The present invention relates to a press for a cupping system, a cupping system including the press, and a method for making cups.

Cupping systems produce cups which are used in the manufacture of cans for foodstuffs or beverages. For example, a cup can be used to produce the base and a lower side wall for a can used to store carbonated drinks, such as colas, beers, etc. Cup-shaped blanks are formed from a metal sheet and are formed into cup-shaped configurations during each stroke of press.

There are typically two types of press that are used for this process: an overdriven press, and an underdriven press. An overdriven press is of the type wherein the drive system is located above the pressing members and conversely an underdriven press is where the drive system is located below the press bed. This invention relates to underdriven presses.

A known type of underdriven press includes an electric motor, which is arranged to drive a flywheel via a drive belt. The output of the flywheel is connected to a drive shaft. Drive is transmitted from the drive shaft to a crankshaft via a gear train. This arrangement is inefficient, increases the number of parts for the machine and results -in an unnecessarily large machine, particularly the depth of the machine (the dimension from the front of the machine to the rear of the machine). It has also been found that the drive system arrangement takes a long time to disassemble and reassemble during maintenance operation. This is undesirable since it means that the press is unavailable for use for longer than is necessary.

A further problem with known underdriven presses is that the height of each pressing member with respect to the press bed can only be adjusted manually by removing the pressing member from its support pillars, attaching spacer members, and reattaching the press member to the support pillars. This task is very time consuming and is difficult to perform.

Accordingly the present invention seeks to provide a press that mitigates at least one of the aforementioned problems, or at least provides an alternative to existing presses. According to one aspect of the invention there is provided a press for a cupping system, including: a press bed; a cupping die set mounted on the press bed; first and second pressing members for actuating the cupping die set; and a drive system for controlling movement of the first and second pressing members, wherein said drive system includes a flywheel assembly and a crankshaft, the crankshaft is located below the press bed when the press is in its normal operating orientation, and the crankshaft is coupled directly to the flywheel assembly. Since the crankshaft is coupled directly to the flywheel assembly a separate drive shaft and gearing that is used in the prior art presses is not required. This provides a more compact press that is easier to disassemble and reassemble than the prior ait devices since the drive system has been simplified.

The flywheel assembly includes a flywheel. Advantageously the flywheel assembly can include at least one of clutch means and brake means. Advantageously the flywheel assembly can include a clutch-brake unit.

The flywheel is connected to a drive unit. The drive unit includes a motor, and preferably an electric motor, and includes an output shaft. The output shaft is connected to the flywheel assembly via drive means such as a flexible drive member, which is typically a drive belt. However, other drive means such as gears can be used. The drive unit drives the flywheel via the output shaft and the drive means.

Advantageously the clutch-brake unit can include hydraulic actuation means. The clutch- brake unit is arranged to selectively drive the crankshaft via the clutch. The clutch-brake unit is arranged to selectively arrest rotation of the crankshaft via the brake. Advantageously the clutch-brake unit is attached to the Awheel and to the crankshaft, the arrangement being such that drive is transmittable from the flywheel to the crankshaft via the clutch-brake unit. The clutch-brake unit is mounted on the crankshaft towards one end thereof.

Advantageously the clutch-brake unit can be attached to a side face of the Awheel. The flywheel is annular. Advantageously the side face includes a recessed portion and the clutch-brake unit is at least partly located in the recessed portion. The recessed portion is substantially co-axial with the flywheel. A tubular member is fixed to a press support structure. The crankshaft extends through the tubular structure. The flywheel is rotatahly mounted on the tubular structure via bearings,

Advantageously the crankshaft, flywheel and clutch-brake unit are arranged substantially co-axially. Advantageously the drive system can include a first connecting assembly for transmitting drive from the crankshaft to the first pressing member, said first connecting assembly including a pair of first connecting rods mounted on the crankshaft, axially spaced apart. Each of said first connecting rods is rotatably attached to the crankshaft, preferably via a bearing, on an eccentric formation. Each of the first connecting rods protrudes substantially radially from the crankshaft. Each of the first connecting rods includes first and second ends and each of the first connecting rods is rotatably attached to the crankshaft towards its first end.

