DE102012104597A1 - Polishing ground piece of glass, useful for treating objects of tableware, comprises cleaning by washing part using acidic solution diluted with water, pre-heating cleaned part, polishing using laser, and carrying out stress relieving - Google Patents

Abstract

Polishing ground piece of a glass having an outer surface provided with designs of matt finish, comprises (a) cleaning by washing a part using an acidic solution diluted with water, (b) pre-heating the cleaned part at a temperature close to transition temperature of glass, (c) polishing using laser under controlled conditions, where outer surface of the part is exposed to laser beam, which causes local melting of surface of the glass and provides a bright polishing view of matt finish, and (d) carrying out stress relieving of the part at a temperature of stress-relief annealing of the glass. An independent claim is also included for a device for carrying out the above method, comprising (a) a cleaning station (10) for carrying out the washing of the part, (b) a preheat furnace (12) for the cleaned part that originates from the cleaning station for heating at a temperature that is close to the transition temperature of the glass, (c) a polishing station (14), which comprises a laser, (d) a stress relieving furnace (16) for stress-relief annealing the part originating from the polishing station, at a temperature of the stress-relief annealing of the glass.

Description

The present invention relates to the field of glass articles that essentially serve tableware.

It relates more specifically to a method of polishing ground glass parts and an apparatus for carrying out this method.

The terms "ground glass parts" are understood to mean glass parts resulting from a grinding process. It should again be noted that the grinding is a completion process at the end of the decoration of glass articles, which results in the cold state by removal of material by means of diamond tools. The pressure mechanically exerted on the glass part by these diamond tools under a continuous stream of water and abrasives finely cuts and digs out the sidewall of the part with different thicknesses and along a well-defined path depending on the desired final design.

At the end of this processing step, the part is called "matted" (taillée mate), d. h., that its outer surface is provided with frosted motifs. To get a so-called "smooth" (lisse) cut, d. H. To obtain a brilliant reproduction, the part must be polished again.

This process of additional polishing is done to date according to two different techniques. The first technique is mechanical polishing, which resembles a polishing done with the help of a Zeroxide grinding powder. This technique of mechanical polishing has the disadvantage that it is long and expensive to realize.

A second technique is to dip the part in an acid bath, i. H. in a mixture formed from sulfuric acid and hydrofluoric acid. This technique of immersion in an acid bath has as major disadvantages its extreme environmental damage and the need for heavy implementation.

One of the main objects of the invention is to propose another polishing technique which avoids the known technical disadvantages described above.

• a) Einen Schritt des Reinigens, indem ein Waschen des Teiles mithilfe einer sauren Lösung, die mit Wasser verdünnt ist, durchgeführt wird,
• b) einen Schritt des Vorheizens, um das gereinigte Teil, das aus dem Schritt des Reinigens stammt, auf eine Temperatur nahe der Übergangstemperatur des Glases zu bringen,
• c) einen Schritt des Polierens mittels Laser, bei dem die äußere Oberfläche des Teils einem Laserbündel unter kontrollierten Bedingungen ausgesetzt wird, was ein lokales Schmelzen der Oberfläche des Glases hervorruft und dem Mattschliff eine brillante Polieransicht verleiht, und
• d) einen Schritt des Spannungsfreiglühens des Teils durchgeführt bei einer Temperatur des Spannungsfreiglühens des Glases.

The present invention therefore proposes a method of polishing a ground glass part having an outer surface provided with mat ground motifs, the method comprising the steps of:

• a) a step of cleaning by performing a washing of the part by means of an acidic solution diluted with water,
• b) a preheating step for bringing the cleaned part originating from the cleaning step to a temperature near the transition temperature of the glass,
• c) a laser polishing step wherein the outer surface of the part is exposed to a laser beam under controlled conditions, causing localized melting of the surface of the glass and giving the ground finish a brilliant polished view, and
• d) performing a step of stress relieving the part at a temperature of stress relieving the glass.

Thus, the present invention is essentially based on a new technique of polishing which aims to brutally raise the temperature of the surface of the glass such that local melting is obtained by exposing it to a laser-type energy source.

There are certainly already techniques of polishing glass by means of a laser, but to date they have been used for different purposes, namely for the purpose of clearing side walls of the glassware. In this case, the initial roughness of the surfaces of the parts to be treated, which is of the order of 0.01 μm, is in principle associated with a method of deformation, and especially with the different surface states of the molds used.

In contrast, in the present invention, the goal is completely different. It's about turning the frosted finish into a brilliant state in the zones of the part that were mechanically attacked by the diamond tools. The exit roughness is thus considerably higher, typically on the order of 0.1 μm, which requires a different approach to the parameters of the laser to be used.

