FIELD OF THE INVENTION

The invention relates to food processing systems, particularly food packaging systems and food grading systems for performing one or more actions of processing food items, such as sealing food packages and inspecting food items bound for food packages.

BACKGROUND

Food processing systems typically have a processing region within which one or more actions of processing food items takes place. These processing regions need to be accessible by an operator for maintenance and cleaning. However, to protect the safety of operators and the hygiene of food being processed, is it often necessary to enclose such food processing regions within an enclosed housing and permit access for maintenance and cleaning using one or more doors or covers.

A typical door on a food processing system may rotate about a hinge located on one edge of the door. A problem with such an arrangement is that adequate clearance must be provided around the machine for the door to swing between the closed and open positions. Another problem is that such a door that can project a significant distance into the walkway between adjacent machines, which is a safety hazard for those working around the machines.

Another factor that must be considered is that it is generally desirable to ensure that a food processing system is as small and compact as possible. It would be straightforward to address the above concerns if food processing machines could be made so large that they had built in clearance for access ports. However, such a solution would increase the cost of producing a larger machine and reduce the number of machines that could be operated in a given area.

It is therefore desirable to provide an access means for a food processing system that takes up as little floor space as possible, in order to allow any particular factory to maximise its capacity for food processing systems and to ensure the safety of those operating the machines.

SUMMARY OF INVENTION

In accordance with a first aspect of the invention, there is provided a food processing system for performing one or more actions of processing food items, the food processing system comprising: a frame, the frame substantially surrounding a processing region within which one or more actions of processing food items takes place, the frame defining one or more openings through a side of the frame for an operator to access the processing region; and a door for selectively opening and closing at least one of said openings through the side of the frame; a hinge coupling the door to the frame and defining a rotation axis such that the door may be rotated relative to the frame about said rotation axis, wherein the door is restricted so as to be rotatable relative to the frame through a normal opening range of no more than 60° to a partially open position; and wherein the door comprises: a panel for closing said at least one opening through the side of the frame when the door is in a closed position; and a sliding mechanism for sliding the panel along a direction of the door when the door is in the partially open position for fully opening the at least one opening through the side of the frame.

The food processing system addresses the problems noted above by providing a door which rotates about a hinge axis to a partially open position, before a panel of the door then slides along a direction of the door to fully open the door. Such an arrangement reduces the clearance around the system for operation of the door. At the same time, by still allowing the door to rotate to a partially open position before the panel slides away from the opening, the system does not need to be built with clearance inside the system for the movement of the panel, ensuring that the system remains compact.

The frame may be part of a housing, which together with the or each door, substantially encloses the processing region within the system. Such a housing may be made up of the frame, door(s) and any fixed panels for closing other parts of the frame. It will be appreciated that, even for a substantially enclosing housing, there may need to be permanent openings for input and output of food or food packages, for example.

The door may be made to rotate about any rotation axis. For example, the hinge may define a vertical rotation axis about which the door rotates. However, preferably, the hinge defines a substantially horizontal rotation axis. This is preferred for a number of reasons. Many common food processing systems convey food product or packages along a horizontal conveyance direction, meaning that they are generally longer in a horizontal direction than in the vertical direction. On such systems, horizontally opening doors would need to be either very long, which would mean they rotate through a greater area when opening, or split into multiple doors, which makes the system more expensive to produce. A vertically opening door is also generally better balanced on the hinge, and provides better clearance for an operator to work on the system. It should be noted that, while only a single hinge is referred to above, the door could equally be mounted on multiple hinges, but these should define a common rotation axis.

In principle, a doorwith a hinge defining a horizontal rotation axis could be rotated about a hinge located along an upper edge of the door, e.g. rotated out from the machine and up; however, the present arrangement is particularly suited to small, compact machines, in which case a handle located along a lower edge of the door may be inconvenient. Accordingly, it may be preferred that the hinge is located towards a lower edge of said door, wherein preferably the hinge is located substantially at the lower edge of the door. In this case, the door will be most conveniently operated from close to its upper edge, which will be more accessible on smaller food processing machines. As indicated above, the hinge may be located at the lower edge of the door, or may be inset from the lower edge but still provided at the lower half of the door.

