AU603937B2 - Glass cutting apparatus - Google Patents

Description

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yr j 0 Thii (h fit conta-ns th~e 4 i,-ad is correct for COMMONWEALTH OF AUSTRALIA The Patents Act 1952-1969 Name of Applicant(s): Address of Applicant(s): Actual Inventor(s): Address for Service: 00 0 o0 0.00 0 0 0 k D0 4 0 0 0 0 00 6000.' GLASS ENGINEERING PTY LTD 21 Michlin Street Moorooka. Qld 4105 Dietmar Schaefer Reinhart Ganzer G.R. CULLEN COMPANY, Patent Trade Mark Attorneys, Dalgety House, 79 Eagle Street, Brisbane, Qlf'4. 4000, Australia.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: GLASS CUTTING APPARATUS The following statement is a full description of the invention including the best method of performing it known to us -i kg (t t ar t (a a CI e ae

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THIS INVENTION concerns improvements in apparatus for cutting sheets of glass and particularly although not exclusively for cutting sheets of laminated glass.

Large sheets of glass measuring say 4 metres x 3 metres are frequently supplied to glass merchants, window manufacturers and the like as basic stock from which smaller sheets are cut as required. These large sheets of glass are usually cut on a glass cutting machine comprising a rectangular support bed having a rigid portion and a movable portion hinged transversely of the support bed. A glass cutting wheel is mounted on a track for transverse movement across the sheet of glass in the region of the hinged connection between the rigid and movable portions of the support bed. After scoring the upper surface of the glass sheet the movable bed portion is tilted downwardly at its free end to break the glass sheet across the score line.

With the increasing use of laminated safety glass in doors, windows and the like, conventional glass cutters have been modified to include a second glass cutter to simultaneously score the undersurface of the lower glass laminate.

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I( t Laminated glass usually comprises two sheets of glass laminated to an intermediate layer of a thermoplastic polymer. Although very effective as a safety glass laminated glasses are usually very expensive compared to conventional glasses and great care must be taken to avoid wastage due to -1 severed.

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00 00 00 0 0 0 0 00 00 0 0000 000000 0o 0 0 0 0 000o 0 D0 0 0 O0 0 00 Prior art cutting machines suffer a number of disadvantages. Although it is relatively easy to simultaneously score the upper and lower surfaces of a laminated sheet, this has necessitated a transverse aperture between the rigid and movable portions of a glass cutting bed to enable a glass cutting head to move across the surface of the glass. Once scored the glass sheet must be moved over the transverse hinge axis and the respective upper and lower glass laminates are fractured by tilting the portions of glass on each side of the score line, first in one direction then the other.

In one type of prior art apparatus the lower glass laminate is fractured on the score line by rolling a wheel 15 with a certain pressure along the score line of the top glass. The upper laminate is then fractured by a lifting bar which is elevated from below the sheet of glass. The lifting bar aligns with the scored line in the glass and.elevates the glass sheet until the mass of the sheet causes the respective 20 portions of glass on each side of the score line to bend thus inducing tension in the uppermost surface of the glass.

Once the upper and lower glass laminates have been severed, a radiant heater (usually a nichrome element encased in a quartz tube) is positioned over the severed region and heat is applied until the thermoplastic polymeric intermediate layer softens sufficiently to enable the 0 00 0 CO 0 00 00 f t Q 0 000o 0 0 0 00000 S0 0 0 0 0 0 t 00000 a a -r 4 respective portions of laminated glass to h- drawn apart to sever the intermediate layer.

Although generally effective in, the cutting of laminated glass such prior art apparatus suffers a number of serious disadvantages which often lead to unnecessary and costly breakages during the process of cutting laminated glasses.

The main disadvantages lie in the step of severing the polymeric intermediate layer and the steps of inducing tension in the glass layers to cause fracture along the score Sooo lines.

0 0 o The step of severing the polymeric intermediate 0000 «oooo layer is extremely slow and consumes unnecessary energy due 0 00 0 a 1 to the inherently poor thermal conductivity of glass.

0 °o 15 Radiant heat must be applied to the region of transversely fractured glass for a minute or more until the thermoplastic 0 4.0 polymeric intermediate layer has softened sufficiently to enable the sheots of glass on each side of the fracture to be drawn apart to sever the intermediate layer.

n Co 20 A particular disadvantage associated with prior art S, laminated glass cutting apparatus relates to the means by which the movable portion of the support bed is supported during tilting movements to sever a glass laminate.