It has never ever been described, nor suggested to date, to use laser polishing to go from a matte finish to a burnished finish.

In addition, it has been found that this laser treatment can only work if the polishing step is preceded by chemical and thermal preparation steps, followed by a heat treatment step.

Only following these steps will lead you to the desired destination.

In fact, as stated above, the method first of all comprises a cleaning step which utilizes a washing of the part using a water-diluted acid solution.

This preliminary step of cleaning is essential to eliminate the contamination of the finish following the actual finishing operation, i. H. the storage conditions of the parts before polishing. In fact, the process of grinding is often performed significantly after the actual molding process, so that the parts experience a more or less long storage while they are polluting.

This cleaning step first comprises a washing performed by spraying under pressure an acid solution, in particular, an acid solution of hydrochloric acid type, sulfuric acid, etc., which are generally used for pickling operations. Advantageously, the cleaning step subsequently comprises a wash, at least one rinse, and a warm airflow drying.

The cleaning step is followed by a preheating step to bring the part to a temperature which is close to the transition temperature of the glass, which is typically about 550 ° C. It allows the glass to have a viscoelastic, d. H. to give viscous behavior. This temperature, called the preheat temperature, must be sufficiently large to render the heat treatment of the surface mechanically compatible, but must also be sufficiently low not to soften the part to be machined and to ensure its geometric integrity. At the end of these chemical and thermal pretreatment steps, the actual polishing step can be performed by subjecting the part to the laser beam under controlled conditions.

Finally, the step of laser polishing is followed by a step of stress relief annealing performed at a temperature of stress relief annealing.

• a) Eine Reinigungsstation, die in der Lage ist, ein Waschen des Teils mithilfe einer wasserverdünnten Säurelösung durchzuführen,
• b) einen Vorheizofen, um das gereinigte Teil, das von der Reinigungsstation stammt, auf eine Temperatur zu bringen, die nahe der Übergangstemperatur des Glases ist,
• c) eine Polierstation, die einen Laser aufweist, wobei sie in der Lage ist, die äußere Oberfläche des Teiles einem Laserbündel unter kontrollierten Bedingungen auszusetzen, was ein lokales Schmelzen der Oberfläche des Glases hervorruft und die Mattschliffe in Brillantschliffe verändert, und
• d) einen Spannungsfreiglühofen, der in der Lage ist, ein Spannungsfreiglühen des von der Polierstation stammenden Teiles bei einer Spannungsfreiglühtemperatur des Glases durchzuführen.

In another aspect, the present invention relates to a device for carrying out the method, which essentially comprises:

• a) a cleaning station capable of washing the part using a water-diluted acid solution,
• b) a preheat oven to bring the cleaned part coming from the cleaning station to a temperature close to the transition temperature of the glass,
• c) a polishing station comprising a laser capable of exposing the outer surface of the part to a laser beam under controlled conditions, causing localized melting of the surface of the glass and altering the ground-cut frosted edges, and
• d) a stress relief furnace capable of stress-relieving the part originating from the polishing station at a stress relief temperature of the glass.

In the following detailed description, given by way of example only, reference is made to the accompanying drawings, in which:

the 1 a schematic top view of a polishing plant according to the present invention;

the 2 a side view of a ground glass part, here a glass with foot, which is suitable to be polished by means of a polishing system according to the invention;

the 3 a side view of a section of the plant of 1 which shows the cleaning station composed of a washing station, a rinsing station and a drying station;

the 4 a cross-sectional view of the washing station is;

the 5 a sectional view of the rinsing station;

the 6 a side view of the drying station is; and

the 7 is a top view of the polishing station by means of laser.

The plant in 1 is used to polish ground parts of glass, with an outer surface, which are provided with matt-ground motifs, as indicated above.

The parts to be treated are usually parts intended for tableware, such as drinking glasses, bowls, carafes, vases, etc. The invention applies to all types of glass and, in particular, glasses of the type soda lime, lead, crystal, etc.

The 2 FIG. 12 shows a ground glass part P having an outer surface provided with matte-ground motifs M resulting from a grinding operation performed cool by removing material by means of diamond tools. In the example, the part P is a glass with a foot, which is shown in a vertical reverse position, with his foot facing upwards oriented, and his drinking cup or cup B, which is directed downwards.

The plant of 1 serves to convert the matte aspect of the subjects M of the part P into a brilliant aspect or a brilliant reproduction.

How out 1 As can be seen, the plant has essentially four main stations, which correspond to the four steps of the method, as described above.

