Screen Mounting System

Abstract

A tensioning frame (22) for tensioning a printing screen (3) includes a plurality of elongated beams (30A-30D) extending around the printing screen (3) to define the tensioning frame (22), at least one of the beams (30A-30D) including an opening (32) and dimensioned to allow the printing screen (3) to be received in a lateral direction (A) through the opening (32). Mechanisms for engaging the tensioning frame (22) with the printing screen (3) are described, as well as apparatus and methods that allow for lateral attachment of the printing screen (3).

Description

[Technical field]

[0001] The present invention relates to a tensioning frame for tensioning a printing screen, a method for loading a printing screen onto a tensioning frame, and a robot for loading a printing screen onto a tensioning frame. [Background technology]

[0002] Industrial screen printers apply a conductive print medium, such as solder paste or conductive ink, to a planar workpiece, such as a circuit board, typically by using an angled blade or squeegee to spread the conductive print medium through a pattern of openings in a printing screen (sometimes called a mask or stencil).

[0003] A printing screen is a substantially planar sheet that is cut prior to use to include openings forming the pattern to be printed. In one common form, the printing screen includes a screen sheet formed of a metal or plastic material, while in another common form, the printing screen includes a mesh including a flexible perforated sheet, such as a woven mesh of polypropylene or stainless steel strands. In either form, the printing screen must be held under tension during the printing operation, which is conventionally accomplished by removably mounting the printing screen to a rectangular tensioning frame. There are a variety of tensioning frames and methods for providing engagement between the printing screen and the tensioning frame, one well-known example of which is the VectorGuard® system, which is described in U.S. Pat. Nos. 5,233, 5,393, 6,431, 6,571, 6,663, 6,711, 6,896, 7,941, and 7,133. Other systems are described, for example, in U.S. Pat. Nos. 5,233, 5,393, 6,433, 6,571, 6,663, 6,711, 6,896, 7,971, and 7,133.

[0004] FIG. 1 is a schematic perspective view of the underside of a known VectorGuard® tension frame 1, FIG. 2 is a schematic perspective view of a known printing screen 3 adapted for engagement with the VectorGuard® tension frame 1 of FIG. 1, and FIG. 3 is a schematic cross-section of a beam 2A of the VectorGuard® tension frame engaged with the printing screen 3. As can be seen from FIG. 1, the tension frame 1 is planar and forms a rectangle defined by a number of (here four) elongated beams 2A-2D extending circumferentially to enclose and tension the printing screen 3 during use. The beams 2 are structurally identical. Adjacent beams are connected by corner pieces 4, one of which also includes a pneumatic port 6. Each beam includes several engagement surfaces 5 for engaging the printing screen 3 during use. As can be seen from FIG. 1, the individual engagement surfaces 5 of each beam 2 are adjacent and together form a compound engagement surface. With particular reference to FIG. 3, it will be seen that each beam (here beam 2A is shown) is hollow and includes an elongated channel formed therein, which extends parallel to the length of the respective beam 2 and has an opening 6 on its engagement side (i.e. its underside). The engagement sides of each beam 2 are coplanar and disposed parallel to the plane of the frame 1. Thus, the beams 2 are generally U-shaped in cross section. Disposed within the channel is an engagement body 7 with three generally radially extending arms. A first arm 8 engages a biasing member (here spring 9) disposed between the arm 8 and the inner surface of the beam 2A. A second arm 10 engages a pneumatically inflatable tube 11 disposed between the arm 10 and the inner surface of the beam 2A and connected to a pneumatic port 13. A third arm 12 has an engagement surface 5. The engagement body 7 is mounted for rotation about a spindle 14 that is an integral part of the beam 2, the rotation being controlled by the expansion of the tube 11 acting against the biasing force of the spring 9. The third arm 12 is sized so that the engagement surface 5 projects outwardly of the beam from the channel opening 6 during at least a portion of the range of movement of the engagement surface during rotation of the engagement body.To tension the printing screen 3, the tube 11 is first expanded to rotate the engagement body 7 clockwise as shown, thus moving the engagement surface 5 to the left as shown and slightly retracting into the channel. The printing screen 3 has a patterned foil / mesh 15 as shown in FIG. 2, and a supporting edging 16 including an edging corner piece 161 is positioned adjacent to the underside of the frame 1. Air pressure is then released from the tube 11, which contracts, allowing the engagement body 7 to rotate counterclockwise as shown under the biasing force of the spring 9, so that the engagement surface 5 moves to the right and slightly outward as shown to engage the corresponding sloped profile of the edging 16, thereby tensioning the printing screen 3.

[0005] Each beam 2 includes a projection 17 located on its inner side, i.e., the side facing the interior of the tensioning frame 1, which projects towards the printing screen 3 in use, i.e., downwards as shown. The distal end of the projection 17 forms an abutment surface 18. It will be appreciated that when the printing screen 3 is placed in the tensioning frame 1 and tensioned by engagement of the engagement surface 5 with the edging 16, the rotational movement of the engagement surface 5 causes the edging 16 to both move laterally away from the centre of the tensioning frame 1, thereby increasing the tension in the printing screen 3, and also slightly upwards towards the centre of the beam 2. This vertical movement lifts the foil / mesh 15 into contact with the abutment surface 18. It will be appreciated that together, the abutment surfaces 18 of each beam 2 therefore act as a bearing edge and define the plane of the tensioned foil / mesh 15 in use.

[0006] In practice, the VectorGuard® tension frame is manufactured by forming each beam 2 and each engagement body 7 as a metal extrusion. Each engagement body 7 can then be slid from the beam 2 onto a spindle 14, and the spring 9 and tube 11 are also inserted into one end of the beam and slid along to its intended position.

[0007] In particular, the VectorGuard® system provides simple, consistent and reliable operation and has been widely adopted by the industry.

[0008] However, a problem exists with such known devices in that it is difficult to automate the mounting of the printing screen to the tension frame, and subsequently to the printing press.