Most prior art apparatus comprises a rectangular movable portion, of the support bed which is supported along the entire length of the transverse tilting axis but which is -si s P jl 00 40 0 04 0 00 000000 0 0 0 00 o 0 0 @oooooo 0 oo 0 00 0 00 0 00 00 0 0 04 o o o a a a So 0 0 0 44 supported by a single centrally located fluid powered ram towards its free end. Accordingly, if the tiltable portion undergoes a twisting action during tilting such that the surface of the free end of the tiltable portion is not substantially parallel with the surface adjacent the tilting axis, unequal tension is applied to the surface of the glass which can cause at least one of the glass laminates to fracture away from the score line.

The problem of unequal tension is particularly noticeable in the reclamation of damaged sheets of laminated glass having a partial fracture line in one glass laminate.

Unless surface tension in a scored laminate is substantially equal across the glass layer to be fractured, the partial fracture line will propagate in an uncontrolled manner across 15 a glass laminate.

In order to overcome or alleviate the problems of prior art glass cutting apparatus there is proposed a method and apparatus for cutting laminated glass which substantially reduces the time for severing the intermediate thermoplastic laminate and which substantially reduces accidental breakage.

According to one aspect of the invention there is provided a laminated glass cutting machine comprising:a support bed having a fixed support portion and a movable support portion spaced therefrom, said movable support portion being tiltable about a transverse tilting axis aligned substantially with an upper edge thereof 400004 0 4 4 00 '00 0 000000 0I 0

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6 adjacent said fixed support portion; means to tilt said movable portion about said transverse axis whereby said movable portion is maintained in a substantially planar state; a scoring means adapted to score opposed surfaces of a glass sheet supported on said support bed, said scoring means being movable transversely of said support bed between spaced respective adjacent ends of said fixed support portion and said moveable support portion; heating means adapted to direct a flow of heated fluid into the region of adjacent severed edges of at least one glass laminate to soften a layer of thermoplastic 00 Oa 0co polymer intermediate opposed laminates of glass; and 0Q means to cause relative separation of said moveable support portion and said fixed support portion whereby said 0 00o 00 thermoplastic polymer layer is severed.

0 00 0* Preferably said movable support portion and/or said fixed support portion includes clamp means to clamp a sheet 20 of laminated glass to be severed. Suitably said clamp means $.t 0$i is located adjacent an aperture between respective adjacent ends of said fixed and moveable portions.

Said scoring means is mounted for travel on a track member extending transversely of said support bed parallel to said transverse tilting axis. If required, said track member may be fixed relative to said fixed portion or said moveable portion or said track member may be movable between an operative position c x a retracted position, Said heating means preferably comprises a

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slotted aperture adapted to direct a flow of heated fluid between adjacent severed edges of a glass laminate. Suitably said heated fluid comprises a gaseous fluid.

If required said heating means may be adapted to direct a source of radiant heat via said slotted aperture into the region of adjacent severed edges of a glass laminate.

In order that the invention may be more clearly understood, reference is now made to a preferred embodiment of the invention in which:- FIG. 1 illustrates a schematic side elevation of a laminated glass cutting apparatus; FIG. 2 illustrates a plan view of the arrangement of 9 0 0 0 5" FIG. 1; 0o aFIG. 3 is an enlarged part cross-sectional view of o 00 0° the glass scoring mechanism; 0 0 0 0 oo FIG.4 is an enlarged part cross-sectional view of the heating mechanism; 20 FIG. 5 is a side elevation of a levelling device for 0040 I t the movable portion of the support bed; i tt FIG.6 is a cross-sectional view of the arrangement of FIG. FIG. 7 shows a front elevation of the glass scoring C C _I mechanism shown in FIG. 3.

In FIG. 1 the apparatus comprises a loading table 1, a cutting bridge 2 and a breaking table 3.

Loading table 1 is tiltably mounted on a frame 4 and pivots to a substantially upright position about pivotal connections 5 to facilitate loading of glass sheets on to loading table I prior to cutting.

Breaking table 3 is pivotally attached to cutting bridge 2 about a transverse axis 6 and a fluid powered ram 7 (the purpose of which is described later) enables relative I, movement between breaking table 3 and cutting bridge 2. A 4 4 S0' fluid powered ram 8 is provided to tilt breaking table 3 0ooo about transverse axis 6 to break the glass laminates after coring. A stabilizing means 15 is provided to maintain the

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15 breaking table 3 in a planar state and to avoid any twisting of the surface of the breaking table 3.

