FI120033B - A method for bending and tempering a glass sheet - Google Patents

Description

A method for bending and tempering a glass sheet

The invention relates to a method for bending and tempering a glass sheet, comprising: - heating a glass sheet by heating the sheets for bending and tempering; along the bending conveyor, and 10 - tempering the bent glass sheet.

Such a method is known, for example, from the applicant's patent publication EP 1597208 (B1). In this known method, bending and tempering are performed on the same conveyor, which limits the production capacity of the device.

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On the other hand, a method is known from FI-101697 in which the bending conveyor and the cooling conveyor are separately extending from each other. In this known method, the bending conveyor is already bent on the arc when it receives the glass. This is disadvantageous because the glass has to bend at one of the bending points. In view of the quality of the end product, it is advantageous for the glass to bend simultaneously throughout its bending distance.

The known methods also have the disadvantage that the ends of the glass remain steeper than the desired curvature, even if the bending conveyor is bent to the desired final curvature.

The object of the invention is to eliminate the capacity and quality problems associated with the above-mentioned known solutions and to provide a method for producing high quality bent tempered glass with a large capacity account. In particular, the object of the invention is to reduce the problem of the flatness of glass sheets.

This object is achieved by the method set forth in claim 1 below. Preferred embodiments of the invention are set forth in the dependent claims.

In the following, one embodiment of the invention will be described in more detail with reference to the accompanying drawings in which

Figures 1-3 schematically illustrate a side view of an apparatus implementing the method of the invention at various stages of operation.

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Figure 4 shows a closer view of a bending conveyor and a tempering conveyor bent to a desired radius of curvature, illustrating the bending of the bending conveyor 4 or at least its initial end over the desired end curvature of the glass sheet.

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Fig. 5 shows in greater detail the bending conveyor and the tempering conveyor in a situation where the tempering conveyor 5 is bent to a smaller radius of curvature R3 as compared to the curvature radius R1 of the bending conveyor 4.

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Figure 6 illustrates changes in the speed of movement of a glass sheet as it exits the furnace and exits the bending conveyor, and Figure 7 further illustrates the actuators used to curve the tempering conveyor.

The device according to the invention includes a heating furnace 1 in which the glass sheets G are heated to a bending temperature. The heated glass sheet 30 from the furnace conveyor 2 is transferred via an intermediate conveyor 3 to a bending conveyor 4 which includes horizontal conveyor rolls, above which are press rolls. The gap between the conveyor rollers and the press rollers substantially corresponds to the thickness of the glass sheet.

The immediate extension of the bending conveyor 4 is a tempering conveyor 5, which also consists of horizontal conveyor rolls and press rolls spaced from the conveyor rolls corresponding to the thickness of the glass sheet. Over the entire length of the hardening conveyor 5 there are upper and lower hardening air housings 7 and 8, 5 which follow the curved shape of the conveyor 5. Also at the end of the bending conveyor 4 can be tempering air boxes 7 and 8. The reference numeral 6 denotes a vertical line at which the bending conveyor 4 and the tempering conveyor 5 can be detached. The tempering conveyor 5 is typically slightly longer than the bending conveyor 4. The press rollers of both conveyors 4 and 5 are provided with tension, i.e. they are rotated at the same circumferential speed as the conveyor rolls, whereby the press rolls also act as conveyor rolls.

Figures 4, 5 and 7 show only the hinged bodies 9 on the sides of the conveyors 4, 5 to which the bearings of the conveyor rollers and the press rollers are fixed.

The articulated bodies 9, in turn, are interconnected by a pivoting mechanism (not shown) which forces the articulated bodies to pivot relative to one another as the carriage is curved. Such a joint mechanism is disclosed, for example, in EP-A-1385795 (B1). Fig. 4 shows a power unit 10 and a lever arm 11 for adjusting the radius of curvature of the bending conveyor 4. The power unit 10 may be a servomotor which, via a coupling, drives a ball screw 10a which in turn pushes and / or pivots the lever arm 11 on which the bridge formed by the articulated bodies 9 rests. The play in the pivoting mechanism (not shown) of the pivoting bodies 9 allows the front end of the conveyor 4 to have a slightly smaller radius of curvature relative to the downstream curve radius.

