WORKPIECE TRANSPORT SYSTEM AND METHOD

The present invention relates to a workpiece transport system and method, in particular a belt-driven workpiece transport system and method, typically for transporting substrates, including thin and flexible boards.

Belt-driven workpiece transport systems utilize flexible belts, typically flat or round belts. The present inventor has recognized disadvantages of belt- driven workpiece transport systems, in that the support can be insufficient at the edges of the workpiece, especially for thin and flexible boards, and that accurate and repeatable positioning of the workpiece in the vertical, z- direction is not possible, because the belts tend to flex and have dimensional tolerances.

It is an aim of the present invention to provide a workpiece transport system and method which provides for support, and preferably rigid support at the edges of a workpiece.

In one aspect the present invention provides a workpiece transport system, comprising: first and second rail transport units which are operable to transport a workpiece therealong, wherein the rail transport units each comprise a transport rail which is operable to support an edge of the workpiece and a workpiece transport mechanism which is operable to engage the edge of the workpiece when supported by the transport rail and transport the same along the transport rail; and a workpiece support unit which is operable to support a workpiece transported by the rail transport units, wherein the workpiece support unit comprises a body member which includes a workpiece support for supporting the workpiece, and first and second edge supports which are disposed to opposite edges of the workpiece support and movable between a first, inoperative position and a second, operative position in which the edges of the workpiece are supported by respective ones of the first and second edge supports.

In one embodiment the transport rails are movable between a first, raised operative position relative to the workpiece support in which the transport rails support the edges of the workpiece and a second, lowered inoperative position relative to the workpiece support, and the workpiece support supports the workpiece when the transport rails are in the lowered, inoperative position.

In one embodiment the rail transport units each further comprise a transport rail actuation mechanism which is operable to move the transport rail between the first and second positions.

In one embodiment the transport rail actuation mechanism comprises first and second actuators which are coupled to opposite ends of the transport rail.

In one embodiment the edge supports are movable between a first, raised operative position and a second, lowered inoperative position.

In one embodiment the workpiece support unit further comprises an edge support actuation mechanism which couples the edge supports to the body member and is operable to move the edge supports between the first and second positions.

In one embodiment the edge support actuation mechanism comprises first and second actuators which are coupled to respective ones of the edge supports.

In one embodiment the edge support actuation mechanism comprises first and second pairs of actuators which are coupled to opposite ends of the respective ones of the edge supports.

In one embodiment the workpiece transport mechanism is a belt transport mechanism which comprises a belt which engages the edge of the workpiece

when supported by the transport rail and is driven to transport the workpiece along the transport rail.

In one embodiment the rail transport units are movable laterally relative to the workpiece support unit and the workpiece support unit further comprises first and second rail transport unit actuation mechanisms which couple respective ones of the rail transport units to the body member and are operable to move the rail transport units between first positions and second positions in which the edge supports are movable to the operative positions.

In one embodiment the rail transport units are movable between first, inner positions and second, outer positions.

In one embodiment the rail transport unit actuation mechanisms each comprise first and second actuators which are coupled to opposite ends of the respective ones of the rail transport units.

The present invention also extends to a screen printing machine incorporating the above-described workpiece transport system.

In another aspect the present invention provides a method of transporting workpieces, comprising the steps of: providing a workpiece transport system comprising : first and second rail transport units which are operable to transport a workpiece therealong, wherein the rail transport units each comprise a transport rail which is operable to support an edge of the workpiece and a workpiece transport mechanism which is operable to engage the edge of the workpiece when supported by the transport rail and transport the same along the transport rail; and a workpiece support unit which is operable to support a workpiece transported by the rail transport units, wherein the workpiece support unit comprises a workpiece support for supporting the workpiece and first and second edge supports which are disposed to opposite edges of the workpiece support and movable between a first, inoperative position and a second, operative position in which the

edges of the workpiece are supported by respective ones of the first and second edge supports; operating the workpiece transport mechanism to transport the workpiece to an operative position above the workpiece support; moving the transport rails relative to the workpiece support such that the workpiece is supported on the workpiece support; and moving the edge supports to the operative position such that the respective lateral edges of the workpiece are supported by the edge supports.

