US3026003A - Silk screen printing machines - Google Patents

Description

March 20, 1962 s. EDELS ETAL SILK SCREEN PRINTING MACHINES 4 Sheets-Sheet 1 Filed Dec. 3, 1957 March 20, 1962 s. EDELS ET AL SILK SCREEN PRINTING MACHINES 4 Sheets-Sheet 2 Filed Dec. 3, 1957 March 20, 1962 s. EDELS ET AL 3,

SILK SCREEN PRINTING MACHINES Filed Dec. :5, 1957 Sheets-Sheet 5 March 20, 1962 s. 'ED-ELS ET AL SILK SCREEN PRINTING MACHINES Filed Dec. 3, 1957 3,6251%?) Patented Mar. 20, 1952 3,926,003 SILK SCREEN PRENTIN MACHINES Siegfried Edeis, Kensington, London, and Arthur William Excell, Thornton Heath, England, assignors to Rejatix Limited, London, England, a British company Filed Dec. 3, 1957, Ser. No. 700,4ti Claims priority, application Great Britain Dec. 4-, 195d 4 Claims. (Ci. 221-225) This invention relates to the dispensing of articles from a hopper for feeding to silk screen printing machines, for example, employed for printing on the curved surfaces of cylindrical articles, such as ampoules, or on part-cylindrical or even flat articles. Such machines comprise, in general, a substantially horizontal silk screen, a movable squeegee blade working on the upper face of a stencil in the screen to force the printing ink through it, and a conveyor for feeding the cylindrical, part-cylindrical or flat articles in succession beneath the screen in stepwise fashion and serving to bring each article in turn against the under side of the screen stencil for printing, the squeegee and screen being operated in synchronism with the feed movements of the conveyor.

According to the present invention there is provided the combination with a hopper having an outlet opening at its lower end, of a pair of dispensing rollers disposed side-by-side adjacent and parallel to each other and spanning the outlet opening of the hopper, each of which rollers is provided with article-receiving recesses at circumferentially spaced locations round its periphery, means to rotate the rollers in synchronism with their lower parts approaching each other, a conveyor disposed beneath the rollers with the length of the conveyor extending transversely to the axes of rotation of the rollers, which conveyor has article-receiving means at spaced locations along its length, means for advancing the conveyor step-by-step in timed relation to the rotation of the rollers, each step being equal to twice the distance between successive article-receiving means, and the rollers being arranged to deposit articles respectively on two article-receiving means of the conveyor at each step of the conveyor which two article-receivingv means are spaced from each other by two article-receiving means.

One embodiment of the invention as applied in a silk screen printing machine employed in printing on the curved surface of cylindrical articles, such as arnpoules, will now be described by way of example with reference to the accompanying drawings.

In the drawings:

FIGURE 1 is a front view of a machine of the invention,

FIGURES 2-12 are details to a larger scale than FI URE 1, of the machine of FIGURE 1,

FIGURE 2 being a plan view of the main shaft,

FIGURE 3 is a view on line IIIIII of FIGURE 2,

FIGURE 4 a plan of the sprocket shaft,

FIGURE 5 a view on line V-V of FIGURE 4,

FIGURE -6 a view on line VIVI of FIGURE 2,

FIGURE 7 a view on line VIIVII of FIGURE 2,

FIGURE 8 a view on line VIIIVIII of FIGURE 2,

FIGURE 9 a view on line IX-IX of FIGURE 2,

FIGURE 10 a view on line XX of FIGURE 2,

FIGURE 11 an end view of the screen oscillating mechanism, and

FIGURE 12 an end view of the hopper.