In addition, it is preferable to bend the entire bending conveyor 4, or at least its starting end, to a slightly smaller radius of curvature R2 than the desired curvature radius of glass R1. This removes the flatness and the final tempered glass is obtained throughout its travel to the desired curvature R1.

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Fig. 5, in turn, shows how the tempering conveyor 5 is movable vertically and horizontally (h and w) simultaneously with the change in the angle CL of its central axis. In this way, the curvature of the tempering conveyor 5 can be controlled independently of the bending conveyor 4, but with the point 6a of the hinge-5 between the conveyors 4, 5 remaining stationary. As the desired radius of curvature Rl changes, the curvature adjustment of the tempering conveyor 5 is made separately from the bending conveyor. During the process curvature adjustment of the conveyor 5, its end must not separate from the joint pivot point 6a of the conveyors 4 and 5. During or immediately after the curvature adjustment, the pivot point 6a of the conveyor 5 is brought into position e.g. Thus, during or immediately after the curvature adjustment, interpolating positioning of the conveyor ends is performed. The ends of the conveyors 4 and 5 are mechanically separated from each other in the conveying direction to enable the curvature adjustment of the tempering conveyor 5 and to allow the tempering conveyor 5 to be detached from the bending conveyor 4 if necessary. The arrows 15 indicate the power means by which the rolls 14 can be raised up and down (vertical movement h). In addition, the rollers 14 can move (maintaining their mutual distance) horizontally while the rocking body 13 supporting the conveyor 5 is pivoted on the rollers 14. The pivot axis of the rocking body 13 coincides with the center of the arc passing through the pivot shafts of the conveyor bodies 9 through the pivot shafts.

Fig. 7 shows a bending mechanism of a quenching conveyor 5 comprising a ball screw 12a operated by servo motor SM1 which, through the arms 12b, curves the bridge formed by the hinged bodies 9 and at the same time the entire conveyor 25 resting on the hinged bodies 9. The arms 12b engage a short distance from the ends of the conveyor 5. The second servomotor SM2 drives the ball screws 17 at the angular gear 16 which engage the opposite outer ends of the conveyor 5. The servomotors SM1 and SM2 are synchronized (location synchronized) with each other so that the conveyor parts 5 are curved by the same amount. To this end, the servomotors 30 may have e.g. The curving could be performed by one actuator, but by two actuators the inaccuracies in the convex curvature caused by the wear due to joint wear can be prevented. In particular, the curvature of the middle region and the ends can be maintained.

The method according to the invention is carried out with the apparatus described above as follows. The glass plate G is heated in the heating furnace 1 to a suitable temperature for bending and tempering. The planar glass sheet G is fed from the furnace 1 to the bending conveyor 4 when it is upright (Fig. 1). The tempering conveyor 5 is already bent to the desired arc already at the stage or before the straight bending conveyor 4 receives the planar glass sheet. The glass plate exit speed 10 from the furnace is e.g. 700 mm / s (Fig. 6) and the speed is slowed down, for example, to 400 mm / s for 1 second while the glass plate moves to the bending conveyor 4. and deceleration to a speed of less than 300 mm / s. The bending of the bending conveyor 4 on the desired arc R1 is started even before the end of the glass sheet has reached 15 completely on the bending conveyor 4. The bending of the bending conveyor 4 is carried out very quickly, typically within 1-2 seconds. During this time, the leading edge of the glass sheet will move to the annealing air rollers 7, 8 at the end of the bending conveyor 4. The quench blasting may be continuously on and the speed of the bent glass sheet is slightly increased, as shown in Figure 6. The increase in speed 20 may be, for example, 10 to 40%. The rate deceleration in the previous step is typically at least 30%, preferably more than 40%. In the bending conveyor, 4 sheets of glass are transported in one direction only.

During the bending process, the conveyor 4, or at least its initial end, is bent over the desired final curvature R1 of the glass sheet. This is illustrated in Fig. 4, wherein the bending conveyor 4, or at least its initial end, is bent with a bending radius R2 that is smaller than the desired final curvature R1 of the glass sheet. This over bending reduces or eliminates the flatness of the glass sheet so that the glass sheet is as close as possible to the ends at the desired curvature of 30 Rl. R2 is several percent, up to 5-10% smaller than R1. If desired, the front end of the conveyor 4 can be arranged to be separately bent. However, the play of the articulation mechanisms usually already provides sufficient over-bending to the front end of the conveyor 4. In addition, the entire bending conveyor 4, starting from its fixed end, can be bent slightly above the desired end curvature of the glass sheet.

