GB1587119A

GB1587119A - Nailing pallets

Info

Publication number: GB1587119A
Application number: GB1809977A
Authority: GB
Original assignee: OSBORNE STEVENS GROUP Ltd
Current assignee: OSBORNE STEVENS GROUP Ltd
Priority date: 1977-04-29
Filing date: 1977-04-29
Publication date: 1981-04-01

Description

(54) NAILING PALLETS (71) We, OSBORNE STEVENS GROUP LIMITED, a British Contpany, of Brighton Road, Crawley, Sussex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to equipment for manufacturing frame assemblies by nailing together components, and specifically to the manufacture of bottom frame sub-assemblies as a stage in the manufacture of pallets of the socalled two-way-entry and four-wayentry kinds.

Pallets of the so-called two-way-entry kind comprise a bottom frame of boards onto which are nailed parallel, elongate, generaily-rectangular-section bearer members positioned normally along opposite ends of the bottom frame and midway across the frame.

The deck boards of the pallet are nailed onto the tops of these elongate bearer members, either directly or with the interposition of stringer boards extending along the longer edges of the pallet. Thus the elongate bearer members aet as spacers between the. bottom frame and the decking of the pallet, and allow aecess for the fork of a lift truck between the bottom frame and the decking through two opposite edges of the pallet only, normally the longer edges.

Pallets of the so-called four-way-entry kind comprise a bottom frame of boards onto which are nailed retangular spacer blocks positioned normally at the corners and centre of the frame and at the midpoints of its side members. Onto the tops of these blocks are nailed stringer boards, and the decking is nailed cross-wise on the stringer boards. With such an arrangement there is access for the fork of a lift truck between the bottom frame. and the decking on all four sides of the pallet.

In the manufacture of two-way-entry and four-way-entry pallets the spacer bearers or blocks can be placed by hand in a predetermined pattern on a supporting jig, after which the boards which will form the bottom frame are placed by hand on the blocks, and the jig is. advanced stepwise on a carrier to successive positions beneath a nailing machine by which the boards are thep nailed to the bearers or blocks. There is thus formed a sub-assembly of a bottom frame and spacer bearers or blocks, Which can then be withdrawn from the nailing machine and inverted, and the stringer boards and decking can be nailed on it ih a separate operation. Such a bottom frame sub-assembly is referred to herein as being of the kind specified.

It is an object of the present invention to provide a novel equipment for supporting and nailing together the bottom boards and spacer members to form bottdm. frame sub-assemblies of the kind specified of either two-way-entry or four-way-entry pallets, as a stage in the automated manufacture of such pallets.

According to the present invention, a machine for manufacturing pallet bottom frame sub-assemblies of the kind specified comprises a conveyor having ari endless flexible conveyor member of the chain, belt or cable kind carrying a series of jig assemblies mounted on and spaced apart along the length of the flexible conveyor member, each jig assembly affording means for locating a set of spacer members for a single pallet supported on the flexible conveyor member in relative positions corresponding to their required positions in a finished sub-assembly, a nailing machine having at least one row df nailing heads extending across the upper run of the flexible conveyor member at right angles thereto, means for driving the conveyor interrnittently to advance the upper run of its flexible conveyor member and the jig assemblies carried by it ih steps of predetermined length past the nailing machine, the lengths of the successive steps df movement of the flexible conveyor member being such as to bring each jig assembly in turn into successive positions beneath the nailing heads, and the nailing machine being operable during the intervals between the stepwise movements of the flexible conveyor member and with the jig assembly stationary in the said successive positions, to nail spaced rows of nails into a set of spacer members located by the jig assembly, and thereby to nail to the spacer members a set of bottom frame boards previously placed on the spacer members, and in which the machine is convertible for use in making bottom sub-frame assemblies either of twoway-entry pallets or alternatively of fourway-entry pallets, the conversion being effected by changing the jig assemblies to locate in the one case sets of elongate spacer bearers supported horizontally on the flexible conveyor member and extending across it at right angles to its direction of movement, and in the other case sets of spacer blocks supported in spaced horizontal rows extending at right angles to the direction of movement of the flexible conveyor member.