[0009] To mount the printing screen 3 on the tension frame 1, it is recommended that the tension frame 1 be placed upside down on a flat surface such as a table. Air pressure is applied to the tension frame 22 to expand the tubes 11, which draw the arms 12 into their channels. The printing screen 3 is then positioned under the tension frame 1 and the supply of air pressure is stopped. The arms 12 can then move under the action of the springs 9 to engage the edging 16 of the printing screen 3 and tension the screen. This allows the printing screen 3 to be centered on the tension frame 1. The mounted tension frame 1 is then turned right side up and the mounted frame is placed in the printing press for use in the printing operation. Mounting the tension frame 1 therefore requires two separate inversions of the frame, with an intermediate screen positioning step followed by a separate machine loading step. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2003 / 093012 [Patent Document 2] International Publication No. 2005 / 046994 [Patent Document 3] International Publication No. 2007 / 091035 [Patent Document 4] International Publication No. 2009 / 047012 [Patent Document 5] GB 2526536 [Patent Document 6] U.S. Pat. No. 5,606,911 [Patent Document 7] U.S. Pat. No. 5,606,912 [Patent Document 8] U.S. Pat. No. 5,941,171 [Patent Document 9] U.S. Pat. No. 6,038,969 [Patent Document 10] U.S. Patent No. 6,067,903 [Patent Document 11] U.S. Patent No. 6,289,804 [Patent Document 12] International Publication No. 2017 / 164493 [Patent Document 13] International Publication No. 2017 / 188555 [Patent Document 14] International Publication No. 2019 / 103284 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention seeks to provide a new form of tensioning frame that is compatible with, for example, VectorGuard® printing screens, thereby allowing cartridge-style side-loading of the printing screen onto the tensioning frame. In this manner, the printing screen can be loaded onto the tensioning frame, for example by a robot, such as an autonomous intelligent vehicle, without removing the frame from the printing press, greatly streamlining the loading process.

[0012] In accordance with the present invention, this objective is achieved by providing a side opening in the tension frame for receiving a printing screen, and by moving various components of the tension frame between an attached position and an operative position to facilitate such installation. [Means for solving the problem]

[0013] According to a first aspect of the present invention, there is provided a tensioning frame for tensioning a printing screen, the tensioning frame including a plurality of elongated beams extending around a periphery of the tensioning frame to define the tensioning frame, the tensioning frame being substantially planar, and at least one of the beams including an opening dimensioned to allow a printing screen to be received therethrough.

[0014] According to a second aspect of the present invention, there is provided a tensioning frame for tensioning a printing screen, the tensioning frame including a plurality of elongated beams extending around a periphery of the tensioning frame to define the tensioning frame. The tensioning frame is substantially planar, Each beam is an engagement body disposed at least partially within the beam, the engagement body carrying an engagement arm for engaging the printing screen in use and movable relative to the beam along a range of movement in a plane perpendicular to the length of the beam; an actuator operatively connected to the engagement body for moving the engagement body, and thus the engagement arm, relative to the beam; The engagement arms are movably mounted to the respective engagement bodies.

[0015] According to a third aspect of the present invention, there is provided a method of mounting a printing screen to a tension frame, comprising the steps of: i) providing a tension frame; ii) inserting the printing screen from the side of the tension frame.

[0016] According to a fourth aspect of the present invention there is provided a robot for attaching a printing screen to a tension frame, the robot comprising: a print screen storage magazine for storing at least one print screen; and a transfer mechanism for laterally moving the printing screen from the printing screen storage magazine to the tension frame.

[0017] Other particular aspects and features of the present invention are set forth in the accompanying claims. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 shows a schematic perspective view of the underside of a known tension frame; [Diagram 2] FIG. 1 is a perspective view showing a schematic representation of a known printing screen; [Diagram 3] FIG. 2 is a schematic cross-sectional view of a beam of the tension frame of FIG. 1 engaged with a printing screen. [Figure 4A] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4B] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4C] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4D] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4E] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4F] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4G] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4H]1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4I] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Figure 4J] 1A-1C are perspective views illustrating an installation sequence using a tension frame according to an embodiment of the present invention. [Diagram 5] FIG. 1 is a schematic top perspective view of a tension frame according to an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing the underside of the tension frame of FIG. [Figure 7] FIG. 6 is a perspective view showing a schematic view of a portion of the tension frame of FIG. 5 attached. [Figure 8] FIG. 6 is a perspective view showing the tension frame of FIG. 5 installed in a schematic manner. [Figure 9] FIG. 13 is a schematic diagram showing the underside of the mounted tension frame. [Figure 10] FIG. 6 is a schematic diagram showing a cross section BB of the beam 30C in FIG. 5. [Figure 11] FIG. 13 is a schematic diagram showing a cross section of beam 30D. [Figure 12] 6 is a schematic diagram showing a CC cross section of the beam 30C in FIG. 5. FIG. [Figure 13] FIG. 13 is a schematic diagram showing a cross section of a portion of beam 30C. [Figure 14] FIG. 13 is a schematic diagram showing the side of beam 30C during the downward movement of the blade. [Figure 15] FIG. 13 is a schematic diagram showing the side of beam 30C during the downward movement of the blade. [Figure 16] FIG. 13 is a schematic diagram showing the side of beam 30C during the downward movement of the blade. [Figure 17A] FIG. 2 is a schematic diagram showing a cross-sectional plane (from above) of a tension frame. [Figure 17B] FIG. 2 is a schematic diagram showing a side view of a tension frame. [Figure 18A] FIG. 2 is a schematic diagram showing a cross-sectional plane (from above) of a tension frame. [Figure 18B]FIG. 2 is a schematic diagram showing a side view of a tension frame. [Figure 19] FIG. 2 is a schematic diagram showing an air pressure control device. [Figure 20] 1A-1C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen attachment sequence. [Figure 21] 1A-1C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen attachment sequence. [Figure 22] 1A-1C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen attachment sequence. [Diagram 23] 1A-1C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen attachment sequence. [Figure 24] 11A-11C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen removal sequence. [Diagram 25] 11A-11C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen removal sequence. [Figure 26] 11A-11C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen removal sequence. [Figure 27] 11A-11C are schematic diagrams showing cross sections of beam 30C at various stages in the printing screen removal sequence. [Figure 28] FIG. 13 is a perspective view that illustrates a schematic representation of a tension frame according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The invention will now be described with reference to the accompanying drawings (not to scale):

[0020] A. Examples of installation and removal from a printing press Before describing the construction of a tension frame according to the present invention, an exemplary installation / removal sequence for providing a printing screen to a printing press according to an embodiment of the present invention will be described with reference to Figures 4A-4J, which illustrate new functionality enabled by this tension frame.