In one embodiment the step of moving the transport rails relative to the workpiece support comprises the step of: moving the transport rails from a first, raised operative position relative to the workpiece support in which the transport rails support the edges of the workpiece to a second, lowered inoperative position relative to the workpiece support in which the workpiece is supported by the workpiece support.

In one embodiment the step of moving the edge supports to the operative position comprises the step of: moving the edge supports from a first, lowered position relative to the workpiece support to a second, raised position in which the respective lateral edges of the workpiece are supported by the edge supports.

In one embodiment the method further comprises the steps of: moving the transport rails laterally outwardly relative to the workpiece support prior to the step of moving the edge supports to the operative position; and moving the transport rails laterally inwardly relative to the workpiece support following the step of moving the edge supports to the operative position, such that the transport rails are disposed adjacent respective ones of the edge supports.

In one embodiment the method further comprises the steps of: performing a machine operation on the supported workpiece; moving the edge supports to the inoperative position; moving the transport rails relative to the workpiece support such that the workpiece is supported by the transport

rails; and operating the workpiece transport mechanism to transport the workpiece from the operative position above the workpiece support.

In one embodiment the machine operation comprises a screen printing operation.

In one embodiment the step of moving the edge supports to the inoperative position comprises the step of: moving the edge supports from a first, raised position relative to the workpiece support in which the respective lateral edges of the workpiece are supported by the edge supports to a second, lowered inoperative position relative to the workpiece support.

In one embodiment the step of moving the transport rails relative to the workpiece support such that the workpiece is supported by the transport rails comprises the step of: moving the transport rails from a lowered, inoperative position relative to the workpiece support in which the workpiece is supported by the workpiece support to a raised, operative position relative to the workpiece support in which the transport rails support the edges of the workpiece.

In one embodiment the method further comprises the steps of: moving the transport rails laterally outwardly relative to the workpiece support prior to the step of moving the edge supports to the inoperative position; and moving the transport rails laterally inwardly relative to the workpiece support following the step of moving the edge supports to the inoperative position.

In one embodiment the workpiece transport mechanism is a belt transport mechanism which comprises a belt which engages the edge of the workpiece when supported by the transport rail and is driven to transport the workpiece along the transport rail.

A preferred embodiment of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which:

Figure 1 illustrates a perspective view of a workpiece transport system in accordance with a preferred embodiment of the present invention;

Figure 2 illustrates a side elevational view of the workpiece transport system of Figure 1;

Figure 3 illustrates a first lateral vertical sectional view (along section I-I in Figure 2) of the workpiece transport system of Figure 1;

Figure 4 illustrates a second lateral vertical sectional view (along section II- II in Figure 2) of the workpiece transport system of Figure 1;

Figure 5 illustrates a third lateral vertical sectional view (along section III-III in Figure 2) of the workpiece transport system of Figure 1; and

Figures 6(a) to (i) illustrate vertical sectional views showing the operation of the workpiece transport system of Figure 1.

The workpiece transport system comprises first and second rail transport units 3a, 3b which are disposed in spaced parallel relation and operable to transport a workpiece W therealong, and a workpiece support unit 7 which is disposed between the rail transport units 3a, 3b and operable to support a workpiece W which is transported by the rail transport units 3a, 3b.

The rail transport units 3a, 3b each comprise a supporting base member 11, a transport rail 15 which is movable vertically to the base member 11 between a raised, operative workpiece transport position, as illustrated in Figure 6(a), and a lowered, inoperative position, as illustrated in Figure 6(b), a transport rail actuation mechanism 17 which is operable to move the

transport rail 15 vertically relative to the base member 11, and a belt transport mechanism 19 which is operable to engage an edge of the workpiece W and transport the same along the transport rail 15.

In this embodiment, as illustrated in Figure 3, the base member 11 includes first and second piston bores 20, 20 therein, which each extend vertically to an upper surface of the base member 11 and are located at spaced locations, here at opposite ends of the base member 11.

