US3412841A

US3412841A - Transferring sheets

Info

Publication number: US3412841A
Application number: US612177A
Authority: US
Inventors: Couch Paul; Richard N Pytel
Original assignee: PPG Industries Inc
Current assignee: PPG Industries Inc
Priority date: 1967-01-27
Filing date: 1967-01-27
Publication date: 1968-11-26
Anticipated expiration: 1985-11-26

Description

Nov. 26, 1968 P. COUCH ETAL 3,412,841

TRANSFERRING SHEETS Filed Jan. 27, 1967 7 Sheets-Sheet l INVENTOIS PA UL COUcH fl/C/MBD IV- PYTEL ATTORNEYS NOV. 1968 P. COUCH ETAL TRANSFERRING SHEETS '7 Sheets-Sheet 2 Filed Jan. 27, 1967 INVENTORS 19101. COUCH 18/010430 IV. PYTEL A'I'TORNEY5 NOV. 26, 1968 p, COUCH ETAL 3,412,841

TRANSFERRING SHEETS Filed Jan. 27, 1967 7 Sheets-Sheet 5 6 5$- a m m -D ;I 1 m Aw p L K (no (J mm 1* 0-508 INVENTOR! IQ/CI/ABD M P YTiL ATTORNEYJ NOV. 26, 1968 p CQUCH ETAL 3,412,841

TRANSFERRING SHEETS Filed Jan. 27, 1967 7 Sheets-Sheet 4 FIG. 5

INVENTORS PAUL COUCH E/CHABD M PYTEL ATTORNEY;

Nov. 26, 1968 P. COUCH ETAL.

TRANSFERRING SHEETS 7 Sheets-Sheet 5 INVENTORS PAUL C OUCH B C/ APB M PYTEL M 4 Filed Jan. 27, 1967 ATTORNEYS Nov. 26, 1968 P. COUCH ETA 3,412,841

TRANSFERRING SHEETS Filed Jan. 27, 1967 7 Sheets-Sheet 6 INVENIORS PA UL COUCH 1 .e/c/mzn M PYTfiL oRNEYS 1968 P. COUCH ETAL'" TRANSFERRING SHEETS 7 Sheets-Sheet 7 Filed Jan. 27, 1967 ATTORNEY) United States Patent 3,412,841 TRANSFERRING SHEETS Paul Couch, New Washington, and Richard N. Pytel, Crestline, Ohio, assignors to PPG Industries, Inc., a corporation of Pennsylvania Filed Jan. 27, 1967, Ser. No. 612,177 Claims. (Cl. 198-21) ABSTRACT OF THE DISCLOSURE Transferring rigid sheets of non-rectangular outline having opposite edge portions angularly disposed relative to one another from an upper conveyor supporting the sheet with its lower edge portion disposed obliquely to a lower conveyor that supports the sheet with its lower edge portion disposed horizontally in a manner that balances the sheet against falling off the lower conveyor when the sheet is dropped from the upper conveyor to the lower conveyor at a transfer station.

This application relates to handling sheets, and while it has utility in automatically transferring glass sheets from one conveyor into another conveyor without dropping the sheets, it also has utility in automatically handling sheets of any rigid material.

US. Patent No. 3,094,969 to Charles R. Davidson and William P. Mitchell, issued Apr. 9, 1963, discloses and claims apparatus for automatically transferring glass sheets which have previously been gripped adjacent their upper edges by tongs for thermal treatment onto a conveyor where each transferred glass sheet is supported along its lower edge and balanced by pegs for further cooling and packaging.

Such unloading devices have been very successful in commercial operations involving rectangular glass shapes because it permitted eliminating laborers who previously transferred the glass sheets by hand. However, the original invention was limited in its utility to unload glass sheets having substantially parallel upper and lower edges. Since the introduction of this patented automatic unloading apparatus, it has become necessary to treat glass sheets having non-rectangular outlines, particularly those having opposite edges that are angularly disposed with respect to one another.

