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(11) | EP 0 077 310 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Treatment arrangement intended for a stencil frame fitted with a screen and with an applied pattern |
| (57) A treatment arrangement for a stencil frame (3c) fitted with a screen (3) and with
the pattern (3d) applied, known as a stencil (2), incorporating organs (4,5) for the
application to the stencil (2) of one of more solutions or solvents and organs (6,
7) for treating the stencil, preferably mechanical treatment with brushes capable
of being rotated, and feed organs (25) designed to feed the stencil (2) through the
arrangement. The feed organ (25) has a roller (26) with an irregular surface, designed
for the purpose of transporting the stencil (2) to be brought into interaction with
the stencil frame (3c). The roller (26) of the feed organ (25) has an outer surface
with a cross-section in the form of a regular 'n'- sided figure. The value of 'n'
is selected so as to be lower than 10, preferably 4 or 6. |
TECHNICAL FIELD.
[0001] The present invention relates to a treatment arrangement, and in particular to a treatment arrangement of a type designed to treat a stencil frame fitted with a screen and with the pattern applied in the usual manner. A stencil frame fitted with a screen and with a pattern applied to the screen in the usual manner is referred to in the following specification as a 'stencil'. The treatment arrangement incorporates organs enabling one or more solutions or solvents to be applied to the stencil, organs for the chemical and/or mechanical treatment of the stencil, preferably mechanical treatment with the help of brushes so arranged as to rotate, and organs designed to feed the stencil through the arrangement.
[0002] The invention finds a particularly suitable application in a treatment arrangement of the type designed for cleaning a stencil after it has been used In a screen printing machine. Thus the treatment arrangement which is the subject of the invention is designed to be capable not only of removing damp and hardened ink, but also of removing pattern material attached to the screen, and also of providing initial treatment of the screen enabling new pattern material to be applied, at the same time washing and rinsing the screen if necessary.
[0003] The treatment arrangement which is the subject of the invention may be used both with patterns produced on a screen by the direct method and with patterns produced on a screen by the indirect method.
DESCRIPTION OF THE PRIOR ART.
[0004] Previously disclosed are a number of treatment arrangements enabling stencil frames fitted with a screen to be treated, more particularly to be washed, after they have been used in a screen printing machine.
[0005] Previously disclosed treatment arrangements for this purpose were designed in such a way that the stencil frame had to adopt a vertical or essentially vertical attitude during the actual treatment process. This required the stencil frame to be held firm whilst the application of the solution and solvents, the mechanical treatment and the spraying of the rinsing fluid, etc., took place via organs so arranged as to move in parallel over the stencil.
[0006] An example of a treatment arrangement of this type is the one described in American Patent 4 214 522, granted to Dag Bille on 29 July 1980 and assigned to Svecia Silkscreen Maskiner AB, Norsborg, Sweden.
DESCRIPTION OF THE PRESENT INVENTION.
TECHNICAL PROBLEM.
[0007] A major requirement has existed for some time to be able to invent a treatment arrangement of a kind in which the stencil is caused to advance inside the treatment arrangement, thereby enabling solutions and solvents to be applied to the stencil from fixed applicators. One particularly important wish is the ability to make use of brushes which are securely attached to a frame but which are free to rotate, so as to permit the mechanical treatment of a stencil moving past the brushes during the cleaning and treatment operations.
[0008] It is obvious that the type of treatment arrangement which utilises fixed rotatable brushes and which utilises fixed feed organs for the solutions and solvents will require a transport device so that the stencil can be caused to pass through the entire treatment arrangement.
[0009] The stencil is exposed to the effect of extremely high forces, however, If brushes arranged In pairs to either side of the stencil and rotating In opposite directions are brought into contact with the stencil, which also places high demands on the transport device If transport is to take place without slip, or at any rate with only very little slip.
[0010] The problem is made more difficult than usual by the fact that the solutions and solvents used are of such a nature as to prevent or at best to reduce significantly the friction between the stencil and the transport device, making it difficult by simple means to cause the stencil to pass through the treatment arrangement, and the problem is made particularly complex .by the fact that the stencil frames have different external dimensions.
[0011] It has therefore been an extremely challenging technical problem to create conditions such that the stencil is capable of being transported In a simple manner through the treatment arrangement without giving rise to any significant slip between the stencil and the transport device. To arrange a transport device in the form of a chain conveyor with clamping organs for stencil frames of different sizes is far too complex and costly a solution.
SOLUTION.
[0012] The present Invention relates to a treatment arrangement designed for a stencil, said arrangement Incorporating organs for the application to the stencil of one or more solutions or solvents and organs for treating the stencil, preferably mechanical treatment with the help of rotatable brushes, and also a feed organ designed to feed the stencil through the arrangement.
[0013] A unique feature of the invention is that the feed organ will Incorporate at least one rotatable organ having an Irregular surface, said surface being designed for the purpose of transporting the stencil to be brought Into Interaction with the stencil frame incorporating the stencil.