In this embodiment, as illustrated in Figure 3, the transport rail 15 comprises an elongate bar 21 which includes a recess 23 along an inner, upper edge thereof, which includes a lower support surface 25, here of arcuate section, which supports the transport belt 61 of the belt transport mechanism 19 and a lateral guide surface 27 which acts to guide the edge of the workpiece W when being transported by the rail transport units 3a, 3b.

In this embodiment the transport rail actuation mechanism 17 comprises at least one actuator 31 which couples the transport rail 15 to the base member 11 and is operative to move the transport rail 15 vertically.

In this embodiment the transport rail actuation mechanism 17 comprises first and second actuators 31, 31 which are coupled at spaced locations to the transport rail 15, here the opposite ends of the transport rail 15.

In this embodiment, as illustrated in Figure 3, each actuator 31 comprises a piston, here a pneumatically-operated piston. In an alternative embodiment the piston could be hydraulically operated.

In this embodiment each actuator 31 comprises a bearing 35, here a tubular sleeve bearing, which is disposed in the respective piston bore 20 in the base member 11, and a piston member 37 which is slideably disposed to the bearing 35.

In this embodiment the piston member 37 comprises a head section 39, here a lower section, which is a sealing fit with the piston bore 20 and a coupling section 41 which extends, here axially, from the head section 39 and is coupled to the transport rail 15.

In this embodiment the head section 39 comprises a sealing element 45, here of a first radial dimension, which is a sealing fit with the piston bore 20, and a collar element 47, which is of a smaller radial dimension than the sealing element 45, such as to define an annular peripheral channel 49, which allows for fluid flow thereabout, as will be described in more detail hereinbelow.

In this embodiment a first chamber 51 is disposed to one side of the head section 39 and a second chamber 53 is disposed to the other, opposite side of the head section 39. With this configuration, the piston member 37 is movable by selective application of a pressure to one of the first and second chambers 51, 53. By applying a positive pressure to the first chamber 51 or a negative pressure (vacuum) to the second chamber 53, the piston member 37 is driven upwardly. By applying a positive pressure to the second chamber 53 or a negative pressure (vacuum) to the first chamber 51, the piston member 37 is driven downwardly.

In this embodiment the belt transport mechanism 19 is attached to the transport rail 15, such as to be moved with the same on operation of the transport rail actuation mechanism 17.

In this embodiment the belt transport mechanism 19 comprises a belt 61, here an endless belt, a plurality of guide elements 63, here freely-rotatable pulley elements, which guide a section of the belt 61 along the support surface 25 of the transport rail 15, a drive element 65, here a driven pulley element, which is driven to move the belt 61, and an actuator 67, here a drive motor, which is coupled to the drive element 65 to drive the same and hence the belt 61.

The workpiece support unit 7 further comprises a body member 71, which includes a workpiece support 73, in this embodiment a rigid plate, for supporting the workpiece W when the rail transport units 3a, 3b are in the lowered, inoperative configurations, as illustrated in Figure 6(b), and first and second edge supports 75, 75 which are disposed to opposite sides of the workpiece support 73 and movable to support the opposite lateral edges of the workpiece W when supported on the workpiece support 73, as illustrated in Figure 6(d).

In this embodiment, as illustrated in Figure 4, the body member 71 includes first and second pairs of first piston bores 77, 77 therein, which extend horizontally to opposite, outer lateral surfaces of the body member 71 and are located at spaced locations, here at opposite ends of the body member 71. In this embodiment respective ones of the piston bores 77, 77 of each of the pairs of piston bores 77, 77 are defined by common through bores.

In this embodiment, as illustrated in Figure 5, the body member 71 further includes first and second pairs of second piston bores 81, 81 therein, which extend vertically to opposite, upper lateral edge surfaces of the body member 71 and are located at spaced locations, here at opposite ends of the body member 71.

