RU2264587C1 - Method of mounting evaporator on refrigerator facing - Google Patents

Abstract

FIELD: refrigeration or cooling.

SUBSTANCE: method comprises applying sizing agent between the outer side and evaporator. The applying of sizing agent comprises injecting semi-liquid sizing agent from the nozzle of the spraying head mounted opposite to the surface which is at a distance from it and converting the jet into sprayed aerosol before it impacts the surface so that the surface undergoes the jet and is covered with a homogeneous layer of sizing agent.

EFFECT: reduced cost.

9 cl, 12 dwg

Description

The invention relates to methods and devices used in the production technology of household-type refrigerators equipped with a so-called “hidden” type evaporator, that is, an evaporator that is installed not inside the refrigerator compartment for storage or cooling, but outside this compartment, and is usually recessed into a heat-insulating material covering the compartment itself.

Domestic refrigerators having a compartment for cooling or storing [products] refrigerated and a “flush” type evaporator are well known in the art. In most cases, the liner that covers these compartments for storing [food] refrigerated in such household appliances is made of thermoformed plastic materials, usually sheet polystyrene, and is thermally insulated from the outside using a layer of heat-insulating material, usually polyurethane, which is applied from the outside such cladding using known foaming processes.

Taking into account the technological considerations of production and the release of the internal space of the [food] storage compartment from clutter caused by the presence of an evaporator, which is made in the form of a laminated panel fixed to the outer surface of said cladding before foaming in such a way that, after foaming, said laminated panel is practically recessed said layer of foamed insulating material and is held captive, i.e. "frozen" between the aforementioned layer and the lining, providing the required thermal insulation interaction.

However, in order to ensure accurate installation and stability of such a laminated panel during various operations preceding foaming, and first of all, taking into account the required strength and integrity provided by the method of attaching this laminated panel to the cladding surface, commonly used technologies require applying a very thin layer on it adhesive on both sides. It is applied by placing between the cladding and the laminated panel so that this panel is practically “glued” to the surface of the said cladding.

The type of this material, adhesive on both sides, and its thickness, of course, is selected so that by all means avoid the weakening of direct heat transfer, which is required in this case of use.

On the other hand, such a technology is well known in the art and is widely used without significant drawbacks or problems caused by both technical and functional reasons.

The closest analogue of the claimed technical solution is the method of installation of the evaporator, known from British patent 1471722 (F 25 B 39/02, 1977). The evaporator has, in particular, one of the sides lying in the plane, and is mounted on the outer surface of the lining, inside which there is a compartment for storing products of the refrigeration device.

However, household refrigerators are very popular and widespread consumer durables, which are usually found in large-scale mass production. Therefore, the need for an additional technological transition, which usually should be carried out outside the automated production line (in order to ensure the possibility of performing certain operations that must be performed manually) and which also requires the use of additional materials, that is, a layer adhesive on both sides, leads to additional growth production costs. This is increasingly unfavorable and less and less acceptable for both manufacturers and the market.

Thus, there is a need to develop a method of installing the evaporator panel on the outer surface of the lining of the household refrigerator before foaming, which is the purpose of this invention. This makes it possible to obtain a significant reduction in the cost of production and the commissioning of a fully automated execution of this operation.

In accordance with the invention, the method of installing an evaporator having one of the sides lying in a plane on the outer surface of the lining, inside which there is a compartment for storing products of the refrigeration device, differs in that it includes an operation in which an adhesive is applied between said outer surface and vaporizer. The application of the adhesive includes the ejection of a stream of semi-liquid adhesive from the nozzle, which is part of the spray head mounted opposite the said surface and located at a certain distance from it, and converting said semi-liquid jet into a spray aerosol before it hits the said surface in such a way that the latter is exposed to said sprayed jet and is suitably coated with an almost uniform layer of said adhesive on the matter.

In addition, the conversion of said adhesive into a sprayed aerosol is carried out by exposing said jet to at least one stream of gas, preferably ambient air, directly after the outlet of said spraying nozzle so that this said spray breaks up into a sprayed aerosol directed towards said outer surface.