[0021] In FIG. 4A, an autonomous intelligent vehicle (AIV) 20 approaches a printing press 21. The AIV 20 has storage for carrying one or more tensioning frames, each of which is optionally attached to a printing screen as shown in FIG. 2. The tensioning frames may be according to the present invention, as described in more detail below, or may be other types of tensioning frames, such as the known VectorGuard® frames described above with reference to FIGS. 1 and 3. In the particular example shown here, the AIV 20 is loaded with a tensioning frame 22 according to the present invention, here preloaded with a printing screen 23. The AIV 20 further includes a printing screen storage magazine for storing at least one printing screen. As shown here, the AIV 20 is loaded with four printing screens 24 that are not attached to the tensioning frames. The AIV 20 also includes a transfer mechanism, generally indicated at 88 (FIG. 4I), for laterally transferring the printing screens 24 from the printing screen storage magazine to the tensioning frames. The transfer mechanism may include, for example, a movable arm or tray capable of pushing the printing screen laterally between its storage location and the tension frame. The AIV 20 operates to rearrange or shuffle the tension frames and printing screens in its magazine so that a selected tension frame or printing screen can be loaded onto or received from the printing press. AIVs with such shuffling mechanisms for planar items are generally known in the art and their operation will not be described in detail here.

[0022] 4B, the AIV 20 is aligned with the printing press 21. In this position, the AIV 20 can load a tension frame or printing screen into the printing press 21 and be received within a printing volume 25 within the printing press 21. As shown, a hatch 26 of the printing press 21 is in an open position to provide exterior access to the printing volume 25. It should be understood that other printing presses (not shown) may have other ways of providing such access.

[0023] 4C, the AIV 20 mounts the tension frame 22, which already contains (by way of example only) a printing screen 23, to the printing press 21. The tension frame 22 is shown fully mounted within the printing press 21, in which position it is supported by clamp rails 27. The AIV 20 has an empty slot 28 in its magazine.

[0024] 4D, after the tension frame is installed and hatch 26 is closed, printing press 21 is ready for operation. A printing operation then begins in which a workpiece (not shown) is printed with a printing medium through a pattern of apertures provided in printing screen 23.

[0025] In Figures 4E-4H, following completion of a printing operation, the AIV 20 lowers the printing screen 23 from the tension frame 22 into a magazine storage slot within the AIV 20. More specifically, in Figure 4E, the AIV 20 is moved into alignment with the printing press 21 and the magazine of the AIV 20 is shuffled so that an empty slot is provided at the vertical height of the printing screen 23 within the printing press 21. In accordance with the present invention, the printing screen 23 is removed from the tension frame 22 through an opening (not explicitly shown) in its beam while the tension frame 22 remains clamped within the printing press 21. In Figure 4F, the printing screen 23 is shown almost completely removed from the tension frame 22. Meanwhile, Figure 4G shows the printing screen 23 received within the slot of the AIV 20. As shown in Figure 4H, the magazine of the AIV 20 is then shuffled so that a new printing screen 24A is moved to the same vertical height as the tension frame 22 clamped within the printing press 21.

[0026] In FIG. 4I, the AIV 20 attaches the printing screen 24A to the tension frame 22, which is still clamped within the printing press 21.

[0027] In FIG. 4J, the AIV 20 can be moved away after the printing press 21 and its tension frame 22 are fully installed and the hatch 26 is closed, ready for a printing operation.

[0028] To enable this functionality, in one aspect, the present invention provides a robot for loading printing screens into a tensioning frame, comprising a printing screen storage magazine for storing at least one printing screen, and a transfer mechanism for laterally transferring the printing screen from the printing screen storage magazine to the tensioning frame. A robot, such as the AIV 20 described above, may comprise a frame storage for storing the tensioning frames, the storage comprising a transfer mechanism adapted to transfer the tensioning frames to the printing press. Advantageously, the robot comprises an AIV as shown in Figures 4A-4C and 4E-4J. However, in other embodiments, such a robot may include a dedicated robot arm located near the printing press, for example with a built-in printing screen storage mechanism and optionally with a built-in frame storage.

[0029] B. Example of tension frame construction 5 and 6 are schematic views of the tension frame 22 from above and below in an unloaded state, i.e., without a print screen housed therein, and in addition (in FIG. 5 only) generally shows a print screen 3 having a foil / mesh 15 (including edging corner pieces 161) attached to its periphery by edging 16, as is well known in the art for the previously known VectorGuard® compatible print screen. The tension frame 22 is sized to receive a print screen 3 of a particular size, which size is generally standard in the art. The tension frame 22 is shown having a rectangular configuration defined by four elongated beams 30A-30D, each beam forming a rectangular side about the periphery of the tension frame 22. Adjacent beams are connected together via corner blocks 31A-31D, for example, using screws, interference fits, or other well known alternative means. Throughout the detailed description, the use of suffixes A-D when added to a reference number is interpreted to mean that the identified component relates to a particular beam 30A-30D or corner block 31A-31D. It will be seen that in this configuration, the tension frame 22 is substantially planar and extends in the XY plane as shown, which corresponds to a horizontal plane in use. At least one of the beams 30A-30D, in this case only beam 30D, is provided with an opening 32 in its side, which opening is dimensioned to allow the printing screen 3 to be received therethrough in a direction parallel to the plane of the tension frame 22, as indicated by arrow A. In the illustrated embodiment, the opening 32 is provided as an open-sided recess formed in the beam 30D and the adjacent corner blocks 31C, 31D. However, in alternative embodiments, the opening 32 can be closed on all sides so as to take the form of a slot or "letterbox" in the respective beam and corner block, for example by providing an optional bar 34 extending between the undersides of adjacent corner blocks, i.e., corner blocks 31C, 31D as shown.Each beam 30A-30D also includes a blade 33 disposed adjacent the inner side of the respective beam, i.e., on the side of the beam facing the interior region of the tension frame 22 where the central region of the printing screen 3 resides during use (see FIG. 8). As will be explained in more detail below, each blade 33 is movable relative to the respective beam 30A-30D along a range of motion in a direction perpendicular to the plane of the tension frame 22, i.e., along the vertical or Z axis as shown. As can be seen from FIG. 6, each beam 30A-30D also includes a plurality of engagement bodies 35 arranged linearly along the length of the respective beam. The engagement bodies are separated by bridges 36 and arranged in a spaced apart configuration, as will be explained in more detail below.

[0030] Figures 7 and 8 are top perspective views that show schematic views of the tension frame of Figure 5 in a partially installed and fully installed configuration. Figure 7 shows the printing screen 3 extending through the opening 36 during installation in direction A, while Figure 8 shows the printing screen 3 fully received within the tension frame 22. From this view, it can be seen that the printing screen 3 does not protrude beyond the footprint of the tension frame 22 when installed.

[0031] Figure 9 shows diagrammatically the underside of the mounted tension frame of Figure 8. Most of the underside of the tension frame 22 is hidden by the underside of the printing screen 3.