5 illustrates, by way of illustration, how the tempering conveyor 5 can also be bent during the process to a slightly smaller or larger radius of curvature R3 than the desired radius of curvature R1. This bending of the quenching conveyor 5 to a smaller or larger radius R3 is firstly possible due to the aforementioned freedoms of movement (h, w and angle a) 10 and said interpolating position, while the pivot point 6a between the conveyors 4, 5 remains in place. The process bending of the tempering conveyor 5 is so small that it does not cause the curvature radius R1 of the glass sheet to change, but instead tightens the glass sheet between the conveyor rollers and the press rolls so that the glass sheet moves upward without slipping. This bending of the conveyor 5 is performed only at the final step of tempering when the glass surface has hardened. In this case, the toughened glass sheets can be removed even vertically straight up into a suitable manipulator, which receives the glass sheet. However, the tempering conveyor 5 can also be detached from the bending conveyor 4 if necessary, whereby the tempering conveyor 5 can be completely rotated so that the height difference between its outlet end and the center is reduced (cf., e.g., Figure 3). Hereby, the glass sheet can be removed from the tempering conveyor 5 at a relatively small angle relative to the horizontal without having to move the glass sheet vertically. In the tempering conveyor, 5 glass sheets can be oscillated back and forth.

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When the apparatus produces successively curved tempered glass sheets of the same desired radius of curvature R1, the curvature of the tempering conveyor 5 is kept constant, except for the very slight increase in curvature during the process. Otherwise, the curvature of the tempering conveyor 5 need only be changed when the desired curvature R1 is changed.

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The method according to the invention is also particularly suitable for the production of bi-directional curved glass sheets. In this case, the rollers are also bent, for example, as disclosed in EP-1597208 (B1).

Claims (8)

1. Method of bending and curing a glass sheet, in which method - the glass sheet is heated in a heating oven (1) for bending and curing, 5. the planar glass sheet (G) is measured from the oven (1) to a bending conveyor (4) where the bending conveyor (4) is right, the bending conveyor (4) and the glass sheet bend to a desired degree of curvature while the glass sheet moves along the bending conveyor (4), and 10. the bent glass sheet is bent, characterized in that during the bending process the bending conveyor (4) or at least its front end over the desired end curvature of the glass sheet, ie. the bending conveyor (4) or at least its front end is bent to a radius of curvature (R2) which is less than the desired final bending radius (R1) of the glass sheet. 2. A method according to claim 1, characterized in that the bending of the bending conveyor (4) is started before the end of the glass plate is brought to the front end of the bending conveyor and the bending conveyor is bent to the desired final bending (R1) and said over bending is carried out before härdkylningszon. Method according to claim 1, characterized in that the curved glass sheet is measured from the bending conveyor (4) on a curing conveyor (5) arranged as its continuation, which is fully bent to the desired bending already at that stage or before the straight bending conveyor. (4) receives the planar glass plate. 4. A method according to any one of claims 1-3, characterized in that the cure cooling air is blown onto the beds of the glass sheet already at the end of the bending conveyor (4) and the curing cooling is continued on the following curing conveyor (5) on the bending conveyor (4). 11 Method according to any of claims 1-4, characterized in that the glass sheet is conveyed in the bending conveyor (4) only in one direction, still slower than before or after the bending conveyor, and that in the curing conveyor (5) the glass sheet is oscillated back and forth or is transported only in one direction. Method according to any of claims 1-5, characterized in that the curing conveyor (5) is bent during the curing process with a somewhat smaller radius of curvature than the desired radius of curvature (R1), however, so that the bending of the glass sheet does not change only in the curing conveyor, without the glass conveyor. is clamped between the curing conveyor's upper and lower rollers. Method according to any of claims 1-6, characterized in that, when bending the bending conveyor (4), and / or the curing conveyor (5), the bending point (6a) between the conveyors (4, 5) is held in place. Method according to any of claims 1-7, characterized in that the curing conveyor (5) is detached from the bending conveyor (4) and the curing conveyor (5) is turned in its entirety so that the level difference between its delivery end and the middle portion decreases without the curvature of the curing conveyor changes.