EP3896196B1 - Method and device for surface treatment of objects - Google Patents

Description

The present invention relates to a device and a method for optimized surface treatment of objects.

Objects containing metal or made of metal as well as objects with or made of plastic must be thoroughly cleaned before surface finishing, such as staining stainless steel or applying an anodized layer, galvanizing or galvanizing, in order to achieve an optimal result of the surface finishing. For this purpose, various cleaning steps are known from the prior art, which an object to be refined should generally go through one after the other. The surface treatment of objects for cleaning purposes usually begins with degreasing the objects. To do this, they are placed in baths for a defined period of time that contain a cleaning liquid to remove grease, oil and other contaminants. After the objects have been degreased, they are often put in a Immersed in a sink containing water before they are placed in a pickling basin containing hydrochloric acid for a defined period of time in the next step. This is where it takes place Removal of unwanted deposits on the surface of objects, especially rust and scale. After staining, the objects are dipped again into a sink containing water and then transferred to a so-called flux basin containing, for example, zinc chloride and/or ammonium chloride, to remove iron. After this pre-treatment step, the cleaned object is usually dried and is then available for the desired surface refinement.

In the state of the art, all of the pretreatment steps mentioned are usually carried out statically, i.e. the objects to be cleaned are immersed in the respective basins in which resting liquids, e.g. degreasing liquid, water, stain, flux liquid and/or other chemical process liquids that are used for the For the purposes of the invention, each is also referred to as a process liquid. However, the disadvantage of this static pretreatment is that the respective pretreatment steps take a comparatively long time, since no or only very little mass exchange takes place between the process liquid surrounding the objects and the remaining process liquid located in the basin.

By blowing air or compressed air into the basin, the process liquid in it can be moved, but this leads to undesirable foaming of the process liquid, which negatively affects the quality of the pretreatment. In addition, the objects to be treated are not flushed inside by the air flowing past and are therefore not optimally pre-treated inside.

From the EP 3 483 304 A1 It is also known to arrange at least one pump per flow direction in the side area of the basin in which the pretreatment takes place. At least one pump that delivers in one flow direction is therefore active, while at least one further pump that delivers in the other flow direction is inactive. The pumps create a laminar or nearly laminar flow in the pretreatment basin.

This use of pumps in a pretreatment tank brings numerous advantages. In particular, the duration of the pretreatment can be shortened by moving the process liquid, which brings with it a significant increase in efficiency and a large potential for savings. In this way, the pickling time can be shortened by up to 50%, for example. In addition, the surface treatment occurs more evenly as a result of the movement of the process fluid, which means less before surface finishing Rework is required. Because the surface treatment in a process liquid moved with pumps leads to objects with a more uniform surface, for example, in a later deposition of material on the object surface, for example later galvanization, fewer incorrect deposits occur and / or less material is required for the deposition the surface of the objects has fewer unevenness that needs to be compensated for.

Nevertheless, this brings out the EP 3 483 304 A1 Known pump system arranged in a pretreatment tank also has disadvantages. The arrangement of at least one pump per flow direction in a pretreatment basin brings with it the immense disadvantage of a loss of space in the basin due to the space required by the pumps arranged on both sides. In existing pools, the use of a corresponding pump arrangement is therefore ruled out simply because there is not enough space in the pool. The pump arrangement is therefore only suitable for newly built pools that can be made larger. However, this is also disadvantageous because a larger basin also requires more process fluid, which leads to higher material, chemical and energy costs. In addition, the costs for the device itself are also high, since at least one pump must be used for each flow direction. In addition, the device is EP 3 483 304 A1 The disadvantage is that the maintenance is complex, as this can only be carried out when production is interrupted due to the arrangement of the pumps on the front sides of the basin.

The DE 10 2009 034 007 A1 describes a coating system, in particular for electrophoretic or autophoretic coating or paint deposition. The system includes a circulation device for the purpose of a more uniform coating. This has a pump arrangement, preferably arranged outside the basin, to which a circulation volume flow of at least one bath volume of the immersion bath per hour can be supplied. By feeding the circulating volume flow into the immersion bath, a strong bath flow is generated. However, the strong bath flow is generated here by the fact that the process liquid previously removed from the basin, after it has been carried over a large distance, passed through pumps, filter devices and heat exchangers, is returned to the basin using nozzles or other pressure-increasing means. Due to the large distance that the process liquid has to bridge outside the basin, this is not possible without pressure-increasing means, but requires a comparatively high amount of energy.

The DE 10 2012 103 906 A1 describes a device for cleaning tubular hollow bodies. In addition to a cleaning container and two holders arranged therein, this also has a tubular element that connects the two holders and inside which a pump is arranged that can change its direction of rotation. By changing the direction of rotation of the pump, the tubular hollow bodies in the dead and shadow areas should be cleaned better.

