GB2212141A

GB2212141A - Glass turning station

Info

Publication number: GB2212141A
Application number: GB8726159A
Authority: GB
Inventors: David Anthony Duncan; Paul George Brough
Original assignee: Anglian Windows Ltd
Current assignee: Anglian Windows Ltd
Priority date: 1987-11-07
Filing date: 1987-11-07
Publication date: 1989-07-19
Anticipated expiration: 2007-11-07
Also published as: GB2212141B; GB8726159D0

Abstract

Sheets of glass 20 standing on one edge are fed from an inlet conveying means 34 to a datum position, whereupon the glass is gripped by turning means 26 having suction pads, turned through 90 degrees in a vertical plane and released on its adjacent edge on to an outlet conveying means 36, wherein various sensors (44, 46, 52 to 62 Fig 2) are provided for sensing the glass dimensions and controlling the timing and speed of operation of the turning means and conveying means responsively to the dimension measurements, so as to avoid collisions between successive sheets of glass being conveyed. <IMAGE>

Description

Improvements in Glass Turning Stations This invention relates to a glass turning station.

Glass turning stations are known per se. The purpose of such a station is to rotate a rectangular (used herein to include square) sheet of glass standing against a backboard through 90 degrees, from a standing position on one edge to a standing position on the next edge. A common reason for this requirement is in the transfer of the glass between successive glass arrisers for bevelling the glass edges, e.g. prior to passage of the glass to a glass toughening station.

Usually, therefore, the glass passes along a conveyor lin- which comprises four arriser stations alternating with three turning stations. Typically, the conveyor line has to deal with various sizes of glass sheet, mixed in passage along the line. It is required for the conveyor line to handle glass at a maximised production rate, whilst at the same time avoiding the risk that one sheet of glass will collide with the preceding one. The problem of reconciling these requirements will be understood by consideration of the mixed rectangular shapes and sizes of glass sheet to be handled, coupled with the repetitive turning of the glass (which may include relatively long but narrow rectangular sheets) as the glass passes along the conveyor line.

It is an object of this invention to provide a glass turning station which can provide an effective solution to the abovedescribed problem.

According to one aspect of the present invention, there is provided a glass turning station comprising an inlet conveying means for conveying a rectangular sheet of glass into a datum position, a glass turning means which grips the glass in the datum position, rotates it through 90 degrees, and releases the glass on to an outlet conveying means, sensor means for sensing at least one dimension of a sheet of glass to be turned, and control means responsive to the sensor means for controlling operation of the conveying means and/or turning means in dependence on the dimension measurement.

Normally, the glass will be conveyed in a substantially vertical plane through the turning station, leaning against a backboard which may have multiple air inlet apertures which provide a thin cushion of air behind the glass in order to prevent risk of damage to said glass as it is conveyed and turned. The glass will thus enter the turning station resting on one edge on the inlet conveying means, and leave the station resting on an adjacent edge on the outlet conveying means.

Preferably, an inlet sensor, conveniently an infra-red sensor, is located adjacent the inlet end of the inlet conveying means for use in measuring the horizontal dimension of the arriving glass sheet. Activation of this sensor preferably initiates operation of an electronic counter, which continues counting as long as the sensor is covered.

When the trailing edge of the glass clears the sensor, the count is stopped.

In an embodiment, the electronic count, which represents the horizontal dimension of the glass, is preferably employed te set the speed of operation (turning speed) of the glass turning means. The said turning means may be generally of a conventional kind, comprising a turning member, typically L-shaped, bearing three vacuum operated suction pads, two at the ends of the respective arms and one at the junction between them. On arrival of a glass sheet at the datum position, the L-shaped member is disposed with one arm directed vertically and one arm directed rearwardly above the inlet conveying means. In order to turn the glass, it rotates to a position in which the originally vertical arm is directed forwardly above the outlet conveying means, and the originally horizontal arm is directed vertically.Conveniently, the electronic count above referred to may also be employed to determine if the suction pad on the originally horizontal arm of the L-member is required. Alternatively, however, a supplementary sensor may be provided adjacent the end of the originally horizontal arm of the L-member. If this supplementary sensor remains covered when the glass reaches the datum position, the control means recognises that the suction pad on the end of the said arm is required.

As the inlet conveying means is employed to bring the glass sheet to rest in the datum position, the same electronic count may be employed to determine the restart time of the inlet conveying means, in case glass being turned by the turning means would not leave sufficient free space for the next arriving glass sheet during its conveyance towards the datum position.