The surfaces of the loading table 1 and the breaking table 3 are covered with a porous fabric such as a thick felt and to assist in moving the glass sheets over the A 20 table surfaces an air cushion is provided. The bodies of table portions 1 and 3 are formed as hollow plenum chambers 0 and the respective upper surfaces of the tables are perforated with fine holes communicating with the plenum chambers. A source of pressurized air is provided to the plenum chambers via pump 9 through a hollow pipe 10 with a flexible connection 11 therebetween.

1' 00 00 00 0 0 0 0 00 0000 0 000000 0 0 0 o00 0 0 0 000 0 00 0 0 00 0 00 0 0at 0 E 4 I An adjustable transverse stop means 12 travels on tracks located on each side of breaking table 3.A control panel 13 is provided to operate the various functions of the apparatus, including a powered roller 14 to assist in moving glass sheets between tables 1 and 3.

FIG. 2 shows a plan view of the arrangement of FIG. 1 however certain items of the apparatus have been omitted for the sake of clarity.

Mounted on tables 1 and 3 are longitudinally extending alignment means 16 to align a sheet of glass prior to scoring and breaking. The alignment means suitably comprises a fixed or angularly adjustable guide bar but preferably it comprises a plurality of rollers eccentrically mounted on a stupport beam. The eccentric mounting enables 15 precise alignment of the guide means and enables adjustment to compensate for wear on the rollers. If required the guide means 16 may be retractable below the respective surfaces of tables I and 3.

Mounted on cutting bridge 2 is a transverse track 17 to support and guide a carriage (not shown) having a glass cutting apparatus attached thereto, FIG. 3 shows an enlarged part cross-sectional view of the glass cutting apparatus associated with the cutting bridge 2 in FIGS, 1 and 2.

After a sheet of glass 20 has been aligned on support tables 1 and 3 and aligned against the stop mechanism C, ~C t

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12 on table 3, toggle actuated clamps 21,21a firmly engage the Esheet of glass against the table surfaces. The clamps comprise a resilient pad 22, a base plate 23 and a reinforcing member 24 all extending transversely of the tables 1 and 3. Fluid powered ram actuated toggle linkages (not shown) selectively oper~ate the clamps 21,21a between an extended clamping position as represented at 21 and a retracted position represented at 21a.

Mounted on clamp 21 is a transversely extending track 17 which slidably supports a glass cutting apparatus 25. Glass cutting apparatus 25 is slidably supported on track 17 by means of opposing rollers 26 pivoted on brackets 27 extending from apparatus 25. Glass cutting apparatus includes a cutting head 28 having a rotatable cutting wheel 15 29 and a conduit 30 through which cutting fluid may be directed to the region of cutting wheel 29. Cutting head 28 is movable between an extended cutt-Ing position as shown and a retracted position by means of a shaft 31 sJlidable in bearings 32 mounted on apparatus 25. To facilitate 20 simultaneous cutting of both sheets of a laminated glass kheet a cutting head 33 iti mounted on a substantially identioal cutting apparatus (not shown) slidable on a track Cnot shown) located beneath the glass sheet being out, After the upper and lower surfaces of the glass sheet have been scored by the cutting apparatus 25, breaking table 3 is then tilted upwardly at its remote end through art

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a I I C C I~ angle sufficient to sever the lower glass laminate along the lower score line. Usually a tilt angle of say 1.5 3 is sufficient to sever a glass laminate.

The breaking table is then tilted downwardly at its free en,. until the upper glass laminate is severed.

After the cutting apparatus passes over the glass sheet to score the break lines it moves to the end of track 17 away frrc.m the edge of the glass sheet being cut.

With clamps 21,21a both closed as shown in FIG. 4, hoating apparatus 35 is located over the upper score line 36 of glass sheet 20. Heating apparatus 35 comprises a large hollow chamber 37 which communicates with a small hollow chamber 38 by means of apertuces 39 in a web 4f, between chambers 37 and 38. Heating apparatus 35 extends over the 15 entire width of breaking table 3 and is closed at both ends.