Another advantage of a horizontal rotation axis is that in the closed position the door may define an angle to a vertical direction, and the door may then be rotatable about the hinge from the closed position towards the vertical direction to the partially open position. In such an embodiment, at least part of the rotation of the door does not increase the footprint of the machine, which is beneficial for reducing the clearance required around the machine. For example, in the closed position, the door may be inclined towards the centre of the frame in the direction extending away from the hinge. The food processing system may therefore be narrower at the top than at the bottom, for example. This inclination of the door in the closed position will generally not be very pronounced, otherwise valuable space inside the system would be lost. However, in the closed position the door could defines an angle of at most 30° to the vertical direction, preferably at most 25°, more preferably at most 20°, further preferably at most 10°, most preferably at most 5° to the vertical direction. Even a small inward inclination of the door in the closed position will allow part of the rotation of the door to take place without increasing the footprint of the system. Indeed, the door may be restricted so as to be rotatable about the hinge from the closed position towards the vertical direction and no more than 30° beyond the vertical direction, preferably no more than 25°, more preferably no more than 20°, further preferably no more than 10°, further preferably no more than 5° beyond the vertical direction, wherein most preferably the door is restricted so as to be rotatable about the hinge from the closed position towards the vertical direction and substantially not beyond the vertical direction. In this latter case, the footprint of the system substantially does not increase during the operation of the door.

It will be clear from the above that it is preferred that the door may only be rotated through a relatively small angle, i.e. sufficient to space the door from the system and allow the panel to slide to fully open the door. Preferably, the door is restricted so as to be rotatable about the hinge through a normal opening range of no more than 45°, preferably no more than 30°, more preferably no more than 25°, further preferably no more than 20°, most preferably no more than 10°. A smaller rotation angle requires less clearance around the machine for rotation of the door.

While the door should only be rotatable through a normal operating range of 60° or less, in some scenarios, it may be necessary to rotate the door further, e.g. for deep cleaning or to access other parts of the system. Therefore, preferably the system further comprises a latch coupling the door to the frame and for restricting the movement of the door to define the normal opening range of the door, wherein the latch may be adjusted or decoupled during maintenance to allow the door to rotate about the hinge beyond its normal opening range. While this is preferred, it is not essential and the door could be removed from the hinge, for example, to allow deep cleaning or maintenance.

Once the door has been rotated to be partially open, the panel may slide along any direction of the door. The door will typically be substantially flat, and so the panel will typically slide along a direction substantially within a plane of the door. The panel itself will also typically be substantially flat and so the panel will typically slide along a direction substantially within a plane of the panel. However, preferably, the sliding mechanism allows the panel to slide along a direction substantially perpendicular to the rotation axis of the hinge, wherein most preferably the sliding mechanism allows the panel to slide along the direction towards the hinge. The preferred sliding direction for the panel may depend on the size and position of the door and the size and position of the opening through the frame of the system. In compact systems, however, the processing region will typically be towards the top of the machine, and the processing region will extend laterally along the length of the machine, and so, in cases in which the rotation axis of the hinge is substantially horizontal, it will be preferred for the panel to slide in the vertical direction, typically downwards towards the base of the system.

The panel referred to above may be considered a movable panel and the frame may comprise a fixed panel, wherein the movable panel slides relative to the fixed panel by the sliding mechanism so as to overlap the fixed panel. Preferably, the movable panel and the fixed panel form a substantially continuous external surface of the system when the door is in the closed position, and wherein the rotation of the door displaces the movable panel from the fixed panel to provide the clearance for the movable panel to slide and overlap the fixed panel. There may be only certain areas of the system that are required to be accessible during use of the system by the operator, and so other areas could be covered by a fixed panel of the frame, which may nonetheless protect certain areas of the system from interference. In a typical arrangement, in the closed position, the fixed panel may be located between the hinge and the movable panel. In other embodiments, there may be a fixed panel mounted within the door, with the movable sliding over this fixed panel within a frame defining the door.

