IE852189L

IE852189L - Marking the surface of glass articles.

Info

Publication number: IE852189L
Application number: IE852189A
Authority: IE
Original assignee: Waterford Crystal Ltd
Priority date: 1985-09-04
Filing date: 1985-09-04
Publication date: 1987-03-04
Also published as: BE905380A; GB8621314D0; IE58527B1; GB2180195A; GB2180195B

Description

This invention relates to an apparatus for marking the surface of an article.

The invention is particularly concerned with marking a glass article to enable a glass cutter to accurately cut the surface of the glass to produce so-called cut glass or cut crystal.

For the accurate cutting of glass, in particular crystal, it is necessary to mark the piece to be cut with indicia corresponding to a desired pattern. At present, it is necessary to mark the piece by manual means.

It will be appreciated that manually marking crystal is not only relatively slow but is also very boring for the operator marking the glass.

It is an object of the present invention to provide an apparatus which permits the automated marking of glass or crystal articles.

The invention therefore provides an apparatus for marking the surface of an article, comprising a marking station, turntable means for rotating the article at the marking station, ink jet printing means at the marking station for discharging ink onto the article in a direction transverse to the axis of rotation of the article, and means for moving the printing means in a direction substantially parallel to the axis of rotation of the article.

By providing appropriate controlling means, which is preferably a microcomputer, a pattern of both circular lines as well as spaced apart vertical lines may be marked on the substrate.

The invention will be understood in greater detail from the following description of a preferred embodiment thereof given by way of example only and with reference to the accompanying drawings in which Fig. 1 is perspective view of an apparatus according to the invention; Fig. 2 is a perspective detail view of a first part of the apparatus of Fig. 2 in a first position of use; Fig. 3 is the part of the apparatus of Fig. 2 in a second position of use; Fig. 4 is a perspective detailed view of a second part of the apparatus of Fig. 1 in a first position of use; Fig. 5 is the part of the apparatus of Fig. 4 in a second position of use; and Fig. 6 is a plan view of a disc for use in the apparatus of Fig. 1.

Referring now to the drawings, there is shown an apparatus 10 according to the invention which comprises a fixed housing 11, a carousel 12 mounted for rotation about a vertical axis atop the housing 11, an article centering station 13 and an article marking station 14.

The housing 11 has various mechanical and hydraulic devices which are necessary for the successful operation of the apparatus 10 but which devices will not be described here in any great detail as they will be understandable to those skilled in the art.

The carousel 12 has four sections 15, 16, 17 and 18, each section 15-18 having a respective set of four turntables 19, 20, 21 and 2 2 thereon. The housing 11 contains a motor for rotating the carousel 12 in a clockwise direction, as viewed in the drawings, and further motors for rotating each set of turntables 19-22 independinelty of the carousel 12 about respective vertical axes. Each of the turntables 19-22 of a set has an open mouthed pipe 23 the purpose of which will be described - 4 - later. Each of the pipes 23 of a set of turntables is connected by appropriated means to a respective tube 24, the tube 24 being connected to a vacuum pump (not shown).

The purpose of the centering station 13 (figures 2 and 5 3) is to centre the article, in this case a circularly symmetrical crystal goblet 100. The centering station 13 is rigidly suspended above the carousel 12 by means of rods 25, the rods 25 supporting a fixed base 26 having a pair of hydraulic rams 27, 28 fixed thereon. Also mounted on the 10 base 26 is a pair of vertical rods 29a, 30a along which are adapted to slide respective guide elements 29, 30 fixed to a movable plate 31. The rams 27, 28 are attached to the movable plate 31 so that by operation of the rams the plate 31 may be moved up or down by the elements 29, 30 sliding on 15 the rods 29a, 30a. Mounted on the movable plate 31 are four centering devices 32, 33, 34 and 35. Each of the devices 32-35 is identical so that the operation of only one of them viz the device 32 will be described.

The device 32 comprises a housing 36 having three equi-20 angularly shaped toothed flanges 37 mounted thereon for sliding radially of the housing 36. Depending from each flange 37 is a vertical leg 38 the free end of which leg has a grommet 39 thereon. The housing 36 has a hydraulic motor therein which receices hydraulic power via a pipe 24a and 25 which motor serves to move three elements 40 simultaneously into and out of the housing via respective apertures 41.