[0032] FIG. 10 is a schematic diagram showing a cross section BB of the beam 30C of FIG. 5. The beam 30C, like the other beams 30A, 30B, 30D, has a two-part structure including a main beam body 37 rigidly connected to a beam cover 38. Each of these parts may be formed from an extruded metal such as steel, aluminum, etc., and may be connected to each other by screws, an interference fit, etc. A void 50 is formed in the gap between the beam body 37 and the beam cover 38, which houses a motion converting mechanism 49 for driving the blades 33, as will be described in more detail below. The beam body 37 is formed as a hollow channel that extends the length of the beam 30C, with an open side or opening 60 at its base. The engagement body 35 is disposed within the channel, and the channel and engagement body 35 are movable along a range of movement in a plane perpendicular to the length of the beam 30C, i.e., along a horizontal X-axis, and within the beam body 37, so that it functions like a shuttle or piston. An actuator, here in the form of a pneumatically expandable tube 43, is operatively connected to the engagement body 35 at its end adjacent the lateral outer side of the beam 30C. The tube 43 extends the length of the beam 30C and is pneumatically connected to the adjacent corner pieces 31B, 31C. In practice, the tube 43 need not be fixedly connected to the engagement body 35, but may simply be disposed adjacent the engagement body 35 so as to be in contact with it over at least a portion of its range of movement, as will be explained below. The other end of the engagement body 35 is operable against a biasing means, such as a compression spring 42, which biases the engagement body 35 laterally outward, i.e., in the positive X direction as shown, toward the tube 43. The compression spring 42 is also disposed within a channel in the beam body 37. The engagement body 35 may be formed from a rigid material, such as, for example, steel, aluminum, carbon fiber, or rigid plastic. The engagement arm 39 is movably attached to the engagement body 35 at its underside such that it is movable relative to the engagement body 35.In the illustrated embodiment, the engagement arm 39 is pivotally mounted to the engagement body 35 via a pivot 40 such that the engagement arm 39 can rotate relative to the engagement body 35 about a pivot axis parallel to the length of the beam 30C or Y axis, as shown. The engagement arm 39 is biased towards an extended position in which the engagement arm 39 projects downwardly through the channel opening by biasing means, which in the illustrated embodiment includes a torsion spring 41. The position of the engagement arm 39 relative to the engagement body 35 is controlled using a profiled edge 44 of the beam 30C, here provided in the form of a ramp on the underside of the beam cover 38. When the engagement body 35 is driven towards the beam cover 37, i.e. in the negative X direction as shown, the engagement arm 39 contacts the profiled edge 44 and rotates clockwise to a retracted position, as shown. The engagement arm 39 carries an engagement surface 47 for engaging a printing screen in use, as described in more detail below. As shown in FIG. 10, the tube 43 is fully expanded, so that the engagement body 35 is driven in the negative X direction to its maximum extent. The engagement arm 39 moves fully into a retracted position by contact with the profiled edge 44 against the bias of the torsion spring 41, in which the engagement arm 39 does not protrude through the opening 60 to protrude below the channel or beam cover 38. In this retracted position, the printing screen can be inserted into the tension frame 22 without risk of a collision between the printing screen and the engagement arm 39. The underside of the beam 30C includes a profiled section 45, in this case formed as a protrusion extending outward in the negative X direction as shown. In this embodiment including the leaf spring 46, a conformal surface is also provided near the profiled section 45, extending downward from the beam body 37. The profiled section 45 and leaf springs 46 contact the edging of the printing screen in use, supporting the printing screen and helping to ensure its centering within the tension frame 22, as will be described in more detail below.

[0033] In an alternative embodiment (not shown), the engagement arm 39 may instead be translationally movable relative to the engagement body 35, e.g., slidable relative to the engagement body 35, e.g., loosely held in a slot provided in the engagement body 35. The engagement arm 39 may then be biased by an alternative biasing means, such as a compression spring, towards an extended position in which the engagement arm 39 projects downwardly through the channel opening 60. In such an embodiment, the profiled edge 44 may act as a cam to raise the engagement arm 39 upwardly relative to the engagement body 35 into the retracted position, such cam mechanisms being well understood per se.

[0034] It should be noted that beams 30A, 30B are of identical construction to the illustrated beam 30C. However, beam 30D, which includes opening 36, is of a slightly different construction, and a corresponding cross-sectional view is shown diagrammatically in FIG. 11. Here, it can be seen that beam 30D is narrower, the beam body 37 has its underside at the same level as the base of the channel, and, unlike beams 30A-30C, there is neither a profiled section 45 nor a leaf spring 46 present. In this construction, there is no obstruction to a printing screen inserted in direction A (positive Y direction as shown) through opening 36.

[0035] FIG. 12 is a schematic diagram showing the CC section of the beam 30C of FIG. 5. This section coincides with the position of the bridge 36 located between the two intermediate adjacent engagement bodies 35. The bridge 36 itself is a protrusion of the beam cover 38. A plate 51 is inserted into the channel, which is planar and extends perpendicular to the length of the beam 30C and parallel to the XZ plane. It is located between the adjacent engagement bodies 35 and can act as a bearing between them. The bridge 36 and the plate 51 provide additional structural rigidity to the beam 30C and in particular help to prevent deformation of the channel or torsional deformation of the beam 30C. The plate 51 includes a recess 52 that accommodates the tube 43. It is noted that the use of such a reinforcing bridge is further described in WO 2021 / 038353.

