CZ164596A3

CZ164596A3 - Tool for producing glass and process for producing such tool

Info

Publication number: CZ164596A3
Application number: CZ961645A
Authority: CZ
Inventors: Tapio Mantyla; Pauli Reuhkala; Tuomo Tiainen
Original assignee: Karhulan Lasi Oy
Priority date: 1993-12-08
Filing date: 1994-12-05
Publication date: 1997-04-16
Also published as: FI935502A0; AU1243695A; EP0733026A1; WO1995015926A1; FI94334C; JPH09509131A; FI94334B

Abstract

A tool for use in glass manufacture, such as a glass mould, plunger or the like, having at least a portion of the surface of the tool provided with a layer produced by a suitable coating method, the layer consisting mainly of a manganese-containing nickel aluminide, the strength properties of which increase as a function of temperature from room temperature to at least 450 DEG C. An inherent feature of the manganese-containing nickel aluminide is that the oxide layer forming on the surface of the tool does not substantially increase after the primary forming of the layer and that the quality of the surface of the surface layer improves in the operational temperatures of the glass mould under the influence of molten glass when compared to the quality after the machining of the surface, i.e. the compound possesses a self-polishing feature.

Description

01--1207.-Se-Ce A tool for the manufacture of glass and a method of making this tool

as a glass mold,

The Ί · -ρ- »η (" ::π :: i..kv

The present invention relates to the manufacture of glass, for example a plunger or the like, in which its surface is at least partially covered by a layer formed by one of suitable methods, for example by plasma spraying, detonation spraying, flame spraying, hypersonic spraying, and where the tool, either in its entirety or only one part, is made of the same material as the surface layer by a suitable method. The surface layer comprises at least one Intermetallic Compound. The present invention also relates to a method of making the tool.

BACKGROUND OF THE INVENTION. mass production of glass containers, such as a bottle, the molten glass is molded into its desired form by a suitable mold into which the molten material is formed either by a plunger or by a combination of gas pressure and vacuum action that acts immediately thereafter while the molten glass solidifies in the mold . The molten glass forming procedure may consist of several phases. During the first phases, the molten glass must be able to move freely over the mold surface and thus the frictional forces between the molten glass and the mold. 1

C form They are decisive for assessing product quality. High frictional forces mean that the molten glass does not clog at the same time in all places, but stiffens gradually and therefore the glass product produced is ultimately corrugated and contains micro-cracks in its elite. In principle, this problem can be avoided by increasing the temperature of the molten glass and thus reducing its viscosity and increasing its liquidity.

But the problem with rising temperature is in it. that, at high temperatures, the glass begins to stick to the mold surface. Nowadays, the temperature of the mold during glass production is about 5 ° C. which allows the use of cast steel molds. In order to reduce friction and improve the quality of the final product, the mold is coated with a graphite-based paint and lubricated with graphite lubricant. The shelf life of the paint is about 2-8 hours and the mold must be lubricated about every 15 minutes. Lubrication is associated with the formation of large amounts of smoke and unpleasant odors. If the production is planned in large quantities, another important goal is to facilitate the transfer of heat from the molten glass to the mold and further to the cooling medium. The requirement for large-scale production is to have a " transition resistance " between the molten glass and the mold was as small as possible. The " narrowest gate " transferring heat from the mold to air. The glass itself has a relatively high thermal convection, but in the molding procedure the glass must be kept in a molding viscosity until the final injection into the mold. From the point of view of glass cooling, the replacement of the material used to make the mold is not very effective. The heat transfer resistance in the region 2 of the actual transfer between the glass and the mold is greater than in the actual form. This is due to the unevenness of the surface and the residual amount of air between the mold and the glass. Heat transfer is very variable as a function of time. At the beginning of the contact, the heat transfer is very effective, but decelerates rapidly when the temperature gradient decreases and the heat convection inside the glass reduces heat flow. The temperature of the outer surface of the mold is usually unchanged, not a function of time. The wall thickness of a conventional container glass is about 2-3 millimeters regardless of the package size. The ratio between the weight of the container glass to that of its outer surface is the same.

