WO1999003789A1

WO1999003789A1 - Device for cooling mould elements

Info

Publication number: WO1999003789A1
Application number: PCT/FR1998/001486
Authority: WO
Inventors: Jean-Pierre Pagnac
Original assignee: Saint-Gobain Emballage
Priority date: 1997-07-17
Filing date: 1998-07-09
Publication date: 1999-01-28
Also published as: AU8633798A; FR2766172B1; FR2766172A1

Abstract

The invention concerns novel devices for cooling mould elements for making glass products, characterised by channels (4) connected to cooling water circuit passing through the mould element (1) bodies, the number of channels, the channel diameter and the water flow rate being selected to limit thermal exchange. Said device is used, in particular, for cooling the shells of a blank mould and of a finishing mould of an injection blow moulding machine. The invention also concerns a method for making glass products using the resulting cooled mould elements.

Description

COOLING DEVICE

MOLD ELEMENTS

The invention relates to new devices for cooling molds and more particularly molds for the manufacture of glass articles such as bottles, flasks, jars, etc.

The role of the mold and the associated tools (bottom, ring, etc.) is on the one hand to evacuate part of the heat energy contained in the glass, in order to freeze it and on the other hand to communicate drop by drop of glass, the shape of the object to be manufactured.

Such tools must be cooled all the more that the manufacturing speed is important.

In the majority of industrial applications existing to date, air is the fluid used. This type of air cooling has various drawbacks; it requires relatively high mechanical ventilation power per tonne of glass produced and causes noise pollution forcing production personnel to wear individual protections against noise.

In addition, the evacuation of the heated air in contact with the tools takes place in the working environment, which has the effect of significantly raising the temperature of the atmosphere near the machine.

In order to increase production rates, it is first of all necessary to improve, from a speed point of view, the cooling of the glass, that is to say to reach as quickly as possible the temperature of the glass corresponding to a viscosity such that the glass container can be released from the mold without collapsing on itself, while maintaining a quality level of the article formed. The forming machines usually used in the container manufacturing industry such as bottles, flasks are of the IS machine type operating according to the press-blown or blown-blown modes.

These I.S. machines form the articles in two stages. First of all, a draft of the article is produced in a “roughing mold”, during this stage a draft of the body of the article is produced and for example the ring, in the case of a bottle is fully formed. The viscosity of the article body must remain such at the end of the roughing step, that it is possible to finish forming the article. The cooling of the glass must therefore be limited to the level of the body of the article. Regarding the ring of the bottle, it must be sufficiently cooled to be able to serve as a hold for a tool which allows transfer to the "finishing mold". In said finishing mold, the article is finished being formed and sufficiently cooled to be released.

It appears that the factor limiting the production rates is the time for the article to cool down in the finishing mold. It has already been proposed to improve this time by increasing the speed of air passage over or in the mold; this type of solution, if it improves the pace, inevitably leads to very noisy working conditions. Indeed, the increase in air speed results in a very significant noise, which can reach 100 to 110 Db A, and an ambient temperature of the machine which can be around 50 ° C., for certain manufacturing operations.

The inventor thus set himself the task of developing a device for cooling mold elements which overcomes the drawbacks mentioned above and more particularly by ensuring an increase in production rates under acceptable working conditions. The invention also aims at a slightly increased, or even lower, energy cost than that corresponding to current devices.

These objects are achieved according to the invention by a device for cooling mold elements for the manufacture of glass articles, such as bottles, flasks, ..., in which channels pass through the body of said elements, said channels being connected to a cooling water circuit and the diameter of the channels, the number of channels and the flow of water in the cooling circuit being chosen to limit the heat exchange. The inventor has been able to demonstrate that it is possible to cool the article by means of a circulation of water within the mold elements, while guaranteeing complete forming of the article. It is therefore in particular thus possible to optimize the cooling of the article in the finishing mold.

The choice of channel and flow characteristics allow cooling of the article optimized in view of previous techniques, but allowing the formation of the article while preserving a forming viscosity adapted to each model produced.