In one arrangement, the changing of the jig assemblies is effected by exchange of jig assemblies each adapted to locate a set of the elongate space bearers at appropriate spacings along the conveyor member, for jig assemblies each adapted to locate a set of the spacer blocks in rows at the same spacings as the rows of bearers, or at different spacings, as required, and vice versa, the machine being provided with alternative sets of the jig assemblies for this purpose.

Thus, for the manufacture of sub-assemblies for two-way-entry pallets, the jig assemblies may comprise each a set of pairs of locating dogs which in use are detachably secured to the flexible conveyor member to protrude outwardly therefrom, for locating the elongate spacer bearers in their required bridging positions each between the spaced dogs of two pairs, whilst for the manufacture of sub-assemblies for four-wayentry pallets, the machine may also be provided with alternative jig assemblies each comprising a set of rigid jig plates which in use are detachably secured to the flexible conveyor member to extend across its outer side at right angles to its direction of movement, in spaced parallel relationship to one another, the plates being provided on their upper surfaces with formations for locating the spacer blocks in their required relative positions. one row of blocks per plate. To convert the machine from two-way-entry work to four-way-entry work the dogs are detached from the conveyor member and the plates for supporting spacer blocks are secured to the conveyor member at suitable spacing, and vice versa.

Where the machine is provided at the delivery end of the conveyor beyond the nailing machine with a set of fixed skids constructed and arranged to engage beneath and lift each completed sub-assembly from its locating jig assembly for removal, the conversion of the machine may also involve exchanging one set of skids appropriate to one form of sub-assembly, for another set of skids appropriate to the other form of sub-assembly.

For use in the manufacture of four-wayentry pallets, the machine may be provided with block feeding mechanism mounted above the conveyor at its end upstream of the nailing machine, with respect to the direction of movement of the upper run of the conveyor member, the block feeding mechanism being operable during the intervals between the stepwise movements of the fexible conveyor member to place spacer blocks mechanically, a row at a time, in their required positions on the flexible conveyor member in which they are located by the respective jig assemblies.

The block feeding mechanism may comprise a set of the feeder devices claimed in our co-pending Patent Application No.

4050/76 (Serial No. 1587117), and if desired, the block feeder devices may be detachable and may be removed for conversion of the machine for two-way-entry pallet working.

The invention may be carried into practice in various ways, but one specific embodiment thereof will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a plan of a machine for the semi-automatic manufacture of bottom frame sub-assemblies of wooden pallets, shown as set up for manufacture of fourway-entry pallet sub-assemblies; Figure 2 is a perspective view of one of the jig assemblies on the conveyor chains of the machine as set up in Figure 1; Figure 3 is an elevation, seen in the direction of the arrow III in Figure 1, of the block feeders of the machine of Figure 1; Figures 4 and 5 are respectively a side elevation and a sectional side elevation on a larger scale, of one of the block feeders; ; Figure 6 is a detail view on a larger scale of one of the board locators on the jig plates of the installation; Figure 7 is a perspective detail view of the skids at the outfeed end of the conveyor, showing part of a completed frame sub-assembly about to engage the skids; Figure 8 is a sectional view on the line VIII-VIII of Figure 1; Figure 9 shows the apparatus of Figures 1 to 8 incorporated in a complete production line; Figure 10 is a view similar to Figure 1 showing the machine of Figures 1 to 8 converted for use in the manufacture of bottom frame sub-assemblies of two-way-entry pallets;; Figure 11 shows a set of locating dogs forming part of one of the alternative jig assemblies used in the converted machine of Figure 1d, and Figure 12 shows the alternative forni of end skid arrangement used with the machine of Figure 10.

The machine 10 illustrated in Figures 1 to i2 is for making bottom frame sub assemblies of wooden pallets and is can vertible for use either in making such subassemblies for two-way-entry pallets or in making such sub-assemblies for four-wayentry pallets or in making such sub-assemblies for four-way-entry pallets as required.

As shown in Figures 1 to 8 the machine is set up for making sub-assemblies of four-wayentry pallets and comprises a power-driven conveyor A having an endless flexible conveyor A having an endless flexible cdn- veyor member comprising two spaced chains 136 bridged by jig plates 135A and running around end sprockets Al. The conveyor is driven at one end by means of a power pack and hydraulic motor A2 having a control system programmed for advancing the flexible conveyor member in controlled steps in the direction of the arrow A3.