On the outside, the mold is a transfer mold; heat is mainly made by convection, ie the possibility of cooling improvement is associated with an increase in the cooling air flow rate, or with an increase in the heat transfer area by the fin coolers. An even more effective way of cooling the mold is to use water or water mist instead of air. However, this creates another problem, namely the possibility of rusting, machinery, and molds. These problems can be overcome by selecting suitable materials for making the mold, or by covering the mold surface with a suitable material, but these solutions require considerable additional investment. When the cooling effect increases on the outside of the mold, it also causes an increase in the temperature gradient between the inside and the outside of the mold. When air cooling is used, the temperature at the outside of the mold side is not reduced by any significant value, thereby increasing the temperature inside the mold. This can be avoided by replacing the material from which the mold is made with a higher conductivity material. 3

However, this is again at the expense of a further increase in investment costs.

As mentioned earlier, there are air pores between the glass and the mold-forming wall. The amount of air pores between the mold and the glass depends! surface, touch temperature, mold material and glass properties. When there is contact between the glass and the mold, the heat is transferred by the convector and inside the pores the heat is transmitted by radiated and convection by air. All heat transfer modes are directly dependent on the transfer area! heat and therefore has a great heat transfer effect. When a material with the highest possible thermal conductivity and surface equality corresponding to its relative roughness of about 20 µm is used, this causes a relatively large amount of cracks on the surface of the final product. Therefore, it is desirable to have as flat and even a surface as possible on the final mold. This provides both good heat transfer and minimization of cracks. Increasing the contact temperature also results in improved heat transfer (finer glass fills any unevenness on the mold surface) and at the same time the surface of the cracks on the surface is reduced. Factors affecting the temperature at which the glass begins to bond is the mold material, the viscosity of the molten glass, the flatness of the mold surface, and the glass pressure on the mold surface. Different materials tend to stick to the surface of the mold, depending on the surface tension of each material. The surface tension to ovQ is between 1.7 ... 1.0x10 ~ aN / cm.

The unevenness of the mold surface affects the bonding of the glass to the mold due to heat transfer, which means that the glass 4 cools unevenly over the mold surface, despite a suitably roughened surface. These " cold spots " then I prevent the glass from sticking to the mold. However, they are still being created on the glass surface at the same time. cracks as mentioned above:.

The present invention relates to the minimization of the aforementioned disadvantages, partly also to their complete elimination and to the ability to control the cooling process of the molded glass and to the strength characteristics of the final surface by improving its quality.

Under a steady cut

This object is achieved by a tool (device) whose surface is mainly composed of nickel aluminide, which further contains manganese, and whose distinguishing feature is that the strength properties and hardness of the compound increase as a function of temperature from room temperature to at least 450 ° C and said coating has a thin and husky oxide layer thereon. This oxide layer is formed on the tool surface at the operating temperature of the glass mold when contacting the mold surface with molten glass. The quality of the tool surface layer is improved by the effect of molten glass, at least in comparison with the quality after mere machining of the mold surface.

The inventive method for producing a tool used in the manufacture of glass is at the operating temperature of the mold being achieved by contacting the mold with molten glass, where a thin and dense oxide layer is formed on the tool surface and the surface layer 5 is improved by the molten glass at least in comparison with with quality that is achieved by mere machining of the mold surface. The surface layer consists mainly of manganese-containing nickel alumiride, whose characteristic feature is that the strength properties and hardness of this component increase as a function of time from room temperature to about 450 ° C. Y in this context, Is the term " machining " used to describe all procedures that need to be done to achieve the final surface finish of the mold. Therefore, for example, all different polishing methods fall just under this term " machining " in this context. At a time when research and search for individual solutions began with this above-mentioned problem, one natural alternative arose and that the material from which the mold is made will be covered with a layer of suitable material or v6; in a particular case, the entire material will be made of this covering material, or only one of its parts. Adverse glass sticking problems and tearing off the cover material can be avoided if the entire tool, or only one portion thereof, is made from the same material in some critical applications as, for example, simpler molding applications.