According to the invention, in the case of channels with a length of 130 mm, for example arranged vertically in the shells of the finishing mold, the diameter of the channels is between 2 and 4 mm and the flow of water passing through said channels is between 25 and 100 liters per hour, depending on the production rate and the model of article manufactured.

More preferably still, the mold elements comprising the channels are made of a material chosen to limit the heat exchange. Contrary to the usual cooling techniques according to which it is always necessary to improve the cooling, the device according to the invention provides, according to a variant, for reducing said conductivity of the material. This choice of material can make it possible to improve other properties. According to the prior techniques, the molds, and more particularly the finishing mold, are made of materials of the cast iron or bronze type which are fragile materials and which present significant risks of oxidation which lead to significant maintenance and frequent repairs.

According to an advantageous embodiment of the invention, the material can be a steel, a weakly conductive material in comparison with the previously mentioned materials. More preferably, the material chosen is an alloy steel based on chromium, which leads to a material having good resistance to corrosion, in particular with regard to glass.

More preferably, the steel has undergone a heat treatment to improve its mechanical properties, in particular its hardness. Advantageously, it has a higher HRC hardness of around 50. This characteristic of the mold makes it possible to avoid degradation of the latter, in particular in the event of impact or wear during conventional cleaning of the type by microbead, abrasive cloth, etc. The tests carried out showed that the molds produced according to the invention could have a thermal conductivity reduced by half compared to those of the molds usually used. Furthermore, the life of these molds is increased from four to five times, in particular due to their hardness and their better mechanical strength and better corrosion resistance. Despite the higher manufacturing costs for the molds according to the invention, they prove to be more economically advantageous. In addition, during their use, their frequency of maintenance, that is to say cleaning, is less important than for the usual molds; this consequence linked to their nature also makes it possible to optimize production rates. According to a variant of the invention, the circulation channels for the cooling water are produced in tubes, for example made of stainless steel, inserted in the mold elements previously drilled. Such an embodiment makes it possible to produce the molds economically on the one hand by carrying out a simplified machining of the molds by forming passages with relatively large diameters and on the other hand, by using tubes with the desired internal and external diameters that the readily available commercially for other applications.

According to a preferred embodiment of the invention, the tubes inserted into the mold elements have at least one indented area at their periphery. Such a notch which will create an air space between the tube and the material constituting the mold will allow the conductivity to be reduced at least locally. Such an embodiment can allow either to decrease the overall conductivity or for example to create a cooling gradient, for example in a vertical direction in the case of a bottle to freeze more or less quickly certain areas of the bottle.

According to a variant of the invention, the channels pass vertically through the mold shells and are associated with upper and lower collectors. This variant which relates more particularly to the cooling of the shells of a mold allows using the collectors to create a cooling circuit associating for example the channels two by two and for example because of the lower collector, to obtain a routing of the water in these two channels in opposite directions , that is to say, that the water which crosses the first channel from top to bottom rises by the second channel by crossing this one from bottom to top. The lower collector therefore makes it possible to connect these two channels by conducting the water from one to the other. The upper collector can allow it to associate on the one hand all the channels leading the water from top to bottom and on the other hand all the channels leading the water from bottom to top; the upper collector can then act as a distributor by being associated with an outside water inlet and an outside water outlet. According to such an embodiment of the invention, it is therefore possible to limit the size of the cooling device since only two water inlet and outlet pipes must be provided around each of the mold shells. The invention has more particularly been described with reference to the cooling of the shells of a finishing mold; indeed, as it was said previously, the cooling of the article in the finishing mold is the factor limiting the manufacturing time of an article. However, since the invention makes it possible to reduce this cooling time in the finishing mold, the invention can also be used for the shells of the roughing mold, the cooling in said roughing mold then being able to become the limiting factor.

Furthermore, the invention is not limited to use at the level of the mold shells but can also be adapted to the cooling of the mold bases, both finishers and blanks, as well as to the ring mold.