Straddling the conveyor A is a nailing machine B having a tool bridge B1 extending transversely over the upper run df the conveyor chains 136 and carrying the nailing heads, which are arranged in one or in two close-spaced rows as appropriate to provide the required nailing patterns.

Secured to the conveyor chains 136 at spaced intervals along their lengths are several jig assemblies 135 each comprised of three rigid parallel metal plates 135A spaced apart and extending transversely to the conveyor run, bridging the conveyor chains and detachably secured to the outer faces of the chains by clamping means not shown.

As shown most clearly in Figure 2, each of the jig plates 135A carries on its upper surface three sets of block locating formations, in the form of longitudinal locating brackets 137 and transverse locating brackets 138 positioned to define three support areas a, b and c each dimensioned to receive one of the wooden spacer blocks of a four-wayentry pallet as shown in outline at 106 in the Figure. It will be seen that the central support area b of each plate 135A is shorter than the two outer areas a and c, to receive a shorter central block 106, and is defined on all four sides by a pair of the brackets 137 and a pair of the brackets 138, whereas each of the larger end areas a and c is defined on three sides only by a pair of brackets 137 and a single bracket 138, for reasons that will be described.Also mounted on the upper face of each jig plate 135A are two pairs of cooperating locating posts 139,140, which locate the transverse' frame boards when applied to the tops of the spacer blocks as will be described. Figure 6 shows one of the posts 140 in detail.

Mounted on a rail 101 forming part of the framework at the infeed fetid of the conveyor A are a set of three block feeders D, E and F shown in detail in Figures 3, 4 and 5, and described in our aforesaid co-pending application No. 4050/76 (Serial No. 1587117). Thus each of the feeders D, F and F comprises a vertically-extending upper guide chute 100 of frame construction, mounted on the supporting rail 101, and having an open upper end 102.The upper chute 100 comprises four angle-section rails 103 joined by cross-memebers 104, the side rails 102 having out-turne"d entry guides 105 through which a succession of wooden spacer blocks 106 for pallets can be inserted to fall freely under gravity in the chute, or be biassed by other means towards the lower end of the chute, and form a vertical stack resting on the bottom plate 107 which closes the bottom of the upper guide chute 100.

Mounted alongside and mainly below the upper guide chute 100 is a vertically-extending lower guide chute 110, also made up of angle-section side rails 111 and cross-straps 112. The upper end portion of the lower chute 110 overlaps the lower end portion of the upper chute 100 and is welded to it at 114 as shown, the side rails 103' and 111 of the two chutes being cut away at 115, 116 respectively to form a window aperture at 117 (Figure 5) in the opposed sides of the two chutes above the bottom plate 107, through which a block 106 can pass transversely to the chute lengths from the bottom of the interior of the upper chute 100 into the top of the interior of the lower chute 110.The internal cross-sections of the two chtes 100 and 110 are slightly larger than the corresponding dimensions of the blocks 106, so that the latter can slide freely along the chute. However, the lower chute 110 is provided at its open lower end 118 with a pair of curved pinch shdes 119 mounted on opposite sides 6f the chute and respectively spring-pressed inwardly towards one another by compression springs 119, so that a block 106' which has slid down the chute 110 to its lower end will be lightly gripped by and frictionally supported between the convex inner faces of the two pinch shoes 119. In this way a stack of three of the blocks 106 can be supported in the chute 110, the upper two blocks resting on the frictionally-gripped lower block 106'.

Mounted on the outer edge of the bottom plate 107, and extending at right angles to the length of the upper chute 100, is a pneumatic ram 120 whose horizontal plunger rod 121 carries a thrust block 122. When the ram 120 is actuated, its thrust block enters the lower end of the chute 100 transversely, through a window 123, and thrusts the lowermost block 106" of the stack in the chute 100 laterally out through the aperture 117 into the upper end portion of the lower chute 110, where it will fall into the position shown at 106"' resting on the other two blocks in the chute 110. The ram 120 is then retracted to allow the stack of blocks in the upper chute 100 to fall through a distance equal to one block height onto the bottom plate 107.

