SK109893A3 - Method of production of glassware articles and device for implementing such method - Google Patents

Abstract

The process according to the invention for the production of glass products comprises feeding part-amounts of molten glass and shaping the latter by means of mould equipment containing at least one hollow shaping element (1) whose internal surface is covered by a layer (5) of corrosion- and heat-resistant porous material; before the molten glass is fed in, the cavity (4) of the shaping element (1) accommodates a material which is capable of intensive vapour formation at the shaping temperature in an amount which somewhat exceeds the amount necessary to fill the cavity (4) of the shaping element (1) with saturated vapours of this material, and the layer (5) of the corrosion- and heat-resistant material is impregnated with this material, the shaping element (1) is warmed to the shaping temperature, its cavity (4) is evacuated to po = (0.02-0.1)Pa, and thermal regulation of said material in the shaping temperature range is then carried out. The device proposed according to the invention for carrying out the process contains mould equipment which includes at least one shaping element (1) having a hermetically sealed cavity (4) in which a material which is capable of intensive vapour formation at the shaping temperature is accommodated in the abovementioned amount, a layer (5) of a corrosion- and heat-resistant material being arranged on the inner surface in the cavity (4) of the shaping element (1), while the cavity (4) itself is connected to a device for evacuating the same.

Description

Technique area

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing glassware comprising supplying and molding glass batches in a die comprising at least one hollow molding member into a cavity into which a material having intensive vapor-forming capability is introduced prior to the glass batch. the molding element heats to the working temperature of the material in the pressing temperature interval and the apparatus for carrying out the method.

BACKGROUND OF THE INVENTION

In the pressing of molten or semi-molten glass products, the intensive heat exchange between the material being processed and the pressing device is of particular importance.

Glass products are molded mostly in the range of 400 problems, the speed of the equipment from which the molding, and the quality of the temperatures while making the rhythm, the resistance that arises a number of that means the pressing current, regulation

The first pressing equipment in at high up to 650 ´C, and depends working operational glass products. Therefore, to solve the uniform and glass pressing equipment.

is a fast high temperature problem related to keeping the interval, the glass below suddenly, the device temperature at the bottom where the pressing process is the limiting temperature is even a slight decrease consequent quality degradation also deteriorates these products because of porous or corrugated parts with necessity limited temperature optimal . Pressing dangerous because of the temperature of the pressed molded glass products, optical and on them, and it has under the mechanical properties will result in various defects, cracks and the like.

If the upper limit of the working temperature is exceeded, the forming surfaces are overheated. This results in the glass being adhered to the molding surfaces, which can be diffuse and thus catastrophic, since in this case the entire press line is interrupted and the entire press device needs to be cleaned or replaced.

A second problem is that it is difficult to keep the pressing device within a limited temperature interval at different heat dissipation rates from the pressing device, which depend on the geometrical parameters of the pressed product and the type of glass. The heat dissipation rate depends on the solidification rate of the glass, the thickness of the product, and the geometry of its individual parts. If, in addition to wide flat parts, the glass product also has surfaces that are rounded or at acute angles, which occurs in particular with lamp shades, the rate of heat exchange varies considerably between the various parts. This results in various defects and cracks in the glass.

An important role in glass pressing is that the elements of the pressing device have different thickness or massive construction and therefore different heat capacity and different heat dissipation capacity.

Known methods for thermally controlling the die and the design of its elements have been individually developed not only for different types of glass (short and long, ie fast and slow to set), but also for certain pressing speeds and for individual parts of the die, which means aspects of the pressing device of the product are indivisibly interconnected. As a result, the processing of different types of glass on the same machine is considerably limited, the working speed of the pressing is increased and consequently the performance of the whole machine is increased.

The known process and apparatus for manufacturing glass products according to US Pat. No. 4,790,867 is a refinement of the cooling system allowing heat dissipation at different speeds depending on the working speed 1 and owing.

This known method and apparatus makes it possible to create a cooling system for the molding elements which is adapted to a wide range of operating speeds of the same pressing device.

However, said method and apparatus do not provide effective heat dissipation from the forming surfaces in contact with the glass. This is due to the high thermal inertia of the cooling system. In this case, the forming element, for example a punch, constitutes a structure consisting of three metal parts which are in direct contact with each other and have different thermal conductivity. This is the punch body itself, the low melting point material (solder) and the thermoregulation element (cooling block). It is understood that heat transfer from surfaces in contact with the glass to the coolant passing through the channels of the thermoregulatory element can only occur on the basis of thermal conductivity. It is known that this heat transfer process depends on a number of factors, such as the thermal conductivity of the material, the layer thickness and the like, and has a high inertia.

In this context, the described cooling system has no possibility of reacting operatively, that is to say, dissipating heat upon rapid temperature changes on the forming surfaces that occur during each cycle of glassware pressing.

Thus, when the pressing speed is increased due to the inertia of the cooling system, the forming surfaces which are in contact with the glass can overheat and can stick to these surfaces.

