FR2468461A1 - RAIL FOR MANUFACTURING FRAME FOR STENCIL MACHINE POCHOIR - Google Patents

Abstract

Rail intended for the manufacture of a frame for a screen printing machine stencil. The rail 11 consists of a profile with a hollow section, one wall 11a of which has a projecting part 12 having opposite surfaces 12a, 12b and intended to be used with a device 13 for holding the frame. The frame can also be used with a second retaining device 3, 3b. The rail is cut and assembled by welding. A stencil 2 is then glued to the frame obtained. Application: positioning and holding of a stencil in a screen printing machine.

Description

The present invention relates to a special section rail and, in particular,

  a type of rail intended to be used

  for manufacturing a frame that can withstand bending.

  A screen or stencil is attached to this frame, and the complete frame, to which the stencil is attached, can then be used in a screen printing machine and held in position by means of frame holding devices which are part of the

  screen printing machine. The present invention aims primarily

  Such a rail can be manufactured in considerable lengths by extrusion, and then cut into suitable lengths in order to produce the various elements of the frame. It is then necessary to strengthen

  by welding at the corners, the ends of the frame elements.

  The rails of the nature indicated above and for the aforementioned purpose are usually made from a

  profile with perforations and grooves in order to

hold a light structure.

  A number of different rails are already known, all of which are obtained from a profile comprising

  perforations and grooves and which are intended to be used

  for the manufacture of a frame to maintain a stencil surely in position. The frame is specially

  shaped to be able to be used with the hand-held

  inside a silkscreen machine.

  The shape of the rails already well known for this purpose depends on the particular problem that we intend to solve

  with a rail having the profile in question. So, we usually

  striving to give the rail profile a shape intended to

  to facilitate the setting up of the stencil, the fixing of this

  ci on the rail and fixing the frame inside the

screen printing machine.

  We know that there are circumstances in the-

  which setting up and fixing a stencil in a

  framework subject it to strong constraints. These

  The size of the stretcher and the stencil are larger. The forces responsible for these constraints can be divided into two types, namely: a) the force causing a bulge of the frame inwardly and towards the center of the stencil, in the same plane as this stencil; and b) the force producing a twisting moment spreading

the frame of the stencil plan.

  The effects of the aforementioned constraints will be notable when the frame is made from a rail formed of a profile having perforations and grooves (section hollow section), and this effect can even be so great, in

  the case of certain sections with hollow sections, that it will prevent

  expensive correct operation of the printing process to

  inside the screen printing machine.

  Thus, a major problem encountered during the

  The bridging of a light frame from a hollow section rail is to obtain the least possible bulging of the frame inwards (under the effect of the force "a above), at the same time as It is desirable that the effect produced by the twisting moment on the frame (under the effect of the force "b" 1 above) be only small and preferably not be

  noticeable when the stencil is fixed in position.

  In order to keep the total weight of the frame and the stencil at a low value when it is fixed in position, it is desirable, on the one hand, for the rail to be light per meter

  current situation and, on the other hand, that the submission of the

  and stability to requirements such as the inconveniences

  above are becoming notable.

  A main wish associated with these frameworks for

  silk screen printing, particularly because the number of unframed formats is extremely limited and only a small number of them exist in practice, is that

  used to form the rail has adequate rigidity

  so that this rail can be used even in the case of large frames. It should be noted in this respect that the height will usually be the same for all frame sizes, but that the width may in principle vary at will, although of course the weight per meter of inward bulge according to "a" above and the effect of the torsional moment

point "b" above.

  To solve the problem thus posed, we will now

  describe a rail according to the present invention, consisting of

  in a section with hollow section and which is intended to be used

  used for the manufacture of a frame to which a stencil can be fixed surely. The complete frame, with the stencil fixed in posi-

  tion, can then be used in a screen printing machine.

  It can be considered as a feature of the present invention that at least one of the walls

  the profile has a projecting portion. This salient part

  lO must have opposite surfaces that deviate one

  on the other and are intended for use with a

keeping the frame.

  Another feature of the present invention

  is that the wall of a profiled element comprises a portion

  lante and is arranged to face the wall of a second profile also having a protruding portion and to move away from the latter when the two profiles are

  arranged on either side of the stencil.

  The protruding portion has two parallel surfaces

  interlaced and parallel to the stencil, but arranged so that both are on one side (above)

stencil plan.

  The present invention also describes a possibility of

  so that the thickness of the wall is greater at

  adjacent to the protruding part than at other points of the rail.

  The thickness of the wall, in the vicinity of surfaces that are

  of the other in the projecting part, but not in the vicinity of this projecting part, is larger than

other points of the rail.

  The present invention thus describes the possibility of producing a profile having a variable thickness according to the various points, so that this profile has a greater resistance to lateral bending. At the same time, it is within the scope of the present invention to give the hollow section profile a greater thickness of material.

  at the top, to compensate for the decrease in thickness and

  any torsion of the profile due to the tensile forces

stencilled.