A second pneumatic ram 130 is mounted in a vertical attitude on the side of the upper chute 100 in a position above and aligned with the open upper end of the lower guide chute 110. The vertical plunger rod 131 of the ram 130 carries a button 132 which, when the ram is actuated, engages the top of the uppermost block 106"' in the stack frictionally supported in the chute 110 by the pinch shoes 119, and thrusts the whole stack of three blocks vertically downwardly through the pinch shoes through a distance equal to one block height, thereby positively thrusting the lowermost block 106' down out of the chute 110 and onto a supporting jig strip 135 positioned below it. The ram 130 can then be retracted to allow a further block to be transferred from the chute 100 to the top of the chute 110 by the next actuation of the horizontal ram 120.

The three block feeding devices D, E and F ,arc mounted side by side in spaced positions on the rail 101 above the conveyor chains 136 at the infeed end of the conveyor.

The conveyor A is advanced stepwise to bring in turn the jig plates 135A of each jig assembly 135 beneath the open lower ends of the chutes 110 of the three feed devices, in the exact positions required for feeding of the blocks onto the areas a, b and c of the respective plate 135A as defined by the guide formations 137, 138. The rams 130 and 120 are then operated in succession, simultaneously in each of the three feeding devices. The ram 130 thrusts the lowermost block 106' of the chute 110 in each feeding device positively downwardly into its position on the jig plate 135A where it is located by the formations 137, 138. When the rams 130 have been retracted, the rams 120 of the three devices are then operated to transfer the bottom block of the stack in the upper chute 100 of each feeding device into the top of its lower chute 110 in readiness for the start of the next cycle.

When all nine blocks have thus been positioned on a jig assembly 135 consisting of a set of three plates 135A, the conveyor A then advances the jig assembly clear of the feeding devices, the bottom frame boards are laid on the blocks 106 carried by that jig assembly, by hand or by a mechanical board feed, not shown, in their required positions.

The transverse frame boards, partially shown in chain lines at g in Figure 2, are located by means of the posts 139, 140, of which the post 140 is shown in detail in Figure 6 and carries a pressure finger 141 pivoted at 142 to the top of the fixed post and spring-biassed inwardly by a compression spring 143 provided with a pressure adjustment screw 144. The pressure finger 141 engages the edge of the board g to grip it resiliently between itself and the other locating post 139. The longitudinal frame boards h are located against the abutted ends of the transverse frame boards g by adjustable guide rods 145 extending along opposite sides of the conveyor A. The rails 145 also locate the outer spacer blocks in the positions a, c of the jig plates 135A.

With the blocks and frame boards thus positioned on the jig assembly 135, the conveyor is advanced until the leading jig plate 135A lies directly under the tool bridge B1 of the nailing machine B, in which position the inwardly-protruding plungers 146 of a pair of pneumatic stop rams 147, one on either side of the conveyor A, protrude into the path of the jig assembly 135 and abut against the front faces of the two outer blocks 106 on the areas a and c thereby pressing these two blocks back against the rear guide brackets 137 so that the blocks are correctly located and are prevented from moving forwards under their own inertia when the conveyor is stopped in this position by means of a limit switch (not shown).The nailing machine is now operated by a command signal from the control system, and applies a single row of nails, or two close-spaced rows of nails, as appropriate which nail through the frame boards g and h and into the row of blocks 106, in a predetermined nailing pattern. The stop ram plungers i46 are then automatically retracted, and the conveyor A automatically advances the jig assembly 135 to bring its next plate 1 35A into its nailing position under the tool bridge B1, when the stop ram plungers 146 are again automatically advanced to check the jig assembly and locate the blocks correctly. The second nailing operation is then performed, to nail the frame boards to the blocks on the intermediate jig plate 135A; and the cycle is then repeated to nail the boards to the blocks on the rearmost plate 135A of the jig.

This completes the construction of the bottom frame sub-assembly on that jig assembly 135, which is advanced forward by the conveyor through and clear of the nailing machine B whilst the next jig assembly 135 on the chains 136 is brought forward by the conveyor, for block feeding, board application and subsequent nailing, as described.

Each completed bottom frame sub-as sembly is delivered at the outfeed end 6f the conveyor A ontd a set of skids 160, shown in detail iri Figure 7, which include upwardly-inclined ramp positions 161 which engage beneath the advancing bottom frame sub-assembly and lift it clear of the locating formations 137, 138, 139 and 140 on the jig assembly 135, and support the frame' subassembly as the jig assembly moves down round the out-feed end sprockets Al 6f the conveyor.From the skids 160 the containers may be removed in any desired manner for Storage, but preferably they arc transferred onto a further conveyor for transfer to the next manufacturing stage which involves inverting the sub-assemblies and nailing on the stringer and decking boards.