[0014] According to the invention it is proposed that the feed organ shall have a surface with a cross-section in the form of a regular 'n'-sided figure, in which the value of 'n' is lower than 10 and is preferably selected as 4 or 6 , preferably 4 .
[0015] The feed organ thus Incorporates not only the rotatable organ with the irregular surface , but also a rotatable organ with a circular surface, of which the rotatable organ with the irregular surface is driven.
[0016] The stencil is fed by these feed devices through rotatable brushes arranged in pairs and rotating in opposite directions.
[0017] The invention specifically requires a number of rotatable organs with an irregular surface and rotatable organs with a circular surface to be arranged in pairs and to be positioned along a system for conveying the stencil through the entire arrangement, and also requires the rotatable organ with the irregular surface and with a horizontal position for the stencil to be positioned beneath the stencil.
ADVANTAGES.
[0018] The advantages which may be considered to be associated with a treatment arrangement according to the present invention are that the stencil can be transported in a simple manner through the entire treatment arrangement without any slip or without any significant slip between the stencil and the transport device, because of the forces which act upon the stencil during the mechanical treatment of the stencil, in particular when the treatment is by means of rotatable brushes rotating in opposite directions to each other.
[0019] What may be regarded as the principal characteristic feature of a treatment arrangement in accordance with the present invention is indicated in the characterizing part of the following Patent Claim 1.
BRIEF DESCRIPTION OF THE ATTACHED DRAWING.
[0020] An embodiment of the present treatment arrangement is described below in more detail with reference to the attached drawing, in which
Figure 1 shows a perspective view of the most essential parts of the treatment arrangement enabling the present invention to be appreciated;
Figure 2 shows a sectional view of part of a stencil;
Figure 3 shows on a somewhat enlarged scale the interaction between a rotatable organ with an irregular surface and a rotatable organ with a circular surface incorporated in a feed organ.
DESCRIPTION OF THE PREFERRED EMBODIMENT.
[0021] Figure 1 illustrates a treatment arrangement 1 for a stencil 2 fitted with a screen 3 , said treatment arrangement being Intended to remove ink and pattern material and also to provide Initial treatment enabling new pattern material to be applied to a used screen fitted in a stencil frame for use In a screen printing machine. The stencil 2 consists of a stencil frame 3c , fitted with a screen 3 and with a pattern 3d applied to the screen. Figure 2 shows the pattern 3d to have been applied to one side 3b of the screen 3 .
[0022] The treatment arrangement 1 incorporates organs for the application to the stencil 2 of one or more solutions or solvents, said organs being in a fixed relationship to the treatment arrangement. Figure 1 shows only a single pipe 4 fitted with a number of jets 5 directed at a brush 6 , although it is obvious that the entire treatment arrangement will contain a number of similar pipes with jets enabling the stencil 2 and also the frame 3c to be given the desired treatment in the different sections.
[0023] The expressions solutions and solvents In this context denote previously disclosed ink and/or pattern removing materials which are also capable of being applied In a previously disclosed manner, e.g. via high-pressure spray nozzles.
[0024] The treatment arrangement incorporates a number of organs facing in the direction In which the stencil is transported for treating the stencil. It is obvious that the design of the organs will vary depending on the nature of the treatment. Each Individual case may involve purely mechanical and/or purely chemical treatment, or a combination of both. The preferred embodiment relates to mechanical treatment, said treatment being performed with the help of brushes securely attached to the frame but able to rotate inside the frame and arranged In pairs, one above and one below. In this way one brush 6 will interact with another brush 7 , with the brushes being so arranged as to rotate in opposite directions in conformity with all the other brushes included in the treatment arrangement.
[0025] If an embodiment of the treatment arrangement in which the stencil requires to be fed through the arrangement in a horizontal position is chosen, then the brushes must, of course, be positioned above and below the transport track.
[0026] If, on the other hand, an embodiment of the treatment arrangement in which the stencil requires to be fed through the arrangement in a vertical position is chosen, then the brushes must, of course, be positioned vertically one either side of the transport track.
[0027] It may be desirable in both embodiments to allow the rotational axis of the brush to form an angle other than a right angle with the direction of transport.
[0028] The typical embodiment of the treatment arrangement 1 is divided up Into five different sections, and each of the sections intended for different treatments can, of course, be allocated Its own particular task. In the preferred embodiment, however, It is proposed that the first section 10 shall be used for the removal of ink, for which purpose not only a first pair of brushes 6 and 7 is required, but also a second pair of brushes 8 and 9 . Materials for dissolving the ink can be applied via the pipe 4 and the jets 5.
[0029] The second section 11 is specifically intended for rinsing and accordingly Incorporates the necessary organs (not illustrated) for applying the rinsing agent to the stencil.
[0030] The third section 12 is used for the removal of the pattern, for which purpose two pairs of brushes are required 15,16 and 17,18 . In this case, too, organs (not illustrated) are required for the application of the solvent.
[0031] The fourth section 13 Is used for a subsequent treatment and for washing the stencil with the help of high-pressure water jets. Section 13 Incorporates rotatable brushes 19,20 . Finally, the fifth section 14 Is used for final rinsing and de-greasing, and use is also made here of fixed brushes which are free to rotate 21,22 .