A second sensor means senses the leading edge of a glass sheet as it approaches the datum position and supplies an output to the control means, whereby the inlet conveying means is slowed down in accordance with a timing cycle to bring the glass slowly into the datum poSition. The inlet conveying means is then temporarily stopped. Mechanical indexing stops are projected outwardly from the backboard, under supervision of the control means, when or shortly after the second sensor means has detected the leading edge of a sheet of glass, to provide a positive location for the said glass leading edge, in order to prevent any possible overshoot beyond the datum position. The indexing stops are withdrawn responsively to the turning means gripping a piece of glass due to the operation of one or more of the suction pads, just prior to initiation of the turning action.

A third sensor means senses the vertical dimension of the glass sheet when it is in the datum position. The result of this measurement is accepted by the control means and, in consequence, it is possible for a revised speed of turning to be set for the turning means. Primarily, however, in conjunction with an encoder associated with the outlet conveying means, the resulting measurement is used to time operation of the turning means in order to ensure that a turned glass sheet will not collide with glass being conveyed by the outlet conveying means. In rare circumstances, the third sensor means may be effective, during the act of glass turning, to revise the speed of operation of the turning means.

A fourth sensor means is associated with the outlet conveying means. If this fourth sensor means is covered when a downstream conveying means stops, the outlet conveying means is stopped, and in turn the turning means and inlet conveying means may be stopped. A safety means prevents the suction pads from releasing if the turning means is stopped during the action of glass turning.

It will therefore be understood that the general aim of the invention is to maximise glass movement along a conveying line whilst avoiding risk of collision between glass sheets being successively conveyed and turned. According to a further aspect of the invention, therefore, there is provided a glass conveying line which comprises a plurality of work stations alternating with a plurality of glass turning stations, sensor means at each turning station for sensing the dimensions of a sheet of glass when it arrives for handling at the turning station, and control means responsive to the sensor means for controlling the speed of glass handling at each turning station in such a manner that, throughout the length of the conveyor line, glass sheets are caused to follow one another along said line substantially as closely as possible without risk of any one sheet of glass colliding with the preceding sheet on the line.

Such a conveying line is achievable by use of glass turning stations in accordance with the first aspect of the invention hereinbefore described.

A glass turning station and glass conveyor line incorporating such a turning station is now described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a glass conveyor line in diagrammatic form; Figure 2 is a diagrammatic view of a glass turning station from the front; and Figure 3 is a simplified block circuit diagram.

Referring to Figure 1, there is shown part of a conveyor line for conveying sheets of glass of mixed sizes, from right to left as illustrated.

The part of the conveyor line shown in Figure 1 consists of a first arriser 10, at which the bottom edge of a sheet of glass passing therethrough is bevelled, a glass turning station 12, and a second arriser 14 at which the next edge, again the bottom edge as a result of turning the glass sheet through 90 degrees, is likewise bevelled. Upstream of the first arriser 10 is a glass loading station at which glass is loaded on to the conveyor line. Downstream of the second arriser is a second turning station, a third arriser, a third turning station, and a fourth arriser. The line may continue to other work stations, for example including a glass toughening station.

Figure 1 also shows a leading sheet of glass 16 being conveyed through the second arriser 14, an intermediate sheet of glass 18 leaving the turning station 12, and a trailing sheet of glass 20 entering the turning station 12 from the first arriser 10. The complete conveyor line has sheets of glass of mixed sizes proceeding from the loading station to the fourth arriser and beyond, the glass sheets following one another substantially as closely to one another as possible without risk of collision between them, having due regard to the mixed sizes of the sheets and also the turning actions which take place at the turning stations.

Given that the entire conveyor line is essentially operating at uniform conveying speed throughout, it is the turning stations which predominantly affect the necessary glass sheet spacings (these spacings generally being changed as the sheets proceed along the line), and the invention is therefore primarily concerned with the turning stations (which are in essence identical) and in particular with the control thereof which determines the glass sheet spacings appropriate to maximised production without risk of breakage due to collisions.

A single turning station is illustrated in Figure 2.

Mechanically this turning station is of a conventional construction, for example being a standard turning station unit manufactured by Schiatty Angelo Srl, and it is therefore not described in detail. It comprises a drive unit housing 22 containing a pneumatically operated ra which is operable through a mechanical linkage system (the final link of which is referenced 24 in Figure 1) to drive a glass turning member 26 in alternate forward and reverse 90 degree rotational steps. The drive unit in the housing 22 also includes conveyor drive motors and a pump.