The workpiece support unit 7 further comprises first and second rail transport unit actuation mechanisms 91, 93 which couple respective ones of the rail transport units 3a, 3b to the body member 71 and are operable to move the rail transport units 3a, 3b between first, inner positions, as illustrated in Figure 6(a), in which the transport rails 15 have a spacing which allows for operation of the rail transport units 3a, 3b in engaging and transporting the workpiece W and second, outer positions, as illustrated in Figure 6(c), in which the rail transport units 3a, 3b are inoperative and spaced away from the body member 71.

In this embodiment the rail transport unit actuation mechanisms 91, 93 each comprise at least one actuator 95 which couples the respective one of the rail transport units 3a, 3b to the body member 71 and is operative to move the respective rail transport unit 3a, 3b horizontally.

In this embodiment the rail transport unit actuation mechanisms 91, 93 each comprise first and second actuators 95, 95 which are coupled at spaced locations to the respective one of the rail transport units 3a, 3b, here the opposite ends of the respective rail transport units 3a, 3b.

In this embodiment, as illustrated in Figure 4, each actuator 95 comprises a piston, here a pneumatically-operated piston. In an alternative embodiment the piston could be hydraulically operated.

In this embodiment each actuator 95 comprises a bearing 105, here a tubular sleeve bearing, which is disposed in the respective piston bore 77 in the body member 71, and a piston member 107 which is slideably disposed to the bearing 105.

In this embodiment the piston member 107 comprises a head section 109, here an inner section, which is a sealing fit with the piston bore 77 and a coupling section 111 which extends, here axially, from the head section 109 and is coupled to the base member 11 of the respective rail transport unit 3a, 3b.

In this embodiment the head section 109 comprises a sealing element 115, here of a first radial dimension, which is a sealing fit with the piston bore 77, and a collar element 117, which is of a smaller radial dimension than the sealing element 115, such as to define an annular peripheral channel 119, which allows for fluid flow thereabout, as will be described in more detail hereinbelow.

In this embodiment a first chamber 121 is disposed to one side of the head section 109 and a second chamber 123 is disposed to the other, opposite side of the head section 109. In this embodiment the first chambers 121 of corresponding ones of the pairs of actuators 95, 95 of the first and second rail transport unit actuation mechanisms 91, 93 are common, such that application of a positive or negative pressure thereto is effective commonly to operate the actuators 95, 95. With this configuration, the piston member 107 is movable by selective application of a pressure to one of the first and second chambers 121, 123. By applying a positive pressure to the first chamber 121 or a negative pressure (vacuum) to the second chamber 123, the piston member 107 is driven outwardly. By applying a positive pressure to the second chamber 123 or a negative pressure (vacuum) to the first chamber 121, the piston member 107 is driven inwardly.

The workpiece support unit 7 further comprises an edge support actuation mechanism 131 which couples the edge supports 75, 75 to the body member 71 and is operable to move the edge supports 75, 75 between first lower, inoperative positions, as illustrated in Figure 6(a), and second, upper operative positions, as illustrated in Figure 6(d), in which the edge supports 75, 75 are disposed beneath the respective lateral edges of the workpiece W when supported on the workpiece support 73, such as to support the lateral edges of the workpiece W which overhang the workpiece support 73.

In this embodiment the edge support actuation mechanism 131 comprises at least two actuators 135 which couple the respective ones of the edge supports 75, 75 to the body member 71 and are operative to move the respective edge supports 75 vertically.

In this embodiment the edge support actuation mechanism 131 comprises first and second pairs of actuators 135, 135 which are coupled at spaced locations to the respective ones of the edge supports 75, 75, here the opposite ends of the respective edge supports 75, 75.

In this embodiment, as illustrated in Figure 5, each actuator 135 comprises a piston, here a pneumatically-operated piston. In an alternative embodiment the piston could be hydraulically operated.

In this embodiment each actuator 135 comprises a bearing 145, here a tubular sleeve bearing, which is disposed in the respective piston bore 81 in the body member 71, and a piston member 147 which is slideably disposed to the bearing 145.

In this embodiment the piston member 147 comprises a head section 149, here a lower section, which is a sealing fit with the piston bore 81 and a coupling section 151 which extends, here axially, from the head section 149 and is coupled to the respective edge support 75, 75.

