DE19916139C1 - Plastic-lined electroplating tank production process comprises creating a reduced pressure between a liner of butt welded plastic plates and a steel casing - Google Patents

Abstract

Plastic-lined electroplating tank production comprises creating reduced pressure between a liner of butt welded plastic plates (2A, 2B) and a steel casing (1). An electroplating tank, comprising a steel casing (1) with a chemically resistant plastic liner, is produced by (a) covering the inside of the casing with plastic plates (2A, 2B) abutting one another to form gaps (4) which widen in the direction towards the casing; (b) welding the plates gas-tightly together in the gap region to form the liner; and (c) creating a reduced pressure in the interspace (5) between the liner and the casing (1). An Independent claim is also included for an electroplating tank comprising a steel casing (1), a chemically resistant plastic liner and an interspace (5) between the casing and the liner, the liner being formed of several chemically resistant plastic plates (2A, 2B) which have been gas-tightly butt welded together and which form a larger angle than that of the casing (1) in the abutting region.

Description

The invention relates to an electroplating trough and a method to produce such.

The well-known electroplating tubs with an outer tub made of steel and an inliner made of chemically resistant plastic composed of prefabricated outer tubs and inliners. The outer tub and the inliner must be very dimensionally correct be so that the outer tub the forces of the electroplating solution in can absorb the inliner and mechanical destruction of the Inliners can be prevented. Because the outside tub and the Inliners made of different materials with different Thermal expansion coefficients are formed due to precautions are taken at different temperatures, the destruction of the inliner, especially in the corner prevent area.

DE 213 954 describes a container lining for electroplating tub known, in the coated in a steel tub plastic lanes overlapping each other are welded. In the overlap area is between the an electrical conductor is arranged on both coating tracks, the expansion joint bil in the overlying coating det to temperature changes due to the different Expansion coefficients to compensate for stresses ren. The electrical conductor is also at one pole connected to a DC voltage source, the other Pole the contents of the electroplating tank, a liquid electrolyte, connected. If a weld seam is faulty, Electrolyte to the electrical conductor so that the Circuit is closed, which is an acoustic and / or optical signal indicating a defective weld is triggered.  

The measures to compensate for the changes in temperature mechanical stresses that occur are complex and expensive, because to create an expansion joint is an electrical shear conductor required, which also welding two he disadvantageously complicates coating webs. It are however no measures to compensate for the the mechanical stresses occurring in the corners see.

In DD 250 140 A1 is an electroplating tub made of a steel tub with inner panels hung on the sides and one on Floor plate made of hard polyvinyl chloride wrote. To avoid stresses due to temperature changes to be able to take runs in the corners between the inside cladding and the bottom plate a strip of soft Polyvinylchloride with the inner lining and the bottom plate made of hard polyvinyl chloride is welded.

But this measure to compensate for temperature-related mechanical stress is complex and expensive because of a Strips of a different material are required, and themselves the welding process is complicated.

DD 234 448 A1 is an electroplating tub made of a steel tub known, in which a plastic tub sits, which is only on the top Edge and partly flush with the steel tray, so that it expands due to temperature increases can expand like a pillow.

However, this arrangement has the disadvantage of being proportionate low mechanical stability because the inner tub is not is flush with the steel outer tub everywhere.

Another electroplating tub is known from DD 213 698.

Sitting in an outer tub made of steel with an edge an inner tub made of polypropylene with a smaller width and  Length than the clear width and length of the outer tub to be enough enough space for length and length caused by temperature increase To create width expansion of the inner tub. At the top the inner tub is a trapezoidal circumferential leg welded, which rests on the edge of the outer tub. The inner bend of the leg is pulled up and arched outwards so that the inner wall extends upwards can stretch and the leg still firmly on the edge of the Outside tub rests.

However, no measures are envisaged to address the Mechanical stresses occurring at the bottom of the tub to compensate.

DD 262 340 describes an electroplating tank in which one Inner polyolefin tub sits in a steel tub. Between the steel pan and the inner pan run U-shaped profiles, on which the inner tub rests to create expansion fields conditions resulting from the compensation of mechanical stresses different coefficients of thermal expansion. Because the inner tub is only supported by the U-shaped profiles the mechanical strength is impaired.

Another galvanic tub is known from DD 145 641.

An inner tub made of plastic has raised weld seams on which the inner tub rests in an outer tub to Space for expansion of the inner tub due to temperature increases to create hung.

Because the inner tub is only on the raised weld seams the mechanical strength leaves something to be desired.

The invention has for its object a galvanic tub and to create a process for their production, which overcome the aforementioned disadvantages as far as possible.  

This object is achieved according to the invention by an electroplating trough with the features of claim 6 and a method for Manufacture of an electroplating tub with the characteristics of the An spell 1 solved.