The turning member 26 is an L-member having two arms at right angles and carrying three vacuum operable suction pads 28, 30, 32 for gripping the glass, two pads 28, 30 at the ends of the respective arms and one pad 32 at the junction between the arms. The suction pads connect to the pump of the drive unit through flexible air lines (not shown).

An inlet conveyor 34 (Figure 1) brings the glass to a position for gripping by one or more suction pads 32 and/or 28, 30 depending on the dimensions of the glass sheet. The L-member 26 is then stepped anti-clockwise through 90 degrees, whereafter the suction pad or pads are released to enable the glass to be conveyed onwards, in its turned position, by an outlet conveyor 36 (again see Figure 1). After the suction pads have released the glass, the L-member 26 is stepped clockwise through 90 degrees, back to its original position, ready to receive the next glass sheet. The inlet and outlet conveyors 34, 36 are driven by the conveyor drive motors in the drive unit housing 22.Subject to operation of the control system to be hereinafter described, all the conveyors which make up the complete conveyor line, including the conveyors in the arrisers, operate to convey the glass at a uniform speed throughout the length of the line.

Control of the aforedescribed standard turning station unit is normally either automatic or manual, as selected by a selection switch 38. In the "auto" switch position, the turning station operates according to a fixed timing cycle.

This can be suitable for glass sheets all of uniform size but requires either skilled loading of the conveyor line or unnecessarily large but safe spacings if sheets of mixed dimensions are to be handled. In the "manual" switch position, controls 40 enable a skilled operator to sequence the application of the suction pads, the start of the turning action, and the return of the turning member, as necessary to suit the particular sheets of glass being handled at the time. A skilled operator is thus required for each turning station.

The present invention provides a control system which bypasses the controls 38, 40, and sequences the stages of operation of the turning station for the purpose hereinbefore described.

Before proceeding to describe the control system, â further feature of the standard turning station unit should be mentioned. This is a backboard 42 against which leans the glass, standing on its bottom edge in a nearly vertical plane while being conveyed. This backboard is provided with a multiplicity of small air inlet apertures (not shown), supplied with forced air to maintain a thin layer of air behind each glass sheet as it is being handled at the turning station, thereby reducing friction and risk of damage to the glass.

The control system with which the present invention is concerned essentially consists of sensor means for detecting dimensions and movement of the glass and a controller which includes a CPU programmed with an operating program whereby, -dependent on signals received by the CPU as a result of detection of glass by the sensor means, control signals are supplied by the CPU to the drive unit of the turning station. The sensor means comprises a plurality of infra-red sensors mounted on and slightly recessed into the backboard 42.

As a sheet of glass enters the turning station, its leading edge passes sensor 44. The output of the sensor 44 resulting from detection of the leading edge is fed to a counter to initiate running of the latter. When the sensor 44 detects the trailing edge of the sheet of glass as said sheet is conveyed towards the centre of the turning station, the counter is stopped and then reset. The resulting count is fed to the CPU which, since the speed of movement of the inlet conveyor is known, is able to compute the horizontal dimension of the glass sheet.In accordance with its operating program, the CPU calculates, from the glass horizontal measurement, firstly if the suction pad 28 at the end of the horizontal arm of the L-member 26 is required, secondly an initial turning speed for the L-member 26, and thirdly the earliest possible restart time for the inlet conveyor 34 (which stops to bring the glass to rest at the centre of the turning station).

The inlet conveyor 34 conveys the glass towards the centre of the turning station with the aim of stopping it at a precisely defined datum position. Accordingly, as the glass approaches this datum position, its leading edge is detected first by sensor 46 and then by sensor 48. The output of sensor 46 also triggers a counter associated with the CPU program, whereby after a predetermined count the CPU supplies a signal to brake the drive motor for the inlet conveyor 34. The inlet conveyor is braked just before the leading edge of the glass reaches sensor 48, the output of which triggers a further timer associated with the CPU program, whereby the glass sheet is conveyed at creep speed into the datum position.The count made by the counter associated with. the sensor 46 is also employed to cause the CPU tc supply control signals to miniature cylinder/piston drives for two indexing stops 50, which as a result are projected out from the backboard into the path of the leading edge of the glass, thereby to prevent possible overshoot and ensure that the glass is exactly located, at its leading edge, in the datum position.

