DE2154895A1 - PROCESS FOR FINISHING MODELS AND CORE BOXES - Google Patents

Description

2154995

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4-324-30 / 1 '* Nov. 3, 1971

J? Irma

• Deere ί * CoiapaTj.y John Beere Koau Moline / II. 61 265 USA

Method of finishing models and core boxes

The invention relates to a method for producing objects such as models and core boxes that are used under abrasive conditions in mold-making and coring processes are determined.

When making models bav /. Sample pieces and core boxes or core canoes for high pressure molding systems are usually made of cast aluminum or cast iron. Aluminum can be cast economically, it can be cast into intricate shapes, and it requires minimal post-casting processing. The aluminum parts are also le.ichb and therefore viährend the i'o.cmhsr position slightly egg: ni handle.

BAD ORIQIMjM.

Alum! Niυmmod e 11 e and core box are however based on applications limited, which does not have high production of molds and Require cores. The aluminum is subject to relatively quick wear and tear, and in the high-pressure process it has. it has been found, for example, that aluminum in general is unsatisfactory where more than about 5000 molds are to be made. Try the aluminum Longer use leads to a loss of accuracy in the dimension of the molds produced and can also lead to lead to unsatisfactory casting mold surfaces, as the aluminum tends to become extremely porous with excessive use.

Metallurgical plants have resorted to cast iron when extensive Production of molds and cores is required. The cast iron is harder and has a reasonable lifespan for the models and core boxes used under high pressure conditions. Cast iron models and core boxes are however more expensive because of the higher costs involved in the casting operations and because there is usually quite a large amount of machinery is required to achieve accuracy and realize intricate shapes. The cast iron is too heavier and therefore its handling is a little more difficult.

The invention is intended to provide an improved technique for the final treatment..voη models and core boxes, whereby an increased service life of these objects can be achieved. In particular, the invention is intended to provide an improved Model finishing system and core box supply, eliminating such items under abrasive operating conditions can be used in process operations without the use of hard metals such as

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To make cast iron for the basket position of the objects necessary.

Another object of the invention is a finishing system of models and core boxes to create which except to extended life for the part to others as well Improvements, including a very convenient method of determining the amount of wear on the parts, improved separability of the parts from the cast threads and cores produced, as well as considerable savings Manufacturing costs.

The method according to the invention relates generally to the final treatment of models and core boxes that are Use in abrasive conditions such as high pressure molding machines or otherwise under conditions conducive to developing abrasion on the surfaces of specimens or models and core boxes tend to be determined. In particular, the invention relates to education of electroless deposited nickel deposits on surfaces of models and core boxes, creating surprising and extremely satisfactory performance characteristics of the models and core box can be achieved.

The method according to the invention goes beyond pure application a more stable layer on both models and core box. So it was found that it is extremely difficult to make models and treat core boxes when it comes to forming coatings that improve the properties of these articles.

309818/0627 BAD ORIOJNM.

Attempts to apply a chrome plating or an electrolytic nickel plating, for example, have been more limited Success. Due to the rather complicated surface areas of different models, the coatings not be applied with any uniformity. It was also found that, with the exception of the more expensive ear plating, the surface hardness of the obtained articles was not improved satisfactorily to reduce the cost of such Justify plating process.

The surface properties of models and core boxes also tend to prevent the successful formation of a suitable plating. So will most items. of this type are checked before they are plated so that it can be determined whether those made from them Molds and cores are satisfactory. This test leads to contamination of the surfaces of the models and Core box by embedding sand and other foreign matter in pores and cracks due to the high pressure molds. The handling of the core box and models leads to other contamination. '· For example from greasy lubricants.

It would be very uneconomical to try plating before testing as models and core boxes are often modified must be in order to achieve the dimensions and shapes necessary for production conditions. Therefore would be the only economical plating operation that could be resorted to, one that is still working after the models and core boxes are subjected to the test have been.