Advantageous further developments result from the Unteran sayings.

According to the invention in the process for producing a Electroplating tub in the outer tub made of steel several plastic plates from a chemical resistant to the electroplating solution ten plastic, for example from a polyfine plastic, especially made of polyvinyl diflouride (PVDF), polyethylene, Po lypropylene or polyvinyl chloride introduced. The Inside of the outer tub covered by the plastic plates. In the area where the plastic plates meet, are the plastic plates designed to be one form a widening gap towards the outer tub. Hereinafter The plastic plates are cut together welded gastight so that between the ver welded plastic sheets formed inliner and the outside tub creates a gap, which with a negative pressure can be applied. Using a vacuum pump finally this vacuum creates in the space where through the plastic plates themselves on the walls of the Put on the outer tub and the gap will narrow. At a the gap disappears completely with sufficiently strong negative pressure constantly. With the narrowing or disappearance of the gap he there is a widening of the angle at which art butting fabric panels together. Bumped the plastic sheets before evacuation, for example, at a right angle one after the other, they are now under after the evacuation an angle of over 90 ° to each other.

Through these changed angular relationships in connection with the extensive, immediate concern of the inliner to the Outside tub is a very stable and resistant type  order made of inliner and outer tub. By the ge changed angular relationships in the area of the abutting in Direction to larger angles, the shear forces are just in Corner area of electroplating tubs noticeably reduced what the Long-term stability of the electroplating tubs significantly improved.

Welding has proven to be particularly advantageous directly in the area of the abutting plastic to make plates, creating a very safe and gas-tight Connection of the plastic plates is given and also none Obstruction of the gap widening towards the outer tub tes is given when rejuvenating due to the negative pressure. By this arrangement is the weld outside the gap or arranged immediately at its end, what the described Excludes disability. It has proven to be advantageous widening the gap evenly, especially with an opening training angle α of less than 20 °. By choosing one Opening angle between 5 and 10 ° by appropriate Ab bevelling of the plastic plates in the area of each other bumping is a particularly suitable increase in the angle under which the plastic plates collide, for example given from 90 ° to 100 °. With such a Opening angle of the gap between S and 10 ° is also a safe closing of the gap with technically simple to reali given negative pressure in the space. Through the safe re closing the gap can on a corner area of the Inli forces acting very securely on the end faces of the Plastic plates that limit the gap, and thus on the Outside tub can be derived. This prevents the like forces are absorbed solely by the weld have to.

Around the gap between the abutting plastic plate to form one or both plastic sheets in beveled in this area. The bevel is made in to such an extent that an evenly expanding Gap with a defined opening angle α results. This  Opening angle in the non-evacuated state is selected so that it preferably depends on the size of the plastic plates respectively the dimensions of the inliner and the ge selected operating temperatures is set. Are the Large dimensions, the bevels are chosen so that the opening angle α is increased. For larger operations temperatures, the opening angles are chosen larger. Here ensures that the liner expands due to the increased operating temperature of the electroplating solution it is taken into account that the temperature-related Expansion of the inliner extends as far as possible to the outer tub, making the supporting effect of the steel outer tub in comes into its own. If the opening angle of the If the gap is chosen larger, this causes a correspondingly increased Increase in the angle at which the plastic sheets after encounter each other during the evacuation.

It has proven to be very advantageous to Ver welding not only by means of a single weld seam, son with multiple welds that run in parallel run to each other and the whole or in part are arranged overlapping. As a particularly suitable sweat The hot gas drawing welding process and the Extrusion welding process proven. Preferably be multiple welds using the hot gas welding process applied and then on these welds a other welds covering extrusion welded open brings. This formation of the weld seams is a me mechanically stable and very gastight arrangement for welding Given the plastic plates to form the liner.

It has proven particularly useful, which verse with a vacuum space after the application of further weld seams to ventilate in the area of the abutting plastic plates ten, which can preferably be done through the same opening, by which the vacuum was created in the space. By lifting the negative pressure through ventilation  the flat areas of the plastic plates differ from the Remove the flat areas of the outer tub and the Shape of the areas in which the plastic sheets under collide at an enlarged angle, largely beibe hold. So this angle proves even after the opening raising the negative pressure as relative to the original Angle enlarged. As a particularly suitable area for the like connections between the plastic plates have Corners of the electroplating tray have been proven, which preferably a rech Show the angle of the outer tub. In this case it shows the corner of the inliner corresponding to the corner of the outer tub, which are formed by the abutting plastic plates an obtuse angle, which is typically larger than 100 °.

When designing the plastic plates to form the gap According to the invention, it is also taken into account that the Welding in the area of art colliding fabric panels a reduction in the angle at which art butt plates together, which is the cause contraction of the weld seam or weld seams their cooling is related. This angle reduction is typically in the range of a few degrees, in particular re in a range below 5 °. This angle reduction is at the choice of the opening angle of the gap is taken into account, so that the plastic sheets after making the electroplating collide the tub at a larger angle than the Angle that the outer tub shows in this area.