[0036] The operation of the blade 33 will now be described with reference to Figures 13 to 16, where Figure 13 is a schematic diagram showing a cross section of a portion of the beam 30C, and Figures 14 to 16 are schematic diagrams showing the continuous profile of the beam 30C during the downward movement of the blade. Referring first to Figure 13, for the sake of clarity, much of the beam 30C has been hidden and only the details of the blade 33 and its associated motion conversion mechanism 49 are shown. The term "motion conversion mechanism" refers to the fact that this mechanism operates to convert a motion in a first direction into a motion in another direction. In fact, the motion conversion mechanism 49 described here converts a linear motion along the length of the beam 30C into a rotational motion and then converts this rotational motion into a linear motion of the blade 33 in the vertical or Z-axis direction. The blade 33 is shown here in its operating position, fully lowered relative to the beam 30C and with the blade 33 in contact with the upper surface of the foil / mesh 15 of the printing screen 3. The blade 33 is connected by a drive pin 52 to a rotor 53 located in a void 50. The drive pin 52 extends through a vertical slot 54 formed in the beam cover 38 to form a slotted link mechanism, as will be described in more detail below. The rotor 53 is in the form of a planar disk extending in a plane parallel to the blades 33, i.e. in the YZ plane as shown, and is mounted to the beam body 37 for rotation about an axis of rotation R extending parallel to the X axis as shown. The rotor 53 is rotated in use by first and second actuating members 55, 56 which engage opposite edges of the rotor 53. The first and second actuating members 55, 56 each comprise a drive rod which is linearly drivable along the length of the beam 30C, i.e. parallel to the Y axis as shown, and which is pivotally connected to the rotor 53. More specifically, a first actuating member 55 is pneumatically drivable along the length of the beam 30C, and a second actuating member 56 is mechanically coupled to the first actuating member 55, for example, via a parallelogram linkage (not shown). In this manner, the first and second actuating members can be driven in opposite directions, thereby rotating the rotor 53 about the axis of rotation R.The drive pin 52 is fixedly connected to the blade 33, for example via a screw thread, but is loosely held within an oval bore 57 formed in the rotor 53 (more clearly visible in FIG. 14). Also shown in FIG. 13 is a locking mechanism, in this case a locking pin 63 mounted between the beam cover 38 and the blade 33, which operates to lock the blade 33 in the operating position shown. As shown, the locking pin 63 passes through an opening in the beam cover 38 and contacts the rotor 53. Then, by profiling the side of the rotor to create a cam surface, the locking pin 63 can be moved parallel to the X-axis as shown into locking engagement with the blade 33 when the rotor 53 is in a predetermined rotational state. A locking spring 64 (here a compression spring) is provided to bias the locking pin 63 to the right, i.e., in the positive X-direction as shown. This locking spring 64 ensures that the locking pin will disengage from engagement with the blade 33 when the direction of rotation of the rotor 53 is reversed. In practice, depending on, for example, the size of tension frame 22, multiple locking mechanisms may be required along the length of each beam 30A-30D.

[0037] In Figures 14-16, the blade 33 is shown partially transparent so that the positions of the rotor 53 and the first and second actuating members 55, 56 can be seen. Figure 14 shows the blade 33 in the retracted position, where the blade is at its highest vertical position so as to be spaced away from the printing screen in use. In this position, the drive pin 52 is located at the top of the slot 54. As shown, the first actuating member 55, which is connected to the rotor 53 via a pivot pin 58 located in an elliptical actuator bore 61 of the rotor 53, is relatively to the right, while the second actuating member 56, which is connected to the rotor 53 via a pivot pin 59 located in an elliptical actuator bore 62 of the rotor 53, is relatively to the left.

[0038] 15 shows an intermediate stage in the downward movement of blade 33. First actuating member 55 is driven to the left and second actuating member 56 is driven to the right, rotating rotor 53 counterclockwise as shown. This causes drive pin 52, and therefore blade 33, to move downward relative to slot 54.

[0039] FIG. 16 shows the final stage of the downward movement of the blade 33, where it reaches its operating position. The first actuating member 55 is driven fully to the left and the second actuating member 56 is driven fully to the right, further rotating the rotor 53 counterclockwise as shown. This causes the drive pin 52 to move down to the bottom of the slot 54, and accordingly the blade 33 to its lowest extent. Although not shown in FIG. 16, in this position the locking pin 63 is engaged, so that the blade 33 cannot be lifted by applying an upward force on it, but only the rotation of the rotor 53 can be reversed by driving the first actuating member 55 and the second actuating member 56 in the opposite direction, i.e., to the left and right, respectively.

[0040] As noted above, both the tube 43 and the first and second actuating members 55, 56 are pneumatically actuated. To accomplish this, the tension frame 22 needs to be provided with pneumatic ports and associated pneumatic paths through the pneumatic ports.

[0041] 17A and 17B show a schematic representation of the pneumatic path arrangement for operating the tubes 43. More specifically, FIGS. 17A and 17B show schematic cross-sectional plan and side views, respectively, of the tension frame 22, with features not relevant to this arrangement being omitted for clarity. The corner blocks 31A-31D include male projections 70 that are received in the respective adjacent beams 30A-30D. A first pneumatic port 65 is provided in the corner block 31B for connection to an external pneumatic source (not shown). This is directly connected to pneumatic lines 66B, 66C leading to beams 30B and 30C, respectively, which in turn are connected to pneumatic lines 66A, 66D leading to beams 30A and 30D, respectively. These pneumatic lines 66A-66D connect to form a closed ring extending through all beams 30A-30D and corner blocks 31A-31D of the tension frame 22. The air pressure lines 66A-66D connect to the tubes 43 at connections 67. Thus, when air pressure is applied through the first air pressure port 65, the tubes 43 of each beam are expanded in unison. When the air pressure supply is turned off, each tube 43 is contracted by the action of its respective compression spring 42.

[0042] 18A and 18B show a schematic representation of the pneumatic path arrangement for operating the blade 33. More specifically, FIGS. 18A and 18B show schematic cross-sectional plan and side views, respectively, of the tension frame 22, with features unrelated to the arrangement being omitted for clarity. A second pneumatic port 82 is provided in the corner block 31B for connection to an external pneumatic source (not shown). This is connected directly to the pneumatic line 68, which extends around the majority of the tension frame 22, i.e., through the intermediate corner blocks 31B, 31A, 31D and through the beams 30B, 30A, and 30D. Each of the corner blocks 31A-31D includes a joint 83 which pneumatically connects the pneumatic line 68 to a respective piston 84, which is linearly movable parallel to the length of the adjacent beams 30A-30D. Each piston 84 provides mechanical actuation to a respective first actuating member 55 to reversibly drive each first actuating member 55 along the length of each beam 30A-30D within the void 50. When air pressure is applied through the second pneumatic port 82, each piston 84 of each beam is driven in concert. Similarly, when negative pressure or vacuum is applied through the second pneumatic port 82, each piston 84 of each beam is driven in concert to return in the opposite direction. At any time when the air pressure supply to the second pneumatic port 82 is turned off, the first actuating member 55 and the second actuating member 56 remain in their current position, which is assisted by the locking mechanism if that current position is the position where the blade 33 is lowered to its operating position. In this way, the tension frame 22 can be held in a loaded state with the blade 33 lowered to its operating position without the application of air pressure.

[0043] In an alternative embodiment (not shown), the pneumatic line 68 can extend around the entire tension frame 22, i.e., through all of the beams 30A-30D via their respective intermediate corner blocks 31A-31D to form a closed ring. Alternatively or additionally, both the first and second actuating members can be pneumatically driven, for example, by providing additional pistons in each corner block for driving the second actuating member, and associated pneumatic lines for driving them.