Advantageously the first connecting assembly can include a plurality of first connector units, and each of the first connecting rods is pivotally attached to its respective first connector unit. Advantageously the first connector unit can include a pivot pin and transverse connector member such as a crosshead. Each of the first connecting rods is pivotally attached to its respective first connector unit towards its second end. In preferred embodiments each of the first connector units is located below the crankshaft. This helps to provide a compact aiTangement. Each of the first connector units is arranged transversely with respect to the crankshaft.

Advantageously the first connecting assembly includes a plurality of first pillars connecting the first connector units to the first pressing member. Preferably at least one pair of first pillars connects each respective first connector unit to the first pressing member. Each pillar in the pair of first pillars is arranged substantially parallel to one another. Each of the first pillars in the pair is connected to its respective first connector unit such that the crankshaft is located between the first pillars, that is, each first pillar is on an opposite side of the crankshaft. Thus the pair of first pillars and its respective first connector unit form a substantially U-shaped frame around the crankshaft, in preferred embodiments, there are at least four first pillars supporting the first pressing member - two supporting each end of the first pressing member. The arrangement is such that rotation of the crankshaft causes each of the first connecting rods to move a limited amount (the throw of the crankshaft) in a substantially vertical plane. This causes each of the first connector units, each of the first pillars and the first pressing member to move vertically a limited amount.

Advantageously the first pressing member can comprise an inner slide.

Advantageously the drive system can include a second connecting assembly for transmitting drive from the crankshaft to the second pressing member. The second connecting assembly can include a pair of second connecting rods mounted on the crankshaft. The second connecting rods are axially spaced apart. Each of said second connecting rods is rotatably attached to the crankshaft, preferably via a bearing, on an eccentric formation. Each of the second connecting rods protrudes substantially radially from the crankshaft. Each of the second connecting rods includes first and second ends, and each of the second connecting rods is rotatably attached to the crankshaft towards its first end.

In preferred embodiments the first and second connecting rods are mounted axially on the crankshaft such that the pair of first connecting rods are outermost (located closer towards the ends of the crankshaft) and the pair of second connecting rods are innermost.

Advantageously the second connecting assembly can include a plurality of second connector units, and each of the second connecting rods can be pivotally attached to its respective second connector unit. Advantageously the second connector unit can include a regulating screw element and a transverse connector member such as a crosshead. Each of the second connecting rods is pivotally attached to its respective second connector unit towards its second end. In preferred embodiments each of the second connector units is located below the crankshaft. Each of the second connector units is arranged transversely with respect to the crankshaft.

Advantageously the second connecting assembly includes a plurality of second pillars connecting the second connector units to the second pressing member. Preferably at least one pair of second pillars connects each respective second connector unit to the second pressing member. Each pillar in the pair of second pillars is arranged substantially parallel to one another. Each of the second pillars in the pair is connected to its respective second connector unit such that the crankshaft is located between the second pillars, that is, each second pillar is on an opposite side of the crankshaft. Thus the pair of second pillars and its respective second connector unit form a substantially U-shaped frame around the crankshaft. In preferred embodiments, there are at least four second pillars supporting the second pressing member - two supporting each end of the second pressing member. The arrangement is such that rotation of the crankshaft causes each of the second connecting rods to move a limited amount (the throw of the crankshaft) in a substantially vertical plane. This causes each of the second connector units, each of the second pillars and the second pressing member to mo ve vertically a limited amount. Preferably the throw of the crankshaft for the second connecting rods is different from the throw of the crankshaft for the first connecting rods. Preferably the throw of the crankshaft for the first connecting rods is typically around 130mm and the throw of the crankshaft for the second connecting rods is typically around 75mm. Preferably the crankshaft is arranged such that the first and second pressing members are actuated around 60 degrees out of phase.

The second pressing member comprises an outer slide having a first part on a first side of the inner slide and a second part on a second (opposite) side of the inner slide.

Advantageously the press can include an adjustment system for controllably adjusting the distance between at least one of the first and second pressing members and the press bed. That is the distance between the or each pressing member and the press bed when the or each pressing member is stationary. In preferred embodiments, the adjustment system is arranged to adjust the position of the second pressing member with respect to the press bed.

Advantageously the adjustment system adjusts the distance between the second pressing member and the press bed by adjusting the positions of the or each second pillar with respect to a central axis of the crankshaft. The ends of the second pillars are adjusted with respect to the central axis of the crankshaft. Each end of each second pillar is connected to its respective second connector unit. The adjustment system adjusts the positions of each pillar substantially simultaneously. Advantageously the adjustment system can adjust the distance between a part of the second connector unit, such as the crosshead, and a central axis of the crankshaft.