Thus as shown in Figure 9; the block-to- base Ihachine 10 forms one end of a con tinilous production line containing, in order a power-driven roll conveyor Gl, a powerdriven turner unit H for inverting each subframe assembly so that it blocks 106 lie uppermost; a further power-driven conveyor (32, a deck-fixing machine J comprising a further chain conveyor J1 which advances the inverted sub-frame assembly, with the stringer and decking boards placed manually Or automatically on it in their required positions, stepwise beneath a further nailing machine J2 by which the decking is nailed to the tops of the blocks, thus completing the pallet assembly, a further power conveyor G3 which transfers the completed pallets onto a Stacker K; and a further power conveyor Q4 for delivering the pallets from the stacker K as required.

To provide additional support for the jig plates 135A under loading by the feed devices D; E and F and by the nailing machine B, three fixed long'itudinal rails 165 ate mounted beneath the upper run of the conveyor chains 136 between the clains as shown in Figure 8. These rails are of steel covered on at least their upper faces with bearing trips or coatings of polytetrafluor- ethylene or other low-friction plastics material, the jig plates 135A resting on the bearing strips Of the three rails.

Moreover, to support the inverted re- turning jig plates 135A carried by lower runs of the conveyor chains 136, two rows of rollers 166 are mounted beneath the conveydr Oh rails 167, as shown in Figure 8. The support of the jig plates 135A by these rollers reduces the loading of the conveyor chains 136 by the weight of the jig. plates, and hence reduces the chain tension in the lower run of the conveyor.

The madhihe shown in Figures 1 to 8 is as described a"nd claimed in our co-pending application No. 4062/76, (Serial No.

1587118) for making bottom frame' sub-' assemblies for four-way"entry pallet but can be converted for making bottom frame sub-assemblies for two-way-entry pallets, the conversion principally involviffg removing the jig asseinblies 135 and replacing them by other jig assemblies adapted to locate elongate rectangular-section spacer bearers.

Thus the three jig plates 135A of each jig assembly 135 are removed completly from the conveyor chains 136 by releasing their attachment clamps, and in their places jig assemblies 240 shdwn in Figure 11 aft attached to the chains 136 at appropiate intervals along their lengths. These jig assemblies 240 comprise pairs of cooperating dogs 241, of which two cooperating pairs are shown in Figure 11.The two dogs 241 of each pair comprise plates cerrying fixing pins 242 which are passed through ap- propriately-situated tubular rivets of the chains 136 and are secured by split pins 243 through their protruding ends, so that each dog plate 241 is separately mounted in position projecting outwardly from the chain 136 as shown, and spaced along the chain from the other dog plate 241, of that pair. Each dog plate 241 carries a slideably mouiited adjustement plate 244 which can be clamped by means of clamping nuts 245 in a required position on the plate 241.

The plates 244 on the two dog plates 241 of each pair cafl be adjusted in directions towards and away from one another and Secured in position by the clamping niits 245, for the purpose of adjusting the effec- tive gap between the two dogs 241 to match the thickness of a spacer bearer 246 to be fitted in the jap as shown in Figure 11.

There are three pairs of dogs per chain in each jig assembly, corresponding pairs' on the two chains being in register with one an- other so that each jig assembly will locate three spacer bearers 246 supported dn the chains 136 in their required relative positions for the nailing to them of the bottom frame board which in this ease comprise lower decking boards 247 nailed directly across the three spacer bearers as shown in Figure 12.

Thus with the replacemet jig assemblies constituted by the dogs 241 fitted instead of the jig plates 135A, the machine can be used for thd mahufacthre of the bottom frame sud-assemblies of two-wav-entry pallets: The three bearers 246 for each sub- assembly are filtred by hand or by a suitable dispenSer between the dogs 241 of a jig as- sembly upstream of the nailing machine B; with the conveyor stationary, so as to locate the bearers in their required relative posi- tions, and the bottom deck boards 247 are then placed by hand across the three beaters 236. The two outer bottom deck boards' 247 are Bcated against the dogs 241 by the guide rails 145, and the intermediate bottom deck boards 247 can be temporarily located with respect to the Outer deck boards by means of a separate guide jig placed temporarily over the set of boards the guide jig having spacing dividers which are interposed between the boards.

