DK141375B - Apparatus for powerless nickel deposition on the surface of an object. - Google Patents

Description

(11) PUBLICATION NOTICE 1 ^ -1375 DENMARK '') o 23 c 3/02 t (21) Application No 5518/71 (22) Filed on 29 · Oct. 1971 (23) Race day 29 · Oct. 1971 (44) The application presented and. The 0ρη petition published on 5 · m & r · 1 -? Αυ

DIRECTORATE OF

PATENT AND TRADEMARKET (30> Priority requested from it

Oct 4 1971, 186355, US

(71) DEERE & COMPANY, John Deere Road, Moline, Illinois, US.

(72) Inventor: Russell Alger Henry Jr., 206, Lee Place, Albert Lea, Minne = sota, US.

(74) Plenipotentiary in the proceedings:

The company Chas. Hude. __ (54) Electric nickel deposition device on the surface of an object.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an apparatus for the electroless nickel deposition on the surface of an article, such as models and core boxes, and with a container for a powerless nickel solution inserted in a circulation system of pump, heater and filter, which consists of a plastic inert to the nickel solution and is suspended in a load bearing construction.

In known apparatus of this kind, the container for the nickel solution is inserted into the circulation system between a heater and a cooler. The nickel solution is pumped with a pump from the container through the cooler and to a regeneration plant, from which it is pumped through a filter and from there back to the container. This known apparatus 2 1A13 7 5 is very filling and uneconomical in operation, since the nickel solution must be constantly heated and cooled again, which causes a large energy consumption. The container itself in this known apparatus is made of a plastic film which is suspended in a stainless steel frame in a hot rinsing bath. This bath, which is to keep the nickel solution in the plastic container at a desired temperature, must, in turn, also be kept at a certain temperature. This means a further complication and makes the device even more uneconomical to operate. A nickel solution container made of plastic foil and mounted on a stainless steel frame has only a very limited carrying capacity and thus a limited capacity. Therefore, in such a container only relatively small objects can be placed to be processed. In addition, there will always be a risk that such a film container will be damaged by an object placed in it, thereby causing it to leak and the nickel solution being lost, while causing disruptions to the operation. In the case of powerless nickel deposition, it is important that the container in which the nickel solution is located can be kept embarrassingly clean in order to avoid contamination of the nickel solution and the deposition of nickel on the container walls. Cleaning a plastic film container is very difficult, so there is always a risk of rapid contamination with the known appliance. For the foregoing reasons, the known apparatus is not suitable for economically powerless nickel deposition on articles in mass production and is particularly unsuitable for providing a satisfactory, durable nickel deposit on articles of large dimensions.

Apparatus for electrically nickel deposition are also known on the surface of articles using a steel container, optionally coated with plastic or glass. However, this container delivers an uneconomically large amount of heat to the surroundings, so that the nickel solution still has to be heated vigorously, therefore the apparatus is uneconomical in operation and its use is limited to nickel deposition on relatively small objects, where only small quantities of solution have to be used.

Generally, models and core boxes for high-pressure molding were usually made of cast aluminum or cast iron. However, aluminum models and core boxes wear out quickly, and their use is therefore limited in cases where high production of molds and cores is not required. However, more resilient cast iron models and core boxes are much more expensive to manufacture. There is a need for models and core boxes that can be manufactured in mass production and economically.

SUMMARY OF THE INVENTION The object of the invention is to provide an apparatus of the kind according to which, despite its simple construction, it is possible to perform powerless nickel deposition also on objects of relatively large dimensions, e.g. models and core boxes, in an economical, reliable and accurate way.

This is achieved according to the invention in that the supporting structure includes a double wall located close to the side walls of the removable container with an insulating gap.