In this embodiment the head section 149 comprises a sealing element 155, here of a first radial dimension, which is a sealing fit with the piston bore 81, and a collar element 157, which is of a smaller radial dimension than the sealing element 155, such as to define an annular peripheral channel 159, which allows for fluid flow thereabout, as will be described in more detail hereinbelow.

In this embodiment a first chamber 161 is disposed to one side of the head section 149 and a second chamber 163 is disposed to the other, opposite side of the head section 149. With this configuration, the piston member 147 is movable by selective application of a pressure to one of the first and second chambers 161, 163. By applying a positive pressure to the first chamber 161 or a negative pressure (vacuum) to the second chamber 163, the piston member 147 is driven upwardly. By applying a positive pressure to the second chamber 163 or a negative pressure (vacuum) to the first chamber 161, the piston member 147 is driven downwardly.

Operation of the workpiece transport system will now be described hereinbelow with reference to Figures 6(a) to (i) of the accompanying drawings.

In a first step, with the rail transport units 3a, 3b in the inner and raised configurations and the edge supports 75, 75 in the lowered positions, as illustrated in Figure 6(a), the belt transport mechanisms 19, 19 of the rail transport units 3a, 3b are operated to drive the belts 61, 61 thereof and transfer a workpiece W downstream along the transport rails 15, 15 to a position above the workpiece support 73.

In a second step, with the workpiece W so positioned, the actuators 31, 31 of the transport rail actuation mechanisms 17, 17 of the rail transport units 3a, 3b are operated to lower the transport rails 15, 15 to the lowered positions and so lower the workpiece W onto the workpiece support 73, as illustrated in Figure 6(b).

In a third step, as illustrated in Figure 6(c), the actuators 95, 95 of the rail transport unit actuation mechanisms 91, 93 are operated to move the rail transport units 3a, 3b outwardly from the inner positions to the outer positions.

In a fourth step, as illustrated in Figure 6(d), the actuators 135, 135 of the edge support actuation mechanism 131 is operated to raise the edge supports 75, 75 from the lowered, inoperative positions to the raised, supporting positions, in which the edge supports 75, 75 support the lateral edges of the workpiece W which overhang the workpiece support 73.

In a fifth step, as illustrated in Figure 6(e), the actuators 95, 95 of the rail transport unit actuation mechanisms 91, 93 are operated to move the rail transport units 3a, 3b inwardly from the outer positions to the inner positions, in which the transport rails 15, 15 are juxtaposed the respective

lateral edges of the workpiece W, such as to provide structural support thereat.

With the workpiece W so supported, the workpiece W is then subjected to a machine operation, such as a screen printing operation.

In a sixth step, following this machine operation, as illustrated in Figure 6(f), the actuators 95, 95 of the rail transport unit actuation mechanisms 91, 93 are operated to move the rail transport units 3a, 3b outwardly from the inner positions to the outer positions.

In a seventh step, as illustrated in Figure 6(g), the actuators 135, 135 of the edge support actuation mechanism 131 are operated to lower the edge supports 75, 75 from the raised, supporting positions to the lowered, inoperative positions.

In an eighth step, as illustrated in Figure 6(h), the actuators 95, 95 of the rail transport unit actuation mechanisms 91, 93 are operated to move the rail transport units 3a, 3b inwardly from the outer positions to the inner positions.

In a ninth step, the actuators 31, 31 of the transport rail actuation mechanisms 17, 17 of the rail transport units 3a, 3b are operated to raise the transport rails 15, 15 to the raised positions and so raise the workpiece W from the workpiece support 73 onto the transport rails 15, 15, as illustrated in Figure 6(i).

In a final step, with the workpiece W so raised onto the transport rails 15, 15, the belt transport mechanisms 19, 19 of the rail transport units 3a, 3b are operated to drive the belts 61, 61 thereof and transfer the workpiece W downstream along the transport rails 15, 15.

Finally, it will be understood that the present invention has been described in its preferred embodiment and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.