  It has been found that a right angle between the upper and outer sides of the frame members facilitates their positioning during welding and cutting to the desired length. This arrangement also facilitates the adjustment to correspond to the holding device of the machine of im-

pressure by screen printing.

  The surface must also have ribs or be uneven or otherwise roughened to ensure better anchoring of the adhesive used

to fix the stencil to the frame.

  The advantages of a rail according to the present invention

  therefore, firstly, that the rail has a geometric shape

  a high degree of resistance to bulging of the frame member inwardly and the center of the stencil under the effect of the pulling forces applied by the stencil.

  the framework and, at the same time, it has been found

  kills a torsion-resistant structure imposed on the

  frame by the pulling forces exerted by the stencil.

  It has also been found that the profile of the rail according to the present invention makes it possible to use this rail with a holding device recently developed for a special frame. This holding device is designed so as, on the one hand, not to be disposed below the stencil and on the other hand, to fix the frame element concerned to the immediate contact of the stencil and in a plane which is only slightly displaced relative to the stencil plane (so as to reduce the torque). This profile also allows the rail to be used with other types of holding device

  designed for older types of frame.

  A presently preferred embodiment,

  indicating the main features of the present

  tion, will be described in more detail, by way of example no

  1, is a perspective view of a frame on which a stencil is held in position; FIG. 2 is a horizontal view of the frame of FIG. 1 maintained in a machine frame; screen printing device comprising holding devices and tracking devices; FIG. 3 is a vertical section through

  line III-III, of the box in Figure 1, intended to illustrate

  tres forces acting on an element of the frame in which the stencil is held in position; and FIG. 4 shows a section of a rail according to the

present invention.

  Figure 1 is a perspective view of a frame

  1 consisting of four elements la, lb, le and ld, whose ele-

  1a and 1c are arranged so as to be parallel and the elements lb and ld are similarly arranged so as to be parallel. The frame members are formed from a single rail having a substantially rectangular section profile with perforations and grooves. The section formed by the rail is called section section

dig.

  A stencil 2 is fixed in position on the elements la to ld so that this stencil is under tension and subjected to tensile forces, then the elements la to ld of the frame

  are permanently attached to the stencil by an adhesive.

  Once the stencil 2 is fixed in position (using an adhesive) on the elements 1a-1d of the frame, the effect of the efforts of

  traction on the stencil will cease because these forces are suppor-

  by the elements la to ld of the frame.

  Figure 3 shows how the forces to which the stencil 2 is subjected tend to move the frame member 1b to the left. The arrow "F" shows the force exerted on the element lb of the frame by placing in position the

  stencil, and the arrow "P" shows the movement or the bomb-

  the element lb of the frame inwards and to the position lb '(Figure 1) under the effect of the force "F". The force "F" also exerts on the element lb of the frame an action in the form of a torsion moment "M" which tends to twist the

  central part of the element lb so that the point lb "tends to

  to rise in Figure 3.

  The reference index 3 serves to indicate a

  maintaining device forming part of the screen printing machine and which consists of a heel 3a, against which the elements

  frame, for example lb, rest, as well as a screw 3b des-

  designed to act on the upper surface of the element lb of

  frame. This holding device is of an old type.

  This holding device has the disadvantage

  that element 3a is located below plane 2 'of the

choir 2.

  FIG. 2 shows how a stencil 2, fixed in position in a frame 1, must be able to be located quickly

  in another frame 4, arranged in a machine for serigra-

  graphy. For the sake of simplicity, the machine for

  phie does not appear in the figures of the attached plate.

  However, the frame 4 has three registration organs 5,

  6 and 7, against which the frame 1 can be adjusted. The rep-

  rabies is achieved using an inflatable hose 8 powered

  compressed air by a tube 9 controlled by a tap 10.

  The swelling of the flexible pipe 8 forces the frame

  2 coming into contact with the locating members 5 to 7.

  Figure 4 shows a section of a rail according to

  present invention which is used with a type of arrangement

  maintaining device different from that shown in Figure 3. This frame holding device has a shape such that it

  does not extend below the plane 2 'of the stencil 2.

  Thus, the present invention discloses a rail 11 for use in the manufacture or construction of a

  frame on which a stencil 2 can be held in position.

  The complete frame, with a stencil fixed in position, can then be used in a screen printing machine. The rail is obtained from a special section with hollow section which is

described in more detail below.