Other details and advantageous characteristics of the invention will emerge below from the description of an exemplary embodiment of the invention with reference to FIGS. 1, 2, 3, 4 which represent:

FIG. 1: a front view in section of a diagram illustrating a half-shell of a mold equipped with a device according to the invention,

FIG. 2: a diagram in partial section of a tube used in the device according to the invention,

• Figure 3: a top view of a shell fitted with a device according to the invention,

FIG. 4: a top view of an upper collector according to the invention,

• Figure 5: a front view, in partial section, of a diagram illustrating a shell of another mold equipped with a device according to the invention. The figures are not shown to scale to simplify understanding.

In Figure 1 is shown a sectional diagram of a half-shell 1 of a finishing mold of an I.S. machine provided for liquid cooling according to the invention. The shell 1 is a part of the mold directly in contact with the glass; as shown in Figure 1, this shell 1 contributes to the formation of the cavity 2 forming the outer surface of the article. In FIG. 1, the bottom of the mold is not shown but its adaptation appears in the mold 1: it is the wedge 3.

Figure 1 shows a channel 4 passing through the shell 1 along a vertical axis parallel to the axis of the article of manufacture. The channel 4 according to the representation, has a diameter of about 10 mm which makes it very easy to machine. In this channel 4 will be inserted a tube 5 illustrated in Figure 2 on which it will be returned later. Also shown in Figure 1, the upper 6 and lower collectors 7. It will be returned more specifically to their functions during the description of Figure 4. The assembly of the collectors 6, 7 to the shell 1 is advantageously carried out by screws, not shown in the figures, 0.5 mm thick flat seals 8, 9 being interposed between said collectors and the shell 1.

The tube 5 shown in Figure 2 has a larger outside diameter, substantially equivalent to that of the channel 4, that is to say about 10 mm. These almost identical diameters will enable the tube 5 to be inserted into the channel 4 and to keep the tube 5 in position by shrinking. In the area shown partially in section, appears the channel 10, in which the cooling water circulates. Also shown in Figure 2, indented areas 11 at the periphery of the tube 5. The tubes 5 can be found commercially quite easily, this type of tubes used for many other applications. It therefore remains only to produce the peripheral notches 11 and machine the outside diameter to prepare them for their use for the device according to the invention. These can be carried out by any means known to those skilled in the art. When the tube 5 is inserted into the channel 4, the hooping is therefore exerted by the shell 1 on the non-indented areas of the tube 5. Once the tube 5 is inserted, the indented areas will create air spaces between the shell 1 and the tube 5 which will limit the heat exchanges between the tube 5 and the shell 1.

In Figure 3, there is shown a top view of a shell 1 having four channels 4a, b, c, d. The number of these channels 4 is variable depending on the dimensions of the shell and the nature of the article produced, and more exactly depending on the heat exchange to be carried out. The choice of the material constituting the shell and the location of the channels 4 in the thickness of the wall of the shell 1 also contribute to the heat exchange obtained. The designer of the shells 1 will therefore be able to optimize these various parameters during the manufacture of said shells 1. FIG. 4 shows the upper collector 6 intended to come over the shell 1 shown in FIG. 3. This collector 6 has a connection 13 for connecting the manifold 6 to a water inlet pipe and a connection 12 for connecting the manifold 6 to a water discharge pipe. The connections 12, 13 are chosen as being "quick couplings" which do not increase the mold change times. These connections 12, 13 are also connected respectively to distributors 14, 15, shown in broken lines in Figure 4, to be each connected to two channels, 4a, 4d on the one hand and 4b, 4c on the other. It is therefore clear that channels 4a and 4d conduct water from bottom to top and that channels 4b and 4c conduct water from top to bottom. The collector 7 which is not detailed in the figures, furthermore comprises pipes for connecting on the one hand the channels 4a, 4b and on the other hand the channels 4c, 4d.

In FIG. 5 is shown a diagram in partial section of a shell 1 of a blank mold of an I.S. machine. provided for liquid cooling according to the invention. The shell 1 delimits a cavity 2 forming the outer surface of the blank. The location 3 of the roughing bottom and the wedge 16 of the ring mold also appear in this figure.

FIG. 5 also shows a vertical channel 4 parallel to the axis of the blank and intended to receive a tube 5 as illustrated in FIG. 2, as well as the upper 6 and lower 7 collectors.