One successively recognizes a cleaning station 10 , a preheating oven 12 , a polishing station 14 and a stress relief furnace 16 ,

The system has a first conveyor 18 in order to continuously pass at least one row of parts (here two rows of parts) sequentially through the wash station 10 and the heating oven 12 to the polishing station 14 (Arrow F1) to promote.

The cleaning station 10 consecutively has a wash station 20 , a first rinse station 22 , a second rinse station 24 , a third rinse station 26 and a drying station 28 which serve to be traversed in this order by the parts P to be treated.

The 3 shows in side view of different stations that the washing station 10 form as well as the sponsor 18 , This allows continuous two rows of parts to be treated in the direction of arrows F1 (ie from left to right in the 1 to 3 ) to treat.

The washing station 20 represented in 4 , has a housing 30 on, the two tunnels 32 and 34 limited, which serve for circulating two rows of parts P to be treated. In the example case, the parts P are analogous to those of 2 , These are glasses with feet, with the foot pointing upwards and the cup or cup pointing downwards, this one directly on the conveyor 18 rests. In each of the tunnels 32 and 34 are several rows of washing nozzles 36 arranged according to an arrangement in reverse U-shape. In the case of an example these are nozzles 36 designed to perform a jet under pressure of a water-diluted acid solution. The pressure of the jet must be sufficiently high, for example 2 to 3 bar, to ensure effective cleaning of the outer surface of the part to be treated.

The step of cleaning thus begins by washing the part using a water-diluted solution, advantageously an aqueous hydrochloric acid (H ₃ OCl). It has been found that in fact such a solution makes it possible to ensure efficient cleaning of the parts, the contamination resulting from the actual grinding process.

This washing occurs continuously as the parts between the washing nozzles 36 move. The washing process can typically take on the order of five minutes. The washing solution is constantly recycled after filtering by suitable means not further described in detail.

The previously washed parts then move through the rinsing stations 22 . 24 and 26 ,

The 5 shows a sectional view of the first rinsing station 22 , It has a housing 38 analogous to the housing 30 from 4 up, which also has two tunnels 40 and 42 for the corresponding passing of the two rows of parts P defined. The rinsing station points in an analogous way to the washing station 22 Rows of rinsing nozzles 44 which are arranged according to an arrangement of an inverted U-shape and are adapted to generate a jet under pressure of a rinsing solution.

The first rinse station 22 allows a first rinse of the parts P, typically with purified or osmosis water.

The second rinse station 24 is carried out in an analogous manner and allows a second purging of the parts P perform, typically with double or reverse osmosis water (eau bi-osmosée).

The third rinse station 26 allows a third rinse with the reverse osmosis water.

The complete duration of a rinse cycle is typically on the order of five minutes.

After rinsing, the parts pass through the drying oven 28 , An example of the drying oven is in 6 shown. In the example, the drying oven 28 four fans 46 on, which are arranged above the parts to be dried and are designed to warm swirling air thanks to warming resistances 48 distribute, which are arranged below each fan. This drying is carried out by convection of heated and fluidized air at a temperature of about 70 to 80 ° C. The complete duration of a drying cycle is typically on the order of five minutes.

This step of cleaning (washing + (multiple) rinsing + drying) is indispensable for the perfect completion of the polishing process by laser, which is then carried out.

At the exit of the cleaning station, the parts P become the heating furnace 12 emotional. Also there move the parts P thanks to the conveyor 18 continuously in the oven. The time of heating up as well as the height of the temperature depend on the geometry of the parts to be treated, as well as the type of glass used.

The temperature of the preheating oven 12 is also of the order of 500 to 550 ° C for a warm-up time of one to two hours.

The parts are thus preheated in the core to a temperature close to the transition temperature of the glass, ie of the order of 550 ° C, depending on the nature of the glass. At the end of preheating, the parts are ready for polishing in the true sense of the polishing station 14 ( 1 ).

How out 1 can be seen, points the polishing station 14 a cabin 50 on, in which the parts P are introduced, here the two rows of parts P, which have just been preheated. The parts thus become a radiation of a laser beam 52 exposed, generated by a laser 54 (shown schematically). In the example, the laser bundle 52 vertically oriented from top to bottom and impinges on a local surface of the part P, the latter being set in motion by suitable means (to be described later) to successively treat the entire external surface of the part. It is conceivable the laser bundle 52 to align in other directions.

In the embodiment, a continuous laser energy source of the CO ₂ type is used. Here, the laser has a wavelength of 10.6 microns and a power of 2 to 4 kW. In addition, the laser has a controller 56 (schematically in 1 shown) in order to adjust the power of the laser, in particular to take into account the geometric characteristics of the part P.