In part, this problem is solved by using a thermoregulatory element made of different metals and with different wall thicknesses, which substitutes for each other when the molding mode is changed. Therefore, at higher operating speeds, a thinner thermoregulation element made of a metal having a medium thermal conductivity, for example stainless steel, is used, while at low operating speeds, an element of high-temperature conductive material, for example aluminum, is made as thick-walled.

However, this does not solve the problem of overall inertia of the cooling system. This problem is only partially solved because the actual process of dissipating heat from the molding surfaces to the coolant remains the same (heat conduction through the multilayer wall) and changes only quantitatively insignificantly.

This method and apparatus are therefore only suitable for a limited range of pressing temperatures due to insufficient cooling system efficiency.

The production and necessity of replacing the heat regulating elements during the pressing process makes the process less dynamic and difficult to operate.

Also known is a process for manufacturing glass products according to US Patent No. 3,285,728, comprising feeding glass in batches and compressing it in a die comprising at least one hollow molding element into which a cavity is fed a material having the ability to vaporize vigorously at operating temperatures. . This material is mercury. The molding element is heated to the working temperature, mercury then provides thermal control of the material in the pressing temperature interval.

This method and apparatus make it possible to control the temperature of the molding surfaces of the molding element when molding the quantity of glass to be dispensed as the molding speed is changed.

However, such a method and apparatus do not allow efficient heat dissipation from the molding surfaces of the molding element for high inertia of the cooling system. The inertia of the cooling system is conditioned by the fact that the hollow space of the molding element, for example a punch, is filled with mercury up to a height exceeding the upper edge of the glass product to be produced when the punch enters the die. In this case, the punch is a solid metal construction with an inner liner formed of liquid mercury. At the same time, heat is dissipated from the forming surfaces depending on the thermal conductivity of the punch and mercury materials. However, since the rate of heat propagation in metals is insufficient, this cooling system does not have the ability to react quickly to the rapid temperature changes in the molding surfaces of the die elements occurring when pressing glass products.

Furthermore, this method and the apparatus do not provide for a uniform temperature distribution on the forming surfaces independent of the temperature and thickness of the glassware.

The temperature profile on the molding surfaces in contact with the glass is uneven during the pressing operation. Typically, the high temperature region is in the middle of the molding element and its upper parts are cooler. As a result, local stresses occur at the top of the product, often resulting in micro-cracks. The geometry and thickness of the product also influence the uneven temperature distribution on the forming surfaces. If the product has acute angled portions, thick-walled portions as well as wide and flat portions, the heat exchange rate and hence the temperature on the shaping surfaces differ greatly. One of the most important factors determining the quality and product range is therefore the isotherm of the molding surfaces in contact with the glass.

Therefore, ensuring a rapid dissipation of heat and bringing it to the entire shaping surface is a necessary condition for equalizing the temperature on the glass surfaces in contact with the glass.

In this cooling system, heat dissipation from the molding surfaces takes place slowly due to its high inertia, while the heat supply from the more heated portion to the less heated portion is virtually non-existent.

In this regard, pressing glass products with complicated geometry and varying thickness in the manner and apparatus described is problematic.

In addition, at a working temperature of, for example, 600 ° C, the pressure of saturated mercury vapors in the hermetically sealed cavity of the punch will be 0.87.10 ⁴ Pa.s, which, with a relatively small wall thickness, is likely to be a hazard and may cause its destruction.

Furthermore, the use of mercury, which is a highly toxic material, is undesirable from an ecological point of view. Mercury acts extremely aggressively on the punch material, reducing its service life.

Summary of the invention .......

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for controlling the temperature of molding elements and to provide a temperature control device which allows to increase heat dissipation efficiency from the surfaces of the molding contacting glass and to achieve a uniform temperature distribution over these surfaces. and from the geometry and thickness of the pressed glass products.

This object has been solved by a process for manufacturing glass products comprising supplying and molding glass batches in a press apparatus comprising at least one hollow molding element into a cavity in which a material having the ability to vigorously generate vapors at working temperature is introduced into the cavity. the molding element is heated to the working temperature and the temperature of said material is controlled in the pressing temperature interval according to the invention, which is characterized in that the inner surface of the hollow space of the molding element is covered by a layer of porous material having high corrosion resistance and high temperature; of the molding element, its hollow space is vented to p _o = (0.02-0.1) Pa, as a result of which the material capable of vigorously evaporating at the working temperature is introduced into the hollow space of the molding element in an amount in excess of the material needed to fill the hollow and to saturate a layer of porous material resistant to corrosion and high temperature.

In the method according to the invention, the main mechanism of heat transfer to the press surfaces is the mechanism of transfer from the largest thermally loaded sections of the molding surfaces to less thermally loaded sections by changing the state of the material stored in the hollow space and having the ability to vigorously evaporate temperature.

The saturated steam produced on the most heat-laden sections removes a certain amount of heat in proportion to the amount of steam generated and the size of the latent evaporation heat, transfers the heat to the less heat-laden sections and transfers it to the sections by precipitation. The high latent evaporative heat values of materials capable of vigorous evaporation also cause rapid heat propagation along the forming surfaces, even in those cases where the temperature difference between the different sections of the forming surfaces is small.