The invention relates to an electroplating tub with an outer tub made of steel and an inliner made of a chemically resistant Plastic and one between the inliner and the outer tub formed space. The inliner is made of several art fabric panels formed in the area of the abutting are welded together gastight. Through a special one Training of the plastic plates in the area of the anein otherwise is achieved according to the invention that in this  Area the plastic sheets at a larger angle butt each other than the angle that the outer tub in this Area shows. Shows the outside tub in this area right-angled corner, so through the plastic plate formed angles in the area of the abutting in this Corner regularly larger than 90 °, especially between 95 ° and 100 °. This angle is causally related hang with the training of plastic plates in the area of Bumping into each other.

A particularly preferred electroplating trough according to the invention shows a space that is subjected to a vacuum. Through this training with the vacuum is on the one hand si ensured that the best possible concern of the by the Plastic sheets formed of inliners on the outer tub is given, which supports the supporting function of the outer tub is advantageously given.

The electroplating tub preferably has an opening for formation of the negative pressure in the intermediate space, which with a vacuum pump can be connected and after training the Vacuum in the gap be sealed gas-tight can. This ensures that the vacuum in Gap is permanently preserved, creating a flat The plastic sheets of the inliner rest on the inside the outer tub and the inventive design of the loading range of abutting the plastic plates permanently given is. It has proven to be particularly advantageous showed to arrange the opening in the area of the outer tub, because this the necessary mechanical rigidity to take of a connecting element to a vacuum pump. With this stiffness it is also possible to use Ven to provide tile that an unwanted inflow of gas into the Prevent a space with negative pressure, whereas they simply evacuate the space possible.  

Furthermore, it has proven its worth to open up the formation of the Un pressure in the space also for ventilation of the space to use, making a particularly durable arrangement Inliner and outer tub is given, which is not the permanent load by the pressure difference between the negative pressure in the Space and the external pressure is given. This causes one increased stability and durability of the invention Electroplating tub.

A preferred embodiment of the invention is in the Figures shown and will be described in more detail below.

Fig. 1 shows a corner area, the electroplating tank before the application of negative pressure and

Fig. 2 shows the corner area of Fig. 1 after loading with a vacuum and after applying additional welds.

In Fig. 1, the formation of a corner is by way of example an electroplating bath according to the invention after insertion of the plastic plates 2 A, 2 B to form the liner 2 in the AUSS enwanne 1 and after the welding of the plastic plates 2 A, 2 B shown by a weld 3 . The weld 3 is applied by means of a hot gas welding process. The weld seam 3 provides a gas-tight connection of the plastic plates 2 A, 2 B. The plastic sheets 2 A, 2 B are formed from polyvinyl difluorite (PVDF), which is particularly chemically resistant to the electroplating solutions. In addition, this plastic shows a certain flexibility, which makes it possible to evade forces, for example due to the electroplating solutions. This evasion typically causes a deformation of the inliner 2 , which is limited by the outer tub 1 made of steel. In the present example, the outer tub 1 is formed from a steel ST37-2 with a thickness of 5 mm. The plastic plates made of PVDF have a thickness of 8 mm. The weld seam 3 shows a diameter of 3 mm.

The two plastic plates 2 , 2 A are bevelled in their end regions, as a result of which a gap 4 is created when the bevels meet. The gap 4 is designed such that it widens in the direction of the outer tub 1 . The weld seam 3 is arranged directly on the inside of the plastic plates 2 A, 2 B in the area of the abutting them and connects the two plastic plates 2 A, 2 B gas-tight with each other.

The outer tub 1 is formed by flat steel plates, the gas-tight in the corner region by welds 1 A and are rigidly connected to each other.

Between the outer tub 1 and the inliner 2 , an intermediate space 5 is arranged, which is evacuated via an opening, not shown, that is to say can be subjected to a negative pressure. The conditions corresponding to FIG. 1 are given under normal pressure. If the intermediate space 5 of the electroplating trough is subjected to a negative pressure during its manufacturing process, the region of the electroplating trough shown in FIG. 1 takes on a shape corresponding to FIG. 2.