The DE 696 30 293 T2 describes a method for cleaning hollow medical instruments, in which a medical instrument to be cleaned is attached to a hose connected to a tank containing a cleaning fluid and cleaning fluid is pumped into the interior of the medical instrument using a piston pump.

The DE 10 2015 014322 A1 describes a device for pickling and phosphating a metallic object, which comprises a treatment container with a treatment liquid into which the object to be treated is introduced. The treatment liquid is circulated by a pump device.

Task of the invention

It is the object of the present invention to provide an alternative device and an alternative method for optimized surface treatment of objects, which avoid the aforementioned disadvantages known from the prior art and are characterized in particular by the fact that the objects that are subjected to the surface treatment are optimal process liquid flows around or through it.

A further object of the present invention is to show a possibility of how existing pools, in which the surface treatment was previously carried out statically, can be easily converted into devices according to the invention with only a few additional components.

Yet another object of the present invention is to provide an alternative method by which an optimal result of the surface treatment can be achieved with a comparatively short duration of surface treatment and with a comparatively small amount of process liquid used.

General description of the invention

The invention solves this problem with the features of the claims and in particular by providing a device for the surface treatment of objects, comprising a process basin and a pump, a tubular structure being arranged in or on the process basin, which is bent over at least part of its length, wherein the two openings delimited by the two ends of the tubular structure point in the same direction, and the length of the tubular structure from its one opening at one end to its other opening at the other end is a maximum of twice as long as direct distance between the two openings bounded by the two ends of the tubular structure, and wherein the pump is arranged within the tubular structure, wherein the pump is a bidirectional pump which is adapted to be able to change its direction of rotation, and wherein the Pump, which is arranged within the at least one tubular structure, has a power of <1 kW.

“Length of the tubular structure” here means the path through the tubular structure from one opening at one end to the other opening at the other end, ie the length of the tubular structure including all bends thereof.

For the purposes of the invention, a process basin is understood to mean a basin that can be filled with process liquid and in which surface treatment of objects can be carried out. Process basins can therefore in particular be basins in which cleaning and/or degreasing, pickling, rinsing, flux treatment and/or another, in particular chemical, pretreatment process takes place.

A tubular structure is understood to mean an elongated hollow body with a round or oval cross-section, in particular perpendicular to its longitudinal central axis. The tubular structure has in particular a central straight or slightly curved section, which is flanked on both sides by two curved sections. Either the two ends of the tubular structure lie in the two spaced-apart curved sections or in optional further straight sections adjacent to them. Preferably, the tubular structure is mirror-symmetrical and the two openings bounded by the ends of the tubular structure point in the same direction. In a preferred embodiment, the tubular structure is C-shaped. If the tubular structure is arranged on or in the immediate vicinity of an end face of the process basin, the two openings, which are delimited by the ends of the tubular structure, preferably point towards the opposite end face.

According to the invention, the length of the tubular structure from one opening at one end to the other opening at the other end is a maximum of twice as long as the direct distance between the two openings that are delimited by the two ends of the tubular structure. This means that process fluid that enters the tubular structure at one end, passes through it and exits the tubular structure at the other end does not have to travel a large distance within the tubular structure. Preferably, the process liquid is guided within the tubular structure only in an arc of 180°, for example in a C-shaped arc. Because the process liquid in the tubular structure does not have to travel a large distance, but rather enters at one end of the tubular structure and, after passing the pump, exits again at the other end of the tubular structure, without having to take various detours such as in the DE 10 2009 034 007 A1 described, it is possible according to the invention for the process liquid to be returned after passing through the tubular structure into the process basin simply by flowing the process liquid into the basin, ie according to the present invention no pressure-increasing means such as nozzles are required for this . According to the invention, a bidirectional pump is arranged within the tubular structure. This means that the pump is positioned at any point within the hollow body, but preferably in the middle within the hollow body, so that its distance from the two ends of the hollow body is the same. The pipe section in which the pump is arranged preferably has a larger diameter than the remaining part of the tubular structure.

A bidirectional pump is understood to mean a pump that is set up to be able to change its direction of rotation or is set up to change its direction of rotation after predetermined time intervals. A bidirectional pump arranged in the tubular structure can therefore pump the process liquid located in the tubular structure in opposite directions depending on the setting. Preferred pump types are propeller pumps, centrifugal pumps, rotary lobe pumps, rotary lobe pumps, flap pumps, gear pumps, eccentric screw pumps, peristaltic pumps and pneumatic diaphragm pumps. The flow speed of the pump arranged in the tubular structure is preferably 1.5 to 6 m/s, in particular 2 to 5 m/s and particularly preferably 3 to 4 m/s.