Glass sheets having such irregular shapes are loaded into tongs most easily for mass production of fabricated products with their upper edge extending horizontally. Consequently, a lower edge portion of the sheets so supported extends angularly with respect to the horizontally disposed upper edge portion. When such sheets are un loaded at a transfer station, the lower edge of the sheet does not contact the bottom edge supporting elements of the lower conveyor substantially simultaneously as is the case with rectangular shaped sheets. Instead, the sheet drops with its widest portion first coming into contact with the bottom edge supporting element and the bottom edge then rocks about its bottom edge portion that makes initial contact and when a plumb line through the center of gravity of the sheet intersects the lower edge in spaced relation to the initial point of contact, a moment of inertia results that tends to rotate the sheet off the peg conveyor. The present invention provides means for avoiding the need of personnel to tend the transfer apparatus when it is used to transfer sheets of irregular outline having an obliquely extending lower edge portion.

One solution to this problem would be to grip the sheet in such a manner that its lower edge portion to be supported on the peg conveyor extends horizontally. In this way, the entire lower edge portion would contact the 3,412,841 Patented Nov. 26, 1968 ice bottom edge supporting element and no moment of inertia would result. However, as a practical matter, in handling different patterns having different angular dispositions between the upper and lower edge portions, it becomes diflicult to adjust a plurality of tongs so that each tong supports a substantially equap portion of the weight of the suspended sheet and also have the tongs support the glass sheets in proper orientation so that the bottom edge portion that is intersected by a plumb line passing through the center of gravity extends horizontally a substantial portion of the glass sheet length. It is far easier to grip a glass sheet by a plurality of tongs when the upper edge of the glass lies in a horizontal plane. Therefore, it became necessary to provide means for stabilizing irregularly shaped glass sheets when transferred from the tong supporting conveyor to the peg conveyor before the resulting moment of inertia rotated the irregularly shaped sheet oil? the peg conveyor.

While this invention was made to solve the problem of transferring glass sheets of irregular outline, it is understood that sheets of any material which require to be transferred automatically to a bottom edge supporting device for a subsequent operation should be susceptible of using the present invention.

A particular embodiment of the present invention will be described to illustrate a preferred embodiment of the present invention. It is understood that this description is for illustrative purposes only and that mechanical equivalents of the various elements may be substituted without departing from the spirit of the present invention.

In the drawings which form part of the description and wherein like reference numbers refer to like structural elements:

FIG. 1 is a fragmentary side elevational view of a transfer station according to the present invention;

FIG. 2 is a fragmentary end view of the transfer station taken along the lines IIII of FIG. 1;

FIGS. 3 and 4 are a fragmentary perspective side view and fragmenary end view respectively, showing the relative position of a glass sheet in a first stage of a glass transfer operation;

FIGS. 5 and 6 are views similar to FIGS. 3 and 4, respectively, showing a second stage of a transfer operation;

FIGS. 7 and 8 are views similar to FIGS. 3 and 4, respectively, showing a still later stage of a transfer operation;

FIGS. 9 and 10 are additional views similar to FIGS. 3 and 4, respectively, showing a glass sheet entering for the subsequent transfer operation; and

FIG. 11 is a schematic operational diagram showing how the various limit switches incorporated in the apparatus are used for the purpose of the present invention to control the operation of the sequence of movements of the novel rigid sheet balancing device.

Referring to the drawings, FIGS. 1 and 2 show two mutually perpendicular views of a glass transfer station located at a common plane of intersection of an upper conveyor C for transporting glass supporting carriages to the transfer station and a lower conveyor 40 that transports glass sheets released from said carriages. FIG 1 also shows in phantom a return conveyor RC that returns empty carriages for reloading. The upper conveyor C comprises a plurality of stub rolls 10 each mounted on a shaft 12 for rotation about bearings 14. The shafts are fixed to sprockets 16 driven by a conveyor motor (not shown) through a conventional drive chain (not shown). The upper conveyor transports a series of carriages 18 int-o and out of the transfer station.

Each carriage 18 comprises an upper rail 20, a pair of curved connecting portions 21 extending downwardly, and

a lower portion 22. The connecting portions 21 interconnect the upper rail and the lower portion 22.

Tongs 24- are suspended from the lower portion 22. The tongs are preferably of the jointed type typically used to grip the upper portion of a glass sheet between gripper members carried at the lower ends of a pair of pivotally interconnected lever arms. The lever arms are pivotally connected at their upper ends to the lower ends of pivotally interconnected, freely suspended links. When the tongs hang freely, the gripper members move toward one another to grip a sheet inserted therebetween.