When the glass is in the datum position, its vertical dimension is detected by the vertically spaced sensors 52 to 62. From the outputs of these sensors, the CPU determines the height of the glass (within a range). The sensor 52, in particular, if producing an output indicating that it is covered by the glass sheet, determines that the suction pad 30 at the end of the vertical arm of the L-member 26 is selected for us.

From the vertical height measurement obtained via sensors 52 to 62, the CPU also determinesthe earliest possible start time for the turning action and the final speed of turning. For this purpose, the CPU also receives an input from an encoder (not shown in Figure 2) on the outlet conveyor 36. From the input, and knowing the predetermined speed of the outlet conveyor 36, the CPU is able to determine the timing and speed of the turning action so that a turned sheet of glass will not collide with the preceding sheet of glass being conveyed on the outlet conveyor.

Additionally to the foregoing, however, it is advantageous to turn the glass at a speed which takes into account its overall dimensions. The L-member 26 is drivable, in the embodiment being described, at any of three possible turning speeds, conveniently referred to as fast, medium and slow. From the horizontal and vertical measurements made, the CPU determines that a glass sheet with a very long edge (say in excess of 1600 mm) will always be turned at slow speed, a sheet of more than a certain area (say in excess of 900 mm square) will not be turned faster than medium speed, and a sheet of less than 900 mm square may be turned at fast speed. Subject to these considerations, the speed of the turning action (speed of rotation of the L-member 26) is determined according to the criteria previously described.It is thus to be appreciated that a turning speed initially selected by the sensor 44 and its associated counter may sometimes subsequently be altered as a result of the measurement of the vertical dimension and/or the position of the preceding sheet of glass. Moreover, if desired, the control means may be programmed to make it possible for the turning speed to be changed during the turning action, as a result of a sheet of glass, as it turns, causing operation of increasingly higher sensors of the group 52 to 62. At the same time, it is to be understood that, when the CPU makes a computation involving the position of the preceding sheet of glass on the outlet conveyor 36, it also takes into account the time period taken up by turning, having due regard to the selected turning speed.The start of the turning action will, in general, only be delayed if selection of a slow turning speed is not sufficient to ensure non-collision with the preceding sheet of glass.

Immediately the CPU has determined if one, two or three suction pads are to be used for a given sheet of glass, it supplies a control signal to the turning station drive unit to initiate operation of the selected suction pads or pads into gripping engagement with the glass located in the datum position. When the CPU receives a confirmatory signal from the turning station drive unit confirming operation of the suction pads, the CPU supplies control signals to retract the indexing stops 50 and then to initiate the turning action at the earliest permitted moment. The L-member 26 is rotated anti-clockwise through 90 degrees, so that its initially horizontal arm above the inlet conveyor 34 is now vertical and its vertical arm is now horizontal above the outlet conveyor 36.At the end of the turning action, the CPU supplies a signal to the drive unit initiating release of the suction pads, whereby the glass is released on to the outlet conveyor to be conveyed downstream. In the meantime, the inlet conveyor 34 is restarted when the glass being turned has been lifted free, at the earliest possible restart time determined by the measurement effected by the sensor 44 and its associated counter.

When the rotated L-member 26 has deposited a sheet of glass on to the outlet conveyor 36, it is immediately returned at fast speed by a clockwise rotation of 90 degrees, to its starting position, ready for the next sheet of glass to be turned.

The foregoing description is complete as far as operation of a single turning station is concerned, if said turning station is treated in isolation. However, the turning station forms part of a conveyor line with arrisers on each side thereof, and the continuous conveyance of glass sheets of mixed dimensions along the line thereby also entails a degree of interaction between the turning station and these upstream and downstream arrisers.

Accordingly, a movement sensor is provided on the downstream arriser, for providing an output signal to the CPU at the turning station. The turning station itself, above the outlet conveyor 36, is provided with sensors 63 and 64, for sensing the presence of a sheet of glass. If the CPU receives a signal from the downstream arriser indicating that it has stopped, and if additionally either sensor 63 or 64 is providing an output indicating the presence of a sheet of glass, then the CPU halts the turning cycle of the turning station. Moreover, at the same time, the CPU may supply a signal to the drive motor of the upstream arriser to stop the operation thereof. In this way, the entire conveyor line may be brought to a halt if there is a failure or breakdown at any one station.Moreover, a temporary stoppage of the line or a part thereof may occur if a succeeding sheet of glass starts to enter the turning station too closely behind the preceding sheet of glass (at least the horizontal dimension of which has been measured). In the latter event also, for as long as the condition giving rise to risk of collision exists, the CPU at the turning station supplies a stop signal to the preceding arriser. In this connection, ithas to be recalled that the inlet conveyor at the turning station is temporarily slowed down and brought to rest when conveying a glass sheet into the datum position. In addition, the turning circle of the glass in the centre of the turning station, known from measurement of its dimensions, may be taken into account with respect to entry of the following sheet of glass into the turning station.