  The rail according to the present invention consists of

  a wall 11a, having a protruding portion 12, of

  smaller than the rest of the wall 11a. A second

  wall l1b, perpendicular to the first, is intended for use

  hold the stencil 2 in position. A third wall llc, per-

  pendicular to the second wall llb, thus faces towards the center of the stencil 2. A fourth wall lld, perpendicular

  at the third wall llc and the first wall 11a, is

  designed to be used with a maintenance device 3 of a familiar model (Figure 3) and is intended in particular for a type of rail profile other than that of the present invention. According to the present invention, at least one of the walls of the profile 11 must have a projecting portion 12, which has faces 12a, 12b which face each other and are intended to be used with a first disc.

  13 of the frame 1. The wall of a first element

  The profiled section 1b has a projection and is arranged

  in order to face the wall of a second element

  ld, having a protruding portion, the two parts

  lantes moving away from each other when both elements

  sections lb and ld are arranged on either side of the stencil 2.

  The projecting portion 12 has two parallel surfaces

  12a and 12b, also arranged to be parallel to the plane 2 'of the stencil 2 but to be placed so that the

  two surfaces 12a and 12b are on one side of the stencil 2.

  The outer surface 11b 'of the second wall 11b is ribbed so as to ensure better anchoring of a layer

  adhesive 2a used to attach the stencil 2 to the frame 11.

  The thickness of the wall, in the vicinity of the protruding portion 12 and the portion indicated at 14, is greater

  to the thickness of the wall in other parts of the profile.

  In the vicinity of the surfaces 12a and 12b which are made

  this in the salient part and correspond to the respective landmarks

  and 16, the thickness of the wall is greater than that

  in other parts of the profile, but not in the wall thickness in the vicinity of the projection 12 and the element 14. The third wall 11c has a thickness exceeding that of the second wall 11b and the fourth wall lld, and this thickness is essentially the same as that of

walls 15 and 16.

  The wall 11d, remote from the wall 11b holding the stencil 2 in position, is designed so that it can be

  used with a second device 3 for maintaining the frame.

  The distance between the wall 11b, intended to keep the stencil 2 in position, and the surface 12a, which is the closest to the projecting portion 12, is equal to or greater than the thickness of the holding device in the vicinity

of the element 13a.

  Thus, the entire holding device is

  located above the stencil plane 2.

  It will also be seen from FIG. 4 that the internal portions of the walls 11b, 11c and 11d comprise a number of ribs 17, partly intended to reinforce the profile constituting the rail and partly to maintain the dimensional stability when the profile is manufactured by extrusion

  aluminum, magnesium or similar material.

  It goes without saying that, without departing from the scope of the invention,

  many changes can be made to the

  rail for a stencil attachment frame.

Claims (10)

  1. Rail (11) for forming a frame (1) on which a stencil (2) is held in position, this frame complete with the stencil held in position then being used in a screen printing machine, the rail consisting of a section with a hollow section and being characterized in that at least   one (11a) of the walls of the profile has a portion   lante (12) having surfaces (12a, 12b) facing each other and intended to be used with a device (13) for maintaining the frame.   2. Rail according to claim 1, characterized in that the wall of one of the profiled elements (lb) is disposed facoh to face the wall of a second profiled element (lId) whose projecting part moves away of the protruding portion (12) of the element (1b) when the two profiled elements (1b)   ld) are arranged on either side of the stencil (2).   3. Rail according to claim 1, characterized in that the projecting portion (12) is designed to have two surfaces arranged parallel to the stencil (2), but placed so that the two surfaces are of the same side of the stencil (2).   4. Rail according to claim 1, characterized in   the outer surface (11b ') of one of the walls is   vated to form an anchor of a layer of adhesive (2a).   5. Rail according to claim 1, characterized in that the thickness of the wall (14) is greater in the vicinity of the projecting portion (12) at other points of this wall. 6. Rail according to claim 1, characterized in   in the vicinity of the opposite surfaces (12a, 12b), the thickness   wall (16) is greater than other points of this wall, but not to that existing in the vicinity of the wall. protruding portion (12).   7. Rail according to claim 1, characterized in that the wall (11d), opposite to the wall (11b) for holding the stencil in position, is designed to be used with a second device (3) for maintaining the frame (1, 11).   8. Rail according to claim 1, characterized in that a wall (11a) has a projecting portion (12) of smaller dimensions than the rest of the wall; in that a second wall (11b), perpendicular to the first wall (11a), is for holding the stencil (2) in place; in that a third wall (11c) is perpendicular to the second wall (11b) and in that a fourth wall (11d), perpendicular to the third wall (lic), is to be used with a second device ( 3) maintaining the frame (11, 1).   9. Rail according to claim 1, characterized in that the distance between a wall (11b), intended to maintain   the stencil (2) in position, and the surface (12a) closest to   sine of the projection (12) is equal to or greater than the thickness (13a), near the stencil (2), of the maintaining (13).   10. Rail according to claim 8, characterized in that the thickness of the third wall (11c) is greater   to that of the second (11b) and fourth (l1d) walls.