Each of the tongs comprises a pair of horizontally extending arms 26 extending outward from the lower ends of the tong links. The extension arms 26 are constructed and arranged for alignment with a pair of lifting arms 28 which are located at the inner end of each of a pair of pivoted levers 30 actuated in unison by solenoids 32 to rotate the levers in unison into a position wherein the lifting arms 28 engage and lift the extension arms 26 of the tongs 24. When the extension arms 26 are lifted, the gripper members are separated to release a sheet gripped therebetween.

Springs 34 are attached to the outer end of the pivoted levers 30 to retract the lifting arms 28 from contact with the extension arms 26. This retraction permits the resumption of free suspension by the tongs 24 to permit the gripping elements to resume their normal position of ap plying force against one another. The tongs are released from sheet gripping engagement only when the extension arms 26 are lifted in response to actuation by the solenoids 32 to rotate lever arms 30.

The lifting arms 28 move in substantially vertical arcuate paths flanking the vertical plane in which a glass sheet G is suspended from the tongs 24. When the solenoids 32 are actuated, pivoted levers 30 pivot with their lifting arms 28 moving upward to engage the bottom surfaces of the extension arms 26 to cause the tongs 24 to release their grip on the glass sheet at the transfer station. The springs 34 normally urge the pivoted lever arms 30 to pivot the lifting arms 28 downwardly in spaced relation below the extension arms 26 to provide clearance for an incoming glass laden carriage 18 and also to permit the carriage 18 after unloading its glass sheet to continue along the conveyor and allow a subsequent carriage to enter the transfer station.

The automatic tong unloader is the subject matter of U.S. Patent No. 3,084,969 of Charles R. Davidson, Jr. and William P. Mitchell. Reference is made to the aforesaid patent and to U.S. Patent No. 3,178,045 to Charles R. Davidson, Jr. and William P. Mitchell for further details of apparatus for handling glass sheets for thermal treatment that incorporates the automatic tong unloading device and various limit switch controls for the aforesaid apparatus.

The lower conveyor 40 popularly termed a peg conveyor, extends transversely and obliquely downwardly from the transfer station toward a packaging station (not shown), and is supported on a car 35 mounted on tracks 36. A brake 37 on car 35 fixes the position of the car 35 along tracks 36 so that the peg conveyor is properly aligned with the upper conveyor 10 at the transfer station. The car 35 is provided with a low standard 38 to support one end of the conveyor 40 and a high standard 39 to support the other end of the conveyor 40.

The peg conveyor comprises a sprocket wheel 42 driven through a peg conveyor clutch 44 by a peg conveyor drive motor 46 carried on the floor of car 35. A first driven shaft 48 supported on the low standard 38 is rigidly connected to the sprocket wheel 42 to rotate therewith and extends horizontally. A peg conveyor brake 50 controls the movement of the peg conveyor 40. A second driven shaft 52 extends horizontally in spaced relation to the first driven horizontally extending shaft 48 on screw jacks 53 carried by the high standard 39.

The latter adjust the vertical position of the end of the peg conveyor that is adjacent the transfer station, thus fixing the slope of the upper run and the lower run of the peg conveyor.

A pair of link chains 54 interconnect sprockets 56 aligned at spaced portions along the first driven shaft 48 and second driven shaft 52. Pegs 58 are attached at their radially inner ends to slats 60, and extend upwardly therefrom at an oblique angle such that they extend substantially vertically when located along the upper run of the lower conveyor 40. The slats 60 extend parallel to the driven

shafts

48 and 52 and interconnect axially spaced alternate links in the opposed link chains 54 that interconnect the first driven shaft 48 and the second driven shaft 52. The axially extending slats 60 are arranged in spaced alignment to one another along the length of the lower conveyor 40. Three pegs 58 are mounted to each slat 60. In addition, three pads 62 of soft compressible material such as rubber or other like material that does not harm a glass edge, are attached to each of the slats 60. The pads are flat and of uniform thickness. Three pegs 58 are attached to and extend through each slat 60. The three pads attached to each alternate slat are disposed to one side of each peg 58 while the pads attached to an adjacent slat are disposed to the other side of each attached peg 58. Each pad 62 extends in a direction transverse to the length of the slats 60 substantially the length of a slat width plus the space between adjacent slats. Six pads 62 cover each slat 69 to provide spaced horizontally aligned areas for each slat 6t) and bridge the space between adjacent slats to receive without damage a bottom edge portion of a glass sheet deposited thereon when the tongs 24 are released from glass gripping engagement. Thus, the pads 62 provide means movable along the lower or peg conveyor 40 for supporting a lower edge portion of a glass sheet in a horizontal plane, because the upper surfaces of the pads 62 attached to each slat 60 are in a common horizontal plane intersecting the vertical plane of the transfer station.