The differences of the claimed method also include the fact that said adhesive substance is applied to said surface over its entire area in a weight amount in the range of 130-220 g / m ² , and said nozzle emitting said adhesive stream is located at a distance of 5-8 cm from said outer surface.

At the same time, the temperature at which the mentioned semi-liquid adhesive leaves the spray nozzle is constantly maintained in the range from 140 ° C to 170 ° C, and the time required to cover the specified surface with this sprayed aerosol does not exceed 30 s, provided that the surface subjected to processing, has an area of 30 dm ² .

The invention also provides a device for ejecting and precipitating a flow of adhesive on a preferably flat surface, in particular on the surface of the lining of a refrigeration device, the difference of which is that it contains at least one of the following elements or one of their combinations:

- spray head

- a device for preparing this adhesive substance and supplying it under pressure to said spray head.

Said spray head comprises a supply pipe for said adhesive substance, a second pressure gas supply pipe, an electromagnetic valve controlling said supply pipe for said adhesive material suitable for the first nozzle. The head also has one or more other nozzles located in the immediate vicinity of said first nozzle, which are arranged to supply said gas stream to the expiration zone from said first nozzle so as to cross an adhesive jet ejected from it. Moreover, said first nozzle and said other nozzles are optionally provided as through holes in a nozzle panel located on the underside of said head.

The device in accordance with the invention may also contain means for moving in an appropriate order the liners under the spray head and additional elements that can at least partially be selectively positioned and moved over the means for moving and which are connected with the possibility of smooth movement with the spray head. In addition, it comprises a control device for controlling the position and movements of said additional elements.

In addition, said spray head may also comprise two independent heating elements configured to selectively heat said adhesive stream and said gas stream.

The method is simple to implement and implement using existing techniques. It provides the required stability of the heat exchange conditions between the evaporator panel and the lining.

The characteristic features and features indicated in the claims are described in more detail below using a non-limiting example, with reference to the accompanying drawings, where:

Figure 1 is a diagram of a coating of adhesive strips of the outer surface of the lining of a refrigeration device in accordance with the method of this invention.

Figure 2 is a schematic perspective view of the arrangement of the device according to this invention.

Figure 3 is a schematic top view of the device according to this invention.

Figure 4 is a perspective view of the assembly of the device shown in the previous figures.

Figure 5 is a functional diagram of the node shown in Figure 4.

6 is a functional diagram of another node of the device according to this invention, made in the form of a section.

Fig.7 is a bottom view of the nozzle included in the node shown in Fig.4.

Fig. 8 is a schematic illustration of the phase of expiration and dispersion (spraying) of a stream of adhesive material exiting the nozzle shown in Fig. 7.

Fig.9 is a view of the lining, past the application of the adhesive substance in accordance with the method according to this invention immediately before and after installing the corresponding evaporator.

Tasks of paramount importance, that is, those tasks that certainly had to be solved in the course of research on this object, are as follows:

- the ability to fully automate the process in accordance with the developed method,

- the possibility of integrating this method into a continuous cycle of in-line production,

- reduction of production costs;

- the absence of any systematic deformation or distortion of the shape of the lining during the installation operation of the evaporator,

- simplicity and high reliability of the method,

- the highest possible safety and low environmental impact,

- uniform coating or, in any case, the characteristics of the ability to cover, satisfying the set requirements.

Based on these initial requirements, a large number of comparative experiments and practical tests were carried out, paying attention also to statistical studies and research methods based on the design of a factorial experiment with fractional replicas in order to determine the main parameters of this method.