Advantageously at least a part of the adjustment system is located below the press bed.

Advantageously the adjustment system can include at least one height adjustment mechanism, and preferably a plurality of height adjustment mechanisms.

The press can include a first part and a second part connected to the or each second pillar, and the height adjustment mechanism is arranged to adjust the relative positions of the first and second parts. Advantageously the first part can be connected to the second connecting rod. Advantageously each of the second connector units can include one of the height adjustment mechanisms. For example, the first part can comprise a member that is connected to the second connecting rod, such as the regulating screw element. The second part can comprise a transverse connector member, such as the crosshead.

Advantageously the adjustment mechanism is arranged to adjust the relative positions of the first and second parts via a screw drive. Each adjustment mechanism can include a gear, such as a worm gear, that is arranged to adjust the relative positions of the first and second parts by actuating the screw drive. Each adjustment mechanism includes an adjustment nut and a gear mounted on the nut. The worm gear is arranged to drive the adjustment nut via the gear. Advantageously the adjustment system includes a drive system having a drive source. The drive source can comprise an electric motor.

Advantageously the drive system can include a first telescopic drive rod for transmitting drive from the drive source to one of the height adjustment mechanisms. The press can include a second telescopic drive rod for transmitting drive to another of the height adjustment mechanisms. Advantageously each telescopic drive rod can be connected to its respective worm gear via a universal joint. Advantageously each telescopic drive rod can be connected to a drive shaft via a universal joint. The telescopic arrangement and universal joints allow for the translational movement of the second connector units. Advantageously the drive system is arranged to operate each of the height mechanisms in a substantially synchronous manner in order to maintain the second press member in a substantially parallel relationship with the press bed.

Advantageously the or each height adjustment mechanism can include at least one piston and at least one piston chamber.

The or each height adjustment mechanism includes hydraulic fluid.

Advantageously the or each height adjustment mechanism can include a drain to allow the hydraulic fluid to escape the piston chamber to assist resetting the press, for example after a crash situation has occurred. Advantageously the or each height adjustment mechanism can include a sensor arranged to monitor the hydraulic fluid pressure. The fluid pressure is indicative of the load applied by the press. The output of the sensor can be used by a controller to monitor the fluid pressure, and hence the load applied by the press. This enables the controller to detect dangerous conditions such as when the press is applying a load over a predetermined value. Advantageously a relief valve can be provided that is arranged to release fluid from the or each height adjustment mechanism. The controller can be programmed to automatically open the relief vaive(s) when the fluid pressure exceeds a threshold value. The controller can also be programmed to detect if a crash is likely to occur since there is typically a spike in the fluid pressure just prior to a crash situation. This enables the controller to act to prevent the crash, for example by applying a brake and / or opening the relief valve.

Advantageously the press can include counter weight means for at least one of the first and second pressing members, and preferably for each of the first and second pressing members. Advantageously the counter weight means can comprise a pneumatic loading system.

According to another aspect of the invention there is provided a cupping system including a press according to any configuration described herein. The cupping system can further include at least one of a cup extraction system and a sheet material feed system. According to another aspect of the invention there is provided a method for manufacturing cups including using a cupping system according to any configuration described herein.

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

Figure 1 is an isometric view of the front of a press for producing cups in accordance with an embodiment of the invention;

Figure 2 is a side view of the embodiment of Figure 1 from a first end;

Figure 3 is a side view of the embodiment of Figure 1 from a second end;

Figure 4 is rear view of the embodiment of Figure 1;

Figure 5 is a plan view from above of the embodiment of Figure 1 ;

Figure 6 is a partial sectional view along line A-A in Figure 5 (with a cupping die set removed for clarity):

Figure 7 is a sectional view along line B-B in Figure 6; Figure 8a is a sectional view along line C-C in Figure 6; Figure 8b is a sectional view along line D-D in Figure 6;

Figure 9 is an isometric view of a height adjustment mechanism used in the embodiment of Figure 1 ;

Figure 10 is an exploded isometric view of the height adjustment mechanism of Figure 9;

Figure 11 is plan view from above of the height adjustment mechanism of Figure 9; Figure 12 a sectional view along line A-A in Figure 11; Figure 13 a sectional view along line B-B in Figure 11; Figure 14 a sectional view along line B-B in Figure 1 1 showing the adjustment mechanism in its maximum height adjustment condition; and

Figure 15 a sectional view along line B-B in Figure 1 1 showing the adjustment mechanism in its minimum height adjustment condition.

