapted to a rounded adhesive surface 26 (FIG. 9). As a result, in addition to the elastic properties of the cooling head 21, adhesively joined surfaces with a complex shape can also be reliably covered by the correspondingly shaped cooling head 21 and separated more easily by cooling. Due to the bellows-like design 22 of the cooling head 21, as can be seen from the before and after comparison of FIGS. 5 to 9, the cooling head 21 is compressed when it is placed on the adhesively joined partners 26 and the elastic sealing effect on the coolant is improved. This also reduces the coolant volume required within the cooling head 21, and so overall less coolant is required overall.

[0064] Identical components and component functions are identified by the same reference symbols.

TABLE-US-00001 Reference List 1 - base body 2 - expansion chamber 3 - line section 4 - dosing unit 5 - housing body 6 - bores 7 - supply hose 8 - screw connection 9 - feed unit 10 - plastic jacket 11 - line section 12 - dosing unit 14 - annular gap 15 - supply line 16 - carbon dioxide tank 17 - pressure bottle 18 - outlet opening 21 - cooling head 22 - elastically deformable sections/bellows 23 - contact surface on adhesively joined connection 24 - connection piece 25 - valve 26 - adhesively joined partners 27 - opening 28 - area of the adhesive joint covered by the cooling head