A particularly preferred pump is a propeller pump.

Regardless of the pump type, the pump arranged in the tubular structure of the device according to the invention is preferably an acid and/or heat-resistant pump, which preferably has a heat resistance up to 65 ° C.

Preferably the pump, which is arranged in the tubular structure, comprises or consists of polyethylene, polypropylene, polyvinyl chloride or mixtures thereof.

According to a preferred embodiment of the device according to the invention, the pump, which is arranged in the tubular structure, is set up to vary the delivery rate, in particular in a range between 10 and 180,000 L/h. The power of the pump is <1 kW, more preferably even less than 800 W. This means that the pump in the device according to the invention works in contrast to other pumps that have a higher drive power and/or have a frequency converter in order to be able to set a variable delivery range , extremely energy efficient. Because a frequency converter has a very high energy requirement. The ones in the The pump used according to the invention, however, has an electronic control and therefore does not require a frequency converter.

The process basin has two opposite long sides and two opposite end faces, whereby the long sides are generally longer than the end faces, but in exceptional cases where the process basin is square, they can also have the same length as the end faces.

According to one embodiment, the tubular structure with the bidirectional pump arranged therein is a bypass which is arranged on an end face of the process basin. The pump conveys process liquid through the bypass and enters the process basin at the end face on which the bypass is arranged and flows towards the opposite end face.

It was found that the passage of the process liquid through the tubular curved structure, which enters the process basin at one end face and flows towards the opposite end face, particularly when objects to be treated are immersed in the process liquid, leads to a turbulent flow profile in the process basin , i.e. to a flow profile in which there is an exchange of substances between the individual liquid layers. In order to avoid the occurrence of flow shadows, the pump arranged in the tubular curved structure is set up to change the direction of rotation after a period of time of, for example, several minutes, in particular after 5-10 minutes, 5-15 minutes or 5-20 minutes, so that the process liquid still enters the process basin at the same end face after passing through the bypass, but through the other opening of the tubular structure. In this way, the device according to the invention with the tubular structure arranged in or on the process basin and the bidirectional pump arranged therein, which is set up to change its direction of rotation after certain time intervals, enables optimal flow around or through the fluid arranged in the process basin objects to be treated.

In embodiments in which the long sides of the process basin are significantly longer than its end faces, the device according to the invention preferably has two tubular structures, with a bidirectional pump being arranged in each of the tubular structures. The tubular structures are each arranged as a bypass on the same end face or as a bypass on the opposite end faces.

Optionally, the device according to the invention also has more than two, for example 3, 4, 5 or 6, tubular structures, with a bidirectional pump being arranged in each of the tubular structures. The tubular structures are preferably each arranged as a bypass on one end face of the process basin, whereby the number of tubular structures per end face can be the same or different. Alternatively, the tubular structures can also be arranged within the basin on its end faces, whereby the number of tubular structures per end face can also be the same or different. The bidirectional pump, which is arranged in each of the more than two tubular structures, optionally has the same properties as the bidirectional pump(s) which are arranged in a device according to the invention with only one or with two tubular structures are, i.e. the pumps have in particular the properties mentioned above with regard to the variable delivery range, the performance, the material, the pump type and the acid and heat resistance.

When arranging two tubular structures on the same end face of the basin, it is preferred that the tubular structures have the same dimensions and are arranged at a distance from one another and with their longitudinal axes parallel to one another at the same height of the process basin.

When arranging two tubular structures on opposite end faces of the basin, it is preferred that the tubular structures have the same dimensions and are arranged with their longitudinal axes parallel to one another at the same height, the openings of the tubular structure arranged on one end face being the openings facing the tubular structure arranged on the other end face. The directions of rotation of the pumps arranged in both tubular structures are identical, so that a flow generated on one side of the process basin is deflected by the tubular structure arranged on the opposite side of the process basin and is amplified by the pump arranged therein and moved back to the opposite side .

According to one embodiment, the tubular structure with the bidirectional pump arranged therein is arranged in the device according to the invention within the process basin on or in the immediate vicinity of an end face, with the openings, which are delimited by the two ends of the tubular structure, in the direction of the opposite one front side. In this embodiment, the tubular structure is not a bypass, that is, it does not run outside the basin like a bypass only in fluidic communication with it, but it is arranged directly in the process basin. The tubular structure can be shaped in the same way as a bypass, in which both ends of the tubular structure point in the same direction. The tubular structure can be arranged with its longitudinal axis directly on the end face of the process basin, with the ends of the tubular structure pointing in the direction of the opposite end face. Alternatively, the tubular structure can also be arranged at a small distance from an end face in the process basin, for example at a distance between the longitudinal axis of the tubular structure and the end face of the process basin of a few centimeters, in particular up to 10 cm, up to 20 cm or up to to 30 cm.