£ 154895

The use of an electroless nickel plating process, in particular, as carried out in accordance with the preferred embodiments of the invention, has been found to be supreme suitable for the final processing of models and core boxes. The electrolessly deposited nickel provides one extremely durable, abrasion-resistant and corrosion-resistant Surface for the clad objects, creating even objects that are made entirely of cast aluminum are, for an extensive production of molds with a high pressure molding line can be used. The electrolessly deposited nickel can surprisingly in Connection with models and core box are applied, that are formed from a variety of materials, even if such materials are used together, for example if there are many individual aluminum models are attached to a cast iron support. The electrolessly deposited nickel can be deposited on such combined materials and on other combinations including cases where Soldering metals of various metallic compositions for Purposes of shape restoration or repair used on the surface of a model.

The electroless nickel has been found to deposit uniformly even where complicated Surface shapes occur. In this way, the electrolessly deposited nickel overcomes deficiency, as in experiments with other plotting processes occur, which in general lead to non-uniform deposition of the material lead different model surfaces.

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Pie according to the invention in the electroless deposition of Nickel applied particular to models and core box Measures initially consist of a carefully carried out cleaning to remove all traces of contamination. It has been found that where such impurities are present during plating, the impurities lead to localized areas of inadequate bonding of the cladding, causing the cladding to be localized can be removed when subjected to abrasion. Therefore, a satisfactory plating of models and core box for use under production conditions without the carefully controlled cleaning operations that characterize the system according to the invention, cannot be achieved.

The inventive method for producing objects such as models and core boxes that are used under abrasive conditions in mold making and coring processes is characterized in that at least on the surface parts of the objects, fc which are subject to abrasion due to repeated abrasive contact with mold and core forming materials, electroless Nickel is deposited as a plating, the nickel deposition evenly over these surface parts and is at least about 0.0064 mm (0.00025 inches) thick. At least partly made of aluminum or alloys based on aluminum existing objects are used, and the surface parts to be plated are cleaned prior to plating, wherein cleaning includes the steps of vapor degreasing, immersion cleaning and . Having immersion in an acid bath and the objects

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are still subjected to zincate treatment. Will Objects used, which consist partly of iron-based materials, which together with the cast alloy on Aluminum base is used as the acid bath an inhibited nitric acid bath is used to prevent attack on the iron-based material. Pass the Objects at least partially made of cast iron, the surface parts of which are cleaned before plating, whereby the Clean the scraps with steam degreasing, (dipping in alkaline Solution, immersion in detergents and! Immersion in an acid bath. For items made entirely of cast iron cleaning can be carried out in an electrolytic bath. When using objects made of aluminum in combination with cast iron, the nickel plating becomes simultaneous and applied uniformly to the surface parts made of these different metals.

Further features, details and advantages of the invention result from the following description of exemplary embodiments with reference to the drawing. Show in it:

1A and 1B a flow chart showing the treatment s stages, how they are applied to a model according to the teaching of the invention,

Fig. 2 is a schematic representation of the device for electroless plating for final machining of models, and

Figure 3 is a cross-sectional view of one for use plating vessel constructed in accordance with the teachings of the invention when plating models and core boxes.

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2154835

1A and 1B illustrate schematically that with the according to the invention device carried out method and the steps of the cleaning process. The special cleaning processes include the initial stage of vapor degreasing. This approach removes the relatively weak retained impurities; but removed, especially because of the aforementioned test measures on the models, degreasing does not remove the stored impurities. The steam degreasing is therefore followed by a cleaning phase, the includes either immersion or electrolytic immersion in alkaline solution.

The cleaning phase can include immersion cleaning, in particular if cast aluminum alloys wholly or partially form the objects to be plated. The immersion is preferably carried out in a non-silicate, non-corrosive aluminum cleaner. The cleaning compound is used in a concentration of 60 to 90 g / l (8 to 12 ounces per gallon) of solution, which is kept between 82 and 93 ⁰ C (180 to 200 ⁰ J ¹ ). A "4-70" alkaline solution from MacDermid Incorporated provides a suitable composition for this immersion cleaning. Alternatively, when the articles are made entirely of an iron-based material such as cast iron, an electrolytic cleaning bath or "electrolytic cleaner" can be used since the iron-based material resists the removal of any material from the model under electrolytic conditions.