As a result, based on these assumptions, a method was developed that to a large extent allows us to achieve these goals and solve the tasks. The main characteristic feature of the method, which distinguishes it at least partially from existing technological methods, consists mainly in the fact that the adhesive is not applied by means of substrates, which are subsequently removed (in the form, for example, in many ways similar to stickers or adhesive labels) and is applied directly to the surface to be treated by spraying with one or more suitable spray heads. Such heads are equipped with both a nozzle from which a thin stream of previously prepared liquid glue is sprayed, and several nozzles from which air jets are blown accordingly. Said nozzles are located in the immediate vicinity of the glue jet and are oriented so that they break and thus spray the glue jet. Therefore, the jet practically turns into a stream of matter that resembles a very finely dispersed and, in this case, practically atomized free aerosol.

Thus, it was found that in order to achieve the above goal, the so-called "SPIRO" method can be used, which essentially represents the execution of one or more nozzles in the immediate vicinity of the nozzle, from which the adhesive is supplied in the form of a continuous jet, which practically sprayed.

The impact produced by various air jets is twofold. In fact, in addition to the first and essentially more important effect of obtaining a wide and long strip of glue, sprayed to a high degree of fineness, which is distributed not only uniformly on the treated surface, but also alternating this strip with limited sections of the untreated surface, as shown schematically in Figure 1 and Figure 9, the effect of maintaining the required temperature of said adhesive in a very short but very important time interval between the release of glue from the nozzle is also manifested before this glue is deposited on the surface of the cladding.

Figure 2 shows an example of a preferred embodiment of the device in accordance with the method according to this invention. Before foaming, in order to form thermal insulation, the liners 1 are arranged in the right order, with their rear side up, on the continuously moving vehicle 2. Usually it is a plate conveyor that moves the said liners 1 under the spray head 3 in the corresponding order.

This spray head is designed in such a way that it can move along three mutually perpendicular axes X, Y and Z. Of these, the X axis is a vertical movement relative to said vehicle 2 (as a result, in the case of claddings of the same type, i.e. having similar sizes, there will be no displacement of the mentioned spray head along the X axis).

The mentioned spray head 3 is then driven in a horizontal plane along the two Y and Z axes using a console 4 connecting the said head 3 with the first element 5, which ensures its horizontal smooth movement along the Z axis direction, extending perpendicular to the direction of movement of the plate conveyor. This first element, in turn, is connected with the second element 6, which also provides horizontal smooth movement of the head, however, in the direction of the Y axis, which is parallel to the direction of movement of the plate conveyor 1.

In addition, there are means (not shown) for actuating the two mentioned movement mechanisms, which are arranged to move, under appropriate control, of said spray head 3 to any position in space, namely to any position located in a horizontal plane parallel to surface 8 of the said cladding to be processed, and located, thus, at the same distance from it.

Since special attention is paid to this spray head 3, it is shown schematically in FIG. 3, FIG. 4 and FIG. 5. Its main parts are:

- building 11,

- pipe 12 for supplying a sticky substance,

- pipe 13 for supplying an air stream for spraying,

- nozzle panel 14,

a solenoid valve 15 for controlling said pipe 12,

two independent heating elements 16, 17 for selectively heating said adhesive stream and said spray air stream, which are provided with respective power cables 16A, 17A,

- a control cable 18 connected to said electromagnetic valve 15.

Said nozzle panel 14, in turn, has at least one preferably central nozzle 19 configured to expel said adhesive, as well as several nozzles 23 for pressurized air which are oriented so as to cause a spray of adhesive.

Since attention is paid to the device as a whole, FIG. 3 also shows its other components, such as device 20 for preparing, heating, diluting, compressing and pumping the adhesive. In addition, the device comprises a control unit 21 for generating and transmitting corresponding sequences of synchronized control signals intended to at least control the operation of the drives of said first element 5 and said second element 6, which determine the position of the console 4, which, in turn, carries the aforementioned spray head 3.

Said device 20 and said control unit 21 are already available on the market or, in any case, can easily be adapted for this purpose by specialists in this field. Therefore, given the fact that these elements are not an integral part of the device according to this invention, they are not further described in more detail.

The following describes the operation of the device according to this invention, the description of which deliberately omitted all those details that are completely obvious or completely included in the circle of knowledge of specialists in this field.