The apparatus according to the invention has significant advantages over the known apparatus. The design of the support structure for the removable container as a double-walled structure at insulating intervals makes it possible to keep the heat dissipation from the nickel bath in the container placed in the structure without having to surround the container with a known device as with the known devices. heated bath of heated liquid and without having to constantly heat the nickel solution itself inside the container, e.g. by means of a submerged heater. The apparatus according to the invention can therefore have a container which is much larger than the containers in the known apparatus, without the risk of an uneconomical heat loss occurring. The use of a high capacity container requires a correspondingly strong load-bearing structure. This requirement is also met by the special design of the support structure so that a double wall structure which can be designed very rigidly and sustainably without the need to use extra bracing elements. As the container can be manufactured at high volume, it has also been possible to economically perform nickel deposition on the surface of large objects such as models and core boxes.

Due to the large container volume of the apparatus according to the invention, it has also become possible to dispense with extra storage and regeneration containers which have been needed in the known apparatus due to the low capacity of the nickel solution container, so that any regenerating substances can now be added to the container. On the whole, the apparatus according to the invention is economical and practical and reliable in operation and, as mentioned, enables economical nickel deposition economically on large objects.

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According to the invention, it is advantageous that the double walls of the supporting structure are coated with a fiberglass reinforced coating and that bathtubs consist of polypropylene. This results in that neither the support structure nor the container can be attacked by the substances in the nickel solution. Furthermore, the fiberglass reinforced coating enables a very light and yet very sustainable design of the load-bearing structure and economical manufacture of the apparatus, so that this can be obtained for relatively small investment costs.

In a convenient embodiment of the apparatus according to the invention, the container has at its top an outwardly flange with which it can rest on the supporting structure. In this way, the container is securely supported in the structure as it is uniformly supported along the entire circumference at the top edge and is easy to handle when it needs to be replaced or inserted into the supporting structure.

According to the invention, it is advantageous for the supporting structure to have downwardly sloping shoulder portions along the circumference of the upper edge of the container. This results in the fact that nickel solution, which springs up over the edge of the bath in the container, can run from this on the sloping surfaces without the risk of the liquid running back and thereby including impurities found on the edge and which could have a harmful effect. effect on the composition of the bath.

The apparatus may be designed such that the circulation system consists solely of the pump, heaters, filter and conduits connecting these parts. Such an apparatus consists of far fewer parts than the previously known circulating system apparatus, and only a single container is needed, namely the nickel solution container itself, and only a single heater. In contrast, the known apparatus with circulation system, in addition to the container for the nickel bath, has a storage vessel and a regeneration vessel as well as a cooler and a heater. Such a complicated arrangement with several containers and uneconomical cooling and heating units is avoided in the particular construction of the apparatus according to the invention with a single container of high capacity and with little heat loss. Due to the few components, the appliance is reliable in operation and simple to maintain and can be manufactured inexpensively.

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The invention will be further explained in the following with reference to the drawing, in which fig. 1 is a schematic view of an apparatus for electroless nickel deposition on the surfaces of models and core boxes; and FIG. 2 is a cross-section through a portion of the container of the apparatus and the supporting structure in which it is suspended.

FIG. 1 and 2 show a preferred embodiment of the apparatus according to the invention. This apparatus is ideal for preserving the solution and provides an efficient plant for the electroless nickel deposition on the surfaces of the objects. In FIG. 1 and 2, a tank 10 is shown which contains a powerless nickel solution 12. A first line 14 extends from the bottom of the tank to a pump 16, and a second line 18 leads the solution to a heat exchanger 20. A third line 22 leads the solution from the heat exchanger to a filter 24 and the solution is returned to the tank 10 through this filter.

The heat exchanger 20 has a steam inlet pipe 26 from which steam is passed through an annular sheath surrounding the heat exchanger line with the solution. The steam is discharged through a conduit 28 and recycled.

Additives are added to the solution either continuously or at desired intervals. These materials include amounts of nickel and sodium hypophosphite to increase the content of these materials in the solution and to replace the amounts deposited during the deposition.

FIG. 2 shows a preferred construction of the tank 10. This tank has a plastic liner formed by a container 32 of a material which is inert to the nickel solution. Polypropylene is a particularly suitable material for this purpose. The container has an outwardly extending flange 34 which rests on the top wall 36 of a support for the container. The wall 36 has a downwardly sloping outer edge portion such that the outer surface of the tank has a similar shape. If part of the solution in the tank should be sprayed out in this area, the solution will flow away from the tank, thereby reducing the possibility of contamination.

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The container 32 is suspended in a supporting structure having a fiberglass coating 38 and inner and outer plywood sheets 40. The plywood sheets 40 are spaced apart by spacers 42 so that the space between the plates 40 forms an insulating space 44 in which fiberglass is provided. increasing the insulation capacity.

In a typical embodiment, the container 32 is made in one piece and has side and bottom walls 6 mm thick. The plywood sheets are 12 mm thick and a approx. 12 mm thick fiberglass reinforced coating is molded around the plywood sheets.

Since the electroless nickel solution must be kept at a high temperature to provide the most effective deposition of the material, the insulating structure of FIG. 2 particularly advantageous. In addition to being highly insulating, the structure described is strong so that the weight of the solution can be absorbed properly.

By preparing the polypropylene container and completely cleaning it prior to introducing the solution, contamination of the bath can be kept to a minimum. The use of a container made of an inert plastic and of a very pure nature is important, since electroless deposited nickel has a high tendency to form deposits on surfaces of many different types. In addition, electrically deposited nickel will begin to deposit on any part of a surface which has only a small amount of contamination or is scraped, thereby forming a core for nickel build-up.

Especially because of the flange 34 of the container 32, it can be easily handled by simply inserting it within the support in the manner shown. This has the advantage that the container 32 can also be easily removed, as it can be lifted and replaced if it is damaged or otherwise unsuitable for use. The container material is suitable for cleaning and the container as well as other parts of the apparatus can be cleaned by periodically circulating nitric acid throughout the system.

The benefits of the construction shown will be readily understood as any risk of contamination is greatly diminished. As a result, a powerless nickel bath can be used throughout its useful life, eliminating the need to discard an entire bath.

The powerless nickel baths are extremely expensive, and a system which avoids the loss of such a bath is therefore of great value.

The other components of the construction shown are also made of materials which are inert, so that the build-up of nickel deposits in the circulation system can be minimized. Chlorinated polyvinyl chloride pipes are preferably used for lines 18 and 22. The heat exchanger may include internal "Pyrex" pipes for the solution and outer steel pipes for the vapor in the annular space between these pipes and the internal pipes of the heat exchanger. The filter 24 preferably includes a polypropylene bag which can filter out particles of more than 5 microns in size. The use of this filter is very important to avoid introducing solid particles into the bath as such particles could act as cores or starting points for unwanted nickel deposition.

In addition to nickel deposition on previously unpainted surfaces of articles, the apparatus described can be used to deposit nickel on articles that have been used so much that excessive wear has occurred in one or more places, or in cases where mistakes in previous coating operations. Prior to the renovation process, a scraping or purification process is performed to remove all parts of the previously applied nickel deposit.

This process is desirable in order for the nickel to be able to deposit uniformly over the entire surface, without any areas being subjected to a too thick build-up of nickel.

The apparatus of the invention is not only useful for nickel deposition on aluminum and cast iron models and core boxes, but can also be used advantageously in the treatment of other materials such as e.g. epoxy or epoxy impregnated with metal.

Given the cost of electroless nickel deposition, it is desirable to avoid deposition on areas that will not come in contact with the mold and core forming materials. Consequently, these areas of the models and core boxes are covered, and again it is necessary to use materials which do not cause contamination of the nickel bath. Plastisol tape and plastisol-based paints as well as polyethylene bags or foils are examples of materials that can be used to protect areas that should be kept out of touch with the nickel solution