Each of the elements 40 has a toothed part 42 adapted for engaging with the a respective toothed flange 37 in a manner of a pair of engaging ratchets. Thus, movement of the 30 elements 40 causes a corresponding sliding movement of the flanges 37, resulting in the legs 38 moving simultaneously towards or away from the axis of the pipe 23, which axis is located centrally relative to the housing 36 and legs 38. The hydraulic motor of the housing 36 is controlled via 35 pressure sensors (not shown) associated with the legs 38. - 5 - The marking station 14 (figures 4 and 5) comprises a base 40 fixed to the housing 11, which base 40 supports a wall 41 and a cover 42. Also mounted on the base 40 is a vertical screw element 44 and a pair of vertical guide rods 5 45, 46. A platform 47 is also provided which platform has holes therein to enable the screw element 44 and the guide elements 45, 46 to pass therethrough. The hole which enables the screw element 44 to pass therethrough is screw threaded and thus, rotation of the screw element 44 raises 10 or lowers the platform 47 relative to the base 40. Rotation of the screw element 44 is achieved by means of a stepping motor 43 housed on the cover 42. Respective guide sleeves 45a, 46a are provided on the platform 47 to slide on the guide rods 45, 46. 15 Mounted on the platform 47 are four print heads 50, 51, 52 and 53. The print heads are of the type manufactured by American Technologies Limited of Essex House, Bridle Road, Bootle, Merseyside L30 4UE, UK and sold under the name Domino Amjet. Essentially, each print head 50-53 comprises 20 a gun body 54 which serves to discharge a stream of tiny drops of ink of equal size from an ink reservoir (not shown) broken up by ultrasonic oscillation. As the drops are formed, they pass through a charging electrode and thus collect a variable electrostatic charge. The drops then 25 pass through a pair of plates 55 which provide a constant high voltage field. The field causes each droplet to be deflected by an amount proportional to the size of its electrostatic charge. If the elecrostatic charge is such that the plates 55 do not produce a deflection, each droplet 30 is collected in a gutter 56 for recycling through the gun body 54.

In the drawings, each print head 50-53 is shown in simple diagramatic form and no specific detail as to how the print heads 50-53 operate will be provided here as such - 6 - information is available in technical literature supplied by American Technologies Limited.

In use, the apparatus 10 functions as follows, in which, it must be appreciated, only the movement and 5 operations relating to one turntable, viz turntable 19, will be described. The movement and operations relating to the remaining turntables 20 to 22 of the same set are similar and occur simultaneously with those of the turntable 19.

In Fig. 1, the goblet 100 is shown in an inverted 10 condition on the turntable 19. The goblet 100 is loaded manually onto the turntable 19 but it could be possible to use automatic loading. During loading the turntable 19 is stationary at the location shown in Fig. 1, which constituts a loading station. 15 After an appropriate period of time has elapsed, in other words to allow for manual loading of the remaining turntables 20-22 immediately to the left of the turntable 19 as viewed in Fig. 1 of the drawings, a vacuum is created in the goblet 100 by the action of the vacuum pump drawing the 20 air therefrom via the pipe 23. The carousel 15 is now moved 90° in a clockwise direction until the turntable 19 is directly below the centering device 32, whereupon the carousel is stopped. The purpose of the vacuum is to prevent the goblet 100 from falling over during movement of 25 the carousel 15.

Air is now allowed to enter the goblet 100 to enable movement of the goblet 100 on the stationary turntable 19. The legs 38 are lowered by the action of the hydraulic rams 27, 28 in lowering the movable plate 31. By means of the 30 hydraulic motor and the interaction of the toothed parts 42 and the toothed flanges 3 7, the legs 38 are moved inwardly so that the grommets 39 contact the surface of the goblet 100.

Should the goblet 100 be off-centre relative to the 35 pipe 23, then the legs 38 will move the goblet 100 and place it centrally relative to the pipe 23. When no further movement of the legs 38 is possible, the pressure sensors activate the hydraulic motor to move the legs 38 away from the goblet 100 and activate the rams 27, 28 to raise the movable plate 31.