On a plate conveyor 2, which moves in the direction shown by the arrow, a number of claddings 1 are installed at an equal distance from each other, following each other in the corresponding order, and the machined surface 8 of said claddings 1 is oriented so that it faces upwards. Above the mentioned surfaces at a certain distance from them is a spray head 3, which is installed as described above. This spray head is driven along two axes, X and Z, by communicating the respective motion components with well-known means (not shown) to said second element 6 and first element 5.

It is also quite obvious that in order to provide movement control and positioning of the console 4 supporting said spray head 3, said console 4 is connected with the possibility of smooth movement to said first movable element 5 by appropriate means (not shown, but conditionally designated as H). Said first element, in turn, is connected with the possibility of smooth movement to said second movable element 6 also by means of which are not shown, but are conditionally indicated in the drawing as K.

At the same time, the adhesive preparation device 20 provides a flow of said adhesive to the pipe 12 through which it then enters the nozzle 19 of the panel 14. However, it is kept closed thanks to the electromagnetic valve 15 mounted on the spray head 3, which is closed position. Thus, said adhesive substance is supplied under pressure to the inlet of said electromagnetic valve.

At predetermined times while the said console 4 is moving, the electromagnetic valve 15 mounted on the spray head 3 opens. Thus from the nozzle 19 of the panel of nozzles 14 is emitted a thin continuous stream of adhesive substance directed downward.

Since said nozzle panel is also provided with nozzles 23 located in the immediate vicinity of the adhesive nozzle 19, and since these nozzles are directed obliquely downward, they practically cause a thin jet of adhesive to be emitted from said nozzle 19. As a result, the adhesive jet directed on the surface 8 of the cladding, is broken up to a spray aerosol.

For processing, which should provide an appropriate coating of this facing surface 8, the spray head 3 is controlled so as to perform repeated movements along the Y and Z axes, that is, to make several passes along the mentioned axes at a time when each surface 8 stops below it. In this case, the sprayed glue stream can be sprayed on this surface with the required uniformity and in accordance with the required coating scheme, as this is shown as an example by schematic in FIG. 1.

In this way, said sprayed adhesive stream acts on a predetermined portion A of the cladding surface and is applied to said surface to be treated in accordance with a predetermined geometry, that is, a pattern. Thus, in fact, these predetermined portions of said surface are substantially coated with said adhesive to a predetermined degree, while the process is fully controllable.

Preferably, both the adhesive stream and the air jets exiting from said nozzle panel 14 are heated immediately before being discharged from said panel. For this, the already mentioned corresponding heating elements 16, 17 are suitably provided with power by means and methods that are widely known in the art.

In the process of implementing the program of comprehensive systematic experiments and a comparative assessment of their results, it was also possible to determine ways and means that provide optimal and favorable results of the process. Basically, these ways and means with the corresponding details are as follows:

- the adhesive substance used in this method has properties generally similar to those of the product widely available on the market under the name PRESSEN 1510. Its main properties are shown in Table A;

- this adhesive is preheated to a temperature in the range between 140 ° C and 170 ° C and ejected from the spray head at this temperature;

- this adhesive substance is then sprayed over and settles on the surface to be treated by ejecting a continuous thin stream from the corresponding nozzle, which is sprayed immediately after leaving the said nozzle;

- this jet of sprayed adhesive must be applied to the surface to be treated in an amount of 130 g / m ² to 220 g / m ² ;

- the speed with which said jet is ejected from the nozzle should be in the range between 100 mm / s and 200 mm / s;

- the distance from the said panel of nozzles 14 to the surface beneath it to be coated should be in the range from 5 cm to 8 cm.

It is clear that the actual size of the resulting glue jet is a critical factor. It was found that the ideal outflow of glue should come from a nozzle, the outlet of which should have a diameter of 0.35 mm to 0.5 mm.

In addition, it was found that the optimal size of the jet at the moment when it hits and settles on the surface to be processed should not be less than 3 mm in width.