Figure 1 shows part of a cupping system 1 in accordance with the present invention. The cupping system includes a press 3, a cupping die set 5, a cup extraction system 7 (shown in part only, for clarity), and a material feed system (not shown).

The press 3 includes a drive system 9, an inner press assembly 1 1 (hereinafter referred to as the inner slide 11), and an outer press assembly 13 (hereinafter referred to as the outer slide 13), and a press bed 15.

The inner and outer slides 11,13 are arranged to move independently of one another in a manner described below. The inner slide 1 1 is mounted between first and second parts 13a, 13b of the outer slide 13. The first and second parts 13 a, 13b are connected together and are arranged to move as a unit.

The drive system 9 includes a motor assembly 17, a drive belt 19, a flywheel assembly 21, which includes a flywheel 22 and a hydraulic clutch-brake assembly 23, a crankshaft 25, a first drive assembly 27 for the inner slide 11 and a second drive assembly 29 for the outer slide 13. The crankshaft 25 is located under the press bed 15. The press 3 is a so called underdriven press, wherein a substantial part of the drive system 9 (at least the crankshaft 25) is located below the press bed 15.

The motor assembly 17 includes an electric motor 31 and an output shaft assembly 33. The drive belt 19 communicates drive from the motor assembly 17 to the flywheel 22.

Drive is transmitted from the flywheel 22 to the crankshaft 25 via the clutch-brake assembly 23. The arrangement is such that the crankshaft 25 is directly connected to the flywheel assembly 21, which provides a more compact press 3. Since the crankshaft 25 is directly connected to the flywheel assembly 21, there is only a gearing effect between the motor assembly 17 and the crankshaft 25, which is provided by the drive belt connecting the flywheel 22 to the output shaft assembly 33. The flywheel 22 is mounted over the crankshaft 25 via a sleeve 24 and bearings 26. The flywheel 22 is arranged to rotate relative to the sleeve 24 and thus rotate relative to the crankshaft 25. The clutch-brake assembly 23 is connected to the flywheel 22. The flywheel 22 is annular. The clutch-brake assembly 23 is mounted on one side 28 of the flywheel, typically the outermost side. The flywheel 22 includes a recess 30 in the side 28 and at least part of the clutch-brake assembly 23 is located in the recess 30. The clutch-brake assembly 23 includes a clutch that is arranged to selectively transmit drive from the flywheel 22 to the crankshaft 25 according to its operational condition. The clutch-brake assembly 23 includes a brake that is arranged to provide a smooth braking effect for normal use and provides an emergency braking function that can arrest movement of the crankshaft 25 in approximately 180° of rotation. This compares with pneumatic clutch- brake devices, which arrest rotational movement at approximately 250°-300° of rotation of the crankshaft 25. Thus there is a significant advantage in using the hydraulic clutch-brake assembly 23.

The flywheel 22 and the clutch-brake assembly 23 are arranged co-axially with the crankshaft 25.

The crankshaft 25 includes a pair of inner throws (cam surfaces) 39 for the inner slide 11 and a pair of outer throws 41 for the outer slide 13. The inner throws 39 are located towards first and second ends of the crankshaft 25. The outer throws 41 are located adjacent the inner throws 39, however they are located between the inner throws 41.

The inner slide drive assembly 27 includes a pair of inner slide connecting rods 43 (see Figures 6 and 8b). Each connecting rod 43 is rotatably mounted on the crankshaft 25 at one of the inner slide throws 39. Each connecting rod 43 protrudes substantially radially from the crankshaft 25. Each connecting rod 43 is connected to a respective inner slide crosshead 45 via a respective pivot pin 47. A pair of inner slide pillars 49 connect each of the crossheads 45 to the inner slide 11. Thus the inner slide 11 is mounted on four of the pillars 49, with two located towards each end of the inner slide 1 1 , The arrangement is such that as the crankshaft 25 rotates the connecting rods 43 move around 130mm in a vertical plane due to the throw of the crankshaft 25, which causes the inner slide 1 1 to move around 130mm vertically. Drive is communicated from the crankshaft 25 to the inner slide 11 via the connecting rods 43, pivot pins 47, crossheads 45, and pillars 49 to the inner slide 11. The movement of the inner slide 11 is retained in substantially a vertical plane since the opposite ends of the inner slide 11 are driven by the pillars 49 substantially simultaneously, thereby maintaining the inner slide 1 1 in a substantially parallel relationship with press bed 15. Operation of the inner slide 11 causes the cupping die set 5 to be actuated to undertake a first cupping operation.