Referring to the drawings, the machine is carried on a table 11 and comprises essentially asubstantially horizontally movable silk screen 12, two squeegee blades 13 operating on the upper face of the screen 12 to force printing ink through two separate stencils (not shown) on the screen, a stepwise-operating conveyor 14 for feeding the articles to be printed, which may be glass ampoules or the like, beneath the screen, and a hopper-andfeed arrangement 16 for loading the ampoules or other articles on to the reception end of the conveyor 14. The entire mechanism is driven by a motor 19 through a reducing gear box 9 and a main shaft 29 on which are carried the driving cams as will be hereinafter described.

The conveyor 14 comprises two chains 17 (see FIG- URE 4) carried on driving sprockets 1'8 and 19 at one end and on idler sprockets 21 at the other end. The driving sprockets 1-8 and 719 are mounted on an auxiliary shaft 22 journalled in upstanding lugs projecting from the table 11 slightly to the left of the hopper-andfeed arrangement 16, as shown in FIGURE 1, and the idler sprockets are carried on idler shafts journalled in lugs mounted near the right-hand end of the table 11 as shown in FIGURE 1. The arrangement is such that the forward movement of the top run of the conveyor is made in the direction from driven sprockets 1S and 19 towards idler sprockets 21. A jockey roller 23 carried by jockey arms 24 pivoted on the auxiliary shaft 22 is provided to keep the conveyor taut.

On the side of the chains most remote from each other are mounted carrier members 25. The members are aligned in pairs across the conveyor 14 so that an empoule or like article lying across the conveyor will be transported at or near the ends by a pair of such carrier members 25. Each carrier member 25 comprises a rectangular piece having a triangular notch cut therein so that the carrier members present upper faces having notches for the reception of ampoules during forward movement of the conveyor 14.

The conveyor 14 is driven so as to advance in a step wise progression with each carrier member 25 moving two consecutive positions on each movement of the conveyor. This movement is under the control of a ratchet wheel 27 actuated by a cam 26 on the main shaft 21 through the link-work shown in FIGURES 3 and 4. A detent wheel 28 having peripheral indentations therein for the reception of a roller 29 is adjustably mounted on the boss 27a of driving ratchet wheel 27. The roller 29 is carried by a spring-biassed detent arm 34} forcing the roller 29 into the indentations with a view to ensuring that the carrier members 25 of conveyor 14 are correctly positioned for receiving the ampoules from the hopper and for presenting the latter to the workholder as will be hereinafter described.

The hopper arrangement for delivering the articles to the reception end of the conveyor comprises a storage chamber or hopper 31 for the cylindrical articles which permits the articles to be fed to two dispensing rollers 32. The hopper is canted backwards slightly, as shown in FIGURE 12, so as to ensure that the ampoules will tend to move against the back face thereof. Projecting. from each end of the top of the hopper are two arms 33 on which a removable closure member 34 is pivotally carried by means of laterally projecting trunnions 35 on said closure member and a pair of registering notches 36 in the arms 33. A number of these pairs of notches 36 are provided so that the position of the closure member 34 can be varied in dependence upon the length of the ampoule or other article being printed. As, however, the closure member 34 is pivoted it hangs down vertically, i.e. at an angle to the hopper 31 so that only the lower ampoules are lightly held against the back plate of the hopper. Weights can, if necessary, be added to the lower end of the closure members 34 to ensure that it hangs vertically.

The rollers 32 are mounted at the same level above the conveyor on axes spaced apart and at right angles to the direction of length of the conveyor 14. The rollers 32 are attached to meshing gears 37 and thus are rotated in opposite directions simultaneously and at the same speed. Each roller 32 has four equiangularly-spaced rec tangular cut-outs or notches 32a in its periphery. Each of said cut-outs 32a receives an article from the storage chamber 31 as it arrives at the top of the roller periphery and delivers the article to a pair of carrier members 25 of the conveyor 14 when the cut-out reaches the lower most position of the roller periphery. A stationary curved guide 39 is provided around the outside of each roller periphery to retain the article in the cut-outs between these two positions. By virtue of the shape of the rollers 32 and the friction between rollers 32 and ampoules in the hopper 31, the ampoules will be agitated by the rotation of the rollers which will tend to ensure'that ampoules in the hopper will enter into the cut-outs 32a in the uppermost position of the rollers.

