GB2216042A

GB2216042A - Spreadable material applicator

Info

Publication number: GB2216042A
Application number: GB8902657A
Authority: GB
Inventors: Alastair Hunter Munro
Original assignee: Mcgavigan John & Co Ltd
Current assignee: Mcgavigan John & Co Ltd
Priority date: 1988-02-23
Filing date: 1989-02-07
Publication date: 1989-10-04
Also published as: GB8902657D0; GB8804124D0

Abstract

A device for applying spreadable material such as ink in paste form to a substrate such as a screen for use in a screen printing process comprises a material applying nozzle (8) arranged to reciprocate transversely of the substrate (4). The nozzle is mounted on a holder (10) which slides along a guideway (18). A drive arrangement (22) for said nozzle comprises a screw drive shaft driven by a motor (24). Switch (M) detect the arrival of the nozzle at one of the two end positions (26) of its traverse of the substrate and reverse the direction of travel of said nozzle until a second end position is reached. The swathe of material applied by the device will be in a ploughed furrow pattern to obtain an even distribution of material. <IMAGE>

Description

SPREADABLE MATERIAL APPLICATOR DEVICE The invention is concerned with improvements in or relating to devices for applying spreadable material to a substrate, particularly but not exclusively for applying pigment-containing inks in paste or cream-like form to a substrate such as a screen in a screen-printing technique.

In the use of screen-printing it is desirable that the spread o ink on the screen should be as even and regular as possible and, importantly, that the optical density of the ink should not vary through evaporation of solvent from the ink.

It is an object of the invention therefore to provide a device capable of improving the spreading of material on a substrate.

The invention provides a device for applying spreadable material to a substrate so as to provide a substantially even layer. thereupon, comprising a support for a substrate, material applying nozzle means, means to provide relative movement between the nozzle means and the substrate in at least one direction of travel and traversing means to cause the traverse of said nozzle means with respect to the substrate in a second direction substantially normal to the first mentioned direction, said traversing means comprising a drive arrangement for a slidable support of said nozzle means, means for restricting movement of said nozzle means to linear movement longitudinally of the screw drive shaft and switch means adapted to detect the arrival of the nozzle means at one of the two predetermined end positions of its traverse of the substrate and reverse the direction of the linear travel of said nozzle means until a second predetermined end position is reached.

Preferably the drive arrangement may be a screw drive shaft on which is slidably mounted the nozzle support.

Advantageously the switch means comprises microswitches. These may be mounted for movement with said nozzle means and adapted to be operated by contact with abutment surfaces provided at each of said predetermined end positions, or alternatively may be mounted upon the abutment surfaces so as to detect contact by the nozzle means.

Conveniently, the operation of the microswitches may be adjusted as desired.

In an example of the invention to be described below, the substrate is the screen of a screen printing machine and the spreadable material is ink in paste or cream-like form.

In this context, the quality of the printing operation may be improved by ensuring that the ink is evenly applied to the screen in a ploughed furrow movement which is arranged so that each traverse produces a substantially continuous swathe of ink of even or substantially even depth so that there is a consistent supply of fresh ink and moreover any evaporation of solvent from the ink occurs at a consistent rate over the screen and is not affected unduly by incomplete swathes or by unduly thick areas of deposit such as may occur at end portions of the traverse path.

The invention therefore further provides a method of applying spreadable ink material to a substrate comprising a screen for a screen printing process comprising, in the use of apparatus as described above, the step of providing a ploughed furrow swathe pattern of ink material upon the screen.

There will now be described, with reference to the drawing, an example of a device according to the invention.

It will be understood that the description is given by way of example only and not by way of limitation.

The drawing shows a general perspective view of a print machine incorporating the device according to the invention.

The print machine, indicated at 2, includes a printing screen 4 supported therein to receive a layer of printing ink 6 extrudable from a nozzle 8. The nozzle 8 is mounted for reciprocating movement transversely of the screen 4 so as to partake of a ploughed furrow movement to deposit successive swathes of ink thereupon.

The nozzle 8 is supported by a holder 10 and the ink is supplied thereto through a hose 12 under the controlled action of an electric pump 14 from an ink supply container 16.

The holder 10 is slidably mounted in a guideway 18 formed in a housing 20 of the machine, the housing containing a drive mechanism 22 comprising a screw (not shown) and operated by an electric motor 24.

The direction of operation of the motor 24 is reversible through a gear arrangement to reverse the direction of rotation of the screw to cause the support 10 to travel to the left or to the right as viewed in the drawing and to cause the nozzle to traverse the screen. The reversal of the screw rotation is controlled by the operation of microswitches M which may be mounted on the support 10 as shown or on contact surfaces associated with side frame members 26 of the machine as desired in order to register arrival of the support 10 at the end of each stroke of its traverse.

Various modifications may be made within the scope of the invention as defined in the following claims.

Claims

CLAIMS:

1. A device for applying spreadable material to a substrate so as to provide a substantially even layer thereupon, comprising a support for a substrate, material applying nozzle means, means to provide relative movement between the nozzle means and the substrate in at least one direction of travel and traversing means to cause the traverse of said nozzle means with respect to the substrate in a second direction substantially normal to the first mentioned direction, said traversing means comprising a drive arrangement for a slidable support of said nozzle means, means for restricting movement of said nozzle means to linear movement longitudinally of the screw drive shaft and switch means adapted to detect the arrival of the nozzle means at one of the two predetermined end positions of its traverse of the substrate and reverse the direction of the linear travel of said nozzle means until a second predetermined end position is reached.

2. A device as claimed in claim 1, wherein the drive arrangement is a screw drive shaft.

3. A device as claimed in claim 2, wherein the nozzle means is mounted for sliding linear movement along said shaft.

4. A device as claimed in any one of the preceding claims, wherein the switch means are microswitches which are positioned to detect contact between said nozzle means and an abutment surface positioned at one of said predetermined end positions.

5. A device as claimed in claim 4 wherein the microswitches are mounted for movement with the nozzle means.

6. A device as claimed in either one of claims 4 and 5, wherein the operation of the microswitches is adjustable.

7. A device as claimed in any one of the preceding claims wherein the nozzle means comprises a nozzle supported upon a holder to which the spreadable material is supplied, there being provided pump means for the supply of said material under controlled pressure.

8. A method of applying spreadable ink material to a substrate comprising a screen for a screen printing process comprising, in the use of apparatus according to any of the preceding claims, the step of providing a ploughed furrow swathe pattern of ink material upon the screen.

9. A device for applying spreadable material to a substrate, constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as shown in the drawing.

10. A method for applying spreadable ink material to a screen of a screen printing apparatus, substantially as hereinbefore described with reference to the drawing.