A soft elongated bumper strip 64 of rubber or the like is fitted over and interconnects the top of each of the three pegs 58 attached to a single slat 60. Thus, the three pegs 58 for each alternate slat 60 and their connecting bumper strip 64 forms an open wall spaced from an open wall formed by the adjacent bumper strip 64 and its adjacent set of interconnected pegs 58 attached to the next alternate slat 60 a sufficient distance to allow for receipt of a glass sheet bottom edge portion on the pads 62 extending over the slats 60 in a room 65 formed between adjacent open walls formed by pegs 58 and bumper strips 64.

A cooling fan unit is disposed above the peg conveyor 40 to one side of the first conveyor containing the stub rolls 10 for cooling glass sheets moving broadside below the cooling fan units 70 as the latter blow cooling air downward past the surfaces of the glass sheets moved intermittently along the peg conveyor 40. This enforced cooling makes it possible for the personnel at the end of the peg conveyor 40 to remove the glass sheets therefrom for inspection and packaging.

A limit switch LS-l is located along the carriage conveyor at the transfer station for actuation by a carriage 18. Another limit switch LS-2 is located along peg conveyor 40 for actuation by the fingers 74 of a cam disk 72 that is rotatable with sprocket wheel 42 about the first driven shaft 48. These limit switches control a circuit to correlate movement of the peg conveyor 40 to that of the carriages 18 along the stub roll conveyor C. Various controls to operate the conveyor system are described in U.S. Patent No. 3,178,045 to Charles R.

Davidson and William P. Mitchell and incorporated carried on the upper surface of the upper rail 20 of the carriage 18 to actuate the solenoids controlling solenoid valves 32 and momentarily thereafter engages clutch 44 to cause motor 46 to drive the lower conveyor 40 until the next tooth 74 extending from cam disc 72 contacts limit switch LS2 to disengage clutch 44 and actuate brake 50 momentarily to stop further movement of the lower conveyor 40 and to deactivate the solenoid valves 32. A differential relay 100 (FIG. 11) is selectively actuated by LS-l or LS2 and normally closes the LS2 circuit when neither limit switch is actuated to prevent mishap.

As stated previously, such an unloading device was perfectly acceptable for releasing rectangularly shaped glass sheets or those having upper and lower edges extending substantially parallel from tong gripping relationship along the upper conveyor onto a bottom edge supporting position along the lower conveyor 40 defining a second path of movement. However, it became necessary to avoid the dropping of nonrectangular glass sheets having a lower edge portion extending obliquely in order to avoid the need for extra personnel to tend the loading station, which need was eliminated with the automatic unloading device of the Davidson et al. US. Patent No. 3,084,969.

The elements of the present invention added to the previous structure in order to prevent dropping nonrectangular glass from the lower conveyor during the automatic transfer operation comprises a first sheet engaging member in the form of a soft roller 80 composed of a soft compressible material such as asbestos or glass cloth mounted on a bar, the roller 80 being suspended by flexible rods 81 from a support bar 82. The roller is disposed to one side of the transfer station and is in position to be engaged by the leading edge of a glass sheet G suspended from tongs 24 when the sheet occupies a position at the transfer station. The roller 80 is disposed to one side of the lower conveyor 40 in a position intersecting the vertical plane occupied by the path of movement taken by glass sheet along the conveyor defined by the stub rolls 10.

On the other side of the lower conveyor 40 a piston cylinder 84 is mounted. A second glass sheet engaging member in the form of another roller 85 is mounted about the free end of the piston rod 86. The Piston cylinder 84 is secured to a slotted bracket 87 in an adjustable position depending upon the size and shape of the glass sheet to be treated.