Advantageously, a laser beam with parallel beams is used, which has a substantially constant energy distribution, d. H. a non-Gaussian distribution. Namely, it has been found that a Gaussian energy distribution is able to produce undesirable streaks on the outer surface of the glass to be treated.

After the laser processing, the parts are often on a second conveyor 58 ( 1 ), which is horizontal and perpendicular to the direction of the conveyor 18 is arranged. The conveyor 58 conveys the parts P in the direction of arrow F2 ( 1 ) to a third conveyor 60 that is horizontal and perpendicular to the conveyor 18 is arranged. The conveyor 58 is pre-heated to the transition of the parts to the stress relief furnace 16 to enable. The conveyor 60 moves the parts P in the direction of the arrow F3 ( 1 ).

In the example, the third sponsor promotes 60 the parts P in two rows through the Spannungsfreiglühstation 16 which is realized here in the form of a bow. in the latter, the stresses of viscoelastic origin produced by uncontrolled cooling of the piece of glass at the end of the polishing process are caused by mechanical instabilities. A heat treatment called stress relief annealing is thus necessary at a stress relieving temperature inherent in the glass and the geometric conditions of the part to be treated.

Reference is now made to the 7 in which the downstream end of the conveyor 18 and a section of the conveyor 58 are visible as described above. It is also the laser bundle 52 can be seen that impinges on a local zone of a part P. The local zone has a general circular shape and extends over a surface of the order of 10 cm ² .

In the illustrated example, the parts P are conveyed continuously in two rows, and there are two parts P at the downstream end of the conveyor 18 seen. These parts P serve alternately from the laser beam 52 to be treated. For this purpose, the polishing station has two robots 62 on, which are assigned according to the two rows of parts T and are guided so that they work alternately.

Multi-axis robots, in particular robots with six axes, are used here. A particular example is given by robots manufactured by FANUC: Model S-700. Each of the robots is programmable to perform a combination of translational motions (arrow F4) and rotational motions (arrow F5) according to a preinstalled program.

Each one of the robots 62 has a basic pedestal 64 on, rotatable about a vertical axis 66 a multi-position arm 68 is mounted, its end with a support 70 is made of graphite, which is designed to ensure the gripping of the part P (here the foot of the glass) by suction, as will be described below.

Each robot performs a combined translational and rotational movement of the part such that the laser beam impinges on a localized zone of the surface of the part, in a direction substantially normal to that of the localized zone. In addition, each of the robots is adapted to perform a removal of the part at the exit of the preheating furnace, ie at the exit of the conveyor 18 , and is capable of the part at the entrance of the stress relief furnace, ie on the conveyor 58 discontinued. The arm 68 of each robot thus pivots about the axis 66 according to an angular range A.

The robots 62 are each programmed to allow the combined translational and rotational movement of the part P under the laser beam 52 is realized in such a way that the bundle gradually sweeps over the surface of the part depending on the geometric properties of the part.

For example, the part may be moved in its axial direction at a linear velocity of the order of 10 cm / second, being subjected to a rotational speed of the order of 100 revolutions / minute.

If the part has a variable curvature, as is the case, for example, with a balloon glass, it is necessary to increasingly change the angular orientation of the axis of rotation of the part with respect to the horizontal.

Also depending on the distance of the localized zone with respect to the axis of rotation, one can be made to change the rotational speed so that the tangential velocity at the level of the localized zone is substantially constant over the entire extent of the surface to be treated.

It is also possible to use the energy of the laser beam 52 via the adjustment control 56 to modulate.

It will be understood that these various parameters can be varied depending on the geometric conditions of the part to be treated and also the type of glass, its thickness, etc.

In the illustrated example case, the foot of each part at the end of the robot arm is replaced by a rubber vacuum (not shown) and by the previously heated graphite carrier 70 at a temperature close to the heating temperature of the part to avoid thermal shocks which may cause cracks in the glass.

If the robot is a part P of the conveyor 18 The teat is actuated to ensure a reception of the foot of the part by pneumatic effect. The nipple is held in operation during all subsequent operations, up to the moment where the part on the conveyor 58 is set.

Thus, the invention effectively enables polished glass parts to be polished by the action of a laser to convert a ground-up or brilliant ground frosted finish. In addition, laser treatment also allows for the brilliant appearance of the exterior surface of the part outside the ground zones.

