US3644934A

US3644934A - Defect-marking device

Info

Publication number: US3644934A
Application number: US79244A
Authority: US
Inventors: Charles T Hawkins; Laverne O Parkhill
Original assignee: PPG Industries Inc
Current assignee: PPG Industries Inc
Priority date: 1970-10-08
Filing date: 1970-10-08
Publication date: 1972-02-22
Anticipated expiration: 1989-02-22

Abstract

Particularly for use in the inspection of flat glass ribbon or sheets traveling at over 200 inches a minute, there is disclosed apparatus actuated by an automatic defect-detecting system and comprising a plurality of chalk marker means. The chalk marker means include a sleeve grasping a piece of chalk, with toothlike serrations on the exterior of the sleeve. When air cylinder means operate to move the chalk to or from a marking position, a stationary leaf spring member engages the serrations and causes the chalk to be rotated, ensuring against its developing a flattened portion and failing to mark. Spring load means urge the chalk and its sleeve toward the glass or other object to be marked.

Description

[ 1 Feb. 22, 1972 United States Patent 4 Hawkins et al.

[54] DEFECT-MARKING DEVICE [72] Inventors:

Charles T. Hawkins, Verona; Laverne 0. P E J h w H Parkhill, Lower Burrell, both of Pa. i osep anary Attorney-Chisholm and Spencer [73] Assignee: PPG Industries, Inc., Pittsburgh, Pa. [22] Filed: Oct. 8, 1970 [21] App]. No.: 79,244

[57] ABSTRACT Particularly for use in the inspection of flat glass ribbon or sheets traveling at over 200 inches a minute, there is disclosed apparatus actuated by an automatic defect-detecting system and comprising a plurality of chalk marker means. The chalk developing a flattened portion and failing to mark. Spring load means urge the chalk and its sleeve toward the glass or other object to be marked.

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....346/l39 C Forrester et al. ........................73/159 6 Claims, 5 Drawing Figures 1,259,429 3/1918 Miller................ 3,151,482 10/1964 Patented Feb. 22, 1972 2 Sheets-Sheet i OPTICAL SCANNER,

P 00 a w s m M M s E R 5 EM EHM K. E A T M U ,W K A O S C H S c A L G FIOA- INVENTORS m MM Mm M m A3 A 2% 0 d aw m r M Patented Feb. 22, 1972 2 Sheets-Sheet 2 INVENTORS CHARLES 7T HAWK/NS LAM/we @MRKH/u,

BY MQS'IWM ATTORNEYS DEFECT-MARKING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to the use of chalk to mark objects that have motion relative to the chalk marking means, and in particular, the invention concerns apparatus and a method for the inspection and marking of flat glass in the form of ribbon or sheets, especially while such glass is in relatively rapid motion with respect to the chalk marking means.

2. Description of the Prior Art A conventional method of inspecting and marking flat glass in ribbon or sheet form comprises stationing an inspector in an appropriate position for viewing the glass, with the inspector having at hand a long rod, to which or within one end of which there is secured a piece of chalk. When he observes a defect, the inspector reaches with the rod and circles it or makes some other suitable indication. This practice is satisfactory so long as the glass being inspected is traveling at relatively low speed, such as under 200 inches per minute, and is not exceptionally wide or defect laden. Of course, when the defect count per square foot goes up to such an extent that the operator is no longer able to mark individual defects, the glass is usually all discarded. The practice indicated above has yielded satisfactory results with line speeds of 200 inches per minute and less, but with the tendency of the art of manufacturing flat glass being always toward the use of higher line speeds, such a practice is becoming increasingly less applicable with satisfactory results. With line speeds of over about 400 inches per minute, it is nearly impossible to maintain a satisfactory level of inspection accuracy with a practice of the kind indicated above. For the lack of the instant invention or some satisfactory equivalent for it, as well as the other equipment that would be required, the art has not developed to a point where there can be envisaged the satisfactorily accurate inspection of flat glass ribbons or sheets 100 to 150 inches wide, passing at a line speed of 500 to 1,200 inches per minute. It is apparent, however, that it may in some instances be desirable to conduct the inspection and marking operation as rapidly as that, if not faster.

As an alternative means and method of marking defect locations on flat glass, the use of ink sprays has been proposed. With such a practice, care must be taken to avoid having the ink dry out or clog, and consequently fail to mark.