Regardless of whether the tubular structure is arranged directly on or in the immediate vicinity of an end face in the process basin, the pump arranged in the tubular structure generates a flow which emerges from the tubular structure and flows towards the opposite end face, whereby As a result of the flow impinging on the opposite end face and the flow against objects to be treated that are immersed in the process liquid, a turbulent flow profile is generated in the process basin, which results in an optimal flow around the objects to be treated, particularly when the direction of rotation of the bidirectional pump is occasionally changed objects.

In this embodiment, the device according to the invention preferably has not just one, but two tubular structures which are arranged within the process basin on or in the immediate vicinity of an end face. The tubular structures can be arranged on or in the immediate vicinity of the same end face or on or in the immediate vicinity of opposite end faces, with the openings, which are delimited by the two ends of each tubular structure, each pointing in the direction of the opposite end face.

Similar to the previously described embodiment with two bypasses that are arranged on the same end face of the process basin, it is also preferred in this arrangement of two tubular structures on the same end face within the basin that the tubular structures have the same dimensions and are spaced apart from one another are arranged with their longitudinal axes parallel to each other at the same height.

With an arrangement of two tubular structures opposite one another End faces within the basin, similar to two bypasses which are arranged on opposite end faces of the process basin, it is preferred that the tubular structures have the same dimensions and are arranged with their longitudinal axes parallel to one another at the same height, with the openings on the a tubular structure arranged on the end face faces the openings of the tubular structure arranged on the other end side. The directions of rotation of the pumps arranged in both tubular structures are identical, so that a flow generated on one side of the process basin is deflected by the tubular structure arranged on the opposite side of the process basin and is amplified by the pump arranged therein and moved back to the opposite side .

According to one embodiment, the device according to the invention has, in addition to the at least one bidirectional pump which is arranged within the tubular structure on an end face of the process basin, also at least two unidirectional pumps which are arranged on the end face of the process basin, which is the end face with the tubular structure opposite. These unidirectional pumps serve to amplify the flow generated by the bidirectional pump and are particularly used in longer process tanks where there is no space for a bypass in which a bidirectional pump is located on the side where the unidirectional pumps are located could be arranged, or due to the space requirement, no tubular structure should be arranged on the end face within the process basin. The two unidirectional pumps have opposite directions of rotation, with only the pump that has the same direction of rotation as the active bidirectional pump being in operation during the pretreatment of objects. When the direction of rotation of the bidirectional pump changes, the previously inactive unidirectional pump starts operating, while the previously active unidirectional pump pauses until the direction of rotation of the bidirectional pump changes again.

Optionally, the device according to the invention also has a shut-off device for the pump arranged in the tubular structure. This shut-off device is designed in particular to interrupt the fluid communication between the pump and the process basin. For example, the shut-off device can include ball valves or other shut-off valves arranged on both sides of the pump, which can be shut off if the fluid exchange between the pump and the process basin is to be prevented, for example for maintenance work.

Further optionally, the device according to the invention also has one or more solid-state filters, also called rectifiers, which can be arranged in particular within the tubular structure or at its ends. On the one hand, the at least one solid-state filter serves to protect the pump from unwanted ingress of dirt or solids, as this can lead to damage to the pump. On the other hand, the solid-state filter also functions as an intervention protection, which prevents operators of the device from accidentally reaching into the pump. Preferably, a solid-state filter is arranged on each side of the bidirectional pump arranged in the tubular structure.

The device according to the invention preferably also has an overflow channel through which fats, oils and/or contaminants can be separated.

• Bereitstellen einer Vorrichtung zur Oberflächenbehandlung von Objekten, umfassend ein Prozessbecken und eine Pumpe, wobei in oder an dem Prozessbecken eine rohrförmige Struktur angeordnet ist, die zumindest über einen Teil ihrer Länge gebogen ist, wobei die zwei Öffnungen, die von den beiden Enden der rohrförmigen Struktur begrenzt werden, in die gleiche Richtung weisen und wobei die Länge der rohrförmigen Struktur von deren einer Öffnung am einen Ende zu deren anderer Öffnung am anderen Ende maximal zweimal so lang ist wie die direkte Distanz zwischen den beiden Öffnungen, die von den beiden Enden der rohrförmigen Struktur begrenzt werden, und wobei innerhalb der rohrförmigen Struktur die Pumpe angeordnet ist, wobei die Pumpe eine bidirektionale Pumpe ist, die eingerichtet ist, ihre Drehrichtung ändern zu können, und wobei die Pumpe, die innerhalb der zumindest einen rohrförmigen Struktur angeordnet ist, eine Leistung von < 1 kW aufweist;
• Anordnen eines Objekts innerhalb des mit Prozessflüssigkeit befüllten Prozessbeckens;
• Umströmen lassen bzw. Durchströmen lassen des Objekts von Prozessflüssigkeit, wobei die Pumpe die Prozessflüssigkeit innerhalb der rohrförmigen Struktur in eine Richtung fördert.