It can be noted that this design is completely different from the known technical solutions of this type, in which the surface is always completely, without any gaps, is subjected to the application of a layer of glue.

It was also found that optimal adhesion can be achieved when the surface area actually treated with glue is at least 95% of the surface 8, which should be subjected to such processing, for reasons of adhesion to it. It is quite obvious that various schemes for applying strips of said glue can be selected. On the other hand, it is clear that the best possible application scheme can be simply and most effectively determined based on existing limitations and experimental checks. This, in turn, is completely within the competence of any specialist in this field of technology.

In particular, it was established and verified experimentally that the optimal characteristics can be achieved, in addition to using the above optimum amount of glue, and also ensuring the exposure time of the treated surface in air, which should not exceed 45 s before installing the evaporator panel on the said surface. In fact, this glue belongs to the so-called type with unlimited open exposure time, that is, it theoretically retains adhesive for an unlimited time. Practice, however, suggests that the evaporator panel should preferably be installed on an adhesive-coated surface within a 24-hour period.

In the course of the experiments carried out in this regard, it was noted that completely satisfactory results are achieved when the time required to cover a given surface with a given aerosol spray does not exceed 30 s with a treated surface of 25-30 dm ² .

It is quite obvious that all the main parameters of the method according to this invention, such as the distance between the nozzles, the pressure values, the angle between the axes of these nozzles, and so on, can be easily determined by simple observation of the operation of the device, as well as the implementation of planned and systematic cycles of experiments with a sequential change in the set of parameters, which is quite accessible for any specialist in this field of technology.

Since attention is paid to the coating agents per se, they can be a NORDSON 3830V type glue applicator, which is able to provide the above process parameters or it can be controlled, adjusted or programmed in such a way as to provide them.

To more clearly determine the characteristics of the two methods of installing the evaporator using glue, namely, in accordance with the known methods and according to this invention on a comparative basis, laboratory tests were carried out, the results of which can be formulated as follows:

The main goal was to measure the stickiness during loading by delamination (multiplicity 90x) and to shift two methods of gluing: both directly on the products used in the experiment and, to increase the comparability of the estimate, on appropriately prepared samples.

The first study measured the viscosities of the two compounds as a function of temperature. As can be noted, judging by the graph below, the mentioned Pressen hot-melt adhesive shows a lower viscosity than the known means with double-sided adhesion, starting from a temperature of - 40 ° C. Then this difference shows a tendency to further increase, reaching a significant value at temperatures above 0 ° C. This fact, which favorably affects at low temperatures, makes such hot-melt adhesive much less stable at high ambient temperatures.

The effect of increasing the quantity of hot-melt adhesive on the ultimate load is negligible, in contrast to the total energy consumption due to the increased amount of work applied to the adhesive mass flow.

Thus, it has been convincingly demonstrated that such hot-melt adhesive does not cause any additional difficulties for the evaporator-lining system at low temperatures. On the contrary, a compromise should be considered as carefully as possible between low viscosity at high temperature, which allows working on an assembly-gluing unit at lower pressures, and relative adhesiveness, taking into account the aforementioned weak adhesiveness at elevated temperatures, especially taking into account the loads to which the assembly can be subjected to foaming.

At the end of this description, attention is drawn to a circumstance that may potentially be significant, although for a specialist in this field it is quite obvious. A preferred embodiment of the method described above is a process actually performed by the automatic device described above. However, due to reasons directly related to production, circumstances may turn out so that in practice it would be inappropriate or even inefficient to use an industrial plant of the type described above. In this case, it is obvious that the method of applying the glue according to this invention can be implemented and performed also in fully manual mode in accordance with at least one of the claims that relate to the coating method. This is the reason that paragraph 1 of the claims clearly relates the method to those that can "also be performed manually."