The hopper arrangement, including the rollers 32, is vertically adjustable so that the drop from the cut-outs or notches 32a on to a pair of carrier members 25 can be varied for different sizes of am-poules. In this way the ampoules can be more positively positioned on to the conveyor and the detrimental effect of dropping the ampoules on to the conveyor from a great height minimised.

The two rollers 32 drop articles simultaneously in pairs on to the conveyor 14, and are so spaced as to fill at each drop two pairs of carrier members 25 on the conveyor 14 that are three positions apart, that is to say, the two pairs filled at each drop are separated from one another by a further two adjacent pairs of carriermembers 25 on the conveyor between them. Thus, considering any four conecutive positions of pairs of carrier member 25, a pair of articles dropping simultaneously from the two rollers 32 will fill, say the first and fourth positions. The rotation of the rollers 32 is intermittent and synchronised with the conveyor feed being driven Off a cam 33 on the main shaft 29 by the linkwork shown in FIGURE 9, so that between each dropping of a pair of articles the conveyor 14 has moved through one feed cyc-le. Consequently, when the next pair of articles is dropped the fourth-position-article has now moved along two places to the second position, the empty pair of carrier members 25 at the third position has moved to the first position and the fourth position is now occupied by the pair of carrier members 25 previously at the sixth place. At the next drop, the pairs of carrier members 25 originally at the fifth and eighth positions will be filled, and so on: it will be appreciated that in this way, when the machine is running, a full line of articles is fed along the conveyor 14 from the delivery drums 32 to the printing screen 12.

When the cylindrical articles on the conveyor 14 arrive below the printing screen 12, they are lifted from the conveyor 14 in pairs by a workholder 41 and pressed against the under sides of the screens.

The workholder 41 comprises two pairs of arms 42 (one arm only of each pair being shown) projecting upwardly from a platform 43 which is in turn carried by upright 44. The upper end of each arm is provided with rollers 45 so that an ampoule may be rotatably carried on the rollers of a pair of said arms 42. The workholder 41 is normally situated between the two chains 17 of the conveyor 14. The pairs of arms 42 are spaced from one another in the direction of length of the conveyor 14 by a distance equal to three times the spacing between consecutive notches in the carrier members 25 and di rcctly below squeegee blades 13.

The workholder 41 is reciprocable to lift ampoules from the conveyor up to the screen by means of the linkage shown in FIGURE 8. This linkage comprises a pivoted lever t'oscil-latable by cam 47 on the main shaft 20- against the influence of a spring 48. The end of lever 46 remote from cam 47 is connected to the upright 44 to raise and to lower workholder 41. Knurled knob 49 is provided whereby the length of reciprocation of the workholder may be varied.

The cam 47 is so arranged that the arms 42 of the workholder 41 raise a pair of articles to the screen 12 after each feeding movement of the line of articles by the conveyor. The order in which the articles are raised to screen 12 is similar to that in which they are delivered on to the reception end of the conveyor 14, that is to say at the first lift the first and fourth articles are raised, at the second lift the third and sixth, at the third lift the fifth and eighth, and so on down the line. It will therefore be seen that every other article in the line is printed by one squeegee 13 and the corresponding stencil, while simultaneously the intermediate article is printed by the other squeegee 13 and stencil. After each pair of articles is printed they are lowered back on to the conveyor 14 and fed onward toward the delivery end thereof.

The screen 12 with the stencils moves to and fro between the articles and squeegees '13 and will, when an article is lifted up to it by the workholder 41 and the squeegees 13 are pressing down upon it, rotate the article and print the latter.

