US3207068A - Stencil printing apparatus - Google Patents

Description

Sept. 21, 1965 T. LECKIE STENCIL PRINTING APPARATUS Original Filed July 13. 1960 9 Sheets-Sheet 1 Inventor:

THOMAS L. LECKIE T. L. LECKIE STENCIL PRINTING APPARATUS Original Filed July 15. 1960 Sept. 21, 1965 9 Sheets-Sheet 2 Tu om: L. LEck Sept. 21, 1965 T. L. LECKIE 3,207,068

STENCIL PRINTING APPARATUS Original Filed July 13. 1960 9 Sheets-Sheet 5 I nventor:

THOMAS L. LECKIE y 3 63A s, i A ttorneys/ Sept. 21, 1965 'r. L. LECKIE STENCIL PRINTING APPARATUS Original Filed July 15. 1960 9 Sheets-Sheet 4 Inventor:

THOMAS L. Lckl Sept. 21, 1965 T. L. LECKIE 3,207,068

STENCIL PRINTING APPARATUS Original Filed July 13. 1960 9 Sheets-Sheet 5 Inventor filo/4A5 L. LEcKIE v mm Sept. 21, 1965 T. L. LECKIE 3,207,068

STENCIL PRINTING APPARATUS Original Filed July 13, 1960 9 Sheets-Sheet 6 THOMAS L. LEcklE Sept. 21, 1965 T. LECKIE 3,207,068

STENCIL PRINTING APPARATUS Original Filed July 15. 1960 9 Sheets-Sheet 7 n n u u f-fi LL 3 i: R 1 E a F z= w. u Q (I) E w I v D; C) N V) C) v) Inventor THomAs 1-.LECK :E

B 63. Afton 1e;

Sept. 21, 1965 T. LECKIE 3,207,068

STENCIL PRINTING APPARATUS Original Filed July 13. 1960 9 Sheets-Sheet 8 I nvenlor TH MAs L. LECKIE Sept. 21, 1965 T. L. LECKIE STENCIL PRINTING APPARATUS 9 Sheets-Sheet 9 Original Filed July 13, 1960 United States Patent 3,207,068 STENCIL PRINTING APPARATUS Thomas Liddle Leckie, Prestwieh, near Manchester, England, assignor to The Bradford Dyers Association Limited Original application July 13, 1960, Ser. No. 42,655, now Patent No. 3,129,442, dated Apr. 21, 1964. Divided and this application Oct. 11, 1962, Ser. No. 234,571 4 Claims. (Cl. 101-123) This application is a division of application Serial No. 42,655 which was filed July 13, 1960, and is now U.S. Patent No. 3,129,442.

This invention comprises a process and machine for the printing of thick fabric in continuous lengths. By thick fabrics I mean fabrics of thickness greater than 1 mm., such as tufted carpets or other pile fabrics (whether the pile is composed of fibres introduced into a fabric base or of yarn pulled out from a woven fabric as in a moquette), or felts, bonded fibre structures or non-Woven structures. The invention is particularly applicable to, and will be described with reference to, pile carpets, but it is not limited to these.

Pile carpets, because of their weight and size and the depth of the pile, present printing problems entirely different from those of the printing of ordinary textile materials. In consequence pile carpets have hitherto been made with the use of yarns of diiferent colours, a process which has various drawbacks. It would clearly be advantageous to make the carpet from grey, i.e. natural coloured, yarn and to print it to any desired pattern in a continuous process such that the carpet as delivered from the factory entered a machine and need not be touched by hand until it emerged as a finished printed product. I have produced what I believe to be the first process and machine by which this can be done.

My invention involves the technique of stencil printing, which of course involves movement of the carpet in stepwise fashion through one or more printing stations; this fact introduces some of the problems that arise.

By stencil printing I mean printing through a stencil, whether that stencil is an imperforate sheet with free openings in it or is a screen with numerous meshes. As is well known, a pattern is formed by closing some of the meshes in the screen and leaving the remainder open to constitute stencil openings. All the meshes in a screen may be left open if a fabric to be printed should be of uniform colour throughout. The present invention is particularly useful in, and will be described by reference to, screen printing, but stencils with free openings may be used.

The invention includes numerous novel features as such and also a series of steps employed in sequence as a continuous process. These various features and steps will now be described with reference to the accompanying drawings, which show the preferred machine and in which:

FIGURE 1 is a diagrammatic side elevation of the entry end of the machine;

FIGURE 2 is a section through the upper part only of the machine;

FIGURE 3 is a diagram to show the movement of a colour box over a screen;

FIGURE 4 is a perspective view of two colour boxes and mechanism for moving them; and

FIGURES 5 and 6 are perspective views of a screen and lifting mechanism in two different positions;

FIG. 7 is a diagrammatic side elevation view of the delivery end of the printing part of the machine;

FIG. 8 is a continuation of FIG. 1 showing the delivery end of the machine;

' FIG. 9 is a diagrammatic plan view corresponding to FIG. 1;

3,207,068 i Patented Sept. 21,1965

FIG. 10 is an enlarged diagrammatic cross-section through the printing part of the machine;

FIG. 11 is a diagrammatic side elevation illustrating the engagement of the carpet by pinned rollers;

FIG. 12 is a plan view corresponding to FIG. 11; and

FIG. 13 is an enlarged section on the line XIII-XIH in FIG. 12.

The machine shown is designed for printing pile carpets and comprises a brushing frame 1, two main side frames 2 each composed essentially of uprights 3 and horizontal members 4 spaced apart from one another by a distance greater than the maximum width of carpet to be printed, an entry station 6 to the printing part of the machine, eight perforated carpet supports 5 spanning the side frames 2 and providing eight printing stations, a take-01f station 7, a steaming vessel 8, a washing apparatus 9 and a withdrawal and lapping mechnism 18. The printing stations are defined by rectangular screens, SISS, mounted to move vertically, and above each screen there is a colour box, these boxes being numbered CB1-CB8.

At each side there is an endless conveyor consisting of a stenter chain 10 including links 11 with side flanges 12 having upwardly projecting pins 13 which engage the selvedges of the carpet. The chains 10 pass round sprockets, of which end sprockets 14 and 15 and carried by shafts 16 and 17, and the shaft 17 is intermittently driven. Whenever the shaft 17 turns the carpet is positively driven by the engagement of the pins 13 with the selvedges.

The driving mechanism may take any suitable form. All that is required is that the carpet should be moved in exact steps and halted with accuracy; that while the carpet is moving the screen and colour boxes should be stationary and raised above the carpet; and that when the carpet is stationary each colour box should move across the corresponding screen.

The ram 24 drives the shaft 17. A stem 28 projecting from the ram cylinder is pivotally connected to an arm 29 that is freely mounted on a shaft 130 and that carries a pawl 131. This pawl engages a ratchet wheel 132 which is fixed to the shaft and at each ram stroke this wheel is turned through one tooth. The shaft 130 carries a gear wheel 133 which meshes with a gear wheel 134 rigid with the shaft 17. This driving gear is provided in duplicate, one part on each side of the ram 24.

In travelling beneath each screen S the carpet slidesover the corresponding support 5, which is a metal table in which many holes 60 are made to allow suction to be applied to the underside of the carpet through the corresponding suction box SB, there being as many suctionboxes (SB1-SB8) as there are screens. The top of each suction box is constituted by a perforated part of the support 5, this part lying within imperforate side edges 61 and end edges 62, the latter bounding the slots in which the rollers 49 to 57 turn. The holes 60 forming the perforations are arranged in rows with the mouths of all the holes of a row lying in a channel 63 and thus communicating with one another. It is found to be advantageous to make these slots form a herring-bone patten as shown in FIG. 13. If all the slots run parallel to the warp there is a tendency for the printing to be uneven,

in tramline fashion. If they all run parallel to the weftthere is undesirable resistance to the movement of the carpet. If they are all inclined in the same direction they tend to push the carpet in that direction, but if theyare arranged in herring-bone pattern the carpet is kept central.

An important feature of the invention is the use of a. free-flowing colouring matter as the printing liquid. In

the screen-printing of textile fabrics it is common to use a fairly thick liquid which flows slowly over a horizontal surface and which is forced over the screen by squeegees.

The pile of a carpet is usually at least deep, and may be as deep as If the colouring matter is of the usual consistency, it will not penetrate the pile deeply.

The viscosity of printing pastes or colouring matter may be measured by the Redwood method described in Standard Methods for Testing Petroleum and its Products issued by the Institute of Petroleum, on page 665 of the 16th edition, dated February 1957. Pastes used in conventional engraved roller printing operations are very thick and may have a Redwood No. l viscosity figure at 75 F. of from 20,000 seconds to 100,000 seconds. The free-flowing colouring matter used in this invention is much more fluid and in general has a Redwood No. 1 viscosity not exceeding 3000 seconds at a temperature of 75 vF. Suitable colouring matters have been found to have viscosities varying between 25 and 1821 seconds. Colouring matters which have a Redwood No. 1 viscosity in excess of 3000 at 75 F. may be used if desired by heating them to a temperature such that their Redwood viscosity is reduced to below about 3000 seconds.

In screen printing as practised hitherto the colouring matter is commonly forced over the screen and through the openings in it by a squeegee which moves across the stencil. No great difiiculty arises so long as the colouring matter is a fairly viscous paste. When, however, pile fabrics and particularly pile carpets are to be printed, I have found it necessary to use the free-flowing colouring liquid (of viscosity little greater than that of water) described above, and this introduces entirely new problems. There is difiiculty in holding the colouring liquid in the container, particularly when printing is not taking place and the screen is being lifted to allow the carpet to move forward in step-by-step fashion. In the present process and machine the colouring matter is supplied to each screen S from a colour box CB. Each colour box is of narrow rectangular shape in plan, extends completely across the screen from one side to the other and in width is only a small fraction of the length of the screen. Its narrow end walls are formed by plates 71 carried by arms 72 which are adjustable in height through devices 73 themselves secured to lifting rails 74. Each screen consists of gauze 75 stretched across the underside of a metal frame 76, and along the side edges the meshes in the gauze are closed. Along the end edges the meshes are also closed over an area at each end large enough to receive the complete colour box. During the printing operation the colour box is moved from one end edge to the other while the screen is stationary, and it is of course necessary to allow the colouring matter to flow freely through the openings in the screen as the box moves but to prevent it from escaping at the end of each printing stroke.

Each colour box has a flexible lower edge formed by rubber strips 70 which make a seal with the imperforate parts of the surface of the screen S, this edge being kept in contact with the screen during the whole of each printing operation and with the imperforate surface at the end of the screen at the end of each printing operation. When the container is in contact with an imperforate end of the screen the colouring liquid is confined within it by the seal.

FIGURE 3 shows a colour box CB on a screen S. The box is shown in full lines .over an imperforate part 140 of the screen and in dotted lines in the position it takes up over another imperforate part 141 at the end of a stroke after traversing the part 142 containing the open meshes.

The wider the colour box, the more difficult it is to make the necessary seal and the greater the width of the imperforate surface required at each end of the screen, with resultant increase in the distance between printing stations. A very narrow colour box, on the other hand, involves slow operation of the machine. A very suitable width of colour box is 4 inches.

The colouring matter required for each colour box CB through a slightly gearter distance than the latter.

is supplied to that box from a container by a pump 81 through a pipe 82 containing a manually adjusted valve 83 to distributors 84. An electrical probe 85 responsive to the liquid level is provided in each box and is electrically connected to cotrol the operation of the pump 81.

Naturally when the screen is lifted to allow the material to move through one step the colour box must be lifted too. It is found in practice that there is some tendency for a screen to sag when lifted, with the result that the seal between it and the flexible edge 70 ceases to be tight. To avoid the risk of colouring matter escaping through this cause between the screen and box the former is moved The pressure between the screen and the flexible edge in the raised position is therefore greater than in the printing position, and the risk of liquid seeping through the seal is practically eliminated. If this same high pressure were exerted during the printing, the resistance of the flexible edge to movement over the screen would be so high as to make the movement difficult.

In the machine shown all the screens S are carried by rails 77 one at each side. The screen rails must be able to rise to allow the fabric to move, and the rails 74 must not only be able to rise but also must be mounted to reciprocate to carry the colour box over the screen. To enable differential lifting movement to take place, the colour box rails 74 are supported by rollers 91 carried by cranked levers 92 pivoted at 93 and all rigid at their lower ends with operating bars 94, one at each side. The two operating bars 94 are reciprocated horizontally through inclined rods 154 by the ram 25 when the colour boxes are to be raised, and they rock the levers 92 from the position shown in FIGURES 4 and 5 to that shown in FIGURE 6.

The screen rails 77 are supported by vertical rods 95 which are raised by cam action when the levers 92 rock to lift the rails 74. The cams are plates 96 rigid with the levers 92 and bearing on the undersides of the rods 95, which are themselves guided in fixed open-ended sockets 97.

When each lever 92 is rocked, the cam plate 96 rises through a distance determined by the length of the middle arm of the lever and the angle of rocking. The roller 91, being carried at the end of the upper arm, moves upwards through a distance that is the difference between the upward movement of the plate 96 (at the junction of the two arms) and the downward movement of the upper end of the upper arm that results from the movement of that end in a circular path. Therefore the screen is moved Ifjurther than, and pressed more firmly against, the colour In order to reciprocate each colour box over the screen beneath it, the rails 74 are caused to slide over the rollers 91. Each is engaged by a sleeve 98 which forms a housing for a pivot pin 99 that enters one end of a connecting rod 150. The other end of this rod is pivotally connected to a crank 151 on a cross-shaft 152. This shaft can be rocked through a crank 153 by the ram 26 shown in FIG. 7 and diagrammatically in FIG. 4, the movement of the ram being cam-controlled so that each colour box makes one stroke each time the carpet is halted for printing. The lifting movement of the rail 74 described above is permitted by rocking of the connecting rod with simultaneous slight longitudinal movement of the rail 74.

I claim:

1. A machine for stencil-printing a thick fabric comprising a horizontal perforated support, a stencil having a plurality of openings in its central part and with imperforate ends above the support, means for intermittently moving a fabric over the support and below the stencil, a bottomless container for colouring matter having a flexible lower edge means for lowering the stencil and the bottomless color container whereby the stencil and container are in constant pressure contact during the lowering and whereby the stencil is placed into printing position, means for traversing the container over the stencil from one imperforate end to the other whereby colouring matter can pass through the stencil openings during the traversing but is retained in the container when it is at each end, separate lifting means for the stencil and for the container and mechanism operative to cause the first of these means to lift the stencil to a greater distance than the container is lifted by the second of these means whereby a pressure is maintained between the stencil and the flexible edge to give a sealing elfect to said edge.

2. A machine according to claim 1 in which the flexible lower edge is constituted by flexible rubber around the bottom of the container.

3. A machine according to claim 1 including a pair of side rails carrying the stencil, a pair of side rails carrying the container, means for raising the stencil rails, means for raising and reciprocating the container rails and mechanism by which both pairs of rails can be raised simultaneously with the stencil rails rising through a greater distance than the container rails to maintain a pressure between the stencil and the flexible edge of the container to give a sealing efiect to said edge.

4. A machine according to claim 3 including a pair of pivoted levers which are rocked to lift both pairs of rails, each lever carrying a roller on which a container-carrying rail is supported, and also a cam plate which bears on the underside of a vertical rod which engages a stencilcarrying rail.

References Cited by the Examiner UNITED STATES PATENTS DAVID KLEIN, Primary Examiner.

Claims (1)

1. A MACHINE FOR STENCIL-PRINTING A THICK FABRIC COMPRISING A HORIZONTAL PERFORATED SUPPORT, A STENCIL HAVING A PLURALITY OF OPENINGS IN ITS CENTRAL PART AND WITH IMPERFORATE ENDS ABOVE THE SUPPORT, MEANS FOR INTERMITTENTLY MOVING A FABRIC OVER THE SUPPORT AND BELOW THE STENCIL, A BOTTOMLESS CONTAINER FOR COLOURING MATTER HAVING A FLEXIBLE LOWER EDGE MEANS FOR LOWERING THE STENCIL AND THE BOTTOMLESS COLOR CONTAINER WHEREBY THE STENCIL AND CONTAINER ARE IN CONSTANT PRESSURE CONTACT DURING THE LOWERING AND WHEREBY THE STENCIL IS PLACED INTO PRINTING POSITION, MEANS FOR TRAVERSING THE CONTAINER OVER THE STENCIL FROM ONE IMPERFORATE END TO THE OTHER WHEREBY COLOURING MATTER CAN PASS THROUGH THE STENCIL OPENINGS DURING THE TRAVERSING BUT IS RETAINED IN THE CONTAINER WHEN IT IS AT EACH END, SEPARATE LIFTING MEANS FOR THE STENCIL AND FOR THE CONTAINER AND MECHANISM OPERATIVE TO CAUSE THE FIRST OF THESE MEANS TO LIFT THE STENCIL TO A GREATER DISTANCE THAN THE CONTAINER IS LIFTED BY THE SECOND OF THESE MEANS WHEREBY A PRESSURE IS MAINTAINED BETWEEN THE STENCIL AND THE FLEXIBLE EDGE TO GIVE A SEALING EFFECT TO SAID EDGE.

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