[0032] In order to be able to cause a stencil complete with its stencil frame to pass through an inlet orifice 23 and to be transported through the entire treatment arrangement as far as the outlet 24 , the transport device requires to incorporate a number of feed organs.
[0033] Figure 3 shows one of these feed organs, and this is identical with the feed organ present in section 10 , with the two feed organs present In section 11 , with the feed organ present in section 12 , with the feed organ present in section 13 , and with the two feed organs 25 present in section 14 .
[0034] Each of the feed organs 25 incorporates at least one rotatable organ 26 with an Irregular outer surface designed for the purpose of transporting the stencil 2 to be brought into interaction with the stencil frame 3c .
[0035] The expression irregular surface in this context denotes that the surface Is formed with Irregularities or edges intended to be pressed against the stencil frame 3c and to drive-the stencil frame 3c through the sections in the treatment arrangement. Accordingly metal contact is required to be present between the outer surface of the feed organ and the frame.
[0036] The rotatable driven organ 26 may with advantage have a surface with a cross-section in the form of a regular 'n'- sided figure, for which the value of 'n' should preferably be selected so as to be lower than 10 . This value should really be selected so as to be 4 or 6 , preferably 4 .
[0037] The feed organ 25 incorporates not only the rotatable organ 26 with an Irregular surface, but also a rotatable organ 27 with a circular surface. Only the rotatable organ 26 need be driven.
[0038] The stencil frame 3c can now be fed between rotatable brushes 6,7 arranged in pairs and rotating in opposite directions and a number of rotatable organs arranged in pairs, included in the feed organ 25 , with an irregular surface and rotatable organs with a circular surface viewed from the side are arranged along the entire length of the system for conveying the stencil frame 3c through the arrangement 1 .
[0039] It should be noted that the rotatable organ 26 with an irregular outer surface is positioned beneath the stencil frame 2 and that the rotatable organ 27 with a circular surface Is acted upon by the pressure exerted by a spring 28 , one end of which is attached to the frame 29 of the treatment arrangement and the other end of which is attached to the organ in the form of a roller 27 , said spring pressure 28 holding the roller 27 against the organ 26 . The roller 27 can be raised and lowered against the spring pressure so as to follow any Irregularities.
[0040] By introducing the frame 3c through the opening 23 the frame will be brought into interaction with the feed organ 25 and it may then be found appropriate to turn the stencil frame 3c with the stencil 3 so that the side 3b becomes the upper side and the side 3a becomes the lower side. The stencil frame 3c will then be fed onwards by the feed organ 25 in section 10 through the brushes 8,9 to the feed organ 25 in section 11 . Rinsing will take place here. The stencil is then fed onwards to section 12 where solvents and solutions are applied In order to remove the pattern, at the same time as feed organs 25 present at that point feed the stencil onwards to section 13 where washing takes place.
1. A treatment arrangement for a stencil frame fitted with a screen and with the pattern
applied, known as a stencil, incorporating organs for the application to the stencil
of one or more solutions or solvents and organs for treating the stencil, preferably
mechanical treatment with brushes capable of being rotated, and feed organs designed
to feed the stencil frame through the arrangement, characterized in that the feed
device (25) Incorporates at least one rotatable organ (26) with an irregular surface,
designed for the purpose of transporting the stencil (2) to be brought into interaction
with the stencil frame (3c).
2. A treatment arrangement according to Patent Claim 1, characterized in that the
feed organ (25) has an outer surface with a cross-section in the form of a regular
'n'-sided figure.
3. A treatment arrangement according to Patent Claim 2,' characterized in that the value of 'n' is selected so as to be lower than 10.
4. A treatment arrangement according to Patent Claim 2, characterized in that the
value of 'n' is selected so as to be 4 or 6.
5. A treatment arrangement according to Patent Claim 1, characterized in that the
feed organ (25) incorporates not only a rotatable organ (26) with an irregular surface,
but also a rotatable organ (27) with an even (circular) surface.
6. A treatment arrangement according to Patent Claim 1, characterized in that the
rotatable organ (26) with the irregular surface is driven.
7. A treatment arrangement according to Patent Claim 1, characterized in that the
stencil (2) is fed between rotatable brushes (6,7) arranged in pairs and rotating
in opposite directions.
8. A treatment arrangement according to Patent Claim 1, characterized in that a number
of rotatable organs with an irregular surface and rotatable organs with a circular
surface when viewed from the side are arranged in pairs and are positioned along the
length of a system for conveying the stencil (2) through the arrangement.
9. A treatment arrangement according to Patent Claim 8, characterized in that the
rotatable organ with the irregular surface is positioned beneath the stencil frame.
10. A treatment arrangement in accordance with Patent Claim 5, characterized In that
the rotatable organ with the circular surface is held by means of spring pressure
against the rotatable organ with the irregular surface and is installed in such a
way that it is free to move and to follow any irregularities.