The invention further relates to a method for the surface treatment of objects, comprising the steps:

• Providing a device for the surface treatment of objects, comprising a process basin and a pump, wherein in or on the process basin there is arranged a tubular structure which is curved over at least part of its length, the two openings extending from the two ends of the tubular structure be limited, point in the same direction and the length of the tubular structure from one opening at one end to the other opening at the other end is a maximum of twice as long as the direct distance between the two openings from the two ends of the tubular Structure are limited, and wherein the pump is arranged within the tubular structure, wherein the pump is a bidirectional pump which is set up to be able to change its direction of rotation, and wherein the pump, which is arranged within the at least one tubular structure, has a power of < 1 kW;
• Arranging an object within the process basin filled with process liquid;
• Allow process liquid to flow around or through the object, with the pump conveying the process liquid in one direction within the tubular structure.

The process liquid used in the method according to the invention is in particular Degreasing liquid, water, stain, flux liquid or another acid or alkali for (chemical) surface pretreatment of objects.

The object that is placed within the process basin filled with process liquid can be any object whose surface is to be treated in a process liquid. Examples of objects are in particular objects made of metal or plastic or objects that include metal, such as gratings and guardrails, and in particular objects containing steel or made of steel, e.g. steel beams or building structures of any kind. In a preferred embodiment, the objects include or consist of iron, Aluminum, zinc, steel and/or other alloys that include iron, aluminum and/or zinc, the objects optionally having a coating to protect against corrosion, in particular galvanizing, galvanizing, cathodic dip coating, anodizing, wet or powder coating .

• das Prozessbecken der verwendeten Vorrichtung zwei sich gegenüberliegende Längsseiten und zwei sich gegenüberliegende Stirnseiten aufweist, wobei die rohrförmige Struktur mit der darin angeordneten Pumpe als Bypass an einer Stirnseite angeordnet ist; und/oder
• die verwendete Vorrichtung zwei rohrförmige Strukturen umfasst, wobei in jeder der rohrförmigen Strukturen eine bidirektionale Pumpe angeordnet ist und wobei die rohrförmigen Strukturen jeweils als Bypass an derselben Stirnseite oder an sich gegenüberliegenden Stirnseiten angeordnet sind; und/oder
• die rohrförmige Struktur der verwendeten Vorrichtung innerhalb des Prozessbeckens an oder in unmittelbarer Nähe zu einer Stirnseite angeordnet ist, wobei die Öffnungen, die von den beiden Enden der rohrförmigen Struktur begrenzt werden, in Richtung der gegenüberliegenden Stirnseite weisen; und/oder
• die verwendete Vorrichtung zumindest zwei rohrförmige Strukturen aufweist, die innerhalb des Prozessbeckens an oder in unmittelbarer Nähe zu einer Stirnseite angeordnet sind, wobei die rohrförmigen Strukturen an oder in unmittelbarer Nähe zu derselben Stirnseite oder an oder in unmittelbarer Nähe zu sich gegenüberliegenden Stirnseiten angeordnet sind, und wobei die Öffnungen, die von den beiden Enden jeder rohrförmigen Struktur begrenzt werden, jeweils in Richtung der gegenüberliegenden Stirnseite weisen; und/oder
• die rohrförmige Struktur der verwendeten Vorrichtung mit der in dieser angeordneten bidirektionalen Pumpe in oder an dem Prozessbecken an einer Stirnseite angeordnet ist, wobei an der gegenüberliegenden Stirnseite des Prozessbeckens zumindest zwei voneinander beabstandete unidirektionale Pumpen angeordnet sind; und/oder
• die verwendete Vorrichtung eine Absperreinrichtung für die Pumpe, zumindest einen Festkörperfilter, der innerhalb der rohrförmigen Struktur oder an deren Enden angeordnet ist, und/oder eine Überlaufrinne umfasst.