Preferably, the door comprises a pair of opposing arms extending away from the rotation axis of the hinge, wherein the panel extends between the arms and slides along the length of the arms such that in the fully open position the space between the arms at the distal ends of the arms is unobstructed. In other words, in the fully open position, the arms and the panel may substantially define a U-shape opening through which an operator can access the system. Whereas it may be typical to provide a door on systems of this type with a rectangular support frame surrounding an interior panel, the present arrangement with opposing arms, e.g. not connected by their ends, allows the panel to slide along the arms, which leaves the space between the arms unobstructed. In embodiments in which the door comprises a pair of opposing arms, preferably the panel extends from a front surface of the arms, which face away from the frame of the system, to the rear surface of the arms, which face towards the frame of the system, to close a gap between the front surface of the arms and the frame when the door is in the closed position. However, if the panel is transparent, this may still provide good sight lines into the machine between the arms.

Preferably, the door will be configured such that the panel can only slide by the sliding mechanism once the door has been rotated on the hinge. Therefore, preferably, the door comprises an engaging element, preferably a rotatable element, such as a wheel, coupled to the panel, the engaging element being arranged to engage a stopping element of the frame when the door is in the closed position, wherein the engagement between the engaging element and the stopping element prevents the panel from sliding by the sliding mechanism when the door is in the closed position. While this is preferred, any mechanism for inhibiting the sliding of the panel could be used. The engaging element referred to above may move relative to stopping element during the rotation of the door from the closed position to the partially open position, whereby in the partially open position, the engaging element is released from the stopping element such that the panel may slide by the sliding mechanism. In particularly preferred embodiments, the engagement between the engaging element and the stopping element may guide the motion of the panel as it moves during rotation and then subsequent sliding. For example, one of the engaging element and the stopping element may define a track along which the other of the engaging element and the stopping element moves, preferably continuously, during the rotation of the door from the closed position to the partially open position and as the panel moves by the sliding mechanism, wherein preferably the other of the engaging element and the stopping element comprises a rotatable element that rotates as it moves along the track. This may allow the rotation and sliding of the panel to be performed in one smooth motion, guided by the interaction of the engaging element and stopping element. In embodiments in which a latch is used to define the normal opening range of the door, the latch may keep the engaging element and the stopping element in contact as the engaging element moves along the track defined by the stopping element or vice versa.

Any form of sliding mechanism for the panel may be used. However, preferably the door may comprise at least one support from which the panel extends, more preferably a pair of opposing supports, e.g. the arms referred to above, which the panel extends between, wherein the sliding mechanism comprises a track in one or both supports along which the panel slides. For example, the sliding mechanism may comprise a rail or groove on the or each support, with which the panel engages such that it may slide along said rail or groove. This is particularly simple mechanism, which keeps the manufacturing cost of the door low.

In embodiments in which the door comprises a pair of opposing supports, and the panel extends between the supports and slides along the length of the supports, a problem that may be experienced is the panel becoming jammed if it is not held level during sliding. Therefore, preferably, the sliding mechanism comprises a timing belt coupled to opposing ends of the panel and coupled to the supports using a series of pulleys, e.g. defining a closed loop path of the timing belt whose path length remains constant during movement of the panel, such that the panel is held level between the opposing supports during sliding. For example, by using a timing belt defining a closed loop path, if one side of the panel is moved, this will tension the timing belt and pull in a direction that ensures that the opposing side of the panel is moved by the same amount. This allows the door to be operated by the user at any point along the door without the risk of the panel becoming jammed.

Another problem with a sliding mechanism on doors that rotate about a horizontal rotation axis defined by the hinge is that the operator has lift the weight of the door, either during opening or closing. Therefore, preferably, the sliding mechanism comprises a resilient member, preferably a gas spring, for biasing against the weight of the panel during sliding. This arrangement assists the operator with opening or closing the door by using the resilient member to counteract the weight of the door. A gas spring or gas strut is particularly useful for smoothing the movement of the door as it moves down and assisting a user in lifting the door when it is moved up.

As has been mentioned above, a typical food processing system may be configured to convey product through the processing region along a product flow direction, wherein the product flow direction is preferably substantially horizontal, and wherein the one or more openings are through a side of the frame that extends along the product flow direction. These openings through the long side of the frame are generally the most difficult to provide access to without requiring a large clearance around the system, and so are most likely to benefit from the arrangement described above. In these embodiments, preferably the door extends along at least 50% of the length of the side of the frame along the product flow direction, preferably along at least 60%, more preferably along at least 70%, further preferably along at least 80%, most preferably along at least 90% of the length of the side of the frame along the product flow direction. An advantage of the present arrangement is that a very large door can be provided that still requires only a small clearance around the system for operation of the door. Hence, this allows a single door to cover most of the long side of the system, which is more convenient for an operator and decreases the manufacture cost of the system compared with the use of multiple doors on each side. Preferably, the door is connected to a switch, such that rotation of the door about said rotation axis activates the switch and causes one or more actions of the food processing system to stop. This increases the safety of the operator using the system.