Immersion or electrolytic cleaning is also not adequate for complete cleaning as some of the heavily embedded Particles of sand or other contaminants

309818/0627 BATH ORIGINAL

resist the removal at this point. Hence follows During the cleaning phase, the objects are immersed in an acid bath. A preferred bath for acid cleaning, though both iron and aluminum alloys form part of the item is an inhibited nitric acid solution, since this solution does not attack the iron violently. Because the invention has special application to models and core boxes a combination of materials such as cast iron and aluminum, the inhibited nitric acid bath stops. a particularly beneficial cleaning agent. A hydrochloric acid pickle is used as a cleaning agent on objects made of brass, cast iron and other ferrous metals applied.

After the cleaning treatment and after the acid bath treatment, the objects are rinsed off. In addition, mechanical Scrubbing, for example with a brush, can be used. Finally, in some cases it may be desirable to do the cleaning and acid immersion with or without mechanical Repeating scrubbing.

Like Pig. 1A and 1B show, the cleaning phase is followed by one Zincate treatment of the objects to be plated, if Aluminum is present. This pretreatment of aluminum surfaces has proven to be ideally suited for Models made entirely or partially of aluminum. The nickel deposition from solution can, from the point of view of the Uniformity and adhesion can only be carried out in a satisfactory manner when the to be plated Surface is perfectly receptive. It has

309818/0627

indicated that the zincate treatment was a suitable one for aluminum The surface can be absorbed and does not have a harmful effect on brass or cast iron or any other brazing material commonly used in the manufacture of Models are used · The special zincate solution contains a combination of caustic soda and zinc oxide and is used used at building temperature. The zincate treatment is followed by a rinse and then immersion of the items in the electroless plating bath · Die Models and core boxes are preferably provided with a cladding about 0.025 ma thickness (0.001 inches)} however, plating thicknesses between 0.0064 and 0.25 ^ ma (0.00025 and 0.010 inches) are also contemplated, where the selected thickness depends on the amount of abrasion, dea the subject will be subject. Vo models and core box not used in mass production or where the surface design is such that no severe erosion occurs, thicker coatings are not required. In the case of high abrasion, a thicker deposit can be used can be used as long as the plating adheres satisfactorily without chipping or flaking. -.

The thick solutions for electroless deposition can have a standard composition, for example a solution which initially contains 5 to 25 g / l (0.1 ounces per gallon) of nickel and 4 % of sodium hypophosphite. In accordance with normal practice, the concentration of nickel and sodium hypophosphite can be gradually increased as the bath ages.

100111/0627

BATH ORIGINAL

The initial operating temperatures are preferably in the order of about 77 to 79 ° C (170 to 175 ° F), maintaining the temperature with increasing age of the bath to about 95 ⁰ C ⁽⁰ 2QO P) is increased. .

Nickel solutions for electroless flattening are relatively expensive, and it is therefore important »any significant one Avoid wasting such solutions. In typical electroless hickel plating processes, the solutions in relatively small containers, so that only a small amount of solution to the at any given time Plating is used. Should the solution become contaminated, the relatively small amount can be used without significant Discard loss.

In the system according to the invention, many of the models to be plated are relatively massive and it is therefore necessary to Use containers with a relatively large capacity. Preferably containers with 18.9 hl are used, containers with a capacity on the order of 11.4 hl to 26.5 hl are generally suitable are. Of course, it is far more important to avoid significant contamination when using solution quantities of these sizes-r Okay as it would mean a significant loss if it were necessary to change the contents of a discard the entire container.