SUMMARY OF THE INVENTION Particularly for use in the inspection of flat glass ribbon or sheets traveling at over 200 inches a minute, there is disclosed apparatus actuated by an automatic defect-detecting system and comprising a plurality of chalk marker means. The chalk marker means include a sleeve grasping a piece of chalk, with toothlike serrations on the exterior of the sleeve. When air cylinder means operate to move the chalk to or from a marking position, a stationary leaf spring member engages the serrations and causes the chalk to be rotated, ensuring against its developing a flattened portion and failing to mark. Spring load means urge the chalk and its sleeve toward the glass or other object to be marked. a

DESCRIPTION OF THE DRAWINGS A complete understanding of the invention may be obtained from the foregoing and following description thereof, taken in conjunction with the appended drawings, in which:

FIG. 1 comprises a schematic diagram, indicating a float glass inspection system containing a chalk marker system in accordance with the present invention;

FIG. 2 is an elevation view, partly broken away, indicating a chalk marker means in accordance with the instant invention;

FIG. 3 is a sectional view, taken on the line III-Ill of FIG.

FIG. 4 is an elevation view, showing how the apparatus of FIG. 2 is raised and lowered; and

FIG. 5 is a detail view in section of a portion of the chalk marker means shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, there is indicated schematically a system whereby a piece of flat glass 2 is inspected and marked. The inspection is done with an optical scanner means 4, which may take the general form of an optical scanner or laser scanner, such as that described in Belgian Pat. No. 742,369, issued May 28, 1970. The optical scanner means 4 produces an output that is fed, as indicated by the line 6, to a computer means 8. The computer means 8 takes into account the location of a defect, considering the line speed of the conveyor line through which the glass ribbon or sheet is being passed, the locations of the edges of the glass, and the scanning speed in the optical scanner means 4. The computer means 8 then delivers, as indicated by the line 10, to the chalk marker means 12 a suitable signal or signals, actuating the means 12, so that as indicated by the line 14, there are then placed on the glass 2, at appropriate locations, indications of the existence of defects in the glass 2 sensed by the optical scanner means 4. The instant invention concerns a particular form that may be taken by the chalk marker means 12.

The particular chalk marker means 12 that is disclosed in accordance with the present invention comprises a piece of chalk of substantial length, means enveloping said piece of chalk, said means enveloping said piece of chalk comprising a plurality of serrations or the like on the exterior periphery thereof, a holder for enveloping means, with said holder comprising means such that when said chalk is turned about substantially its longitudinal axis, there is performed a scraping or sharpening operation upon the generally conical main face of the piece of chalk concerned.

Referring now to FIG. 2, there is shown a bracket piece 16, upon which there is mounted an air cylinder I8. The air cylinder 18 is operatively connected to a yoke or fork 20 at a.

pivot point 22, and the air cylinder 18 is somounted to the bracket piece 16 as to be capable of swiveling about a pivot point 24. The yoke or fork 20 is connected at a pivot point 26 to a barrel 28 having therein an opening 30, for a purpose hereinafter later to be disclosed. Also mounted to the bracket piece 16, as by means ofscrews 32, is a leafspring means 34.

Contained within the barrel 28 is a sleeve 36 that engages snugly a piece of chalk or crayon 38. A spring 39 urges the sleeve 36 toward the glass 2. On the exterior periphery of the sleeve 36, there are provided a number of ridges or serrations 40. These protrude through or may be reached through the opening 30 mentioned hereinabove, and are in operative contact with the leaf spring means 34. See FIG. 3.

FIG. 2 shows the barrel 28 in such position that the chalk or crayon 38 is in contact with the glass 2. In comparison, FIG. 4 shows in phantom the position of the barrel 28 and glass 2 after air'cylinder 18 has been suitably operated to cause the chalk or crayon 38 to be lifted away from the glass 2.

It is to be understood that, depending upon the shape adopted for the ridges or serrations 40, it is possible, when the air cylinder 18 is caused to operate, either in the process of bringing the chalk or crayon 38 into contact with the glass or in the process of removing the chalk or crayon 38 from contact with the glass 2, to rotate suitably the sleeve 36 and its contained chalk or crayon 38. This is important because of the consideration of the necessity of preventing the chalk or crayon 38 from developing a flattened portion that may mark the glass 2 inadequately or not at all.

It is further to be understood that, in connection with a method for automatically inspecting and marking flat glass that is traveling in a conveyor line at some speed such as 200 to 1,000 inches per minute, with the flat glass having some width such as to 150 inches, it is appropriate to provide means comprising a plurality of chalk marker devices as indicated above, with the device being spaced at various locations across the transverse extent of the sheets or ribbon being inspected and marked. For example, with a ribbon about inches in width, it is appropriate to provide about 140 of such chalk marker means, spaced each 1 inch apart.