Preferably, the door comprises a handle coupled to the panel for rotating the door by the hinge and for sliding the panel by the sliding mechanism. The position of one handle on the panel that controls the rotation of the door and the sliding of the panel allows the operator to open the door in one smooth motion.

It is generally preferred that an operator can inspect the processing region of the system while the door is closed, and so preferably the panel is at least partially transparent to allow an operator to view the processing region while the door is closed. For example, there may be a region within the panel that is transparent within an otherwise opaque panel. While preferred, the panel could also be entirely opaque.

The above description has focused on a single door on one side of the system; however, it will be appreciated that there could be multiple of these doors provided on each system, typically on different sides of the system. Preferably, the frame defines one or more openings through a first side of the frame for an operator to access the processing region and defines one or more openings through a second side of the frame opposite the first side, wherein the door is a first door for selectively opening and closing at least one of said openings through the first side of the frame, and further comprising: a second door for selectively opening and closing at least one of said openings through the second side of the frame; a second hinge coupling the second door to the frame and defining a rotation axis of the second door such that the second door may be rotated relative to the frame about said rotation axis, wherein the door is restricted so as to be rotatable relative to the frame through a normal opening range of no more than 60° to a partially open position; wherein the second door comprises: a panel for closing said at least one opening through the second side of the frame when the door is in a closed position; a sliding mechanism for sliding the panel along a direction of the door when the door is in the partially open position for fully opening the at least one opening through the second side of the frame. This second door will preferably have the same construction as the first door, and so may have all of the preferred features described above.

As mentioned above, the food processing system may be a food packaging system for performing one or more actions of packaging food items or quality control of packaged food items, preferably a tray-sealing system for sealing food product in trays, a seal-testing system for testing the integrity of sealed food packages, or a checkweigher system for checking the weight of food packages. Alternatively, the food processing system may be a food preparation system for performing one or more actions of preparing food products for packaging, preferably a food inspection system for inspecting food product to assess one or more characteristics, such as an X-ray system, a food weighing system for weighing food items, a food grading system, or a food flavouring system for coating food product in flavouring or marinade.

In accordance with a second aspect of the invention, a method of manufacturing a food processing system for performing one or more actions of processing food items comprises: providing a frame, the frame substantially surrounding a processing region within which one or more actions of processing food items takes place, the frame defining one or more openings through a side of the frame for an operator to access the processing region; providing a door for selectively opening and closing at least one of said openings through the side of the frame; and coupling the door to the frame by a hinge defining a rotation axis such that the door may be rotated about said rotation axis, wherein the door is restricted so as to be rotatable relative to the frame through a normal opening range of no more than 60° to a partially open position; wherein the door comprises: a panel for closing said at least one opening through the side of the frame when the door is in a closed position; and a sliding mechanism for sliding the panel along a direction of the door when the door is in the partially open position for fully opening the at least one opening through the side of the frame.

This method corresponds to a method of manufacturing the food processing system according to the first aspect of the invention. Accordingly, all of the preferred features described above with reference to the first aspect may be incorporated into the manufacture of the system according to this second aspect.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described with reference to the accompanying drawings, of which:

Figures 1 A and 1 B show a front view of a food processing system with a door in a closed position and a fully open position respectively;

Figures 2Aand 2B show a perspective view of the food processing system and an enlarged view of a part of the door and frame respectively in the closed position;

Figures 3Aand 3B show a perspective view of the food processing system and an enlarged view of a part of the door and frame respectively in a partially open position;

Figures 4Aand 4B show a perspective view of the food processing system and an enlarged view of a part of the doorand frame respectively in the fully open position;

Figure 5 shows an enlarged view of a part of the door and frame of the food processing system with the door in a maintenance position; and

Figures 6A and 6B show the inside of the door and an enlarged portion of the inside of the door respectively of the food processing system.

DETAILED DESCRIPTION

An embodiment of the invention will now be described in detail with reference to the Figures.