A vacuum is again applied to the goblet 100, and the carousel 12 is moved 90° in a clockwise direction until the axis of the turntable 19, and thus the axis of the goble 100, is in line with the print head 50 whereupon the carousel is stopped. With the vacuum still applied, the turntable 19 is activated so as to rotate and the print head 50 is activated to discharge a jet of ink onto the goblet 100 to mark the goblet 100 with a predetermined pattern. The way the pattern is marked on the goblet 100 will be described in more detail below.

The ink is discharged in a direction transverse to and intersecting the axis of rotation of the turntable 19. If the ink is discharged continuously, and the print head 50 is maintained at a fixed height relative to the base 40, a circumferential circle is marked on the surface of globlet 100. If the ink is intermittently discharged from the print head 50 once or several times per revolution of the turntable 19 while the print head 50 is slowly raised by the rotation of the screw element 44, then one or more vertical lines may be marked. When the desired pattern has been marked on the goblet 100, the carousel 12 again moves in a clockwise direction to an unloading station which is at a position 90° anticlockwise of that shown in Fig. 1 and the goblet 100 is unloaded after the vacuum is removed. The carousel is now moved 90° to the position shown in figure 1 and a new goblet is placed on the turntable 19 and the cycle is repeated.

It will be appreciatd during normal operation of the apparatus 10, all of the sets of turntables 19-22 are in use so that four goblets at the centering station 13 are - 8 - processed simultaneously with the marking of four other goblets at the marking station 14 and the loading and unloading of other goblets at the loading and unloading stations. 5 It is preferred that the apparatus 10 be under the control of a microcomputer which monitors and controls all of the events necessary for the successful operation of the apparatus 10. In particular, it is preferred that each print head 50-53 be under the control of the microcomputer. 10 In a most preferred embodiment of the invention, the microcomputer may be pre-programmed with a plurality of separate subprogrammes for the control of the print heads 50-53. For example, it would be possible to key into the microcomputer the product number associated with a 15 particular pattern to be marked on the article which microcomputer would then operate the print heads and the marking station in an appropriate manner.

Thus, for example, if it were desired to mark the goblet 100 with three concentric rings at specific intervals 20 apart, the microcomputer would control the action of the stepping motor 43 causing it to hold the print head 50 at a particular level relative to the base 40 for a sufficient duration related to the speed of rotation of the platform 19 to enable ink to be discharged from the print head 50 so as 25 to mark the goblet 100 with a first ring; stop the discharge of ink from the print head 50 and move the print head 50 to the next desired level relative to the base 40 whereupon the discharge of ink would be started again, and then repeat these steps again for the third ring. Finally the print 30 head 50 would be returned to the start level while the carousel 12 rotates 90° to bring the corresponding goblet of the next set into position for marking.

If it is desired to additionally mark the globlet 100 with vertical lines at equidistant spaced apart intervals ^ r - 9 - the following procedure may be followed.

A disc 60 (Fig. 6) is contained in the housing 11. The disc 60, which is preferably metal, has a shaft-engaging hole 61 for rotating the disc 60, and a plurality of 5 relatively small holes 62 located in a specific pattern therein. The concentric lines 63-68 shown in the drawing are present only for ease of understanding the function of the disc 60 and are absent from the actual disc 60.

The disc 60 preferably has a reflective surface. It 10 will be seen from Fig. 6 of the drawings that the concentric ring 6 3 has three holes thereon, the ring 64 has four holes, and so on up to eight holes for the ring 68. The disc 60 is rotated, preferably under the control of the microcomputer referrerd to above, at a speed related to the speed of 15 rotation of the turntable 19.

A beam of light, preferably a laser beam, is shone normally onto the reflective surface of the disc 60. The laser beam is mounted on a tracking device in the housing 11 so that it is movable radially relative to the disc 60. 20 Thus, the laser beam may be positioned so as to shine, for example on the ring 64.

A laser beam detector is also mounted on the tracking device so that light which is reflected from the disc 60 is transmitted into the detector. As long as the detector 25 receives reflected light, a signal is sent to the microcomputer which, in turn, stops the discharge of ink from the print head 50 during vertical movement of the print head 50.