When various covering materials were evaluated, the first alternatives were naturally different ceramic coating materials and some commercially widely used superalloy coatings. The disadvantages of ceramic materials are, for example, springiness and poor heat transfer properties. These materials are also not advantageous in terms of their immunity to thermal fluctuations, which is one of the most common disadvantages of these overlays. Another disadvantage of these 6 coatings is their ability to be machined and especially. disadvantage is then it. that the mold surface cannot be simply polished in these cases. Various supersiltins, based on nickel cobalt content, yielded good results, or better solved at least during the tests. However, the resulting properties of the end products were not as expected and there was no significant improvement in the quality of the glassware tool. Likewise, the coating of these materials was not a good solution to the problems. In experiments with some covering materials, namely known intermetallic compounds but also relatively new in their use as construction materials, it has been found that these materials offer unexpected advantages. The use of intermetallic compounds as constructional materials is particularly useful because of their brittleness. Until the effects of certain additives, such as bera, have been observed. to increase the tensile properties that make intermetallic compounds available for use as either cover coatings or as basic structural material. While experimenting, it was surprising to find that some intermetallic compounds had a fairly high temperature at which glass was adhered to their surface. A typical feature of some intermetallic compounds was that their strength properties increase up to a certain limit value when the room temperature is raised to a higher temperature. For example, hardness may increase about twice during the transition from room temperature to 500 ° C. Certain intermetallic compounds are also capable of exhibiting an increase in strength properties up to about 800 ° C. At room temperature, these modified compounds are fine and thus easily machinable and polishable, which are important factors on the basis of which the material used to make the mold for glass production is decided. The intrinsic properties of the intermetallics are their good thermal conductivity. When the mold base material, usually cast steel, is coated with an intermetallic compound layer and then carefully polished, it is possible to significantly reduce the formation of microcracks in the final glass article. However, it is better to be ready at some critical stages of manufacture to manufacture tool parts, such as mold parts, or molds all from the same material as the cover coat, but in this case to use the material as a basic structural material. In this way, it is possible to avoid tearing off the surface layer or problems of sticking the glass to the surface of the mold. By using a suitable cover material, either only as a cover coat or as part of the base material surface, it is possible to reduce the wall thickness of the final glass article and thus produce a glass product of lesser weight, the strength of which is as good as that of the glass article he had thicker walls, and had been smeared with previous methods.

When good machinability is combined and the strength and hardness of the material increases, the material is hardened. overall durability, with temperature rises from room temperature to normal operating temperature, that is to say about 5G0-650 ° C, it is clear that this kind of material ... can be used as a coating material for 8 glassware tools.

The strength of the usable intermetallic compounds will increase from room temperature to at least 450 ° C. The properties of these compounds can be improved by suitable alloying, thereby improving their room temperature properties, or further improving their strength properties when the temperature rises to about 800 ° C. These alloying elements include boron, Cten increases strength, properties at room temperature) and hafnium (improves strength properties at higher temperatures than room temperature). Iron, titanium, manganese, zirconium, cerium, and niobium are all other elements that can also be used to alloy for the purpose of improving the properties of intracellular compounds.

Usually, the surface quality of the glass making tool is best when the tool is new, that is, immediately after it has been machined as defined above. The tendency of molten glass to adhere to the tool surface is the lowest when the tool surface (mold) is suitably oxidized. Nonetheless, various lubricating agents for lubricating the tool surface, or today's conventional topcoats, must be used regularly during production to avoid sticking, molten glass, to the mold surface. The optimum thickness of the oxide layer is achieved after about 24 hours of normal glass production operation in conventional coatings used today. Then, l < an increase in the thickness of the oxide layer, and the layer subsequently becomes brittle and tends to form flakes on the surface and fall off during the subsequent production of glass. The increase in thickness is due to the diffusion of oxygen 9 through the oxide layer towards the metal and the diffusion of metal through the oxide layer and further towards the free surface of the mold.

As already mentioned, the oxide layer on the mold surface tends to form flakes (or flakes) during manufacture. These fallen flakes are then adhered to the surface of the molten glass and thereby cause a deterioration in the surface quality of the glass being produced and consequently a deterioration of its strength characteristics. These flakes are produced both by the release of the oxide layer and by the lubricants used during manufacture. Therefore, it is necessary to clean the mold at periodic intervals, for example by sandblasting its mold, thereby removing, irregularly adhering, the lubricant and the peeled oxide layer. It is naturally necessary to polish the mold after polishing before it is used again. This again leads to the initial state and the cycle can be repeated for as long as possible before the new one needs to be replaced. When testing several different alumina compounds as intermetallic compounds forming a coating layer on a glass bottle mold, a surprising fact was noted regarding the particular advantage of manganese-containing nickel aluminides.