The inner slide 1 1 includes a counter balancing system 51, which is preferably a pneumatic bellows cylinder type arrangement.

The outer slide drive assembly 29 includes a pair of outer slide connecting rods 53 (see Figures 6 and 8 a). Each connecting rod 53 is rotatably mounted on the crankshaft 25 at one of the outer slide throws 41. Each connecting rod 53 protrudes substantially radially from the crankshaft 25. Each connecting rod 53 is connected to a respective outer slide crosshead 55 via a respective regulating screw element 57. A pair of outer slide pillars 61 connect each of the crossheads 55 to the outer slide 13. Thus the outer slide 13 is mounted on four of the pillars 61, with two located towards each end of the outer slide 13. The arrangement is such that as the crankshaft 25 rotates the connecting rods 53 move around 75 mm in a vertical plane due to the throw of the crankshaft 25, which causes the outer slide 13 to move around 75mm vertically. Drive is communicated from the crankshaft 25 to the outer slide 13 via the connecting rods 53, regulating screw elements 57, crossheads 55, and pillars 61 to the outer slide 13. The movement of the outer slide 13 is retained in substantially a vertical plane since the opposite ends of the outer slide 13 are driven by the pillars 61 substantially simultaneously, thereby maintaining the outer slide 13 in a substantially parallel relationship with press bed 15.

Operation of the outer slide 13 causes the cupping die set 5 to be actuated to undertake a second cupping operation. The throws 39,41 are arranged such that the inner and outer slides 11,13 operate out of phase by around 60°.

The outer slide 13 includes a counter balancing system 51 that is similar to the counter balancing system 51 used on the inner slide 11. The outer slide drive assembly 29 includes a press height adjustment system 58. The purpose of the height adjustment system 58 is to adjust the distance between the outer slide

13 and the press bed 15 by around 25mm, that is, typically plus or minus 12.5mm (Figures

14 and 15 show maximum and minimum height positions respectively).

The height adjustment system 58 includes two height adjustment mechanisms 59, one for each of the crosshead 55 - regulating screw element 57 pairs (see Figures 9 to 15). Each height adjustment mechanism 59 is arranged to adjust the position of the regulating screw- element 57 with respect to its crosshead 55, thereby adjusting the position of each of the crossheads 55 with respect to the longitudinal axis of the crankshaft 25. This is because the pillars 61 are fixed to their respective crossheads 55, and the outer slide 13 is fixed to the pillars 61, and therefore adjusting the position of the crosshead 55 with respect to the centre line of the crankshaft 25 effectively adjusts the position of the outer slide 13 with respect to the press bed 15,

Each crosshead 55 includes a substantially cylindrical body 63 and two arms 65 extending substantially radially outwards from a curved surface of the substantially cylindrical body 63. The arms 65 are diametrically opposed to each other. Each ami 65 includes a through hole 67 for receiving one of the pillars 61. The regulating screw element 57 includes a body 69 having a first cylindrical portion 71 having a slot 73 for receiving an end of the outer slide connecting rods 53, and through holes 75 for receiving a pivot pin 77.

The body 69 includes a second cylindrical portion 79, which has a smaller diameter than the first cylindrical portion 71. The second cylindrical portion 79 includes an external screw thread 81.