[0044] FIG. 19 illustrates, in schematic form, an exemplary pneumatic control for the tension frame 22. As illustrated, the first pneumatic port 65 and the second pneumatic port 82 are pneumatically supplied in use by a pneumatic source 85 via a pneumatic logic network 69. The pneumatic logic network 69 is used to control the pneumatic flow through each of the pneumatic lines and paths 66A-66D, 68. The use of pneumatic logic allows for sequencing of the two pneumatic flows to operate the tension frame 22 during the printing screen loading and unloading sequences described below. Furthermore, the operation of the pneumatic source 85 may be advantageously controlled by a control means 86 such as a computer, processor, or the like. Advantageously, the pneumatic logic network 69, the pneumatic source 85, and the control means 86 may all be provided within a printing press, generally designated by reference numeral 87, to allow for in situ operation. In this case, the control means 86 may also control some or all of the printing operation of the printing press 87. Dedicated pneumatic lines for connecting to each of the first pneumatic port 65 and the second pneumatic port 82 may be provided within the printing press 87 and positioned to align with the tension frame 22 when mounted in a printing position within the printing press 87. If the mounting operation is performed outside of the printing press, the pneumatic logic network and / or pneumatic source may be connected and directly operated, for example, by an operator.

[0045] In an alternative embodiment, at least a portion of the pneumatic logic network may be provided internal to the tension frame 22.

[0046] C. Installation Sequence Example 20-23, an exemplary loading sequence for mounting the printing screen 3 on the tension frame 22 according to the present invention will now be described. Each of Figs. 20-23 is a schematic diagram showing a B-B cross section of the beam 30C of Fig. 5, similar to Fig. 10.

[0047] a) As shown in FIG. 20, the installation sequence starts with the tension frame 22 in the preload position, the blade 33 is raised to its withdrawn position and the tube 43 is expanded to move the engagement body 35 against the bias of the compression spring to its leftmost position as shown, i.e. towards the inner area of ​​the tension frame 22. In this position, the engagement arm 39 is pushed by the profiled edge 44 into its retracted position against the bias of the torsion spring 41. With the tension frame 22 in this position, the printing screen 3 is inserted laterally through the opening 32 (not visible in FIG. 20). The relevant pneumatic supply to the tension frame 22, controlled by the pneumatic logic network 69 for this step, is summarized as follows: Air pressure supply to the first air pressure port 65: ON Air pressure supply to second air pressure port 82: OFF

[0048] b) The blade 33 is then lowered to an operating position in which its abutment surface 48 contacts the foil / mesh 15 of the printing screen 3, as shown in Figure 21. Although not visible in this figure, a locking mechanism is involved to lock the blade 33 in this operating position. The relevant pneumatic supply to the tension frame 22, controlled by the pneumatic logic network 69 for this step, is summarised as follows: Air pressure supply to the first air pressure port 65: ON Air pressure supply to second air pressure port 82: ON (positive pressure)

[0049] c) As shown in Figure 22, the tube 43 starts to contract, so that the engagement body 35 is urged to the right by the compression spring 42 and thus the engagement arm 39 starts to move towards its extended position. The relevant pneumatic supply to the tension frame 22 controlled by the pneumatic logic network 69 for this step is summarized as follows: Air pressure supply to the first air pressure port 65: OFF Air pressure supply to second air pressure port 82: OFF

[0050] d) As shown in FIG. 23, the tube 43 is fully retracted, so that the engagement body 35 is driven fully to the right and the engagement arm 39 moves to its extended position, allowing its engagement surface 47 to contact the inclined surface 71 of the edging 16. The complementary angles of the engagement surface 47 and the inclined surface 71 ensure the engagement of the printing screen 3 and the tensioning frame 22. The edging 16 is pushed into full contact with the leaf spring 46 of the profiled section 45, which acts to cam the edging 16 upwards. The printing screen 3 is now fully engaged and tensioned and the printing operation can be carried out. The relevant air pressure supply to the tensioning frame 22 controlled by the pneumatic logic network 69 for this step is summarized as follows: Air pressure supply to the first air pressure port 65: OFF Air pressure supply to second air pressure port 82: OFF

[0051] From the above, it will be appreciated that the printing screen 3 remains mounted and tensioned within the tension frame 22 without the need to maintain air pressure to the tension frame 22. Thus, the mounted tension frame 22 can be easily stored, transported, or installed in a printing press as needed.

[0052] It should be noted that while the tension frame 22 described above can be mounted from the side as described above, this is not required and the printing screen 3 is optionally mounted by placing the printing screen 3 under the tension frame 22 in a manner similar to the prior VectorGuard® style tension frame, i.e., as shown in FIG. 20. The same mounting steps b)-d) are then performed as described above, followed by the steps of flipping the mounted tension frame to reach the working orientation as shown in FIG. 23. Alternatively, the printing screen can be placed on a surface and then the tension frame can be placed on top of the printing screen 3 while in the working orientation, i.e., as shown in FIG. 20, and then the same mounting steps b)-d) as previously set out are performed. These mounting methods can be facilitated by conformal surfaces, for example, the shape of the leaf springs 46 will aid in centering the printing screen when mounted in these manners. It will also be recognized by those skilled in the art that these mounting methods can be facilitated by providing engagement arms 39 movably attached to the respective engagement bodies 35. The insertion of the printing screen 3 is performed while the engagement body 35 has been moved by the expansion of the tube 43 to its leftmost position, in which the engagement arms 39 are in their retracted position, thereby ensuring that the engagement arms 39 are retracted during installation of the printing screen 3. The risk of the engagement arms getting stuck or being misaligned in relation to the edging 16 of the printing screen is thus excluded. This advantage can be realised in embodiments in which no openings are provided in the sides of the tension frame, allowing lateral installation of the printing screen 3.

[0053] Being able to mount tension frame 22 in any of these ways provides great flexibility to the end user in those cases where, for example, the end user does not have ready access to an installation robot or AIV.

[0054] D. Example of removal sequence 24-27, an exemplary unloading sequence for removing the printing screen 3 from the tension frame 22 according to the present invention will now be described. Each of Figs. 24-27 is a schematic diagram showing a B-B cross section of the beam 30C of Fig. 5, similar to Fig. 10.