TABLE A

PRESSEN 1510 - hot-melt adhesive

1. MANUFACTURER AND MATERIAL

Commercial name of the product: PRESSEN 1510

Chemical characteristic: hot-melt adhesive

Manufacturer: Beardow & Adams (Adhesives) Limited

2. INGREDIENT INFORMATION

Chemical characterization: hot-melt adhesive containing thermoplastic polymers, adhesive resins, paraffins and antioxidant additives.

DESCRIPTION

PRESSEN 1510 is a universal pressure-sensitive adhesive based on synthetic polymers, intended for use in assembly, where it provides high-strength compounds. Sticks together plastics (high-strength epoxy-based polymers, polypropylene, polyvinyl chloride, polyethylene, nylon), rubber (natural, synthetic, neoprene), porous materials (leather, fabric, paper and cardboard), metals (aluminum, steel, painted steel). It has excellent adhesion, even for difficult materials. It is characterized by excellent thermal stability, excellent strength both at high and low temperatures, as well as resistance to aging and delamination.

SPECIFICATIONS Test method Softening point 80 ° C VA QA 102 Viscosity at 180 ° C (S.27 / 20 rpm) 7000 cp VA QA 101 Color Light amber tone Open exposure time Not limited Adhesive ability Very high

Recommended application temperature: from 160 ° C to 180 ° C depending on the substrate to be bonded.

Claims (13)

1. A method of installing an evaporator having one of the sides lying in a plane on the outer surface (8) of the lining (1), inside which there is a compartment for storing products of the refrigeration device, characterized in that it includes an operation in which the adhesive is applied between the said outer surface (8) and the evaporator, the application of the adhesive includes ejecting a jet of semi-liquid adhesive from the nozzle included in the spray head mounted opposite the said surface and (8) located on it at a certain distance, and converting said semi-liquid jet into the sprayed spray before entering it into said surface such that the latter is exposed to said spray jet and accordingly covered almost uniform layer of said adhesive. 2. The method according to claim 1, characterized in that the conversion of said adhesive substance into atomized aerosol is performed by exposing said jet to at least one stream of gas, preferably ambient air, immediately after the outlet of said atomizing nozzle so that this said jet is broken up to a spray aerosol directed to said outer surface (8). 3. The method according to claim 1 or 2, characterized in that said adhesive substance is applied to said surface over its entire area in a weight amount in the range of 130-220 g / m ² . 4. The method according to claim 1 or 2, characterized in that said nozzle ejecting said stream of adhesive substance is located at a distance of 5-8 cm from said outer surface. 5. The method according to claim 3, characterized in that said nozzle emitting said stream of adhesive substance is located at a distance of 5-8 cm from said outer surface. 6. The method according to claim 1 or 2, characterized in that the temperature at which the said semi-fluid adhesive sticks out of the spray nozzle is constantly maintained in the range from 140 to 170 ° C. 7. The method according to claim 3, characterized in that the temperature at which said semi-fluid adhesive sticks out of the spray nozzle is constantly maintained in the range from 140 to 170 ° C. 8. The method according to claim 4, characterized in that the temperature at which said semi-fluid adhesive sticks out of the spray nozzle is constantly maintained in the range from 140 to 170 ° C. 9. The method according to claim 5, characterized in that the temperature at which said semi-liquid adhesive sticks out of the spray nozzle is constantly maintained in the range from 140 to 170 ° C. 10. The method according to any one of claims 1, 2, 5, 7-9, characterized in that the time required to cover a given surface with a given aerosol spray does not exceed 30 s, provided that the surface to be treated has an area of 30 dm ² . 11. The method according to claim 3, characterized in that the time required to cover a given surface with a given aerosol spray does not exceed 30 s, provided that the surface to be treated has an area of 30 dm ² . 12. The method according to claim 4, characterized in that the time required to cover a given surface with a given aerosol spray does not exceed 30 s, provided that the surface to be treated has an area of 30 dm ² . 13. The method according to claim 6, characterized in that the time required to cover a given surface with a given aerosol spray does not exceed 30 s, provided that the surface to be treated has an area of 30 dm ² .

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