It is further to be understood that the air cylinder 18 is of the double-acting type, with the air inlets to its ends being controlled by a suitable solenoid, in accordance with signals obtained from a computer means, such as computer means 8.

Considering the shape of the teeth or serrations 40 shown in FIG. 3, it will be appreciated that in the embodiment of the invention depicted in the drawings, there is obtained, as indicated in FIG. 4, an action such that when the barrel 28 is being raised, nothing happens, but when the barrel 28 is being lowered so that the chalk or crayon 38 is brought into contact with the glass 2, as indicated by the arrow 70, there is produced, as indicated by the arrow 72, a rotary motion of the chalk or crayon 38, whereby such chalk or crayon 38 is sharpened, not only by its contact with the glass 2 but also by its friction against the portion 74 of the barrel 28.

FIG. is a side view, in section, of the uppermost portion of the barrel 28. In FIG. 5, it is shown how the spring 39 bears against a washer 80, which is itself urged toward the chalk or crayon 38 by means of a spring 82. A sleeve 84 extends between the washer 80 and the sleeve 36 that has on its periphery the serrations 40. The purpose of the structure comprising the above-mentioned parts shown in FIG. 5 is to ensure that the indexing action upon the chalk or crayon 38 takes place reliably in one direction but does not occur to any substantial extent when the leaf spring means 34 is in contact with the serrations 40 and is passing in the opposite direction with respect to them. Instead, as is shown in FIG. 4, the rod or tube 86 encircled by the spring 39 is secured to the sleeve 36. A structure of this kind operates, it has been found, to bring about the substantially monotonous" revolution of the chalk or crayon 38 without backsliding, and this is important to the operation of the preferred embodiment of the invention in the manner contemplated.

We claim:

1. Apparatus for marking flat glass comprising, in combinanon,

a generally cylindrical piece of marking material,

a sleeve surrounding said piece, said piece having serrations on its exterior,

tubular means surrounding said sleeve, said tubular means having therein an opening,

means within said tubular means for urging said piece and sleeve toward said glass, means for swiveling said tubular means about a pivot point,

and

leaf spring means projecting through said opening and engaging said serrations, whereby during movement of said tubular means about said pivot point said piece of marking material is rotated.

2. Apparatus as defined in claim 1, characterized in that said marking material comprises a piece of chalk.

3. Apparatus as defined in claim 1, characterized in that said'tubular means comprises a portion in contact with said piece of marking material at its end and near said glass, whereby during the rotation of said piece of marking material a portion thereof is sharpened.

4. Apparatus as defined in claim 3, characterized in that said marking material comprises a piece of chalk. Apparatus as defined in claim 1, further characterized in that means are provided cooperating with said sleeve for causing said piece of marking material to be rotated with said tubular means is swiveled about said pivot point in a first direction while permitting said piece of marking material to remain substantially stationary while said tubular means is swiveled about said pivot point in a second direction opposite to said first direction.

6. Apparatus as defined in claim 5, further characterized in that said means cooperating with said tubular means comprises a second sleeve means of substantially the same diameter as saidsleeve, a rod connected to said sleeve,

a washer encircling said rod and engaging said second sleeve means in the vicinity of its (periphery,

a compression spring encircling sai ro an bearing against said sleeve and said washer, and

spring load means urging said washer toward said sleeve.

Claims

1. Apparatus for marking flat glass comprising, in combination, a generally cylindrical piece of marking material, a sleeve surrounding said piece, said piece having serrations on its exterior, tubular means surrounding said sleeve, said tubular means having therein an opening, means within said tubular means for urging said piece aNd sleeve toward said glass, means for swiveling said tubular means about a pivot point, and leaf spring means projecting through said opening and engaging said serrations, whereby during movement of said tubular means about said pivot point said piece of marking material is rotated.

3. Apparatus as defined in claim 1, characterized in that said tubular means comprises a portion in contact with said piece of marking material at its end and near said glass, whereby during the rotation of said piece of marking material a portion thereof is sharpened.

6. Apparatus as defined in claim 5, further characterized in that said means cooperating with said tubular means comprises a second sleeve means of substantially the same diameter as said sleeve, a rod connected to said sleeve, a washer encircling said rod and engaging said second sleeve means in the vicinity of its periphery, a compression spring encircling said rod and bearing against said sleeve and said washer, and spring load means urging said washer toward said sleeve.