Figs. 2 and 3 illustrate a construction as they in the German patent application P filed at the same time (lawyer file PH 43 £ 5) with the title "Device

for finishing models and core boxes " and is claimed. This device provides an ideal

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Device for storing the solution and on the other hand for Provide an effective arrangement for performing electroless plating. According to these figures contains a Container 10 a tickel solution 12 for electroless plating. A first conduit 14 leads from the bottom of the container to one Pump 16. The second line 18 carries the solution to a heat exchanger 20 to. A third line 22 conveys the solution from the heat exchanger to a filter 24 and the material is returned to bath 12 through this filter.

The heat exchanger 20 comprises a steam inlet pipe 26, which serves to circulate the steam through a heat exchange line, which contains the solution to guide the surrounding single coat. The steam is used to recirculate through a Line 28 discharged.

Additives are introduced into the solution either continuously or at desired intervals. These materials can use certain amounts of nickel and sodium hypophosphite Increasing the proportion of these materials in the solution and replacing the amounts deposited during the demolition process have been include.

Fig. 3 illustrates a preferred embodiment of the Container 10. This container has a plastic insert 32 made of a material that, as far as the electroless plating process is affected, is inert. Polypropylene is a for. material particularly suitable for this purpose. The insert 32 has an outwardly directed outer edge 34 which is on the upper wall part 36 of a load-bearing Construction for Einjage 32 is at rest. The wall 36 has a downwardly sloping outer edge part,

309818/0677

so that the outer surface of the container is given such a shape. Should some of the solution in the container splash into this area, the solution will flow away from the container and diminish the possibility of contamination.

The construction supporting the container closes with a glass fiber coating 38 and inner and outer plywood parts a. The plywood sheets 40 are by 2x3 inch pieces 42 separated from each other, which thereby spatially separate the plates 40 from each other * so that the construction characterized by an insulating space 44, the glass fiber layer contributing to the insulating ability.

As the solution, for electroless deposition at elevated temperatures to allow the most efficient deposition of the cladding material is the isolated one Structure of FIG. 3 is particularly advantageous. In addition to / its inherent insulating property is the one described The arrangement is also strong in its structure so that the weight of the solution can be easily absorbed.

By making the liner out of polypropylene and thoroughly cleaning this liner before the solution is introduced, the contamination of the electroless bath can be kept to a minimum. The usage an insert made of an inert plastic and extreme cleanliness are important because it is deposited without current Nickel has a strong tendency to form deposits of many different types on surfaces. In addition, begins the electroless deposition of nickel on any surface area containing even a small amount of contamination or scratched as this will nucleate the deposition of nickel.

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In particular because of the band 34 formed on the insert 32, the insert or the insert can be handled very easily by simply inserting it into the supporting structure in the manner shown. So becomes the extra Advantage of a removable insert; 32 scored. The use so it can be easily lifted and replaced if damaged or otherwise unsuitable for use. The insert material is very suitable for kneeling, as is the insert and the rest of the system can be effective by flushing ait nitric acid through the device The system should be cleaned at regular intervals.

The advantages of the illustrated structure are obvious, since any risk of contamination is greatly reduced. This is how an electroless nickel bath will last for its entire service life can be used away without the need to discard a full bath. As already stated, are de-energized Nickel baths are extremely expensive and therefore a system that avoids the loss of such a bath is of great value.

The other parts of the structure shown are also made of inert materials, so that the formation of Ni disgusting deposits ia the circulatory system to be kept on a »Hinisum can. For the lines 18 and 22, tubes made of chlorinated polyvinyl chloride are preferably used. The heat exchanger Pyrex inner pipes can be used to guide the solution and an outer steel pipe to absorb the steam in the ring-shaped Have space between these tubes and the internal lines of the heat exchanger. The filter 24 is preferred a polypropylene bag designed to filter out particles larger than 5 microns. The usage

309818/082?

this filter is especially important from the point of view Avoiding the introduction of solid particles into the plating bath, which act as seeds for the undesired deposition of nickel could serve.

Except for plating previously unplated objects The described system for re-plating objects is of "use" to the point used where excessive abrasion has occurred in one place or another or where in a previous one Plating Mistakes Were Made · The re-plating process is preceded by a step to remove each applied nickel plating. Removal is desirable in order for the nickel to spread uniformly over the entire surface is deposited without any specific areas exhibit excessive nickel deposition.