In order to control the conditions of the process according to the invention, a thin film of material capable of vigorously evaporating at the operating temperature must be present on the inner surface of the hollow molding element. In addition, it is necessary to ensure the circulation of this material from the sections where the steam has collided with the sections where intense evaporation takes place. For this purpose, the inner surface of the molding element is covered with a layer of porous material resistant to corrosion and high temperature.

The saturated porous material, after heating, is introduced into the cavity, is capable of vaporizing vigorously and generating capillary pressure to transfer liquid from the condensation sections to the evaporation sections. In this way, the liquid is redistributed on the forming surfaces on which the constant thickness of the heat transfer film is maintained.

The venting of the hermetically sealed cavity to a value of po = (0.02 to 0.1) Pa is necessary so that only the pure vapors of the material introduced into the cavity are present in the cavity during the pressing operation. Thus, predetermined pressure values of the saturated vapor of the liquid heat transfer medium in the hermetically sealed cavity can be achieved as a function of the height of the vacuum and the temperature, i.e. to ensure that the liquid metal vapor in the cavity is saturated during each pressing.

The material capable of vaporizing vigorously at operating temperature is fed into the molding cavity in an amount in excess of that required to fill the molding cavity with saturated vapors of the material and to saturate the corrosion and high temperature porous material layer. Said amount of material capable of vaporizing vigorously at the working temperature is conditioned by the fact that the inner surfaces of the molding element are still to be covered with a liquid metal film which should not dry out during compression. In the absence of a heat transfer medium, a critical situation can occur on the shaping surface, a so-called heat exchange crisis, where the heat transfer film is missing at the intense heat supply site, resulting in a local overheating of the surface. If the cavity is overfilled with the heat transfer medium, the inertia of the molding element during the pressing operation is increased.

The described measures and the physical phenomena accompanying them provide for intensive and practically unconventional circulation of the heat transfer medium in a circle of successive liquid-vapor-liquid conversions, thereby allowing the transfer of a considerable amount of heat from the heat-loaded sections to less heat-loaded sections. The intensification of the heat removal from the hot sections in turn allows the glass products to be pressed at high speed, regardless of the geometry and thickness of the pressed glass products, while maintaining their high quality. It is worth noting that, since the steam penetrates unhindered from the hot sections to the cold sections, irrespective of the inner space arrangement of the molding element, the method according to the invention allows glass objects to be extruded with complex geometry, which also allows to expand the range of pressed glass products. .

Advantageously, a material capable of vigorously vaporizing at the operating temperature is introduced into the hollow space of the fastener in an amount that is 3 to 7% higher than the amount required to fill the hollow space with saturated vapors of the material and to saturate the corrosion resistant and high porous layer. temperature.

When attaching a layer of corrosion-resistant and high-temperature material to the inner surfaces of the hollow molding element, a small gap may occur between the inner surface of the hollow molding element and said layer. In order to ensure perfect thermal contact between the porous layer and the wall of the molding element, it is desirable that the gap be filled with liquid material introduced into the hollow space of the molding element. Said amount of material capable of intensively perfect saturation of the layer by the temperature between the evaporation gap provides a material resistant to both its and the inner wall of the molding material as said layer is complete and corrosion-resistant and has a high permanent presence in the element.

so that the amount of material that is at working temperature is the inner surface

It is desirable to vaporize intensively proportional to its density, the area of the inner surface of the space, and the thickness of the layer of heat-resistant material.

capable of directly hollow corrosion

Optimum amount (m) of heat transfer medium in a hermetically sealed and vented hollow space for perfect saturation of the corrosion resistant and high

- 9 temperature is given by the following formula:

m = (1.03 to 1.07)? δ S, (1) where Q is the density of the heat transfer material, δ is the thickness of the layer of porous material resistant to corrosion and high temperature,

S is the surface area of the inner surface of the hollow forming element.

This amount (m) of the heat transfer medium in the cavity is sufficient to continuously transfer heat to the molding surface during the pressing process, which is followed by the subsequent conversion of the liquid heat transfer medium to saturated steam and its further conversion into liquid by condensation.

It is desirable to use alkali metals, either individually or in combination with each other, as materials capable of vigorous evaporation at operating temperature.

Such materials as cesium, potassium, sodium, lithium, as well as the eutectic potassium-sodium alloy, have a complex of physical properties over a range of glass pressing temperatures (400 - 650 ° C) that ensure efficient heat transfer in a hermetically sealed and vented hollow of the molding element. Such properties include the wetting capability of a porous layer resistant to corrosion and high temperature when saturated with a heat transfer medium, high latent evaporation heat, high thermal conductivity of the heat transfer medium, low viscosity in both liquid and vaporized conditions, high surface tension values and high temperature stability. .

It is preferred that sodium is used as the alkali metal.

The complex of the above characteristics, which are characteristic of the efficiency of the heat transfer medium, can be unified into a certain quality criterion (N):

N = Q δ r / μ (2) where Q is density, δ is surface tension, r is latent evaporation heat μ is the viscosity of the heat transfer medium.