If the turning station is brought to rest while in the act of turning a sheet of glass, a safety interlock built into the CPU operating program ensures that the operating suction pad or pads are not released in mid-cycle. The same interlock is operative if, for any reason, it becomes necessary to operate either one of two emergency stop controls 66 provided on the turning station drive unit.

Other principal operating units of the turning station, such as an air pressure supply fan to the backboard, are connected to the CPU to initiate a stop in the event of failure, and in all such instances the safety interlock referred to serves to prevent release of a sheet of glass currently being gripped at the turning member 26.

Figure 3 is a simplified block diagram of the control system circuit, wherein the CPU containing the operating program is referenced 70 and the turning station drive unit 72.

The CPU 70 receives inputs from the entry sensor 44 via associated counter 45, the speed control sensors 46, 48, the outlet conveyor sensors 52 to 62, the outlet conveyor encoder 69, the outlet conveyor sensors 63, 64, and the downstream arriser movement detector 67. Outputs in the form of control signals are supplied to the upstream arriser drive motor (output 74) and the indexing stop drives 51, in addition to the turning station drive unit 72, all in accordance wit the operating sequence determined by the CPU program, as hitherto described.

The turning station and conveyor line as above-described may incorporate various modifications and/or refinements, some of which are mentioned hereinafter.

Firstly, instead of relying dn the horizontal dimension measurement determined by the sensor 44 and its associated counter for controlling the suction pad 28, a supplementary sensor 70 may be provided adjacent the end of the initially horizontal arm of the L-member 26. This supplementary sensor 70, if remaining covered when the glass reaches the datum position, serves to indicate to the CPU that the suction pad 28 is required.

Secondly, in the case when a sheet of glass, which is tall and narrow in its turned position, is deposited on the moving outlet conveyor, an initial wobbling and instability of the glass can occur. For avoidance of this disadxan- tageous effect, a sensor 72 is provided adjacently but above the sensor 46. This sensor 72 operates in conjunction with the supplementary sensor 70 to detect if, prior to turning thereof, a horizontally long sheet of glass of small height is entering the turning station. If, as the glass approaches the datum position, the sensor 70 remains covered but the sensor 72 is not covered, the CPU provides a control signal for temporarily slowing down the outlet conveyor at the moment the said glass, in its turned orientation, is being released on to said outlet conveyor.

Thirdly, a pair of horizontally spaced sensors 74, 76 may be provided at the upstream or preceding arriser (see Figure 1). Thus, although in general the arrangement as previously described will prevent a following sheet of glass colliding with the glass in front which has arrived at the turning station, it will be appreciated that such collisions are avoided because the preceding arriser receives an appropriate stop signal from the CPU, when necessary. However, especially if the following glass is a large and/or heavy sheet, its inherent momentum can sometimes carry it forward a short distance after the virtually instantaneous stopping of the arriser. For overcoming this effect, the sensors 74, 76 are preferably arranged to operate in conjunction with the sensor 70 and/or the sensors 44, 46, for example.

In dependence on whether or not any one or more of the sensors 70, 44, 46 remains covered, sensors 74, 76 detect the leading end edge of the following sheet of glass, and consequential on a detect signal being received from either one or both such sensors, and dependently on the state of the sensors 70, 44, 46, the CPU sends a stop signal to the preceding arriser in time to prevent a possible collision, even if the sheet of glass in the preceding arriser is carried forward for a short distance due to its inherent momentum.

Finally, while the foregoing description refers to inlet and outlet conveyors at the turning station, and further conveying means associated with the upstream and downstream arrisers, it is to be appreciated that the entire glass conveying line may consist of a substantially continuous line of driven conveying rollers, of which the only distinct sections are the sections of the line corresponding to the aforedescribed inlet conveyors at the turning station, which sections are distinct because they must necessarily be separately driven in order to bring the conveyed glass to rest in the datum position.