[0055] e) As shown in Figure 24, the locking mechanism (not shown) is released and the blade 33 is raised towards its withdrawn position whilst the engagement arm 39 continues to tension the printing screen 3. The relevant pneumatic supply to the tensioning frame 22 controlled by the pneumatic logic network 69 for this step is summarised as follows: Air pressure supply to the first air pressure port 65: OFF Air pressure supply to second air pressure port 82: ON (negative pressure)

[0056] f) As shown in Figure 25, the blade 33 is fully raised to its withdrawn position and the tube 43 starts to expand, moving the engagement body 35 to the left against the bias of the compression spring 42. The engagement surface 47 moves out of contact with the inclined surface 71, releasing the tension on the printing screen 3. The relevant pneumatic supply to the tension frame 22, controlled by the pneumatic logic network 69 for this step, is summarized as follows: Air pressure supply to the first air pressure port 65: ON Air pressure supply to second air pressure port 82: ON (negative pressure)

[0057] g) As shown in Figure 26, the tube 43 is almost fully expanded, the engagement body 35 is pushed almost fully to the left and the engagement arm 39 starts to rotate towards its retracted position due to impact with the profiled edge 44. The relevant pneumatic supply to the tension frame 22 controlled by the pneumatic logic network 69 for this step is summarized as follows: Air pressure supply to the first air pressure port 65: ON Air pressure supply to second air pressure port 82: OFF

[0058] h) As shown in Fig. 27, the tube 43 is fully expanded, the engagement body 35 is pushed fully to the left and the engagement arm 39 is fully in its retracted position. The printing screen 3 can now be removed via the opening 32. The relevant pneumatic supply to the tension frame 22 controlled by the pneumatic logic network 69 for this step is summarized as follows: Air pressure supply to the first air pressure port 65: ON Air pressure supply to second air pressure port 82: OFF

[0059] FIG. 28 shows, in a perspective view, a tensioning frame 80 according to another embodiment of the invention, with a partially unattached printing screen 3. As in the previous embodiment, the tensioning frame 80 includes four beams 81A-80D, with an opening in beam 80D through which the printing screen 3 can be attached or removed. However, in this embodiment, a second opening is provided in beam 81B, so that the printing screen 3 can alternatively be attached or removed through the second opening. This type of tensioning frame allows the possibility of loading the printing screen 3 onto the tensioning frame while in the printing press using a robot such as an AIV from a first side of the printing press, and then removing the printing screen 3 from the tensioning frame 80 from a robot such as an AIV from the other side of the printing press. This type of configuration potentially allows faster changeover of printing screens, since a new printing screen can be installed as soon as the previous printing screen has been removed. Furthermore, the loading AIV can also be kept clean, since it only handles clean printing screens. Alternatively, the unloading AIV may be kept as a soiled or disposal AIV that handles only used printing screens.

[0060] The above embodiments are merely illustrative; other possibilities and alternatives within the scope of the invention will be apparent to those skilled in the art.

[0061] For example, while the above embodiment uses an AIV to install and remove the printing screen, other forms of robotics, such as a fixed robotic arm, can be used.

[0062] In the above embodiment, the locking mechanism comprises a locking pin that is directly driven by the cam surface of the rotor 53 into and out of engagement with the blade 33. However, the locking mechanism can be implemented in many different ways, including using a dedicated actuation mechanism to place the locking pin 63 into locking engagement with the blade 33, or using spring bearings or the like, as will be appreciated by those skilled in the art. As a further alternative, the locking mechanism can include a latching mechanism. In such an arrangement, the locking mechanism may be latched into a locked position upon rotation of the rotor 53 in a first rotational direction through a predetermined rotational angle, as will be appreciated by those skilled in the art. To unlock the locking mechanism, the rotor 53 is then driven in the same (i.e., first) rotational direction through a small angle, unlatching the locking mechanism, thereby allowing the blade 33 to rise to its withdrawn position when the rotor 53 is then rotated in the opposite rotational direction.

[0063] With such a latching mechanism, alternative drive configurations can be used for the first and second actuating members 55 and 56, and thus the rotor 53. In particular, the above embodiment uses a simple piston 84 that can be driven back and forth by selectively applying positive and negative air pressure to the second pneumatic port 82, and thus the first and second actuating members 55 and 56. However, if a latching locking mechanism is employed, this simple piston 84 can be replaced by a spring-return piston that only requires the application of positive air pressure to the second pneumatic port 82, thereby actuating the spring-return piston, and thus the first and second actuating members 55 and 56 and the rotor 53, from their original positions (with the blades 33 in their withdrawn positions) to latch and unlatch. When unlatched, the pneumatic supply is switched off by the pneumatic logic network 69, allowing the spring return to return the piston, the first and second actuating members 55 and 56 and the rotor 53 to their original positions.

[0064] In the above embodiment, both the actuator for moving the engagement body and the first and second actuation members are pneumatic, it is equally possible to use other forms of actuation for either or both of these components, in particular electrical actuation using an electric actuator such as a rotary or linear motor. If electrical actuation is used, the aforementioned pneumatic logic can be replaced by a suitably programmed electronic logic, as is well known in the art per se.

[0065] Additionally, where pneumatic actuation is used to move the engagement body, other pneumatic actuators such as pneumatic pistons or cylinders may be used.

[0066] The motion converter mechanism described above uses a slot linkage, but other forms of motion converter mechanism are possible as well, for example a Geneva or Swiss mechanism. A mechanically simpler variation could use a rack and gear mechanism, where a rack moves linearly along the length of each beam in place of the actuating members, and gears replace the rotors described above.

[0067] Although the tensioning frame described herein is illustrated with respect to mounting a known VectorGuard® type printing screen, the tensioning frame according to the present invention can be equally used or easily adapted for use with other printing screens that include edging with profiles or structures provided to allow interaction with the engagement features. [Explanation of symbols]

[0068] 1 Tension Frame 2A, 2B, 2C, 2D Beam 3. Print Screen 4 Corner Pieces 5 Engagement surface 6 Air pressure port (through hole) 7 Engagement body 8 First Arm 9. Spring 10 Second Arm 11. Air-inflatable tube 12 Third Arm 13 Pneumatic port 14 Spindle 15 foil / mesh 16 Edging 161 Edging Corner Piece 17 Protrusion 18 Abutment surface 20 A.I.V. 21 Printing machine 22 Tension Frame 23,24,24A Printing screen 25 Print Volume 26 Hatch 27 Clamp rail 28 Empty Slots 30A, 30B, 30C, 30D Beam 31A, 31B, 31C, 31D Corner Blocks 32 Opening 33 Blade 34 Bar 35 Engagement body 36 Bridge 37 Beam body 38 Beam cover 39 Engagement arm 40 Pivot 41 Torsion spring 42 Compression spring 43 Tube 44 Profiled Edges 45 Profiled Sections 46 Leaf spring 47 Engagement surface 48 Abutment surface 49 Motion conversion mechanism 50 Void 51 Plate 52 Drive pin 53 Rotor 54 Slots 55 First operating member 56 Second operating member 57 Bore 58,59 Pivot pin 60 aperture 61,62 Actuator bore 63 Lock pin 64 Rock Spring 65 First Pneumatic Port 66A, 66B, 66C, 66D Pneumatic lines 67 Connection 68 Pneumatic Line 69 Pneumatic Logic Network 70 Male proboscis 71 Slope 80 Tension Frame 81A, 81B, 81C, 81D 82 Second Pneumatic Port 83 Joint 84 Piston 85 Air pressure source 86 Control Means 87 Printing machine 88 Transfer mechanism A Loading direction R rotation axis