Figures 1A and 1 B show a front view of a food processing system 1. In this embodiment, the food processing system is a tray-sealing system. The system comprises a frame 10 which, together with a door 100 on the front side and a door on the rear side (not shown) form a housing that encloses a processing region 20 within the frame 10, the housing being supported by four feet 11 of the frame 10. The system 1 receives trays to be sealed through an input opening 21 through the frame in an upstream end of the system. The trays to be sealed are conveyed along the processing region 20 within the frame, where the trays are sealed by one or more processes taking place within the system. The sealing is generally performed using a number of units mounted on the top of the system, including in this case a film feed 3, a cutting and sealing unit 4 and a film uptake 5, but different food processing systems may have different types and arrangements of processing units. The sealed trays then exit the system through a downstream opening 22.

The system 1 is generally elongate along the conveyance direction, i.e. between the input and output ends of the system. The door 100 is provided in one of the substantially vertical elongate sides of the system. A second door (not shown), constructed identically to the first, may be provided in the opposite side of the system. The door 100 extends along substantially the whole length of the system, i.e. between the input 21 and output 22 opening. The door closes one or more openings 24 through the side of the frame, which expose the processing region 20 inside the frame.

Figure 1A shows the door 100 in a closed position. The door 100 comprises opposing arms 101 and 102, with the first arm 101 being located at an upstream end of the system 1 , close to the input opening 21 and the second arm 102 being located at a downstream end of the system 1 , close to the output opening 22. Each arm extends upwards, away from a hinge 50 located along the lower edge of the system housing defined by the frame 10. The hinge 50 extends between the lower ends of the arms 101 , 102 and coupled the lower end of these arms to the frame 10 such that the arms may rotate in a vertical plane. A panel 110 extends between these opposing arms 101 , 102. The panel is formed of a transparent plastic material, such as polycarbonate. Connected to an external face of the panel is a handle 111 , which runs along the entire length of the panel 110 along the conveyance direction of the system. In the closed position, the panel 110 extends between the opposing arms at the distal ends of the arms, i.e. distal to the hinge 50, such that the opening 24 to the processing region 20 is closed by the panel 110 located over the opening 24.

Figure 1 B shows the door 100 in a fully open position. In this position, the door has been rotated through a relatively shallow angle about the hinge 50, and then the panel 110 has been lowered along guides in the arms 101 , 102 towards the hinge 50 so that the panel no longer covers the opening 24. In this fully open position, the panel 110 now overlaps a lower fixed panel 12 of the frame 10. This fixed panel 12 of the frame 10 may enclose within it parts of the machine below the processing region, which may need to be accessed less often such as electronics for the system 1 , or a lifting mechanism for the tray sealer.

The door opening mechanism will now be described in more detail with reference to Figures 2Ato 5.

Figure 2A shows a perspective view of the system 1 with the door in a closed position. In this Figure, it can be seen that the side of the system in which the door is located is inclined slightly away from the vertical, so that the base of the housing i.e. where the hinge 50 is located, is slightly wider than the top of the housing, i.e. where he distal ends of the arms 101 , 102 are located, so that the door 100 slants inwards towards its top at an angle of about 8° from the vertical direction. In this closed position, the arms 101 , 102 are recessed into the frame and the movable panel 110 of the door is flush with the fixed panel 12 in the lower part of the housing. It can also be seen in this Figure that an upper edge of the panel 110 defines a curved top edge to the panel. This causes the panel to extend from substantially level with the exterior side of arms 101 , 102, to substantially level with an interior side of the arms 101 , 102, and prevents there from being an open gap above the panel and between the arms. That is, the panel 110 curves over so that the panel meets a top surface of the system 1 .

Figure 2B shows the upper end of one of the arms 101 of the door 100 in the closed position and shows the closing mechanism, which holds the door closed, along with a latch mechanism 30 used to restrict the movement of the door when opening. As can be seen in Figure 2B, the arm extends upwardly at an angle of about 8° from the vertical. Figure 2B shows the panel 110 located at the upper end of the arm 101 in the closed position. Figure 2B also shows the handle 111 connected to the external face of the panel 110. Also in this closed position, an electronic switch 6 located on the frame 10 is closed by an electronic connector 103 located in the upper end of the arm 101. As can be seen, for example in Figure 3B, which shows the door in a partially opened position, rotation of the door away from the closed position breaks the connection between the electronic switch 6 and the connector 103, which causes the system to cease operating in response to an opening of the door.