Air lines

90 and 92 communicate with opposite end portions of the piston cylinder 84 and are tied into a pressurized air source (not shown) through a two-way valve 94 and a master control valve 96. When valve 94 is tripped to deliver air under pressure to line 90, piston rod 86 and its attached roller 85 are extended. When valve 94 is tripped to deliver air under pressure to line 92, piston rod 86 and its attached roller 85 are retracted.

The second sheet engaging member 85 is disposed above and to the rear of the horizontal line of support for the lower edge of the glass provided by the series of pads 62 attached to slats 60 when the latter are in a common vertical plane with the tongs 24. The retracted position of the piston rod 86 and member 85 is disclosed in FIGS. 2, 4 and and its extended position shown in FIGS. 6 and 8. In either position, the second sheet engaging member 85 is disposed above the horizontal line of support provided by the pads 62 immediately beneath the conveyor C. However, in its retracted position, the second glass engaging member 85 is disposed entirely to one side of the path of movement for the glass sheet G along the upper conveyor C provided by the stub rolls 10. In its extended position, the second glass engaging position is disposed below the oblique lower edge of the sheet gripped by tongs 24 at the transfer station.

In a typical operation, the limit switch LS1 is actuated by a cam 76 carried along the top edge of a carriage 18 when the carriage is in position wherein the glass sheet G is above the lower conveyor 40 and slightly above one of open walled rooms or spaces 65. This trips relay 100, causing solenoids 32 to operate in unison, thus lifting the lifting arms 28 and releasing the tongs 24 from gripping engagement with the upper edge of the glass. Limit switch LS-l also actuates the two-way valve 94 to a position such that air flows into piston cylinder 84 through line 90 to extend the second sheet engaging member 85, as depicted in FIGS. 5 and 6.

With the second sheet engaging member 85 extended, the relatively thin rear portion of the glass cannot pivot sufliciently in a clockwise direction to rotate ofi the lower conveyor 40 when it is dropped from the tongs 24. In addition, the first sheet engaging member is in position to limit rocking motion of the glass in a counter clockwise direction as seen in FIGS. 3, 5, 7 and 9. The sheet rocks gently back and forth between the first sheet engaging member 80 and the second sheet engaging member until its lower edge portion settles on one of the aligned pads 62 and on the second sheet engaging member 85 with its oblique lower edge resting in a temporary orientation intermediate its initial orientation and a horizontal disposition within the space or open room 65. At the same time, the space 65 moves downward as the motor 46 drives the lower conveyor 40 to a position where the next tooth 74 on cam disc 72 engages limit switch LS2. This engagement actuates relay to disengage clutch 44, thus disengaging the lower conveyor 40 from its driving motor 46. Limit switch LS2 also energizes brake 50 to cause lower conveyor 40 to come to a stop. Inertia permits movement of the lower conveyor to a position wherein the tooth 74 which engaged limit switch LS2 to end the lower conveyor movement is just beyond the position of engagement with limit switch LS2. In this position, the next open room 65 is in vertical alignment with conveyor C and in position to receive the next sheet to be transferred.

The stub rolls 10 are also energized to remove the carriage 18, thus releasing limit switch LS-l from engagement by the lug 76, thus permitting springs 33 to cause the lifting arms 28 to be lowered into positions clear of the path of movement of tong arms 26. When the tooth 74 on cam disc 72 engages limit switch LS2, the two way valve 94 is reversed in position to allow the pressurized air to flow through line 92 into the piston cylinder 84 to retract the second sheet engaging member 85 to prepare for the entry of a succeeding glass sheet gripped at its upper edge of the carriage as shown in FIGS. 9 and 10. The sheet is then free to pivot from the intermediate orientation to a final orientation wherein the lower edge portion is supported by pads 62 in a horizontal orientation.

In a typical operation, glass sheets are conveyed in series through the length of a tunnel-like furnace for treatment such as heating preparatory to shaping and/ or tempering along the conveyor C and are transferred onto the lower conveyor 40 after such treatment. The sheets are cooled to a temperature suitable for handling by blowing air downward along the major sheet surfaces from fan unit 70 as the sheets move broadside in a stepwise manner. Each step of the movement clears the lower conveyor 40 to receive a subsequent sheet from the upper conveyor C. Carriages are returned to a sheet loading station along return conveyor RC.