The crosshead body 63 includes a cavity 83. At the base of the cavity there is provided a cylinder 85, a piston 87, which fits into the annular spacer 85 and is sealed thereto by O- rings 89. Hydraulic fluid is provided in an annular chamber 86 formed by the cylinder 85 and piston 87. A drain (not shown) is provided for enabling fluid to be removed from the chamber 86. The drain helps to release the press after a crash situation since the empty chamber 86 allows the press some further movement to free itself, which otherwise would not be available. Each height adjustment mechanism 59 includes a sensor (not shown) for monitoring the hydraulic fluid pressure. The fluid pressure is indicative of the load applied by the press. The output of the sensor can be used by a controller to monitor the fluid pressure, and hence the load applied by the press. This enables the controller to detect dangerous conditions such as when the press is applying a load over a predetermined value. A relief valve (not shown) is provided to control release of hydraulic fluid from the chamber 86 via the drain. The controller can be programmed to automatically open the relief value when the fluid pressure exceeds a threshold value. The controller can be programmed to detect if a crash is likely to occur since there is typically a spike in the fluid pressure just prior to a crash situation. This enables the controller to act to prevent the crash, for example by applying a brake and / or opening the relief valve when the condition is detected.

Each height adjustment mechanism can be provided with a drain 125 for removing lubricating fluid.

Each mechanism 59 includes an adjustment nut 93 and a frusto-conical retainer ring 91 that is arranged to restrain the axial position of the adjustment nut 93. The adjustment nut 93 has an outer octagonal form that is arranged to fit into a nut holder 95. A collar 107 retains the nut holder 35 and nut 93 within the body 63.

The adjustment nut 93 includes an internal screw thread 94 that is arranged to mate with the external screw thread 81 formed on the regulating screw element 57. The nut holder 95 includes external teeth 97 that are arranged to mate with an external teeth 99 on a wonn gear 101.

The worm gear 101 extends into the crosshead body 63 via a hole 103 such that the worm gear 101 tangentially engages the nut holder 95. The worm gear 101 is arranged to drive the nut holder 95, the adjustment nut 93 and hence change the relative position of the regulating screw element 57 to the crosshead 55.

The wonn gear 101 includes a shaft 105, which protrudes out of the hole 103.

The height adjustment system 58 further includes a drive system 100 for actuating the height adjustment mechanism 59 substantially simultaneously (see Figures 6 and 7). This ensures that each end of the outer slide 13 is adjusted by the same amount, thereby maintaining the outer slide 13 substantially parallel to the press bed 15.

The drive system 100 includes an electric motor 109, a drive shaft 1 10, a chain 1 1 1 connecting the motor 109 to the drive shaft 110, and first and second telescopic drive rods 113, The drive rods 113 are telescopic to account for the translatioiial movement of the crossheads 55 during operation of the press. Each drive rod 113 is connected to the drive shaft 1 10 via a universal joint 121. Each drive rod 113 is connected to its respective worm gear shaft 105 via a universal joint 1 15. The drive shaft 1 10 is supported by bearings 1 12.

In order to adjust the position of the outer slide 13 with respect to the press bed 15, the motor 109 is actuated. The motor 109 transmits drive to the drive shaft 110 via the chain 11 1. Drive is transmitted from the drive shaft 1 10 to each of the worm gear shafts 105 via the telescopic drive rods 113. This causes each worm gear 101 to rotate, thereby imparting drive to each of the adjustment nuts 93 via their respective nut holder 95. As each adjustment nut 93 rotates, it causes its respective regulating screw element 57 to move axially, in a substantially vertical direction, with respect to the crosshead 55, Thus the crosshead 55 effectively adjusts its position with respect to the centre line of the crankshaft 25. This has the effect of moving the outer slide pillars 61 vertically upwards or downwards thereby adjusting the position of the outer slide 13 with respect to the press bed 15. This adjusts the vertical position of an upper part of the die set 5 with respect to a lower part of the die set 5.

It is to be noted that the throws of the crankshaft 25 are not adjusted when the mechanisms 59 are operated since the length of the outer slide connector rods 53 is not adjusted and therefore the distance between the centre line of the pivot pin 77 and the centre line of the crankshaft remains the same. The apparatus further includes arms 123 that are pivotally attached to the press and are arranged to receive the die set thereupon, to enable the die set to slide into a gap formed between the press bed 15 and the upper and lower slides 1 1,13.

It will be apparent to the skilled person that modifications can be made to the above embodiments that fall within the scope of the invention, for example the height adjustment mechanisms 59 can be included in the inner slide drive assembly 27 in addition to, or as an alternative to the outer slide drive assembly 29.

The inner and outer slides 11,13 can be rearranged such that the inner slide 11 is mounted on the pillars 61 and the outer slide 13 is mounted on the pillars 41.