Analogously to the preceding description of a finishing mold with reference to FIG. 1, four channels 4 are formed in the shell 1. In accordance with the reality of the process for manufacturing glass articles using an IS machine , the position of the roughing mold in FIG. 5 corresponds to an opening of the glass article at the bottom of the mold, that is to say that it is inverted with respect to that of the finishing mold shown in FIG. 1.

The locations 17 and 18 of one of the four fixing screws of the upper 6, respectively lower 7 collectors to the shell 1, as well as the seals 19 and 20 of the upper 6, respectively lower 7 collectors are also visible. The profile 21 is used for attaching the mold to the machine. An operation of the cooling circuit with water inlet and outlet by the upper collector, as explained above, can be transposed to the present roughing mold.

A preferred embodiment of the invention provides a closed cooling water circuit using filtered and softened water. This avoids any risk of fouling and scaling of the channels 10 of the tubes 5 in which the water circulates. Indeed, such a problem could disrupt the desired heat exchange and therefore disrupt the manufacture of glass articles. The cooling circuit can then be itself cooled by a water / water or water / air exchanger.

It appears from these figures that the production of the device according to the invention does not disturb the basic design of the glassware molds. Indeed, the external dimensions of the molds are not modified and therefore absolutely does not change the equipment of the IS machine. On the other hand, the part external to the mold of the cooling circuit in the immediate vicinity of the IS machine can not '' consist only of two water pipes which also do not have a large footprint. Tests have been carried out, in particular for the manufacture of small bottles more particularly intended for the beer market. These tests were carried out with tubes 5 with a length of 130 mm and having an internal diameter (diameter of channel 10) of 3.2 mm. Tubes 5 were at number of four, inserted in channels 4, such as in FIG. 3, within the shells 1 of a finishing mold. The cooling water flow rate was 50 liters per hour per channel 10. The thermal conductivity of the material constituting the shells was 17 W / m. ° K, at 20 ° C. In the case of a finishing mold for a “Champenoise” type bottle, the tubes 5 have a length of 265 mm, an internal diameter of 3.2 mm. Four tubes being used, the overall average water flow is 300 l / hour, that is to say 75 l / hour per channel. By using the same shell materials as for beer bottles, a substantial reduction in the glass / mold contact time is obtained compared to what is achievable with air cooling.

The same result is obtained with a blank mold for bottles of the “Champenoise” type, the liquid cooling system of which differs from that previously described only by a length of the channels of 235 mm instead of 265 mm.

The results of these tests showed on the one hand that it was possible to increase the production rates and on the other hand that the noise emitted around the machines is reduced.

Claims

1. Device for cooling mold elements for the manufacture of glass articles, such as bottles, flasks, ..., characterized in that channels pass through the body of the elements, in that they are connected to a cooling water circuit, and in that the number of channels, the diameter of the channels and the water flow rate are chosen to limit the heat exchange.

2. Device according to claim 1 comprising channels with a length of 130 mm, characterized in that the diameter is between 2 and 4 mm and in that the water flow is between 25 and 100 liters per hour .

3. Device according to one of the preceding claims, characterized in that the mold elements are made of a material chosen to limit the heat exchange.

4. Device according to claim 3, characterized in that the material is an alloy such as a chromium-based alloy steel.

5. Device according to claim 3 or 4, characterized in that the material has an HRC hardness greater than 50.

6. Device according to one of the preceding claims, characterized in that the channels are made in tubes inserted in the mold elements previously drilled.

7. Device according to claim 6, characterized in that the tubes comprise at least one indented zone at their periphery.

8. Device according to one of the preceding claims, characterized in that the channels pass vertically through the mold shells and in that they are associated with upper and lower collectors.

9. Use of a device described according to one of claims 1 to 8 for cooling the shells of a finishing mold of an I.S. machine.

10. Use of a device described according to one of claims 1 to 8 for cooling the shells of a roughing mold of an I.S. machine.

11. A method of manufacturing glass articles, such as bottles, flasks, etc., in which mold elements are used, the body of which is crossed by channels connected to a cooling water circuit, the number of channels, the diameter of the channels and the water flow being chosen for limit heat exchange.