If desired, limit switches LS-1 and LS2 can also control intermittent operation of the carriage conveyor C instead of the arrangement disclosed in the aforesaid US. Patent No. 3,178,045 to Charles R. Davidson, Jr. and William P. Mitchell. Under such circumstances, the carriage conveyor section is normally driven through the two-way relay 100 except when cam 76 on carriage 18 engages limit switch LS1. This stops the carriage conveyor C until such time as tooth 74 engages limit switch LS2 to resume movement of the carriage conveyor C.

Under such circumstances, solenoids 32, clutch 44 and valve 94 are operated through a time delay relay. In addition, limit switch LS2 initiates operation of the transfer station section of carriage conveyor C through another time delay relay.

An optimum arrangement of the elements of the present invention exists when the bottom edge portion of the glass sheet that is ultimately supported in a horizontal orientation on the pads 62 of an open room 65 along the lower conveyor 40 rests on an oblique line extending between the upper surface of the pad 62 that contacts the bottom edge portion of the sheet and the upper surface of the second sheet engaging member 85, wherein said oblique line makes an angle with the horizontal that is at most half the angle at which the lower edge portion of the sheet is originally oriented with respect to the horizontal. In such case, the extended second sheet engaging member 85 cooperates with the first sheet engaging member 80 and the pads 62 (which serve as means for supporting the lower edge of said sheet along said lower conveyor 40 in a horizontal plane) to balance the sheet temporarily with its bottom edge portion at a relatively small angle to its ultimate orientation. Therefore, the bottom edge portion has a minimum angle to pivot when the second glass engaging member 85 is retracted.

An illustrative embodiment of the present invention has been described for purposes of illustration. It is understood that various changes may be made without departing from the spirit of the invention as defined in the claimed subject matter which follows.

What is claimed is:

1. Apparatus for transferring a rigid sheet of nonrectangular outline, having a lower edge portion angularly disposed relative to its upper edge comprising an upper conveyor defining a first path of movement,

a lower conveyor defining a second path of movement,

a transfer station located in a vertical plane common to said first and second paths of movement,

means movable along said upper conveyor for supporting said rigid sheet for movement along said upper conveyor with said lower edge portion disposed at an angle to the horizontal,

means movable along said lower conveyor for supporting said lower edge portion in a horizontal plane,

means to release said rigid sheet from said sheet supporting means when said sheet is poised above said lower edge portion supporting means,

a first sheet engaging member disposed at one side of said transfer station for engagement by a leading edge of a sheet entering said transfer station,

a second sheet engaging member disposed at the other side of said transfer station in spaced relation to said first sheet engaging member, and

means for extending and retracting said second sheet engaging member,

said second sheet engaging member being located in such a position that it extends across said first path above said lower edge portion supporting means and below said lower edge portion of said sheet when extended to break the fall of said sheet when released by said sheet releasing means and entirely to one side of both said first and second paths when retracted to permit clearance for sheets to enter and leave said transfer station.

2. Apparatus as in claim 1, wherein said second sheet engaging member extends to balance said lower edge portion in an orientation intermediate said initial angle to the horizontal and the horizontal and retracts to permit said lower edge portion to pivot into engagement with said means for supporting said lower edge portion in a horizontal plane.

3. Apparatus as in claim 1, for use in transferring glass sheets, wherein said means for supporting said lower edge portion in a horizontal plane is composed of a material that is not harmful to glass. A

4. Apparatus as in claim 1, wherein said means movable along said lower conveyor for supporting said lower edge portion in a horizontal plane comprises spaced pads having upper surfaces in a common horizontal plane intersecting said common vertical plane, and

said second sheet engaging member is constructed and arranged with its upper surface intersecting said common vertical plane along an oblique line to the portion of the upper surface of one of said spaced pads along which said bottom edge portion rests when said sheet fall is broken, wherein said oblique line makes an angle with the horizontal that is smaller than the angle at which said lower edge portion is originally disposed to the horizontal.

5. Apparatus as in claim 4, wherein said second sheet engaging member is so constructed and arranged with respect to the upper surface of said pad that said oblique line makes an angle with the horizontal that is less than half the angle at which said lower edge portion is disposed relative to the horizontal.

References Cited UNITED STATES PATENTS 973,422 10/1910 Gifford 2l47 1,476,050 12/1923 Buttress.

ALBERT J. MAKAY, Primary Examiner.