The device used in the method according to the invention can in particular be designed as described above with reference to the device according to the invention as such, that is, in particular, that

• the process basin of the device used has two opposite long sides and two opposite end faces, the tubular structure with the pump arranged therein being arranged as a bypass on one end face; and or
• the device used comprises two tubular structures, a bidirectional pump being arranged in each of the tubular structures and the tubular structures each being arranged as a bypass on the same end face or on opposite end faces; and or
• the tubular structure of the device used is arranged within the process basin on or in the immediate vicinity of an end face, the openings which are delimited by the two ends of the tubular structure pointing towards the opposite end face; and or
• the device used has at least two tubular structures which are arranged within the process basin on or in the immediate vicinity of an end face, the tubular structures being arranged on or in the immediate vicinity of the same end face or on or in the immediate vicinity of opposite end faces, and the openings defined by the two ends of each tubular structure each facing towards the opposite end face; and or
• the tubular structure of the device used with the bidirectional pump arranged therein is arranged in or on the process basin on one end face, with at least two spaced-apart unidirectional pumps being arranged on the opposite end face of the process basin; and or
• the device used comprises a shut-off device for the pump, at least one solid-state filter which is arranged within the tubular structure or at its ends, and/or an overflow channel.

In the method according to the invention, an object arranged in the process basin is preferably flowed around by process liquid for a period of time t, with the direction of rotation of the pump arranged in the tubular structure then being changed so that the process liquid is conveyed in the opposite direction within the tubular structure. The time period t can be, for example, several minutes, in particular 5-10 minutes, 5-15 minutes or 5-20 minutes. After a further period of time t or a shorter or a longer period of time, the direction of rotation of the pump is preferably changed again. Particularly preferred is the direction of rotation of the pump in the method according to the invention during the treatment of objects in the process basin after each predetermined time interval, for example after each 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 , 13, 14, 15, 16, 17, 18, 19 or 20 minutes. In the method according to the invention, a turbulent flow of the process liquid surrounding the objects to be treated is generated, which is brought about in particular by changing the direction of rotation of the pump and by the fact that the stream of process liquid emerging from the tubular structure flows at the end face of the process basin opposite the tubular structure or on the objects to be treated arranged therein.

According to one embodiment of the method according to the invention, the formation of the turbulent flow in the process basin is further supported by the use of unidirectional pumps which are arranged on the end face of the process basin, which is the end face on which the tubular structure with the bidirectional pump arranged therein is arranged , opposite. In contrast to the bidirectional pump, which can change its direction of rotation and does not pause during the surface treatment of the objects arranged in the process basin, the unidirectional pumps cannot change its direction of rotation or can only change its direction of rotation for a short time, for example for cleaning purposes, for example to move around to flush out a blockage or similar. Creating a flow is only possible in one direction using unidirectional pumps. It Therefore, only those unidirectional pumps that have the same direction of rotation as the bidirectional pump are active.

Detailed description of the invention

• in der Figur 1 eine schematische Ansicht einer ersten Ausführungsform der erfindungsgemäßen Vorrichtung,
• in der Figur 2 eine schematische Ansicht einer zweiten Ausführungsform der erfindungsgemäßen Vorrichtung,
• in der Figur 3 eine schematische Ansicht der Ausführungsform aus Figur 2 während einer Oberflächenbehandlung von Objekten,
• in der Figur 4 eine schematische Ansicht der Ausführungsform aus Figur 2 während einer Oberflächenbehandlung von Objekten mit skizziertem Strömungsprofil,
• in der Figur 5 eine 3D-Ansicht einer dritten Ausführungsform der erfindungsgemäßen Vorrichtung,
• in der Figur 6 eine schematische Ansicht einer vierten Ausführungsform der erfindungsgemäßen Vorrichtung, und
• in der Figur 7 eine schematische Ansicht einer fünften Ausführungsform der erfindungsgemäßen Vorrichtung zeigen.

The invention will now be described in more detail using exemplary embodiments and with reference to the figures

• in the Figure 1 a schematic view of a first embodiment of the device according to the invention,
• in the Figure 2 a schematic view of a second embodiment of the device according to the invention,
• in the Figure 3 a schematic view of the embodiment Figure 2 during surface treatment of objects,
• in the Figure 4 a schematic view of the embodiment Figure 2 during surface treatment of objects with a sketched flow profile,
• in the Figure 5 a 3D view of a third embodiment of the device according to the invention,
• in the Figure 6 a schematic view of a fourth embodiment of the device according to the invention, and
• in the Figure 7 show a schematic view of a fifth embodiment of the device according to the invention.

The Figure 1 shows a schematic view of a first embodiment of the device according to the invention for the surface treatment of objects. This includes a process basin 1 with, in particular, a rectangular base area, which has two opposing end faces 6 and two opposing long sides 5 . In the process basin 1 there is process liquid 10, which can in particular be degreasing liquid, water, rinsing liquid, stain, flux liquid or another acid or alkali for (chemical) surface pretreatment. On one end face 6, the process basin 1 has a tubular structure 3 , within which a bidirectional pump 2 is arranged. The tubular structure 3 is designed as a bypass in the embodiment shown. The bidirectional pump 2, which is set up to change its direction of rotation at predetermined time intervals, is arranged in a straight middle part of the bypass or the tubular structure 3 and points to both ends of the tubular structure 3, at which they open into the process basin 1 , the same distance. Arranged on both sides of the tubular structure 3 A solid-state filter 8 and a shut-off device 7 are arranged in each bidirectional pump 2 . The direction of flow through the bypass is indicated by the arrows at the transitions between the bypass and the process basin 1. In the state shown, the process liquid 10 therefore flows from bottom to top through the bypass, whereby if the direction of rotation of the pump 2 changes, it would flow through the bypass in the opposite direction, ie from top to bottom (indicated by the dashed arrows).