Located within small chamber 38 is an elongate electric heating element 41 supported along its length at spaced intervals by ceramic supports 42. At the lowermost portion of chamber 38 is a narrow slot 43 extending over the entire 20 length of heating apparatus With the heating element 41 activated a source of pressurized air is directed into chamber 37 -to cause a narrow curtain of heated air to be directed onto the region of upper score line 36. After a predetermined interval of timeo fluid powered ram 7 (FIG. 1) extends to a predetermined distance to separate the fractured shoots of glass thus exposing more of C 'C I i' C I a a~ C C C CI I 841CC C I

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Cl C 400 C 4 the thermoplastic polymer intermeaiate layer. After yet a further predetermined interval Im Je ram 7 extends a further predetermined distance and the procedure is repeated until the intermediate layer is severed, Clamps 21,21a are then released and the out portion of glass is then removed from the breaking table 3, FIG. 5 shows a cro ss -sectional view of a Stabilizing means 50 to stabilize breaking table 3 warping or twisting either when stationary or duringj tiltinlg movement,

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II 4 a I II I C C C Ce C C The stabilizing means comprises a pair of spaced extendable members 51 pivotally attached at one end to a base frame member 52 and pivotally attached at their other end to a bracket 52a located at position towards the free end of 15 breaking table 3.

Extendable members 51 comprise an outer tubular member 53 having telescopically located therein a tubular member 54 slidable along rollers 55 fixed with member 51, Transversely extending flanges 56 locate over polo, 55 to 20 guide tubular member 54 over rollers Mounte. on one face 56 of member 54 is a toothed rack 57 which co-operates with a pinion 58 attached to a shaft 59 journalle. in bearing 60. The shaft $9 ex~tends between spaced members 51 to a. similar rack atnd pinion assembly whereby extension or retraction of~ one o the members 51 is associated with a directly oo-otdlnateat

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C I 4 .j C4t; extension or retraction of the other of members 51, thereby ensuring planarity of the breaking table at all times.

FIG. 6 is a cross-sectional view through the arrangement of FIG. FIG. 7 shows a front elevation of the cutting apparatus The cutting apparatus comprises a body 70 having a pair of spaced guide wheels 71 which roll over the surface of the glass to be cut. Body 70 is attached to a shaft 72 slidably located in a bushing 75 and is retractable to a position above the glass surface by a fluid powered ram. The shaft 72 is biassed downwardly by a spring means to apply a predetermined load against the surface of glass to be cut.

A cutting head 73 is rigidly mounted on shaft 72 whereby the lower edge of cutting wheel 74 extends below the lower surface of wheels 71 by a predetermined amount.

It will be clear to a skilled addressee that many c modifications and variations may be made to the invention without departing from the spir' nd scope thereof.

Claims (9)

1. An apparatus for cutting laminated glass, said apparatus comprising:- a support bed having a fixed support portion and a movable support portion spaced therefrom, said movable support portion being tiltable about a transverse axis aligned substantially with an upper edge thereof adjacent said fixed support portion; means to tilt said movable portion about said transverse axis whereby said movable portion is maintained in i. a substantially planar state; a scoring means adapted to score in use 0 0 co o opposed surfaces of a glass sheet supported on said support 0 00 0 0o" bed, said scoring means being movable transversely of said 0 "os" 0 o support bed between spaced respective adjacent ends of said 0 00 .0 a fixed support portion and said movable support portion; ,o heating means adapted to direct a flow of heated fluid into the region of adjacent severed edges of at least one glass laminate to soften a layer of thermoplastic polymeric material intermediate opposed laminates of glass; and Cf' means to cause relative separation of said moveable support portion and said fixed support portion "e 8 whereby said layer of thermoplastic polymeric material is c 00 severed.

2. An apparatus as claimed in claim 1 wherein o J moveable support portion and/or said fixed support portion includes clamp means to clamp a sheet of glass to be -A' severed.

3. An apparatus as claimed in cli.,n 2 wherein said clamp means is located adjacent an aperture between respectiveadjacent ends of said fixed and movable portions.

4. An apparatus as claimed in any preceding claim wherein said scoring means is mounted for travel on a track member extending transversely of said support bed parallel to said transverse tilting axis.

An apparatus as claimed in claim 4 wherein said track member is movable between an operative position and a retracted position.

6. An apparatus as claimed in any preceding claim go 0 wherein said heating means comprises a slotted aperture o 00 oo0 adapted to direct a flow of heated fluid between adjacent 0 O"00Q0 severed edges of a glass laminate. 0 00 0 oo o

7. An apparatus as claimed in claim 6 wherein 00 4 0 04 S4*" said heated fluid comprises a gaseous medium.

8. An apparatus as claimed in any preceding claim wherein said heating means is adapted to direct a source of a radiant heat into the region of adjacent severed edges of a glass laminate.

9. An apparatus for cutting laminated glass substantially as hereinbefore described with reference to the accompanying drawings, DATED this 28th Day of August 1990. GLASS ENGINEERING PTY LTD By their Patent Attorneys CULLEN CO yy 1