Claims

1. A tensioning frame configured to apply tension to the printing screen, a plurality of elongated beams defining an interior area of ​​the tension frame within which a central area of ​​the printing screen is located; at least one of the beams includes an opening dimensioned to allow the printing screen to be received therethrough in a direction parallel to a plane of the tension frame; Each beam is an engagement body disposed at least partially within the beam, the engagement body having an engagement surface for engaging a printing screen and movable relative to the beam along a range of motion in a plane perpendicular to a length of the beam; an actuator operatively connected to the engagement body for effecting movement of the engagement body along a range of motion in a plane perpendicular to a length of the beam; Tension frame.

2. The actuator is selected from the group consisting of a pneumatic actuator, a pneumatic piston, and an electric actuator.

2. The tension frame of claim 1.

3. a plurality of said beams defining an interior region of said tension frame in which a central region of a printing screen is located, and said actuator is operable to move said engagement body in a direction toward said interior region; A tension frame according to claim 1 or 2.

4. a biasing means for biasing the engagement body in a direction away from the interior region; 4. The tension frame of claim 3.

5. Each engagement surface is formed on a respective engagement arm that is movably mounted to a respective engagement body, the engagement arms being movable relative to the engagement body between a retracted position to allow the printing screen to be fully inserted into the tension frame and an extended position in which the engagement surface may contact the printing screen. A tension frame according to any one of claims 1 to 4.

6. The engagement arms are pivotally or slidably attached to the respective engagement bodies.

6. The tension frame of claim 5.

7. the engagement arm is tensioned to the extended position; A tension frame according to claim 5 or 6.

8. each beam includes a blade movable along a range of motion in a direction perpendicular to the plane of the tension frame between a withdrawal position in which the blade is spaced from the printing screen and an operating position in which the blade contacts the printing screen; A tension frame according to any one of claims 1 to 7.

9. Each beam is a respective actuating member movable along the length of each of said beams; a respective motion conversion mechanism operative to convert motion of the respective actuating member into motion perpendicular to the plane of the tension frame, the motion conversion mechanism being arranged such that motion of each blade is driven by the respective actuating member via the respective motion conversion mechanism.

9. The tension frame of claim 8.

10. Each of said actuating members is pneumatically or mechanically driven.

10. The tension frame of claim 9.

11. Each motion conversion mechanism is provided with a slot link mechanism or a Geneva mechanism. A tension frame according to claim 9 or 10.

12. a lock for locking the blade in an operating position; 12. A tension frame according to any one of claims 8 to 11.

13. A tensioning frame configured to apply tension to the printing screen, a plurality of elongated beams defining an interior area of ​​the tension frame within which a central area of ​​the printing screen is located; at least one of the beams includes an opening dimensioned to allow the printing screen to be received therethrough in a direction parallel to a plane of the tension frame; Each beam is an engagement body disposed at least partially within the beam, the engagement body carrying an engagement arm for engaging a printing screen and movable relative to the beam along a range of motion in a plane perpendicular to a length of the beam; an actuator operatively connected to the engagement body for effecting movement of the engagement body along a range of motion in a plane perpendicular to a length of the beam; The engagement arms are movably attached to respective engagement bodies. Tension frame.

14. Each engagement arm is pivotally or slidably mounted to a respective engagement body; 14. The tension frame of claim 13.

15. The actuator is selected from the group consisting of a pneumatic actuator, a pneumatic piston, and an electric actuator.

15. A tension frame according to claim 13 or 14.

16. a plurality of said beams defining an interior region of said tension frame in which a central region of a printing screen is located, and said actuator is operable to move said engagement body in a direction toward said interior region; 16. A tension frame according to any one of claims 13 to 15.

17. a biasing means for biasing the engagement body in a direction away from the interior region; 17. The tension frame of claim 16.

18. 1. A method for mounting a printing screen to a tension frame, comprising: i) providing a tension frame according to claim 1 or 13; ii) inserting a printing screen into the side of the tension frame; A method comprising:

19. The tension frame is an engagement body disposed at least partially within the beam, the engagement body carrying an engagement arm for engaging the printing screen and movable relative to the beam along a range of movement in a plane perpendicular to the length of the beam; Equipped with the engagement arms are movably mounted to respective engagement bodies, where step i) comprises moving the engagement arms to a retracted position relative to the engagement bodies, and where in step ii) the printing screen may be fully inserted into the tension frame without contacting the engagement arms; 20. The method of claim 18.

20. After step ii), iii) moving the engagement arms relative to the engagement body to an extended position and moving the engagement body relative to the beam to bring the engagement arms into contact with the printing screen and tension the printing screen; 20. The method of claim 19, comprising:

21. the beam includes a blade movable along a range of motion in a direction perpendicular to the plane of the tension frame between a withdrawal position in which the blade is spaced from the printing screen and an operating position in which the blade contacts the printing screen; The blade is in the withdrawn position during step ii); After step ii), iv) moving said blade from said withdrawal position to said operating position so that said blade contacts said printing screen; 21. The method of claim 19 or 20, further comprising:

22. step ii) includes inserting the printing screen into the tension frame using a robot; 22. The method according to any one of claims 18 to 21.

23. The method of claim 22, further comprising, prior to step i), an initial step of positioning the tension frame within a printing press.

23. The method according to any one of claims 19 to 22.

24. A robot for mounting a printing screen to a tension frame according to claim 1 or 13, comprising: a print screen storage magazine for storing at least one print screen; a transfer mechanism for laterally moving the printing screen from the printing screen storage magazine to the tension frame; A robot equipped with

25. The tension frame may further include a frame storage for storing the tension frame, and the transport mechanism may be adapted to transport the tension frame to a printing press.

25. The robot of claim 24.

26. including autonomous and intelligent vehicles; 26. The robot according to claim 24 or 25.

Images