The Figure 2 shows a schematic view of a second embodiment of the device according to the invention for the surface treatment of objects, which in addition to the elements in the Figure 1 Embodiment shown also has a second bypass or a second tubular structure 3 with a bidirectional pump 2 arranged therein. Like the pump 2 arranged in the first tubular structure 3 , this bidirectional pump 2 is also set up to change its direction of rotation at the same predetermined time intervals as the first bidirectional pump 2 , with both pumps 2 each having the same direction of rotation. The flow generated by the bidirectional pump 2 arranged on one end face 6 of the process basin is therefore deflected by the bypass arranged on the opposite end face 6 and amplified by the bidirectional pump 2 arranged therein.

The Figure 3 shows schematically the already in the Figure 2 shown embodiment of the device according to the invention for the surface treatment of objects, with two objects 9 to be treated immersed in the process liquid 10 . The various flows within the process basin 1 are shown in the form of lines from which it can be seen that during the surface treatment of the objects 9 a large part of the flow is driven in a circle, with the flow being deflected at the end faces 6 of the process basin 1 in each case the oppositely arranged tubular structures 3 takes place. However, there is also an exchange of substances between the individual liquid layers, as is the case in particular Figure 4 you can see. This was found in experiments in which the movement of individual particles within a device according to the invention or in a method according to the invention was tracked using a phosphor marker. The motion of such a single particle is in the Figure 4 sketched.

The Figure 5 shows schematically a 3D view of a third embodiment of the surface treatment device according to the invention. This includes a cuboid process basin 1 with two opposing long sides 5 and two opposite end faces 6. On one of the end faces 6, two tubular structures 3 are each arranged in the form of a bypass. A bidirectional pump 2 (not shown) is arranged within each tubular structure 3 , the pumps 2 being set up to change their directions of rotation simultaneously after predetermined time intervals.

The Figure 6 shows a schematic view of a fourth embodiment of the device according to the invention, in which two tubular structures 3 with bidirectional pumps 2 arranged therein are not arranged as bypasses, but rather within the process basin 1 on opposite end faces 6 . The tubular structures 3 are each arranged with their longitudinal axis on the respective end face 6 or at a short distance from it, with the two ends of each tubular structure 3 facing the other ends of the other tubular structure 3 . After passing through a tubular structure 3 , the process liquid 10 located in the process basin 1 is moved towards the opposite end face 6 , where it is deflected as it passes through the tubular structure 3 arranged there and moved back towards the other end face 6 . The bidirectional pumps 2 arranged in both tubular structures 3 are set up to simultaneously change their direction of rotation and then move process liquid 10 in the opposite direction through the tubular structures 3 or through the process basin 1 .

Although according to the Figure 6 two tubular structures 3 are arranged in a process basin 1 , depending on the dimensions of the process basin 1 , only one tubular structure 3 with a bidirectional pump 2 arranged therein may be sufficient to carry out the method according to the invention. Such an embodiment is in the Figure 7 shown, in which the optional solid-state filters 8 arranged on both sides of the bidirectional pump 2 in the tubular structure 3 are also shown Figure 8 shows a schematic view of a fifth embodiment of the device according to the invention, in which a process basin 1 comprises a bypass or a tubular structure 3 on an end face 6 with a bidirectional pump 2 arranged therein. On the opposite end face 6, the device has two unidirectional pumps 4 , which have an opposite direction of rotation and only one of which is in operation (indicated by the dashed or solid lines). These unidirectional pumps 4 function as auxiliary pumps to support or amplify the flow generated within the tubular structure 3 by the bidirectional pump 2 . This embodiment of the device according to the invention is particularly suitable for process basins 1 in which due to the length of the process basin 1 on the side opposite the tubular structure 3 , a further pump is required in order to increase the flow generated by the bidirectional pump 2 , but in which there is no space outside the process basin 1 for a further tubular structure 3 in the form of a second bypass, for example because the process basin 1 stands with this end face 6 against a wall.