The screen 12 is carried by a pair of angle members 51 (see FIGURE 11) and is firmly held in position by means of clamps 52. The angle members 51 are reciprocated by means of a linkwork including a link 54 moved by an eccentric 53 mounted on driving shaft 21 as shown in FIGURES 10 and 11. The link 54 is joined to a screen-mechanism-rocking-arm 55, which imparts movement to the angle members 51, by means of a pin 56 on the link 54- and an elongated longitudinal slot 57 in the screen-rnechanism-rocking-arm 55. A wing nut 58 engages the free end of the pin 56, which is screw threaded, to secure the pin position in the slot 57. By adjusting the portion of pin 56 in the slot 57, the angular movement of the screen-mechanism-rocking-arm 55, and thus the amplitude of the reciprocatory movement of the screen will be altered, whereby ampoules of different diameters may be printed by the machine.

The squeegee blades 13 are carried by rods 61 mounted for vertical movement on a vertical support plate 60, the position of which can be altered towards and away from driving sprockets 18 and 19. The rods 61 are raised and lowered under the influence of a cam 62 on the main shaft 20 by means of the linkwork shown in FIGURES 6 and 7. To achieve the necessary pressure during printing, weights 63 can be added to these rods 61. During the printing operation the squeegee blades 13 will bear upon the screen 12 with the force of the rods 61 and weights 63. The cam 62 is so shaped, however, that during the return non-printing movement of the screen 12 the squeegee blades bear less heavily on the screen 12 and serve only to control the spreading of ink thereon. Raised cam portions 64 are provided on cam 62 so that the squeegees 13 are lifted clear of the screen 12, and the ridges of ink forming on the screen on the advance side of the squeegees, just prior to the end of the screen stroke, and are lowered to the screen on the opposite side of the ridges at the end of the screen stroke so that the ink-ridges will be on the advance side of the squeegees during the return stroke. Each squeegee 13 has a separate fine adjustment 65 for height which allows the densities of the printings to be varied independently, and the squeegee blade 13 is suitably jointed to the squeegee holder so that it can be readily adjusted to suit the level of the screen 12.

The operation of the squeegees 13 and screen 12 is synchronised with the conveyor movement, so that every time the conveyor 14 comes to rest and a pair of articles is lifted up to the screen 12 for printing, the screen 12 performs its printing stroke in one direction. During the time when the conveyor 14 is advancing and no articles are lifted up to the screen 12, the screen 12 performs its return stroke in the opposite direction. It should be noted that the squeegees 13 are both moved. vertic lly in timed relation to the movement of the screen 12 and the vertical movement of the squeegees 13 is adjustable independently for both the forward and return strokes, according to the quantity of ink required for the particular job in hand.

A heating means 7-1 comprising an element (not visible) in housing 72 is provided near the delivery end of the conveyor chain to facilitate the drying of articles on the conveyor. A reflector 73 is hinged to the housing 72 to improve the drying process.

The machine is fully adjustable for different diameters of articles and provision is made for the adjustment of squeegees and stencils so that the printed matter can be positioned on any part of the articles circumference. The mechanism for varying the width apart of the conveyor-carrier-plates to accommodate articles of different lengths consists in that the shafts carrying the sprocket wheels have turned down portions 75 into which spring loaded latches 76 on the sprockets 18 and 19 may engage so that the corresponding sprockets 18 and 19 can be adjusted. Auxiliary shaft 22, carrying sprocket wheel 19, is shown in detail but the shaft carrying idler sprockets 21 has similar turned down portions.

The machine can be employed simply to produce one kind of printed ampoule or other article at double the output for the same machine speed. Alternatively, two series of ampoules or the like can be printed at one and the same time; thus, different stencils can be used to give different printed matter on the two series of articles, or the same stencils can be used with different coloured ink, or both different stencils and different colours can be employed. In the case where there are two series of articles being printed at the same time, an automatic sorting mechanism could be fitted at the delivery end of the conveyor to separate the two kinds of articles.

Further, by reversing the main movement of the squeegees and screen, flat and slightly curved articles can be printed.