Figure 2B also shows a latch mechanism 30. The latch mechanism comprises an elongate latch plate 31 which has an elongate slot 32 running along the length of the latch plate 31 . The slot 32 receives a bolt 15 connected to the frame, so that the latch plate can move relative to the frame by the bolt 15 moving along the slot. The slot 32 is shaped so that an end closer the arm 101 is wider than an end away from the arm 101 . The slot transitions between the wide and narrow portions with a step 33, which acts as a first stop of the latch, which catches the bolt 15 to hold the latch in a first position. The narrow portion of the slot defines an end of the slot 34, which acts as a second stop of the latch for receiving the bolt 15 and holding the latch in a second position. At the opposing end of the latch plate 31 , there is a notch in the latch plate, which receives a bolt 105 in the arm 101 of the door 100 to define a fixed coupling point of the latch plate 31 to the door 100. The notch is open on the lower side of the cam plate, such that the latch may be removed from the bolt 105 to completely disengage the latch.

On an interior side of the door 100 is located an engaging member 112 in the form of a wheel, which projects in towards the centre of the system 1 from the panel 110and interacts with a closing mechanism mounted to the frame. The closing mechanism comprises a cam plate 13, which is fixed to the frame 10. A cam plate is provided at each end of the system, close to the corresponding arm 101 , 102, and an engaging member 112 is provided at each end of the panel 110 to interact with the corresponding closing mechanism. The cam plate 13 is a plate of metal fixed to the frame 10 that interacts with the engaging member 112 during opening and closing of the door 100. In the closed position, the cam plate defines a recessed stopping element 14 along an upper edge of the cam plate 13. When the door is in the closed position, the wheel 112 sits in the recessed stopping element 14. Since, in this closed position, the cam plate is located beneath the wheel 112, which is connected to the panel 110 of the door 100, the panel is prevented from opening by sliding along the length of the arms.

Figure 3A shows the door 100 in a partially open position. Here, the door has been rotated about the hinge 50 by an operator pulling on the handle 111. In the partially open position, the door has been rotated by an angle of about 8° so that it is substantially vertical. As can be seen in Figure 3A, the panel 110 of the door 100 is no longer flush with the fixed panel 12 in the lower part of the frame 10, instead being spaced in front of the fixed panel 12.

Figure 3B shows the upper end of one of the arms 101 in the partially open position, and shows the arrangement of the wheel 112 relative to the cam plate 13 and the arrangement of the latch mechanism 30 in the partially open position. As can be seen in Figure 3B, in this partially open position, the wheel 112 has rolled along the upper edge of the cam plate 13 and out of the recessed stopping element 14. From the recessed stopping element 14, the cam plate defines a curved track 16 for the wheel 112 to follow as the door is opened. This track curves from being generally horizontal when the wheel initially moves out from the recessed stopping element 14 to being generally vertical. In the partially open position of the door 100, the wheel 112 has moved out from the recessed stopping element and has rolled around the curved part of the track 16 so that it may now roll vertically down the rest of the track 16, which corresponds to the sliding of the panel 110 of the door 100.

In the partially open position of Figure 3B, the latch mechanism 30 holds the door so that it cannot rotate beyond the vertical position that it has now adopted. In particular, the rotation of the door has caused the bolt 105 in the door, which is received in the notch 35 of the latch plate 31 , to pull the latch plate substantially horizontally. Accordingly, the bolt 15 in the frame 10 has moved along the slot 32 in the latch plate 31 and has engaged the step 33 in the upper edge of the slot 32, which prevents the door from rotating further.

Figure 3B also shows that a gas spring 113 is in an extended position. One end of the gas spring 113 is connected to the panel 110 at the same position as the wheel 112. The other end of the gas spring 113 is connected to a lower part of the arm closer to the hinge 50. This gas spring is biased against the weight of the panel 110 and so urges the panel upwards, but is not so stiff as to prevent the panel from sliding down the door to the fully open position under its own weight.