The plastic plates 2 A, 2 B lie flat on the steel plates of the outer tub 1 . In the area of the abutting plastic sheets 2 A, 2 B, the gap 4 tapers from the original opening angle α of about 10 ° at normal pressure due to the negative pressure until it completely disappears. In this case, the two plastic plates 2 A, 2 B abut one another flat, whereby bending in the area of the abutting is given with the formation of an enlarged angle in the area of the abutting. In contrast to the region of the planar abutment of the plastic sheet 2 A, 2 B to the steel plates of the outer tub 1 the sowing is enwanne 1 in the region of the corner, respectively, relative to an extension of the angle of butting in the area of butting of the plastic plates 2 A, 2 B to given the corner angle of the outer tub 1 . This enlargement of the angle here from a right angle in the direction of an obtuse angle of about 100 ° be in connection with the surface abutting the two plastic plates 2 A, 2 B an improved absorption of forces by the electroplating solutions, without causing destruction or Separation of the plastic plates leads. With the help of further welds 3 A, 3 B, the resistance to the forces caused by the electroplating solutions can be increased considerably. It has proven particularly useful to form the weld seams 3 , 3 A, 3 B parallel to one another, partially overlapping each other and finally to apply a large-area weld seam 3 C by means of extrusion welding. This extensive welding of the plastic plates 2 A, 2 B is a reduction in the angle at which the plastic plates 2 A, 2 B abut one another, which is the cause of the contraction of the welds 3 , 3 A, 3 B, 3 C at their Cooling is based. However, this reduction is small relative to the enlargement of the angle by designing the gap with a corresponding opening angle α, so that overall, even taking this reduction into account, an overall increase in the angle at which the plastic plates 2 A, 2 B abut one another is given .

The formation of a corner of the electroplating trough according to the invention shown in FIGS. 1 and 2 represents an exemplary embodiment of a connection of plastic plates 2 A, 2 B, which is preferably used in the area of the corners of the electroplating trough. In other areas, other trainings of connections are used in addition to the exemplary form of training shown.

Reference list

1

Outside tub

2nd

Inline skates

2nd

A plastic plate

2nd

B plastic plate

3rd

Weld

3rd

A Welding seam according to the hot gas welding process

3rd

B Welding seam using the hot gas draw welding process

3rd

C Weld seam using the extrusion welding process

4th

gap

5

Space
α opening angle of the gap

4th

Claims (10)

1. A method for producing an electroplating tub with an outer tub ( 1 ) made of steel and an inliner ( 2 ) made of a chemical-resistant plastic, wherein in the outer tub ( 1 ) several plastic plates ( 2 A, 2 B) are introduced so that the inside of the outer tub (1) through art subsequently panels (2 a, 2 B) is covered and that the plastic plates (2 a, 2 B) he abut a direction outer tub (1) further with the groove (4) forming the Plastic plates ( 2 A, 2 B) to form the inliner ( 2 ) in the gap area are welded together gas-tight and then an intermediate space ( 5 ) formed between the inliner ( 2 ) and the outer tub ( 1 ) is opened with a vacuum. 2. A method for producing an electroplating tray according to claim 1, characterized in that the plastic plates ( 2 A, 2 B) for forming the inliner ( 2 ) are welded together in a gas-tight manner in the area of the abutting, the welding being carried out from the interior of the inliner ( 2 ) off. 3. A method for producing an electroplating tray according to claim 1 or 2, characterized in that on a weld ( 3 ) for gas-tight connection of the plastic plates ( 2 A, 2 B) at least one further weld ( 3 A, 3 B, 3 C ) is applied, and that the welds ( 3 , 3 A, 3 B, 3 C), in particular by means of a hot gas welding process and / or by means of an extruder welding process. 4. A method for producing an electroplating trough according to one of the preceding claims, characterized in that the plastic plates ( 2 A, 2 B) are formed in the area of the bumping in such a way that they have an opening angle (α) of less than 20 °, in particular between 5 ° and 10 °, widening gap ( 4 ). 5. A method for producing an electroplating trough according to one of the preceding claims, characterized in that the plastic plates ( 2 A, 2 B) are formed from a polyfine plastic, in particular polyvinyl difluoride (PVDF). 6. A method for producing an electroplating trough according to one of the preceding claims, characterized in that the intermediate space ( 5 ) is then ventilated. 7. electroplating tub with an outer tub made of steel, with an inliner made of a chemically resistant plastic and a space formed between the inliner and the outer tub, characterized in that the inliner ( 2 ) by several plastic plates ( 2 A, 2 B) from one Chemically resistant plastic is formed, these plastic plates ( 2 A, 2 B) are butt welded together gas-tight and in the area of the butting show a larger angle than the outer tub ( 1 ) in this area. 8. Electroplating tray according to claim 7, characterized in that the plastic plates ( 2 A, 2 B) in the area of the abutting the plastic plates ( 2 A, 2 B) several superimposed on welds ( 3 , 3 A, 3 B, 3 C) ) for gas-tight welding. 9. electroplating trough according to claim 7 or 8, characterized in that the intermediate space ( 5 ) has a negative pressure. 10. electroplating trough according to claim 9, characterized in that the electroplating trough has an opening for forming or for removing the negative pressure in the intermediate space ( 5 ).