If however, light is not reflected from the disc 60, 30 and this will occur when the beam passes through one of the holes 61 in the ring 64, a signal is sent to the microcomputer which in turn activates the print head 50 to discharge ink onto the goblet 100. The duration of discharge of the ink will last only for as long as light is 35 not reflected from the disc 60, which duration, it will be - 10 - appreciated, is relatively short. Thus only a few drops of ink will be discharged from the print head 50 to leave a dot :uark on the goblet 100 at that location. As there are four holes in the ring 64 and as the speed of rotation of the 5 goblet 100 is related to the speed of rotation of the disc 60, vertical movement of the print head 50 will result in four vertical lines being marked on the goblet 100 equidistant from each other. The discharge of ink from the print head 50 for marking rings on the goblet 100 is 10 independent of the laser beam signal to the computer, and it will be appreciated that it is not necessary to stop the discharge of ink from the print head 50 when the print head is stationary as the discharge of ink from the print head 50 for the purpose of marking rings on the goblet 100 will be 15 coincident with the marking of the goblet 100 for the purpose of a vertical line.

If it is desired to mark the goblet 100 with six vertical lines equidistant from each other, then the laser beam is tracked radially outwards relative to the disc 60 so 20 that it is positioned above the concentric ring 66.

It is preferred that the ink which is discharged onto the goblet 100 should dry immediately. It has been found that ink sold by American Technologies Limited under the code "DA 10 Black Ink" is suitable for this purpose. 2 5 In order to warn the operator of the apparatus 10 that the carousel 12 is about to move, it is desirable that a strobe light 70 be provided which, under the control of the microcomputer, will flash just prior to the movement of the * carousel. 30 Sometimes, during the course of manual inspection of the goblet prior to marking it by means of the apparatus 10 a flaw is detected in the glass which, if the glass was cut at the location of the flaw, would eliminate the flaw thereform.

Thus, at the manual inspection stage, it is preferable to manually mark a detected flaw with a suitable marker.

When this marked goblet arrives at the centering station 13, a detector 80 may be used to detect such a mark. Each of the turntables 19-22 has a respective detector 80 associated therewith at the centering station 13. When the goblet arrives at the centering station 13, the detector 80 is activated and the turntable 19 is rotated to rotate the goblet in front of the detector 80. The detector 80 may be of a well known type which has the ability to sense the presence of a mark on the goblet. Under the direction of the microcomputer, the orientation of the flawed goblet may be arranged at the centering station 13 such that when the flawed goblet arrives at the marking station 14, ink is discharged so as to coincide with the manually placed mark on the flawed goblet which, later, at the cutting stage, has the flaw removed therefrom to leave an unblemished cut glass goblet.

This invention is not limited by or to the specific embodiment described which can undergo considerable variation without departing from the scope of the invention. - 12 -

Claims

1. An apparatus for marking the surface of an article, comprising a marking station, turntable means for rotating the article at the marking station, ink jet printing means 5 at the marking station for discharging ink onto the article in a direction transverse to the axis of rotation of the article, and means for moving the printing means in a direction substantially parallel to the axis of rotation of the article. 10

2. An apparatus according to claim 1, further comprising an article loading station and conveyor means for transporting the article to the marking station from the loading station. •»

3. An apparatus according to claim 1 or claim 2, wherein 15 the turntable is carried by the conveyor means, the article being loaded on the.turntable at the loading station.

4. An apparatus according to claim 3/ further including a centering station intermediate the loading station and the marking station, the centering station comprising means to 20 centre an article relative to the axis of rotation of the turntable while the conveyor means is temporarily halted.

5. An apparatus according to claim 4, wherein the centering means comprises a plurality of members symmetrically disposed and movable radially relative to the 25 axis of rotation of the turntable for engaging the outer surface of the article.

6. An apparatus according to any of claims 2-5, further including vacuum means for maintaining the article on the turntable during movement of the article by the conveyor means to the marking station and during rotation of the article at the marking station.

7. An apparatus according to claim 6, wherein the vacuum means comprises a pipe extending to the centre of the turntable from the opposite side to that which supports the article, and means for supplying vacuum to the pipe.

8. An apparatus according to any one of claims 2 to 7, wherein the conveyor means comprises a carousel.

9. An apparatus according to any preceding claim, wherein the apparatus is adapted to accommodate a plurality of articles for simultaneous processing at the or each station.

10. An apparatus for marking the surface of an article substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS.