GB2059876A - Method and apparatus for printing a sheet of yarns - Google Patents

Abstract

The apparatus prints a sheet of yarns with colours such that on subsequent tufting, for example, a carpet of a desired pattern is formed. The apparatus includes a number of printing stations, each having a dye-coated roller and a series of printing rollers movable to press selected yarns against the dye. The printing rollers are driven in accordance with pattern data stored in a computer and synchronising signals representing movement of the yarn.

Description

SPECIFICATION Method and apparatus for printing a sheet of yarns This invention relates to a method and apparatus for printing a.sheet of yarns with differently coloured dyes in accordance with a desired pattern to be obtained when the yarns are formed into a product such as a woven or tufted carpet.

Many prior proposals have been made in this field; see for example British patent specifications nos 900,341, 938,734, 1,017,171, 1,035,805, 104,953 and 1,374,620.

In general terms, this prior art suggests the ube of a sheet of yarns passing across a plurality of dye-applying stations, each station having a roller rotating in a trough containing dye. The yarns are normally spaced from the rollers by a small distance, but the two may be brought into contact by some form of relative movement to apply dyes to the yarns in a pattern such that, when the yarns are beamed and subsequently tufted on a conventional plain tufting machine, a carpet of a desired pattern is produced. The relative movement may be by a row of presser members above each roller which are selectively actuated to press selected lengths of selected yarns onto the dye film on the appropriate roller. Alternatively, the surface of the roller may consist of small pads, each of which may be extended to contact a selected yarn or group of yarns.

In these prior proposals, the contact between the yarns and the rollers, and thus of the pattern of the final product, is controlled by mechanical means, typically by sets of cams or pattern bars.

For example, in the one type of prior apparatus believed to have been put into commercial use, each dye-applying roller is formed of 44 rows each of 1 28 pads. Each row is controlled by a pattern bar milled to provide cam surface for controlling the movement of the pads. Thus for any desired design of carpet, it is necessary to calculate from the designer's sketches the required printing program, to calculate from this the required form of the pattern bars, and then to manufacture over 250 bars (for a six-colour installation) by precision milling. This is an extremely tedious procedure, and the high costs involved can only be contemplated when a lengthy run of carpet is to be produced. Moreover, such known machines are extremely prone to misprinting and breakdown owing to their mechanical complexity and the likelihood of breakages in the pattern bars.

It is therefore an object of the present invention to provide apparatus for printing a sheet of yarns in which these disadvantages are eliminated or substantially mitigated. It is also an object of the invention to provide such an apparatus, in which the pattern to be printed can be easily and quickly set up and changed without the production of mechanical control parts.

The invention accordingly provides apparatus for printing a sheet of yarns with colours for subsequent processing to form a textile product having a coloured pattern, the apparatus comprising a plurality of spaced printing assemblies each including a trough for holding dye, a dye-applying roller rotatable in the dye, and a plurality of printing elements individually movable toward the dye-applying roller selectively to move selected yarns temporarily into engagement with the dye-applying roller; a memory adapted to store data representing a desired pattern; speed sensor means for supplying signals representative of movement of the yarn; and actuating means for actuating said printing elements in response to data stored in the memory and to said signals.

In another aspect the invention provides a method of printing a sheet of yarns with colours for subsequent processing to form a textile product having a coloured pattern, comprising passing the sheet of yarns through a plurality of spaced printing assemblies, each printing assembly comprising a rotating dyeapplying roller and a series of printing elements individually movable toward the dyeapplying roller selectively to move selected yarns temporarily into engagement with the dye-applying roller; the method further including the steps of: coding a desired pattern into digital signals, storing the coded signals in a memory, moving the sheet of yarns at a pretermined speed with respect to the dye-applying roller, and controlling actuation of the printing elements in accordance with the stored data in synchronism with the yarn movement.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of a yarn printing installation embodying the invention; Figure 2 is a diagrammatic illustration of the control of one printing roller in greater detail; Figure 3 is a side elevation showing the printing mechanism; and Figures 4a, b, carve control signal waveforms.

Referring to Fig. 1, a creel 10 supplies yarns to form a yarn sheet 1 2 to be printed.

Typically. the yarn sheet 1 2 will comprise 1 28 yarn ends. The yarn sheet 1 2 passes through a yarn reservoir 14, a printing apparatus designated generally at 16, a first compensating apparatus 18, a steam dye-fixing unit 20, a washing/drying unit 22, and a second compensating apparatus 24, to be warped on a beam 26. The items 10 and 18-26 are well-known in the art and will therefore not be further described.

The printing apparatus 1 6 comprises dyeapplying rollers 28 each rotating in a trough 30 containing a desired dye. In the present embodiment six rollers 28 are provided, but it will be apparent that any suitable number may be used. The yarn sheet 12 normally passes above the rollers 28, but the yarns may be selectively brought into engagement with the rollers to be dyed, as will now be described.

Referring particularly to Figs. 2 and 3, each roller 28 has associated therewith a series of printing rollers 30 and a corresponding series of electro-pneumatic devices 32.

The roller 28, which is of relatively large diameter, is located beiow the yarn sheet 1 2 and extends transversely throughout the width of the sheet, and it is driven at the same speed as the dye-applying rollers of the other assemblies, preferably by a common drive.

The rollers 30, which are of relatively small diameter and are freely rotatable, are located above the sheet of yarns. There may be one roller 30 directly above each yarn or each roller may extend across a plurality of yarns, e.g., four or eight, and each roller 30 preferably has a corresponding number of grooves to prevent lateral displacement of the yarns during printing.

Each roller 30 is mounted at one end of a carrier 34 which is pivotally suspended intermediate its ends on the free end of an arm 36 whose other end is secured to the frame of the apparatus. At the end of the carrier 34 remote from the roller 30, there is a counterweight 38.

The roller 30 is shown in its operative position in which it is pressing yarn into contact with a film of dye on the roller 28.

The roller 30 is pivoted to its printing position by the piston rod 40A of a pneumatic pistonand-cylinder device 40, whose valve gear within a casing 42 is controlled by a solenoid within a casing 44. When and for how long the roller 30 is held in its printing position is determined by a programmed computer, as will be later described. When the air inlet valve is closed and the air outlet valve is opened, and the pressure of the piston rod 40A on the upper face of the carrier 34 is thus relieved, the weight 38 causes the carrier to pivot clockwise (in Fig. 2) so that the roller 30 rises clear of the yarn, and the yarn rises clear of the dye on the roller 28. The arm 36 has a tail portion 36A which is a push fit in a slot 46 between two superimposed plates 48 secured to the framework, so that the arm 36 and the carrier 34 can be easily removed and replaced when necessary.The tail portion 36A is preferably forked and the fingers of the fork lie to opposite sides of and engage two pins between the plates 48 to prevent iateral displacement of the arm 36.

Referring now particularly to Figs. 2 and 4, the desired pattern of a carpet or the like is translated from the artist's sketch to squared paper 50 on which each square represents one tuft; this is of course well known per se.

The pattern on the squared pattern point paper 50 is then encoded onto paper or magnetic tape 52. For example, when working with a six-colour pattern for a six-colour printing machine, each colour will be assigned a respective digit, say 1-6. There will also be assigned an end-of-line code, say 0, and an end-of-pattern code, say 9. This encoding can be performed very rapidly and easily by unskilled personnel.

The tape 52 thus containes a stream of data consisting of the colour of sequential pattern points interspersed with end-of-line signals and end with an end-of-pattern signal.

This is converted into a form more suitable for controlling the printing machine. The conversion can be performed on-line while the machine is running, but we prefer to perform the conversion off-line in a digital computer 54, to provide an operating magnetic tape 56.

The data conversion consists essentially of allowing for the spacing between the dyeapplying rollers 28. It will be appreciate that if adjacent points in a pattern row are to be printed with, say, colours 1 and 6 then the respective yarns in the yarn sheet will be printed by the first and sixth dye-applying rollers at different moments in time as a function of the speed of the yarn sheet. The conversion process thus converts the row-byrow pattern coding into rows of 8 X 1 6 bit words for each dye-applying station, each group identifying those yarn ends which must be printed at that station at a given moment.

This conversion is a straightforward process of moving the colour codes, which can easily be realised by a skilled person using many suitable forms of data processing, and is therefore not described in further detail.

The operating tape 56 is loaded when the pattern is to be printed on a control computer 58 (Fig. 2). Each dye-applying station is provided with a slave interface unit 60 which communicates with the computer via a master interface unit 62. The master interface unit 62 is also connected to and controls the power supply to the printing assemblies and to an air compressor 64. Each slave interface unit 60 is mounted on the framework adjacent a dye-applying roller 28 and is also connected to a speed sensor to be described and to the solenoids.

In operation, the printing procedure is deformed when the slave interface unit 28 actuates the solenoids in the casings 44 in accordance with a row of data from the computer 58 and a timing signal from the speed sensor for that station.

Selected printing rollers 30 are thus moved towards the dye-coated rollers 28, pressing the yarn on to the surface thereof, so that dye is transferred from the coated rollers 28 on to the yarn. After a predetermined period which is variable, the slave interface unit 60 removes the power from the solenoids, thereby terminating the printing of these particular segments of yarn.

When the printing is to be performed, the slave interface unit 60 requests a row of data at any given time from the computer. However, the slave interface can store two rows of data at any time which permits, when appropriate, power to be supplied long enough to the solenoids to enable the printing rollers to print on two or more successive segments, and also permits data access at any time in the printing cycle.

The slave interface unit 60 also receives timing signals from the speed sensor which senses the speed of the yarn.

The speed sensor includes a toothed wheel 66 and two magnetic proximity switches 68, 70. The toothed wheel 66 is mounted coaxially on the roller 28 and rotates with the roller 28 relative to the proximity switches 68, 70 which provide a timing signal to the slave interface unit 60, to control actuation of the solenoids. The timing signal is a pulse waveform produced by a combination of signals from switches 68, 70. The switches 68, 70 are circumferentially and radially adjustable to provide output waveforms 72, 74 respectively, as shown in Figs. 4a and 4b. These waveforms 72, 74 are continuously combined in a logic circuit in the slave interface unit to provide a timing signal 76 as shown in Fig.

3c. This timing signal has an ON period 78 controlled by the trailing edges 80, 82 of the pulse waveforms 72, 74. The timing signal 76 is applied via the. slave interface unit 60 to control the actuation of the solenoids. The printing of a pattern on the yarn is kept regular, and the length of printed segments is controlled by varying the duration of the ON period by adjusting either one, or both, of the proximity switches 68, 70.

Alternatively, the printing procedure may be controlled by a binary shaft encoder system which provides signals to each slave interface unit continuously as the yarn moves. The shaft encoder signals are in the form of binary digits and the least significant bit of the encoder can be set to change state for a given yarn movement, for example, 1 bit per 1/16".

The printing frequency of the rollers 30 is controlled by the encoder frequency and the print segments can also be advanced or retarded by the slave interface unit at each roller 28 to obtain correct print registration or phasing of the pattern. The length of each nominal print segment can be adjusted in fractions of the segment length, the fraction depending on the shaft encoder pulse frequency, so that a practical value of actual print length can be set.

The invention makes it possible to greatly simplify the control of the printing apparatus, and in particular to make the setting-up of a desired pattern extremely simple, quick and cheap. It is possible to code an artist's design and print and tuft a short length of carpet for experimental purposes, which was previously hopelessly impractical for reasons both of time and expense.

It also becomes possible to achieve greater flexibility in control. For example, the computer can be programmed to alter the colour codes in a specified way before these are read out to the slave units. Thus a design of dark blue pattern on pale blue background, to take one simple example, can be printed as light blue pattern on dark blue background by a simple program instruction and without making any change at the printing stations.

Another technique which becomes possible is to design and code a pattern for, e.g., 4metre wide carpeting and to use the coded data also for producing 12-foot wide carpeting by reducing the number of yarn ends in the sheet and by programming the computer to suppress the data relating to the missing yarn ends. Those yarn ends which are omitted can be chosen for each design so as to cause the least visual disturbance to the pattern.

In a particularly preferred form of the invention, each of the movable rollers 30 engages eight yarns, and two yarns from each group of eight are fed side-by-side to four separate warp beams, e.g. through flexible tubes. This is convenient for manufacturing carpet in which, as is conventional, there are four pattern repeats across the carpet width. This technique minimises the amount of data to be stored, since it is necessary to code and record only one widthwise repeat of the pattern.

Claims (12)

1. A method of printing a sheet of yarns with colours for subsequent processing to form a textile product having a coloured pattern, comprising passing the sheet of yarns through a plurality of spaced printing assemblies, each printing assembly comprising a rotating dye-applying roller and a series of printing elements individually movable toward the dye-applying roller selectively to move selected yarns temporarily into engagement with the dye-applying roller; the method further including the steps of: coding a desired pattern into digital signals, storing the coded signals in a memory, moving the sheet of yarns at a predetermined speed with respect to the dye-applying roller, and controlling actuation of the printing elements in accordance with the stored data in synchronism with the yarn movement.

2. A method as claimed in claim 1, in which a desired pattern is coded line-by-line, onto a first memory medium, and the coded design is then converted in a digital computer into rows of data characters representing the printing required simultaneously in each of the spaced printing assemblies, which rows of data are stored on a second memory medium for loading when desired into said memory.

3. A method according to claim 1 or claim 2, in which the pattern repeats n times across the finished product, each printing element engages a group of n yarns or a multiple thereof, and after printing the yarn sheet is warped onto n beams, the yarns from each said group being equally divided between the beams.

4. A method of printing a sheet of yarns, substantially as hereinbefore described with reference to the drawings.

5. Apparatus for printing a sheet of yarns with colours for subsequent processing to form a textile product having a coloured pattern, the apparatus comprising a plurality of spaced printing assemblies each including a trough for holding dye, a dye-applying roller rotatable in the dye, and a plurality of printing elements individually movable toward the dyeapplying roller selectively to move selected yarns temporarily into engagement with the dye-applying roller; a memory adapted to store data representing a desired pattern; speed sensor means for supplying signals representative of movement of the yarn; and actuating means for actuating said printing elements in response to data stored in the memory and to said signals.

6. Apparatus according to claim 5, in which the printing elements each comprise a freely-rotatable printing roller movably mounted on a framework; and said actuating means includes a respective solenoid for each printing roller and arranged on actuation to move the printing roller toward the dye-applying roller.

7. Apparatus according to claim 6, in which each printing roller is mounted at one end of a carrier which is pivotally suspended intermediate its ends, a counterweight being provided at the other end of the carrier to bias the printing roller away from the dye-applying roller.

8. Apparatus according to any of claim 5 to 7, in which the speed sensor means for each printing assembly comprises a toothed wheel mounted for rotation with the dyeapplying rollers and two magnetic proximity switches positioned to be actuated by passage of the teeth.

9. Apparatus according to claim 8, includ ing means for manually adjusting the radial and circumferential position of one or both proximity switches whereby fine adjustment of the spacing and length of printed segments may be made during operation of the apparatus.

1 0. Apparatus according to any of claims 5 to 9, including a respective electronic slave unit associated with each printing assembly, and in which the actuating means includes a master unit interfacing between the slave units and the memory.

11. Apparatus according to claim 10, in which the memory stores said data in rows of words, the master unit is arranged to transmit a row of words in response to speed signals from the slave units, and each slave unit is adapted to store two consecutive rows of words.

12. Apparatus according to any of claims 5 to 11, in which the memory is comprised in a computer, and the computer is programmed to selectively transpose the data to give a corresponding transposition of the printed colours.

1 3. Apparatus according to any of claims 5 to 12, in which each printing element engages n fibres or a multiple thereof, and including means for warping the printed fibres onto n beams and guide means for distributing the fibres equally to the beams.

1 4. Apparatus according to claim 5 and substantially as herein described with reference to the accompanying drawings.