Claims (20)

A method of polishing a ground glass part having an outer surface provided with ground finish motifs, characterized by comprising the steps of: a) a step of cleaning by washing the part with an acidic solution, b) a step of preheating to bring the cleaned part originating from the step of cleaning to a temperature near the transition temperature of the glass, c) a step of polishing by laser exposing the outer surface of the part to a laser beam under controlled conditions, causing localized melting of the surface of the glass and giving a brilliant polished appearance to the frosted finish, and d) performing a stress relief annealing step of the part at a stress relieving temperature of the glass. A method according to claim 1, wherein the washing of the cleaning step is carried out by spraying under pressure an aqueous acid solution, in particular an acid solution of the hydrochloric acid or sulfuric acid type. A method according to claim 1 or 2, wherein the cleaning step comprises successively washing, at least rinsing and drying with warm fluidized air. The method of claim 3, wherein the step of purifying comprises first flushing with osmosis water and at least a second flushing with reverse osmosis water. A method according to any one of claims 1 to 4, wherein the step of laser polishing comprises combined translational and rotational movement of the part under the laser beam to cause the latter to increase the surface area of the part Dependence of the geometric properties of the part passes over. The method of claim 5, wherein the combined translational and rotational movement of the part is performed such that the laser beam impinges on a localized zone of the surface of the part in a direction substantially normal to that located zone. A method according to claim 5 or 6, wherein the step of laser polishing comprises regulating the power of the laser in dependence on the geometrical characteristics of the part. A method according to any one of claims 1 to 7, wherein the step of laser polishing is carried out with a CO ₂ type laser having a wavelength of 10.6 μm and a power of 2 to 4 kW. Device for carrying out the method according to one of claims 1 to 8, characterized in that it comprises: a) a cleaning station ( 10 ) capable of washing the part (P) using a water-diluted acid solution, b) a preheating furnace ( 12 ) to the cleaned part, which is from the cleaning station ( 10 ) is brought to a temperature which is close to the transition temperature of the glass, c) a polishing station ( 14 ), which is a laser ( 54 ), wherein it is able to connect the outer surface of the part to a laser beam ( 52 ) under controlled conditions causing a local melting of the surface of the glass and forming the frosted cuts into brilliant cuts, and d) a stress relief annealer ( 16 ), which is capable of stress-relieving that of the polishing station ( 14 ) at a voltage release temperature of the glass. Apparatus according to claim 9, wherein the cleaning station ( 10 ) a washing station ( 20 ) having a plurality of washing nozzles ( 36 ) capable of performing a syringe under pressure of the water-diluted acid solution. Apparatus according to claim 9 or 10, wherein the cleaning station ( 10 ) successively a washing station ( 20 ), at least one rinsing station ( 22 . 24 . 26 ) and a drying station ( 28 ) with hot turbulent air. Apparatus according to claim 11, wherein the cleaning station ( 10 ) a first rinse station ( 22 ) with osmosis water and at least one second rinse station ( 24 . 26 ) with reverse osmosis water. Apparatus according to claim 11 or 12, wherein each rinsing station ( 22 . 24 . 26 ) a plurality of rinsing nozzles ( 44 ) capable of performing a syringe under pressure of a rinse solution. Device according to one of claims 9 to 13 with a conveyor ( 18 ) to continuously pass through at least a series of parts (P) through the cleaning station (Fig. 10 ) and the preheating furnace ( 12 ) to the polishing station ( 14 ) to move. Device according to one of Claims 9 to 14, in which the polishing station ( 14 ) at least one multi-axis robot ( 62 ), which is capable of a combined translational and rotational movement of the part (P) under the laser beam ( 52 ), so that the latter increasingly passes over the surface of the part, depending on the geometrical properties of the part. Device according to Claim 15, in which the multi-axis robot ( 62 ), moreover, a removal of the part (P) at the output of the preheating furnace ( 12 ) and a settling of the part (P) at the entrance of the stress relief furnace ( 16 ). Apparatus according to claim 15 or 16, wherein the multi-axis robot ( 62 ) performs the combined translational and rotational movement of the part (P) in such a way that the laser beam ( 52 ) impinges on a localized zone of the surface of the part in a direction substantially normal to that located zone. Device according to one of claims 9 to 17, wherein the polishing station by means of laser ( 14 ) a regulation control ( 56 ) the power of the laser ( 54 ) depending on the geometric properties of the part (P). Device according to one of Claims 9 to 18, in which the laser ( 54 ) of CO ₂ type having a wavelength of 10.6 μm and a power of 2 to 4 kW. Device according to one of Claims 9 to 19, in which the laser beam ( 52 ) has parallel rays and has an energy distribution that is substantially constant.

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