Various further modifications of the aforedescribed and illustrated arrangement are possible within the scope of the invention hereinbefore defined.

Claims

Claims 1. A glass turning station comprising an inlet conveying means for conveying a rectangular sheet of glass into a datum position, a glass turning means which grips the glass in the datum position, rotates it through 90 degrees, and releases the glass on to an outlet conveying means, sensor means for sensing at least one dimension of a sheet of glass to be turned, and control means responsive to the sensor means for controlling operation of the conveying means and/or turning means in dependence on the dimension measurement.
2. A glass turning station according to claim 1, wherein the glass is conveyed and turned in an approximately vertical plane.
3. A glass turning station according to claim 2, wherein the glass leans on a backboard having multiple air inlet apertures for establishing and maintaining a thin cushion of air behind the glass.
4. A glass turning station according to claim 1 or claim 2 or claim 3, having an inlet sensor located adjacent the inlet end of the inlet conveying means for use in measuring the horizontal dimension of the arriving glass sheet.
5. A glass turning station according to claim 4, wherein activation of the inlet sensor initiates operation of an electronic counter, which continues counting as long as the sensor is covered.
6. A glass turning station according to claim 5, wherein the electronic count is employed to set the speed of operation (turning speed) of the glass turning means.
7. A glass turning station according to any of claims 1 to 6, having a turning means comprising an L-shaped turning member bearing three vacuum operated suction pads, two at the ends of the respective arms and one at the junction between them.
8. A glass turning station according to claim 7 when appendant to claim 5 or claim 6, wherein the electronic count is employed to determine if the suction pad on the originally horizontal arm of the L-member is required.
9. A glass turning station according to claim 7, having at least one supplementary sensor for determining which suction pad or pads are required.
10. A glass turning station according to claim 5 or any claim appendant thereto, wherein the electronic count is employed to determine the restart time of the inlet conveying means, in case glass being turned by the turning means would not leave sufficient free space for the next arriving glass sheet during its conveyance towards the datum position.
11. A glass turning station according to claim 4 or any claim appendant thereto, wherein a second sensor means senses the leading edge of a glass sheet as it approaches the datum position and supplies an output to the control means, whereby the inlet conveying means is slowed down in accordance with a timing cycle to bring the glass slowly into the datum position.
12. A glass turning station according to claim 11, including mechanical indexing stops projected outwardly from the backboard, under Supervision of the control means, when or shortly after the second sensor means has detected the leading edge of a sheet of glass, to provide a positive location for the said glass leading edge, in order to prevent any possible overshoot beyond the datum position.
13. A glass turning station according to claim 12, wherein the indexing stops are withdrawn responsively to the turning means gripping a piece of glass due to the operation of one or more of the suction pads, just prior to initiation of the turning action.
14. A glass turning station according to any of claims 11 to 13, including a third sensor means which senses the vertical dimension of the glass sheet when it is in the datum position.
15. A glass turning station according to claim 14, wherein, in conjunction with an encoder associated with the outlet conveying means, the resulting measurement is used to time operation of the turning means in order to ensure that a turned glass sheet will not collide with glass being conveyed by the outlet conveying means.
16. A glass turning station according to claim 14 or claim 15, including a fourth sensor means associated with the outlet conveying means.
17. A glass turning station according to claim 16, wherein, if the fourth sensor means is covered when a downstream conveying means stops, the outlet conveying means is stopped, and in turn the turning means and inlet conveying means may be stopped.
18. A glass turning station according to any of claims 1 to 17, including safety means which prevents the suction pads from releasing if the turning means is stopped during the action of glass turning.
19. A glass turning station according to any of claims 1 to 18, having a further sensor means for slowing- the output conveying means when a tall and narrow glass sheet is being released thereon.
20. A glass conveying line which comprises a plurality of work stations alternating with a plurality of glass turning stations, sensor means at each turning station for sensing the dimensions of a sheet of glass when it arrives for handling at the turning station, and control means responsive to the sensor means for controlling the speed of glass handling at each turning station in such a manner that, throughout the length of the conveyor line, glass sheets are caused te follow one another along said line substantially as closely as possible without risk of any one sheet of glass colliding with the preceding sheet on the line.
21. A glass conveying line according to claim 19, wherein each turning station is arranged in accordance with any of claims 1 to 18.
22. A glass turning station substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.
23. A glass conveying line substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.