Changing the quality criterion (N) for these materials in the working temperature range (400-650 ° C) confirms that sodium is the most suitable working material. Taking into account that the cost of sodium is low, it is obvious that sodium is the most suitable working material for molding elements.

Suitably, a saturated sodium vapor pressure of 0.08 to 12 kPa is applied in the cavity of the molding element.

Said saturated sodium vapor pressure is optimal to provide the necessary molding surface temperature of the hollow molding member and to redistribute this temperature on the molding surface from the warmer to colder sections independently of the molding speed and geometry and the thickness of the molded articles.

Suitably, a material which avoids chemical interactions with sodium is used as the porous material resistant to corrosion and high temperature. The material should be in the form of a metal mesh.

The use of this material avoids the formation of deposits on the porous structure and clogging of the pores, which again contributes to uniform saturation of the entire porous structure with liquid sodium and its unrestricted circulation in the said layer. The formation of this layer in the form of a metal mesh allows the formation of capillary pressure which ensures the said circulation.

The method of pressing glass products according to the invention provides the following possibilities:

- ensuring the isothermal temperature distribution on the forming surfaces;

- increasing the efficiency of heat removal from the forming surfaces (the densities of the transferred heat flows can in this case be up to several W / cm ² );

- an increase in the performance of the pressing process by 30 to 40%;

- reducing the wall thickness of the molded product by 20 to 30%;

- pressing products of different thicknesses, irrespective of their geometry;

- Improving the quality of glass products and reducing the amount of unsupports by ensuring perfect plastic deformation of the glass on the forming surfaces.

The object of the present invention is also solved by a glassware manufacturing machine which is designed as a pressing device comprising at least one molding element with a hermetically sealed cavity in which the material is capable of vaporizing vigorously at operating temperature, the pressing device having a thermal control element. of said material in a pressing temperature interval. The device according to the invention is characterized in that it has a device for deaerating the hollow space of the molding element and on the inner surface of the molding cavity a layer of porous material resistant to corrosion and high temperature is placed. vaporize at the working temperature associated with the venting device of the molding element, wherein the material capable of vaporizing vigorously at the operating temperature is stored in the molding cavity in an amount in excess of the amount necessary to fill the cavity with saturated vapors of the material layers of porous material resistant to corrosion and high temperature.

By placing a layer of porous material with high corrosion and temperature resistance on the inner surface of the hollow space of the molding element, it is ensured that at the working temperature a permanent wetting layer is formed on the inner surface of the molding element like liquid film of material capable of vaporizing vigorously at working temperature. pores of the layer. This means that the porous material resistant to corrosion and high temperature fulfills the function of a special wick in which the material capable of vigorous evaporation at the working temperature circulates at a high speed. In this way, this layer ensures rapid transfer of heat from the larger heated portions of the surface of the molding element to the less heated portions and consequently ensures the formation of conditions on the molding surfaces that approach the isotherm.

The nozzle located in the wall of the molding element fulfills two functions. Firstly, a material capable of vaporizing intensively at the working temperature is introduced into the hollow space of the molding element, and secondly, it is provided for venting the hollow space of the molding element. Therefore, with a vacuum device, which may be a device of the same purpose.

Any known evaporation at the working temperature is also associated as an intensive material. It is suitable to use an alkali metal of which sodium is most suitable.

As already mentioned, these materials, such as cesium, potassium, sodium, lithium, as well as the eutectic potassium-sodium alloy, have a complex of physical properties over a range of pressing temperatures of glass products (400 to 650 ° C) which ensures efficient heat transfer in hermetically sealed the vented cavity of the molding element. Sodium is the cheapest material.

It is desirable to place on the inner surface of the molding element as a layer of corrosion-resistant and high-temperature material a layer of such material that eliminates the chemical interaction with sodium. This material may be formed as a metal mesh attached to the inner surface of the hollow space of the molding element.

Using this material does not form a deposit on the porous structure and does not clog pores, which again contributes to uniform saturation of the entire porous structure with liquid sodium, penetration of liquid sodium into a possible gap between the inner surface of the molding wall and the layer of porous material resistant to corrosion and high temperature. if unrestricted circulation of liquid sodium to said layer.

The shape of the metal mesh having said layer makes it possible to achieve a capillary pressure which ensures the circulation of liquid metal over the entire inner surface of the hollow space of the molding element.

The solution according to the invention thus makes it possible to increase the efficiency of heat removal from the surface of the glass-contacting molding elements and to achieve a uniform temperature distribution on this surface regardless of the pressing speed, geometry and thickness of the pressed glass products.

The method for molding glass articles is carried out by supplying a metered amount of glass and compressing it with a molding apparatus comprising at least one hollow molding element, which may be a mold, a punch or a ring.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary device according to the invention capable of carrying out the method of manufacture according to the invention is shown in the drawings, wherein FIG. 1 is a schematic vertical partial axial section through a pressing device; and FIG. 2 shows a vertical partial axial section through the bladder.

