PRODUCTI ON METHOD OF GLASS STEMWARE

Technical Field

The invention subject to the application is related to a method that has been developed for the production of glass stemware and a mould that is used to apply said method.

Known State of the Art ( Prior Art)

In the prior art, a production method known as the rotational blowing method is used during the production of streched stem processing of household, especially the production of wine glasses.

During the production of glass stemware, first of all a drop of molten glass is cut off from the feeder and is dropped into the blank mould via dripping method. After the drop of glass is dropped into the blank, the blank rotates and lifts upward and it is connected to the neck ring. Following the connection the plunger moves downward inside the glass drop and forms the parison (semi shaped glass product). At this point the parison is suspended at the neck ring. During the entire process the parison is connected to the neck ring and it rotates around its own axis. Immediately after the formation of the parison, the two-part shaping mould (finisher) closes such that the parison is placed there-between. After the mould is closed, air is blown into the inner cavity of the parison and the parison is blown up and the glass widens towards the walls of the mould and the glass takes its final form. During the blowing process, the parison is rotated inside the mould and this is also called the rotational blowing production technique in the prior art. Moreover, in the rotational blowing technique a lubricating/wetting coating is used on the mould surface and as a result an additional surface film is formed between the molten glass and the mould.

In this process, as the parison is rotated inside the mould, the glass surface becomes more transparent and a smoother texture is obtained.

Production cannot be made with the lines that form an engraving or pattern on the known mould also known as the finisher in the rotational blowing production method.

l As the parison is continuously rotated inside the mould, it is not possible for the relief designs that are to be applied on the mould to be transferred onto the glass surface.

Therefore the patterns that can be transferred onto the product by means of this method, may be formed of helical/vertical lines that can be formed on the glass surface by means of a blank and/or plunger. The patterns mentioned herein can be applied onto the blank mould and onto the outer surface, and they may also be applied to the inner surface, by means of a plunger.

In the stem pulling production method, a method of shaping by means of fixed blowing without rotating the parison inside the mould has been tried in order to transfer complex patterns onto the parison. However in this solution method two significant problems have been encountered. One of these problems is that the glass surface is not smooth and it remains hazy and that the molten dense glass mass, that accumulates at the bottom of the stem during the formation of the parison by means of the downward movement of the plunger which moves inside the drop of glass when a rotation process is not carried out, sticks to the mould.

In order for the glass surface to be smooth and for it not be hazy, the entire finisher which is used as cast steel in the rotational blowing method, is produced entirely from steel and tests have been carried out. Although the surface quality of the products is increased by means of this change, in the present method the second problem mentioned above could not be prevented. During the formation of the parison by means of the downward movement of the plunger inside the drop of glass, the molten dense glass mass that accumulates at the stem section, cannot be cooled inside the steel mould material. As the temperature of the molten glass increases, the surface tension decreases and the tendency of the glass to stick to the contact surface increases. Therefore the stem section adheres to the mould.

As a result, in order for engraved embossed patterns to be applied to the glass surface, the process and the mould in the prior art needs to be developed, the fixed blowing method needs to be used and the adherence of the stem section to the mould needs to be prevented while ensuring that the glass surface is smooth and transparent.

Brief Description and Aims of the I nvention

In the invention subject to the invention, a fixed blowing production method has been developed, which allows the transfer of the gravure relief designs onto the glass surface of the body of the glass stemware that are produced by means of a stem drawing method, and which ensures that the glass surface is smooth and transparent and enables to take the stem section of the glass stemware out of the mould without it being stuck to the mould, and a mould that is used to enable the application of said method has been developed.

During the development of the fixed blowing production method and the mould used in this method, subject to the invention, the following has been aimed;

• In order to apply the engravings on glass without losing the quality of the glass surface, and

• Enabling to take the stem section of the parison out of the mould without it being stick on the mould.

Definition of the Figures Describing the I nvention

In order to describe the fixed blowing production method developed by this invention and the mould used in this method and the description of these figures have been provided below.

Figure 1 : Sectional view of the inner section of the mould subject to the invention.

Figure 2 : Sectional view of the glass stemware produced, using the method and the mould subject to the invention.

Definitions of the Aspects/ Sections/ Parts of the I nvention

The parts and the aspects in the figures that have been given in order to further describe the mould used in the method and the fixed blowing production method developed by means of this invention have each been numbered and the definition of each number has been provided below.

1 . (Mould) Finisher

2. Mould inner surface

3. Mould stem section 4. Mould insert

5. Glass stemware

Detailed Description of the I nvention

During the fixed blowing production method, subject to the invention, the production phase starts off as being the same with the rotational blowing production method which is a part of the known state of the art.

First of all the molten drop of glass is cut off from the feeder, and is dropped, dropwise into the blank. After the drop of glass is dropped into the blank, the blank rotates and lifts up and it is connected with the neck ring. Following the connection the plunger moves down inside the drop of glass and forms the parison (semi-formed glassware). At this point, the parison is suspended on the neck ring.

According to the development of the fixed blowing production method subject to the invention, the difference from the rotational blowing production technique is that the parison does not rotate by being connected to the neck ring, and as a result, immediately after the formation of the parison, the two part shaping mould (1) is closed with the parison being sandwiched there-between, and the parison is received inside the mould (1).

The bottom section of the mould (1) used in the fixed blowing production method subject to the invention, is the stem section (3) of the mould wherein the dense and thick glass mass is accumulated during the downward movement of the plunger inside the drop of glass.

As it has already been mentioned in the state of the art, if the present mould material and the surface coating and the parison are fixed, the surface quality of the product is reduced. In the case that the mould material is changed and the surface quality is improved, the hot and dense glass mass that accumulates at the stem section, sticks to the stem section (3) of the mould. In the mould (1) used in the invention subject to the invention, a mould insert (4) is placed into the stem section (3) and as a result, the adherence of the dense molten glass located on the parison to the mould (1) is prevented.

The mould insert is placed and fixed into the main mould material by means of mechanical connection methods. The mechanical methods mentioned, can be screw connection, click fit or tab connection. The characteristic of the mould insert (4) is that it is a material that has a contact angle with fluids that is >50°. By this means the adherence of the molten glass onto the surface of the mould is reduced and it is easier to take the stem section out of the mould.

The stem section (3) located on the mould (1) is the area that starts from the stem slab section of the glass stemware to the section where the body is connected to the stem. This section can be seen as the part referenced with number 6 in Figure 2. Due to this, the sizes of the stem section (3) and the mould insert (4) depends on the type of product.

According to the other embodiment of the invention, in order to increase the contact angle with fluids at the area where the mould insert (4) is located, nano sized roughness can be formed on the surface of the mould insert (4). As a result the contact angle of the material with fluids is increased and the adherence of the molten glass is prevented.

Additionally, as the rotation of the parison inside the mould (1) is not carried out in the fixed blowing production method subject to the invention, after the parison is taken out of the mould (1), it is also possible to transfer the engraving relief designs located on the inner surface (2) of the mould onto the glassware, during the shaping of the parison.