Glass manufacturing – Processes – With measuring – sensing – inspecting – indicating – or testing
Reexamination Certificate
1999-11-30
2002-12-24
Derrington, James (Department: 1731)
Glass manufacturing
Processes
With measuring, sensing, inspecting, indicating, or testing
C065S029120, C065S066000, C065S077000, C065S078000, C065S079000, C065S080000, C065S082000, C065S109000, C065S110000, C065S158000, C065S174000, C065S224000, C065S230000, C065S240000, C065S241000, C065S242000, C065S227000
Reexamination Certificate
active
06497119
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a method for producing stemware, tumblers and the like hollow glassware by blow molding a molten solid gob of glass.
The invention is further directed to a device for producing stemware, tumblers and the like hollow glassware with a blow molding stage comprising a blow head with a blow work ring, a blowing unit, a mold, and a bottom plate in which a molten gob of glass can be shaped to form the desired hollow glass, and with devices containing a removal stage for removal of the hollow glassware from the blow molding stage and for delivery to subsequent processes.
In the known methods for producing the aforementioned molded hollow glass bodies, the starting glass is prepared in a glass-melting furnace operation or glass-melting tank operation. Accordingly, DE-A1-32 39 517 shows a method for producing goblet-type glass objects in which a glass gob delivered from the feeder of a glass melting furnace is placed on a press plunger and is pressed between this press plunger and a preform to form a glass tablet or pellet. The table which is still plasticized is then disengaged from the preform and placed on an annular body on which it sinks in a goblet-shaped manner at least in its middle portion through the influence of gravitational force. This tablet is then given its definitive shape in a mold.
A method of the type mentioned above requires a melt tank for removal of the glass gob for the hollow glasses to be molded. This glass tank operation and the subsequent hollow glassware production process are directly connected, so that the following kinds of interactions occur:
Inhomogeneous glass tank operation and glass tank charging, depending on the weight of the product.
It is necessary to adapt to the glass tank capacity when changing over production machinery (retooling or conversion), so that additional inhomogeneities occur in the melting process.
Since a glass tank feeds several production lines, only clear glass can be melted in the tank, and this clear glass can be colored in a costly, complicated process only immediately before being fed into the respective production machinery.
The product changeover period is dependent on the magnitude of the weight difference between the successive products because this has a considerable effect on the duration for changing over the feed devices into the new stable operating state.
With smaller batch sizes, there is an increase in the number of production changeovers, resulting in a corresponding reduction in production efficiency. In addition, modern production machinery, since it is conceived originally for large batches, requires extensive outlay on molds and tools for the respective product combined with a corresponding input of personnel and operating means.
Moreover, one result of the previous type of mechanical stemware production was a high proportion of remainder glass which can amount to as much as 50 percent by weight. This remainder glass (cullet) requires costly transporting devices and feed devices for purposes of remelting in the tank, where it occasions additional expending of heating energy.
The individual production machines of a production line are linked together in the known methods and devices and must consequently be adapted to one another. As the quantity of linked arrangements increases, so also does the breakage rate because there is a risk of breakage each time the glass is handled.
SUMMARY OF THE INVENTION
It is the object of the invention to carry out the method mentioned above and to construct the device mentioned above in such a way that a more economical production of the aforementioned hollow glassware is made possible. It will be possible to carry out the production of this hollow glassware independent from the tank operation glass melting process.
According to the invention, this object is met with respect to the method by the following steps:
production of solid glass blanks in the form of fabricated semifinished products in their own separate manufacturing line;
storage and supply of semifinished products;
feed of semifinished products from the reserve to the manufacturing line for shaping the hollow glassware accompanied by preheating of the semifinished products;
supplying preheated semifinished product for further heating;
heating of the semifinished product to blowing temperature to form a plastically deformable solid glass gob by additional heating;
mold blowing of the plasticized glass gobs to form hollow glass in a blow mold with support of the blown hollow glass body by a bottom lifter;
removal of the hollow glassware from the blow mold and delivery to subsequent processes. With respect to the device, the object is met by:
a stage with storage devices and transport devices for supplying and feeding intermediately stored solid semifinished glass products for the hollow glassware which is to be formed and which has been produced beforehand in its own separate device;
a subsequent preheating stage with heating devices for preheating the solid semifinished products;
a stage with transport devices for supplying the solid semifinished product to a semifinished product heating stage with heating devices for further heating of the semifinished products at least to a temperature close to the blowing temperature;
a transfer stage with devices for transferring the solid semifinished products that have been further heated in the semifinished product heating stage into the blow mold stage, where they are made available as plastically deformable solid glass gobs for blow molding the hollow glassware.
Since the glass raw material is in the form of semifinished product which is adapted to the end product and produced in stock in a separate process and is not heated to the necessary blowing temperature until immediately before the blowing process in a separate continuous furnace, a homogeneous glass tank operation with consistent melt quality is possible.
Simple conversion of the hollow glass fabrication from clear glass to colored glass is also possible.
The invention also advantageously results in a glass tank operation which is independent from the manufacturing line for the molded hollow glass body with respect to time, location and organization. The hollow glass manufacturing process can be carried out in a manageable, less cost-intensive environment, so that great flexibility is achieved in site selection. The high-technology, high-investment glass tank operation can also be carried out independent from and remote from the hollow glass manufacturing process.
As a result of the invention, the glass tank can also be used in a three-tiered manner without retooling interruptions for producing the semifinished products. This enables a more flexible manufacture of smaller batch sizes. It is also possible to test new techniques and/or technology at individual function modules of the device according to the invention without disrupting the entire production process. The invention also opens up possibilities for economizing on personnel, material, energy and mold costs.
There are a number of possibilities, some of which are shown hereinafter, for arranging and producing glass blanks in the form of fabricated semifinished products for mold blowing in their own separate manufacturing line.
According to a further development of the invention, a first possibility consists in producing semifinished product indirectly by punching (stamping) or cutting round flat glass disks from a flat glass as semifinished products for mold blowing.
This possibility has the following advantages:
simple manufacturing process, simple transport and simple supplying of semifinished products;
good, simple handling of the flat semifinished product;
splitting up of semifinished product production spatially into flat glass blank and the actual semifinished product production.
However, the following factors must be taken into account:
technological cost of semifinished product production;
the glass waste resulting from cutting out or punching out must be remelted;
the risk of destruction or dama
Gruber Alois
Hartel Robert
Heller Kurt
Horina Michael
Kreiss Edwin
Derrington James
Schott Glas
Striker Michael J.
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