DETAILED DESCRIPTION OF THE INVENTION

An exemplary method of manufacturing glass articles is described in relation to a device having a punch formed as a hollow molding element. By the method according to the invention, a layer of capillary porous refractory material is applied equidistantly to the surface of the cavity on the inner surface of the punch cavity. The capillary porous structure is formed as a fine mesh porous mesh weave metal mesh made of fine stainless steel wire that eliminates chemical interactions with the material capable of vaporizing vigorously at the working temperature. The mesh can be made, for example, of stainless steel wire, the warp wire having a thickness of 0.09 nm and a weft wire of 0.055 nm. The mesh gets a shape corresponding to the hollow space path. Subsequently, the mesh is connected to the inner wall of the punch by an electric resistance weld, for example an argon spot arc weld.

Then, the pressing device comprising the die, the ring and the punch is heated in a known manner, for example by means of a gas burner, to the lower limit of the temperature interval of the pressing of a particular glass. As is known, this lower limit is 400 to 450 ° C, e.g. for aluminum-borosilicate glass, 450 C.

The next stage rests on p _o - (0.02 up to venting the hollow space)

0.1 Pa to allow the desired vapor pressure of the vapor-permeable material (heat transfer medium) to be reached in the hermetically sealed cavity of the punch during the pressing operation, depending on the vacuum height and temperature. This means that further attention should be paid to vapors of the liquid heat transfer medium which are in a saturated state and are subject to the ideal gas state:

m p V = - R T (3) μ where p is the saturated vapor pressure of the heat transfer medium,

V is the volume of the hollow space of the punch, m is the mass of saturated vapors of the heat transfer medium in the hollow space,

R is the universal gas constant,

T is the temperature in degrees Kelvin, μ is the relative molecular weight of the heat transfer medium.

At the same time, venting removes gases in the hollow space of the punch which could greatly affect the punch's work by blocking a portion of the working surface of the temperature control device capable of vaporizing vigorously at the working temperature (condenser). In addition, air oxygen needs to be removed from the punch cavity to eliminate or at least reduce the possibility of forming oxides that could collect in areas of intense evaporation and could clog the capillary openings of the capillary porous structure. Tests carried out have shown that compliance with the above requirements for purging the punch hollow space was achieved within a pressure range of P _o = (0.02 to 0.1) Pa. The upper limit of Po = 0.1 Pa is chosen experimentally with respect to the permissible oxides build-up on the porous structure during the punch operation, which has no significant effect on the capillary properties of the porous material in the area of intense evaporation of the heat transfer medium (punch pole).

The lower limit _{of the} P - 0.02 Pa may be zero. However, achieving a high vacuum requires expensive equipment and is time consuming. When using laboratory vacuum devices, p _o - (0.02 to 0.1) Pa can be achieved at no significant cost. Further pressure reduction was virtually unacceptable to the punch work during the stamping operation.

It is therefore expedient to vent the punch space to a value of Po = (0.02 to 0.1) Pa.

After reaching the required vacuum value in the punch cavity, the material is capable of vigorously evaporating at the working temperature, which is heated to the lower limit of the working temperature in the amount m, where m = (1,03 to 1,07) 9 δ S (1) that is, in an amount that exceeds the amount necessary to fill the cavity of the molding element with saturated vapors of the material and to saturate the corrosion and high temperature resistant material layer.

It can be seen from relation (1) that this amount is proportional to the density of said material, the areal content of the inner surface of the punch cavity and the thickness of the layer of corrosion-resistant and high-temperature material. The amount of material supplied exceeds by 3 to 7% the amount required to completely fill the cavity in the punch with saturated vapors of the material and to saturate the layer of porous material resistant to corrosion and high temperature. The material in the liquid state fills the porous structure of the metal mesh over the entire inner surface of the punch.

The lower limit is related to the weight of the heat transfer medium by the phenomenon of sublimation of the heat transfer medium from the intensive heat supply area (punch pole) in the lower part of the punch to the condensation area of the heat transfer medium in the upper part of the punch. Here, the vapors of the liquid material are condensed into drops and thus redistribution takes place in the cavity of the punch.

The tests carried out have shown that by supplying the heat transfer medium in an amount which exceeds by 3% the amount necessary to saturate the metal mesh, a possible lack of the heat transfer medium on the metal mesh can be prevented. The upper limit of the excess amount of heat transfer medium of 7% is determined by the phenomenon associated with the drying of the heat transfer fluid film at the point of intense heat dissipation. Drying of the liquid heat transfer film leads to an emergency situation due to local overheating of the punch wall (local heat exchange crisis).

It has also been shown in the experiments carried out that by supplying the amount of heat transfer medium increased by 7% relative to the amount required to saturate the metal mesh, this error did not occur during the pressing operation. Compliance with these requirements is therefore subject to an excess heat transfer medium m m - (3 to 7)%

Alkali metals, either singly or in combination, for example cesium, rubidium, potassium, sodium or the eutectic potassium-sodium alloy are used as the material capable of vigorously evaporating at the working temperature.

However, sodium has the best thermo-physical properties in the glass molding temperature interval.

After venting the punch cavity and filling the amount of liquid metal, the cavity is hermetically sealed. The punch is clamped into the press clamping device and after the necessary glass has been introduced into the die, it is lowered into the die, thereby forming the glass into the desired shape.

At the moment of contact of the punch with the glass, intense heat exchange begins between the forming surface and the molten glass. The heat flux passing from the molten glass to the lower, most heavily loaded portion of the punch is taken by evaporation of the liquid metal heat transfer fluid film and is transferred to the upper least overheated portion of the punch where saturated vapors of the heat transfer medium partially condense to transfer latent heat of vapor. the condenser and the inner wall of the upper punch. Also contributing to this is the high thermal conductivity of the liquid metal film, by means of which the temperature from the larger heated lower part of the punch is transferred to its upper part.

At places of intense evaporation of liquid sodium, where there is an increased consumption of the heat transfer medium, its consumption is complemented by new liquid sodium which is supplied by the capillary pressure of the heat transfer medium in the capillary porous structure.

In this way, therefore, during the pressing operation, the heat transfer medium is continuously circulated, which ensures the transfer of heat from the hot to the cold sections of the butcher. The extracted heat flows are transported virtually without inertia by steam and transfer heat to relatively cold sections by condensation of saturated vapors in the form of latent evaporative heat.

The temperature control of the punch forming surface during the pressing operation is derived from the change in the pressure of the saturated gases of the heat transfer medium in the punch cavity from pi to p2 by regulating the coolant consumption in the condenser. It is worth noting that there is practically an isothermal temperature distribution in the cavity of the punch at any time.

Under thermodynamic equilibrium conditions between a capacitor and a saturated liquid metal vapor, the temperature-pressure relationship is indeed given by the above-mentioned dependence (3).

If, for any reason, a section with a temperature Ti lower than T, which is determined by the thermodynamic equilibrium relationship, appears on some section of the punch forming surface, the saturated steam becomes saturated in this section of the hollow space of the punch, resulting in steam its condensation to produce latent evaporative heat. If the temperature of any section of the punch forming surface is increased, it means that Ti is greater than T. In this section of the punch cavity, the liquid metal condensate passes into a saturated steam state, thereby removing heat from the section. The amount of heat removed gives the weight of the heat transfer medium to be evaporated and the latent heat of vaporization. The existence of the two processes already described in this system ensures isothermal non-inertial heat distribution over the entire inner surface of the punch.

The determined temperature of the punch forming surface is provided during the pressing operation by controlling the pressure of the saturated vapors of the heat transfer medium in accordance with the thermodynamic equilibrium conditions when the equilibrium changes to a lower or higher temperature.

Therefore, a saturated sodium vapor pressure of p1 and p2 kPa is generated in the punch space.

The selection of the pressure limits of saturated vapors of the heat transfer medium is conditioned by the existence of an optimum temperature range of the molding surfaces during the pressing of the glass.

At molding surface temperatures below the limit, errors in the pressing process, such as the porous surface of the product, micro-cracks, deformations and the like, occur. This temperature is known to be 400 C. C.

The upper temperature limit is determined by the thermal diffusion of the glass into the metal of the forming surfaces and the formation of opal. This temperature is 650 ’C.

Under thermodynamic equilibrium conditions between condensate (heat transfer medium) and saturated liquid metal vapor, the temperature-pressure relationship is given by the equation (3) above for the ideal gas state.

It can be seen from equation (3) that the temperature of the forming surfaces can be controlled by varying the saturated sodium vapor pressure in the punch cavity. In addition, this equation (3) implies that in order to maintain the temperature of the forming surfaces Ti = 400 ° C, a saturated sodium vapor pressure of 0.08 kPa must be provided in the cavity, while the temperature of the forming surfaces T2 = 650 ' C, the saturated vapor pressure of sodium must be maintained at P2 = 12 kPa.

Experimental industrial pressing of air navigation light filters and kitchen containers made of colored and tinted glass resistant to temperature changes was carried out on the device according to the invention. Various variants of filling the elements of the pressing device have been tried, both in terms of the amount of material capable of vaporizing intensively and with regard to the use of different materials at different technological parameters of the pressing process.

An analysis of the results of experimental industrial compression is given in the attached Table 1. By way of comparison, the following table (in Example 14, 15) obtained by pressing the same products on the all-metal construction of the die is shown.

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As can be seen from the above examples, the present invention makes it possible to produce glass products of high quality, regardless of their geometry, thickness and compression speed.

The glassware manufacturing apparatus is a pressing tool comprising as punches a punch 1, a die 2 and a ring 3 (FIG. 1).

According to the invention, the at least one shaping element is hollow.

For ease of understanding, the exemplary (Fig. 2) hollow described below.

The punch of the present invention is an embodiment in which the punch 1 of the light-punched light punch 1 in FIG. 2 is the airborne hollow space 4.

a layer for signaling and having filters shown, is sealed in a hollow anti-corrosion chamber and made of the non-rusting surface of the punch .1 fastened

On the inner surface of the material of the heat-resistant mesh 5, which has the shape of a steel. The screen 5 is, for example, a spot weld. However, it is also possible to attach the mesh to the inner surface of the punch 1 in another manner.

It is preferable to use a dense mesh 5 made of stainless steel which allows a capillary porous structure (wick) to be formed on the inner surface of the punch 1. in which liquid sodium is circulated during the molding operation. Depending on the configuration of the molding element and its geometric dimensions, it is also possible to attach several layers of mesh 5 to its inner surface, thereby increasing the overall thickness of the layer and thus the amount of circulating sodium.

In this case, it is necessary for the mesh 5 to be firmly and well connected to the wall 6 of the inner surface of the molding element for the machine to function properly.

Only when the mesh 5 is perfectly attached to the inner surface of the molding element is wetting with liquid sodium ensured, which also creates the most suitable heat dissipation conditions.

net

5, made of corrosion-resistant most perfectly meets the requirements of chemical inactivity to liquid sodium at high temperatures, thereby avoiding the formation of deposits on the porous structure and clogging its pores.

In the cavity 4 of the punch 1, the material 7 is capable of vigorously producing vapor at the working temperature. As already mentioned, metals of the alkaline earth metal family, either individually or in combination, are used as material 7 for this purpose. Sodium is particularly suitable for this purpose.

The glassware manufacturing apparatus also has a device for controlling the temperature of the material schop capable of vigorously producing vapors at a pressing temperature interval.

A condenser 8 in the form of a spiral tube 9 located in the cavity 4 of the punch 1 is used as a device for controlling the temperature of the sodium vapors in the pressing temperature interval in this exemplary embodiment. The ends of the spiral tube 9 through which the coolant is fed and discharged outside of the hollow space 4 in the upper part of the punch 1. Compressed air, water, a mixture of water and air, or nitrogen gas may be used as a cooling agent.

The amount of coolant to be supplied, depending on the temperature of the sodium vapor, is controlled during the pressing process by a known special device 10 and the temperature of the sodium vapor is measured by a two-chamber thermometer 11.

Other variants of the arrangement of the capacitor 8 are also possible, for example in the form of a Field Tube.

In the wall 6 of the punch 1, a sleeve 12 is mounted which is connected to the device for vacuuming the hollow space 4 of the punch 1. The vacuum device is not shown in the drawing, since a known device such as a vacuum pump can be used for this purpose.

Furthermore, the sleeve 12 has another function. Sodium is fed into the cavity 4 of the punch 1.

The amount of sodium introduced into the cavity 4 of the punch 1 should exceed by 3 to 7 percent the amount necessary to fill the cavity 4 with its vapor at the working temperature and to saturate the metal mesh layer 5.

Everything stated to be valid for the punch 1 applies equally to the die 2 and the ring 3 when they are hollow.

The glassware manufacturing plant works as follows:

For example, a porous material is deposited on the inner surface of the hollow punch 1 by means of spot welds, by means of which two-layered mesh 5, made of stainless steel, is deposited in two layers.

The punch 1 is heated to the operating temperature by any means known in the art, for example by means of a gas burner or by briefly immersing the punch 1 in a smaller amount of glass.

Furthermore, the hollow space 4 of the punch 7 is vented through the nozzle 12 by means of a special device, for example by means of a vacuum pump. As a result of this, the sodium metal is introduced into the hollow space 4 in the molten state and in an amount exceeding 3 to 7% filling the cavity 4 with sodium vapor and to saturate the porous layer of the mesh 5 made of corrosion-resistant and high-temperature metal.

The vaporization of a portion of the sodium is intensified and the cavity 4 of the punch 1 is filled with its vapors until the pressure p _o = (0.02 to 0.1) Pa is reached. The second portion of sodium is sucked in the liquid state into a porous layer resistant to corrosion and high temperatures until the layer is completely saturated, thus wetting the inner surface of the cavity 4 of the punch 1.

Then, the top of the sleeve 12 is hermetically sealed.

Next, the necessary amount of glass is introduced into the die 2 and the ring 3 and the punch 1 are lowered onto the die 2.

In this case, the wall 6 of the punch 1, which is in contact with the glass and has a low thermal resistance, transfers heat from the glass to its inner surface on which the layer is a liquid sodium saturated porous mesh 5. that is in contact with the enamel are not the same. As a rule, the central part of the punch 1 is at a higher temperature. As a result, the temperature on the inner surface of its hollow space 4 and on the porous layer of the mesh 5 adhering thereto is uneven.

The temperature gradient causes liquid sodium to be transferred from less heated to more heated sections. Heat is also transferred along with sodium. The sodium is circulated at a very high rate because the entire process is carried out under vacuum. The circulation rate as well as the heat transfer rate is higher, the higher the temperature gradient on the punch work surface, 1.

At the same time, the intensity of sodium evaporation increases, resulting in an increase in the pressure in the cavity 4 of the punch 1 to Ρ2 = 12 kPa. Sodium vapor condenses on the surface of the spiral tube 9 of the capacitor 8, which is inside the cavity 4 of the punch 1. The precipitated sodium vapor then drips down in the form of drops, and the liquid sodium evaporates again and the whole cycle is repeated.

Saturated vapor pressure is controlled automatically by the condenser 8. If the temperature on the molding surfaces increases, which happens at high pressing speeds, the temperature in the cavity 4 of the punch 1 rises, the vaporization rate of sodium increases and the vapor pressure increases. increase. The bimetallic thermometer 11 simultaneously sends a signal to the device that controls the coolant supply. This device increases the supply of coolant to the condenser 8. Hereby, the intensity of the condensation of sodium vapors increases and their pressure in the cavity 4 of the punch is reduced to the initial value.

In this way, the surface temperature of the punch 1 can still be maintained at a desirable level, thereby ensuring high performance of the entire die apparatus and product quality.

Using the apparatus according to the invention for pressing light filters from thermal glass, the following results were obtained:

- the pressing speed has increased by a factor of 1.5 to 2 times,

- the weight of the products has been reduced by 15 to 30% due to the possibility of reducing their wall thickness,

- the products have been completely eliminated from warping, thereby enhancing their lighting characteristics and improving their appearance,

- the yield of good products increased by 1.5 to twice as a result of a significant reduction in non-yields having different thicknesses and cracks.

Industrial ....... utilization

The method and the device according to the invention can be used in the field of glass production in the molding of products of various geometrical dimensions from different types of glass, as well as in the molding of metal, plastic and glass fiber-filled plastics products.

The invention can be used more efficiently in the molding of glass articles which are subject to increased surface quality requirements and their light and light characteristics.

Claims (10)

A method for producing glassware, comprising supplying and molding glass batches in a press apparatus comprising at least one hollow molding element, into a cavity into which a material having the ability to vaporize intensively at working temperature is introduced before the glass is introduced, after which the molding the element is heated to operating temperature and the temperature of said material is controlled at a pressing temperature interval, characterized in that the inner surface of the molding cavity is covered with a layer of porous material having high corrosion resistance and high temperature; its hollow space is vented to 0.02 to 0.1 Pa, after which the material capable of vaporizing vigorously at operating temperature is introduced into the hollow space of the molding element in an amount in excess of the material needed to fill the hollow space with saturated vapors of this material and of porous material resistant to corrosion and high temperature. Method for producing glass products according to claim 1, characterized in that the material capable of vigorously evaporating at the working temperature is fed into the hollow space of the molding element in an amount which is 3 to 7% higher than the amount necessary to fill the hollow space with saturated vapors. and to saturate the layer of porous material resistant to corrosion and high temperature. 3. A process according to claim 2, wherein the amount of material capable of vaporizing is proportional to its density, the surface area of the molding element, and the thickness of the layer of porous material resistant to corrosion and high temperature. The process for producing glass products according to claim 3, characterized in that alkali metals, either individually or in combination, are used as the material capable of vigorous evaporation at the operating temperature. 5. Method manufacturing glass .... j ú c i sa t use sodium • 6. Method manufacturing glass .... j ú c i s a molding element with create 0.08 to 12 kPa. 7. Method manufacturing glass .... j ú c i sa t resistant to corrosion and high of the products of claim 4, wherein the alkali metal of the products of claim 5 is such that in the hollow space the saturated sodium vapor pressure of the products of claim 6 is such that the porous material at temperature is a material which eliminates the chemical interaction with sodium . 8. A method according to claim 7, characterized in that the material eliminating the chemical interactions on sodium is formed as a metal mesh. Apparatus for producing glassware formed as a compression device comprising at least one molding element with a hermetically sealed cavity in which a material capable of vigorously vaporizing at operating temperature is deposited, the pressing device having an element for controlling the temperature of the material at a pressing temperature interval characterized in that the device is provided with a device for venting the cavity of the molding element and on the inner surface of the cavity of the molding element (1) there is a layer (5) of corrosion-resistant and high temperature porous material while in the wall (6) of said molding element (1), a sleeve (12) is provided for supplying a material capable of vaporizing vigorously at an operating temperature, which is connected to a device for venting the cavity of the molding element (1), wherein the material capable of vaporizing vigorously at an operating temperature in the hollow space (4) shape and a saturation layer of porous material resistant to corrosion and high temperature. The glassware manufacturing device according to claim 9, characterized in that the material stored in the cavity (4) of the molding element (1) capable of vaporizing vigorously at operating temperature is at least one metal of the alkali metal group. The glassware manufacturing device according to claim 10, characterized in that sodium is deposited as an alkali metal in the hollow space (4) of the molding element (1). The glassware manufacturing device according to claim 11, characterized in that a layer of material which eliminates the chemical interaction with sodium is attached to the inner surface of the hollow space (4) of the molding element (1) as a layer of corrosion-resistant and high-temperature material. . The glassware manufacturing device according to claim 12, characterized in that the material layer which eliminates the chemical interaction with sodium is formed by a metal mesh (5), which is rigidly connected to the inner surface of the hollow space (4) of the molding element (4). 1).