It will be appreciated that considerable modification of the above described arrangement is possible without departing from the scope of the invention. Thus, the sprocket-driven conveyor chains could be replaced by pairs of conveyor tracks arranged to be intermittently moved in timed relation to the screen as described in the provisional specification.

The machine may also be provided with a mechanism to detect Whether or not an article is on the conveyor just prior to the printing stroke, such as for instance, if the hopper has only fed one ampoule or the like instead of two. This mechanism then prevents the appropriate squeegee from making its printing stroke, thus preventing the under side of the screen from being fouled due to too much ink being pushed through the screen.

We claim:

1. The combination of a hopper having a single outlet with a stepwise advancing conveyor comprising a plurality of adjacent article receiving means for receiving respectively cylindrical articles and means for advancing said conveyor through a distance equal to the length taken up by two adjacent article receiving means; said hopper comprising a pair of rollers spanning the opening and being located with their axes parallel, perpendicular to the direction of travel of said conveyor, lying in a plane substantially parallel to the plane of the conveyor, and spaced by a distance equal to the length taken up by three adjacent article receiving means, said rollers each having a plurality of notches therein for receiving articles, said hopper further comprising guide means surrounding said rollers to retain in position articles within said notches until these are below the axes of the rollers and means for rotating said rollers in synchronism and with the notches in phase.

2. The combination with a hopper having an outlet opening at its lower end, of a pair of dispensing rollers disposed side-by-side adjacent and parallel to each other and spanning the outlet opening of the hopper, each of which rollers is provided with article-receiving recesses at circumferentially spaced locations round its periphery, means to rotate the rollers in synchronism with their lower parts approaching each other, a conveyor disposed beneath the rollers with the length of the conveyor extending transversely to the axes of rotation of the rollers, which conveyor has article-receiving means at spaced locations along its length, means for advancing the conveyor step-by-step in timed relation to the rotation of the rollers, each step being equal to twice the distance between successive article-receiving means, and rollers being arranged to deposit articles respectively on two articlereceiving means of the conveyor at each step of the conveyor which two article-receiving means are spaced from each other by two article-receiving means.

3. The combination with a hopper having a front wall, a back wall which slopes forwardly from top to bottom, and side walls extending between the front and back walls, and having an outlet opening at its lower end, of a pair of dispensing rollers disposed side-by-side adjacent and parallel to each other and spanning the outlet opening of the hopper, each of which rollers is provided with article-receiving recesses at circumferentially spaced locations round its periphery, means to rotate the rollers in synchronism with their lower parts approaching each other, a conveyor disposed beneath the rollers with the length of the conveyor extending transversely to the axes of rotation of the rollers, which conveyor has articlereceiving means at spaced locations along its length, means for advancing the conveyor step-by-step in timed relation to the rotation of the rollers, each step being equal to twice the distance between successive articlereceiving means, and the rollers being arranged to deposit articles respectively on two article-receiving means of the conveyor at each step of the conveyor which two article-receiving means are spaced from each other by two article-receiving means.

4. The combination as claimed in claim 3 wherein the back wall of the hopper slopes forwardly from top to bottom, the front of said hopper being closed by a wall member pivoted on the hopper at the top thereof, the pivot axis being spaced from the adjacent edge of the side wall by an amount sufficient to permit the front wall member to hang vertically.

References Cited in the file of this patent UNET ED STATES PATENTS 2,114,323 Simonton et al Apr. 19, 1938 2,207,351 McLaughlin et al. July 9, 1940 2,613,861 Goerlitz Oct. 14, 1952 2,785,828 Patzer Mar. 19, 1957 2,877,924 Childers et al Mar. 17, 1959 2,907,499 Agronin Oct. 6, 1959 FOREIGN PATENTS 211,715 Germany July 9, 1909 569,047 Great Britain May 2, 1945 693,128 France Aug. 18, 1930

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