The inventive method was with reference to the Application of cladding to aluminum and cast iron models and core boxes is described. But it can also other model materials, e.g. EpoacLd or metal impregnated Epoxy, can be used in an advantageous manner in the procedure according to the invention.

In view of the cost of electroless nickel solutions, it is desirable to avoid plating on surfaces which are not in contact with the materials forming the mold or the core. Hence these Areas of the models or the core box covered that

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do not lead to contamination of the plating bath. Plastisol tapes and paints based on plastisol and polyethylene bags or films are examples of materials that can be used to protect surfaces that should not come into contact with the nickel plating solution.

When models are electrolessly nickel-plated in the manner described, various other advantages occur in addition to the increased service life of the models. In particular, the separation of the model surfaces from the molding material takes place significantly lighter, obviously due to the extremely smooth surface that the deposited nickel forms and the Lubricity due to the phosphorus content of the deposited material. The abrasion of plated objects can also be determined by the fact that the deposited nickel has a silvery matt appearance, the provides a contrast to the materials used for models and core boxes. When part of the nickel plating is worn away, this fact becomes so easy due to the contrast between the claimed object surface and the remaining nickel plating can be seen.

The improved abrasion is due to the hardness of the electroless deposited nickel compared to the aluminum and the cast iron. Cast aluminum typically has a Brinell hardness of about 80, cast iron of about 200 and electroless nickel of about 500. The hard one is electrolessly deposited Nickel can be further enhanced by heat treatment; However, this is to achieve the discussed Improvements not necessary.

305818/0821

To the previously mentioned advantages unvoiced deposited nickel is still _f that the application of the method described allows considerable savings in a foundry operation. For items to be used in mass production, it is about 50% cheaper to use nickel plating than to make a cast iron model or core box. Even where the more expensive cast iron objects are used, the sexinless nickel plating brings improved wear properties, better separation and the visible wear indicator.

Claims (6)

Claims 1. Process for the production of. Objects such as models and core boxes that are used ;, under attrition conditions in the case of mold manufacturing and core formation processes are characterized in that at least on the surface parts of the objects, which are subject to abrasion due to repeated abrasive contact with mold and core forming materials electroless nickel is deposited as a plating, the nickel deposition over these surface parts evenly distributed and in a thickness of at least is approximately 0.0064 mm (0.00025 inches). 2 · Method according to claim 1, characterized in that g e k e n η - ' draws that at least in part of aluminum or alloys on aluminum basis existing objects be used that the surface parts to be plated are cleaned before plating, wherein the Complete the steps, steam release, immersion cleaning and Comprises immersion in an acid bath and that the articles are further subjected to a zincate treatment will. 3. The method according to claim 1 or 2, characterized in that g β k θ η η draws that articles are used which consist in part of iron-based materials, the used together with the aluminum-based cast alloy w $ rd, 'and that the acid bath is an inhibited nitric acid bath is used to avoid attack on the iron-based material. 3098I8 / 0627 4. The method according to claim 1, characterized in that the objects at least occasionally consist of cast iron so that the surface parts of the objects to be plated are cleaned before placing, cleaning the steps of steam degreasing, immersion in alkaline solution, dipping in detergents and dipping in an acid bath. 5. The method according to claim 4, characterized in that objects made entirely of GnBeisen used and the Eemnigen. in an electrolytic Bath is carried out. 6. The method according to at least one of claims 1 to ^, characterized in that from a combination of metals including aluminum and / or cast iron existing objects are used, and the nickel plating simultaneously and uniformly on from such different metals existing surface parts takes place; 7- method according to at least one of claims 1 to 6, characterized in that a container with a removable inert plastic insert for receiving the nickel solution used to form the placement is used and the insert is periodically cleaned during its use, in order to keep the container for the de-energized To keep nickel solution practically pure continuously. 309818/0627