When such a mold was used in the manufacture of glass bottles, it was unexpectedly found that the surface quality of the plunger on the mold. the glass mold began to improve about an hour and a half after production began. When this production was then discontinued, the mold surface was inspected and found to be better polished than when it was completely new, J. immediately after its machining. That is, the surface quality of the glass bottles and their strength properties, particularly their impact resistance, have been radically improved over the course of their own manufacturing process, instead of: these properties have deteriorated, as was the case before. The oxide layer that forms the surface coating was very dense and thin, and its thickness was not significantly increased once the layer had already formed. This self-cleaning and oxidized coating essentially comprises mixed manganese and aluminum oxides.

These nickel aluminides are a Ni-.3C ΓΓ · ΗνΙη · + · Β compound and have their own specific feature - self-polishing and all the resulting benefits. Clearly better properties than the rest of the known materials used were found. as topcoat coatings. A feature of all of the aforementioned known cover materials is that the quality of the surface formed by them is reduced immediately from the start of production and until the mold has to. be replaced. Another negative factor of these cover materials is the constant need for lubrication of the mold surface and peeling of the flakes from the oxide layer.

The surface coating of the present invention allows the temperature to rise at which the glass begins to stick to the mold, typically at about 500-540 ° C, up to a temperature range of about 550-630 ° C, while at the same time providing good mold surface quality. for glass, all of which leads to improved surface properties of the glass article. By using the method of the present invention, it is also possible to avoid the harmful exfoliation of the oxide layer flakes, which is a common manifestation of coating coatings at other times. The use of the invention can also significantly reduce the need for continuous lubrication of the mold, again when compared to standard known cover coatings in the first mold. The precise cause of this property improvement (thin and dense oxide layer having self-polishing properties) of the tool surface has not been found yet, probably due to the chemical and physical properties of the topcoat materials presented herein, and this cause goes beyond both the operating temperature of the glass mold and the chemical and mechanical properties of the molten glass.

Cover coatings can be made in a variety of ways, such as by plasma spraying, detonation spraying, or by hypersonic velocity flame spraying, or by spraying or other suitable method. Various known methods can also be used to make the molding. molds of solid base material.

Embodiments of the tool of the present invention may be applied within the scope of the scope of the invention defined in the appended claims. 12

Claims

/ (to -Α -JI? lldd * Λ f i i JA10INISYIA | PAT E N T O REQUIREMENTS; oHiAmsAwgyd avy a! I '9 6 ΙΛ 9 0 1.) A tool used to make glass, for example. The glass molding mold, the plunger or the like, in which at least a portion of the surface thereof is provided. a surface layer which has been applied by any suitable method, such as by plasma spraying, detonation spraying, or by hypersonic velocity flame spraying or elaboration, or in which the tool or part thereof is made of the same material as the surface layer to assist any suitable methods. and wherein the surface layer of the tool comprises at least one intermetallic compound, characterized in that the surface layer consists mainly of manganese-containing nickel aluminide, the characteristic of which is that the strength properties and hardness of the compound increase as a function of temperature from room temperature to a temperature of at least 450 ° C; and - has a thin and dense oxide layer which is formed on the surface of the tool at the operating temperature of the glass mold, by contacting the molten glass with said mold surface; and wherein the quality of the surface layer on the tool is improved under the influence of molten glass compared to the surface quality immediately after machining.

2. A tool according to claim 1, wherein the surface layer consists mainly of nickel aluminide type Ni3 < 1 >; Al + Mn) + B.

3. A method of manufacturing a tool usable for the manufacture of glass. Such as a mold for producing glass, a plunger, or the like, at least a portion thereof. its surface is formed by a topcoat which has been formed on this surface by any suitable method such as plasma spraying, detonation spraying, or hypersonic velocity spraying or flame spraying, or in which the entire instrument, or only one part thereof, is made of the same a material such as said surface layer by a suitable method, the surface covering layer comprises at least one intermetallic compound, characterized by: In particular, said surface layer consists mainly of manganese-containing nickel aluminide, the characteristic of which is that the strength and hardness of the compound increases as a function of temperature from room temperature to at least 450 ° C and that layer is influenced at the operating temperature of the glass-forming mold by contact with the molten glass, thereby forming a thin and dense oxide layer on the surface of the tool, thereby improving the quality of the topcoat due to the molten glass, as compared to that of the surface. Machining. 14