In summary, it should be noted that all of the embodiments of the present invention described above are optimally suitable for the surface treatment of objects, since in all embodiments a turbulent flow is generated in the process basin 1 by the at least one tubular structure 3 with the bidirectional pump 2 arranged therein, which flows optimally around the objects 9 arranged in the process liquid, with the formation of flow shadows being completely avoided by regularly changing the direction of rotation of the pump 2 . In contrast to a laminar flow, a mass transfer takes place between the individual liquid layers, which has an advantageous effect on the result of the surface treatment, in particular a qualitatively better, in particular more uniform surface treatment with a treatment time that is preferably shortened by up to 50% compared to a static pretreatment is achieved.

The features of the invention disclosed in the above description, in the figures and in the claims can be essential for the implementation of the invention in its various embodiments, both individually and in any combination.

List of reference symbols:

1

Process basin

2

bidirectional pump

3

tubular structure

4

unidirectional pump

5

Long side of the process basin

6

Front side of the process basin

7

Shut-off device

8th

Solid state filter

9

object

10

Process fluid

Claims (14)

1. Device for surface treatment of objects, comprising a process basin (1) and a pump (2), characterized in that a tubular structure (3) is arranged in or at the process basin (1), which tubular structure is curved over at least part of its length, wherein the two openings which are delimited by the two ends of the tubular structure (3) face in the same direction, and wherein the length of the tubular structure (3) from its one opening at one end to its other opening at the other end is at most twice as long as the direct distance between the two openings which are delimited by the two ends of the tubular structure (3), and wherein the pump (2) is arranged within the tubular structure (3), wherein the pump (2) is a bidirectional pump, which is arranged to be able to change its direction of rotation, and wherein the pump (2) which is arranged within the at least one tubular structure (3) has a power of < 1 kW.
2. Device according to claim 1, characterized in that the process basin (1) has two opposing longitudinal sides (5) and two opposing front sides (6), the tubular structure (3) with the pump (2) arranged therein being arranged as a bypass at one front side (6).
3. Device according to one of the claims 1 or 2, characterized in that it comprises two tubular structures (3), wherein a bidirectional pump (2) is arranged in each of the tubular structures (3), and wherein the tubular structures (3) are each arranged as a bypass at the same front side (6) or at opposing front sides (6).
4. Device according to claim 1, characterized in that the tubular structure (3) is arranged within the process basin (1) at or in the immediate vicinity of a front side (6), the openings delimited by the two ends of the tubular structure (3) facing in the direction of the opposite front side (6).
5. Device according to claim 4, characterized by two tubular structures (3) arranged within the process basin (1) at or in close proximity to a front side (6), wherein the tubular structures (3) are arranged at or in close proximity to the same front side (6) or at or in close proximity to mutually opposing front sides (6), wherein a bidirectional pump (2) is arranged in each of the tubular structures (3), and wherein the openings delimited by the two ends of each tubular structure (3) each face in the direction of the opposite front side (6).
6. Device according to one of the preceding claims, characterized in that the at least one tubular structure (3) with the bidirectional pump (2) arranged therein is arranged at one front side (6) in or at the process basin (1), wherein at least two unidirectional pumps (4) spaced apart from one another are arranged at the opposite front side (6) of the process basin (1).
7. Device according to one of the preceding claims, characterized in that it comprises one or more of the following elements:

   - a shut-off device (7) for the pump (2);

   - at least one filter (8) for solids arranged within the tubular structure (3) or at its ends:

   - an overflow gutter.
8. Device according to one of the preceding claims, characterized in that the pump (2) which is arranged within the at least one tubular structure (3) is an acid and/or heat resistant pump having a heat resistance up to 65 °C.
9. Device according to one of the preceding claims, characterized in that the pump (2) which is arranged within the at least one tubular structure (3) has a variable conveying range between 10 and 180,000 L/h.
10. Device according to one of the preceding claims, characterized in that the pump (2) which is arranged within the at least one tubular structure (3) has an electronic control.
11. Device according to one of the preceding claims, characterized in that the pump (2) which is arranged within the at least one tubular structure (3) is selected from the group comprising propeller pumps, centrifugal pumps, rotary pumps, rotary piston pumps, flap pumps, gear pumps, eccentric screw pumps, peristaltic pumps and pneumatic diaphragm pumps.
12. Process for surface treatment of objects, comprising the steps of:

    - Providing a device according to one of the preceding claims;

    - Placing an object (9) inside the process basin (1) filled with process liquid (10);

    - Allowing process liquid (10) to flow around and/or through the object (9), the pump (2) conveying the process liquid (10) inside the tubular structure (3) in one direction.
13. Process according to claim 12, characterized in that the object (9) is flowed around by the process liquid (10) for a time period t and subsequently the direction of rotation of the pump (2) is changed so that the process liquid (10) inside the tubular structure (3) is conveyed in the opposite direction.
14. Process according to one of the preceding claims, characterized in that the process liquid (10) surrounding the object (9) moves in a turbulent flow profile.

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