Figure 4A shows the door in the fully open position. As shown in this Figure, the door 100 has not rotated any further relative to the partially open position of Figure 3A, since it is restricted by the latch mechanism 30. However, the panel 110 has slid down between the arms in order to open the opening 24 and allow an operator to access the processing region 20.

Figure 4B shows the upper end of one of the arms 101 in the fully open position. Here, it can be seen that the position of the arms relative to the cam plate 13, attached to the frame, has not changed, since the rotation of the door is still restricted by the latch mechanism 30. This Figure also shows that the panel 110 has slid down along the length of the arm 101 towards the hinge 50, with the wheel 112 being guided along the substantially vertical portion of the track 16 defined by the cam plate. Again, the latch mechanism 30 ensures that the door 100 has not rotated further, and keeps the wheel 112 in contact with the track 16 of the cam plate 13. In this fully open position the gas spring 113 has now compressed, as the panel 110 has moved down the arm 101.

To close the door, the movement described above is reversed. First, an operator lifts the panel 110, sliding it up the arms 101 , 102, assisted by the gas spring 113. The wheel 112 coupled to the panel 110 follows the track 16 of the cam plate 13 vertically upwards to the partially open position, and then over the curved section of the cam plate as the operator begins to rotate the door back towards the closed position. The wheel 112 is received in the recessed stopping element 14 of the cam plate 13 in the closed position, which then holds the door closed. Opening and closing of the door through the normal opening range has been described above. However, in some circumstances, it may be necessary to rotate the door further to access other parts of the system. Figure 5 shows the door 100 in a maintenance position.

In this position, the latch mechanism has been adjusted to permit further rotation of the door. In particular, a door latch cam 36 is used to raise the side of the latch plate 31 closer to the frame 10, so that the bolt 15 no longer is received on the step 33 in the upper edge of the slot 31 , and instead the latch plate 31 can move further relative to the bolt 15 until the bolt reaches the end 34 of the slot 31. In this position, the door 100 has now been rotated to beyond the vertical by an angle of about 8°. It should also be noted that the door could be rotated further by removing the latch 30 by lifting the end of the latch plate 31 coupled to the door 100 so that the bolt 105 passes outside of the notch 35 in the latch plate and the door is no longer coupled to the latch mechanism 30.

Figures 6A and 6B show the sliding mechanism for the panel 110 in more detail. Figure 6A shows the opposing arms 101 , 102 extending away from the hinge 50, with the panel 110 extending between the arms. As shown most clearly in Figure 6B, at each end of the panel 110 is a block 114, which defines a slot. The slot of the block 114 receives a plate-shaped rail 116 of the corresponding arm. This rail 116 is defined by the side face of the arm, which faces towards the panel 110. A first longitudinal edge of the rail is defined on by the edge of the side face of the arm, which faces towards the interior of the system. The second longitudinal edge of the rail 116 is defined on the other side by a slot 117 cut through the side face of the arm. This block 114 is thus able to slide up and down the rail 116 and allow the panel to move up and down the arms 101 , 102 of the door.

Figure 6B also shows that the wheel 112 is connected to the block 114, as is the upper end of the gas spring 113.

Figures 6A and 6B also show a timing belt 40 used to ensure the panel 110 remains level as it slides between the arms 101 , 102. The timing belt defines a closed loop path inside the door 100. The timing belt 40 is coupled to the block 114 by a bracket 115, which clamps the belt to the block 114. From this block 114, the timing belt 40 extends up inside the arm 101 to a first pulley 41 located at the top of the arm 101 . From the pulley 41 , the timing belt 40 extends down the arm 101 to a pulley 42 located at the bottom of the arm 101 and close to the hinge 50. The belt then extends across between the arms to a third pulley 43 located at the bottom of the arm 102, and then extends up the arm 102 to the block 114 on the arm 102, where it is connected to the block 114 by another bracket 115. The belt then continues to a fourth pulley 44 located at the top of the arm 102. The timing belt then extends back down the arm 102 to the third pulley and then the second pulley in parallel with the path already described. Finally, the belt 114 extends from the second pulley back to the block 114 to form the closed loop.

When one end of the panel 120 is slid in either direction by moving the block 114 along its rail 116, this pulls the belt 40, which then pulls in the same direction on the opposite block 114 in the opposing arm. This keeps the panel 110 level between the arms 101 , 102 and allows the door to be operated form anywhere along the length of the door, including at either end.