As before, with the bearers and boards positioned and located as a set by a set of the dogs 241 upstream of the nailing machine B, the conveyor can be advanced stepwise under the control of the control system, to place each of the three bearers 246 in turn beneath the row of nailing heads and to hold the bearers and boards stationary in that position, with the respective bearer in engagement with the plungers 146 of the stop rams 147, whilst the nailing machine is operated to nail the bottom boards to that bearer; and then the conveyor advances through a further step.

When the boards have been nailed in this way to the third and rearmost bearer 246 of a set, the completed bottom frame subassembly is advanced past the nailing machine to the outfeed skids 260 which lift it clear of the dogs 241 and deposit it onto the delivery power conveyor G1. The outfeed skids 260 are shown in detail in Figure 12, and it will be seen that they are slightly different from the skids 160, having straight, continuously inclined upper ramp surfaces which engage beneath the bearers 246. The set of skids 260 is substituted for the set of skids 160 as a further step in the process of converting the machine 10 for manufacture of two-way entry bottom frame sub-assemblies.

The dogs 241 will be positioned at spacings along the chains 136 determined by the particular dimensions of the pallets to be manufactured, and the settings of their plates 244 adjusted correspondingly. Thus it will be seen that the machine 10 is capable of being set up for manufacture of pallets of a wide range of dimensions, the guide rails 145 being adjustable to accommodate different pallet widths.

For conversion of the machine 10 back to its condition for making sub-assemblies of four-way-entry pallets, it is only necessary to remove the dogs 241 from the conveyor chains, and to replace the three jig plates 1 35A at spacings determined by the pallet dimensions, and to change the skids 260 for the skids 160, and to replace the block feeder devices D, E and F and the nail 101 if they have been removed. Normally only two sizes of four-way-entry wooden pallet will be required, namely the imperial size 48 x 40 inches, and the metric size 1200 x 1000 mm.

When the machine 10 shown in Figures 1 to 8 is to be converted for two-way-entry assembly work, the rail 101 with the three block feeder devices D, E and F may be removed as a complete assembly if required, (and is shown in that condition in Figure 10), although this is not strictly necessary as there is ample room for placing the sets of bearers and bottom boards by hand in their positions located by the dogs 241 upstream of the nailing machine, even with the feeder devices D, E, and F still in position.

WHAT WE CLAIM IS: 1. A machine for manufacturing pallet bottom frame sub-assemblies of the kind specified, which comprises a conveyor having an endless flexible conveyor member of the chain, belt or cable kind carrying a series of jig assemblies mounted on and spaced apart along the length of the flexible conveyor member, each jig assembly affording means for locating a set of spacer members for a single pallet supported on the flexible conveyor member in relative positions corresponding to their required positions in a finished sub-assembly, a nailing machine having at least one row of nailing heads extending across the upper run of the flexible conveyor member at right angles thereto, means for driving the conveyor intermittently to advance the upper run of its flexible conveyor member and the jig assemblies carried by it in steps of predetermined length past the nailing machine, the lengths of the successive steps of movement of the flexible conveyor member being such as to bring each jig assembly in turn into successive positions beneath the nailing heads, and the nailing machine being operable during the intervals between the stepwise movements of the flexible conveyor member and with the jig assembly stationary in the said successive positions, to nail spaced rows of nails into a set of spacer members located by the jig assembly, and thereby to nail to the spacer members a set of bottom frame boards previously placed on the spacer members, and in which the machine is convertible for use in making bottom sub-frame assemblies either of twoway-entry pallets or alternatively of fourway-entry pallets, the conversion being effected by changing the jig assemblies to locate in the one case sets of elongate spacer bearers supported horizontally on the flex- ible conveyor member and extending across it at right angles to its direction of movement, and in the other case sets of spacer blocks supported in spaced horizontal rows extending at right angles to the direction of movement of the flexible conveyor member.

2. A machine as claimed in Claim 1 in which the changing of the jig assemblies is effected by the exchange of jig assemblies each adapted to locate a set of the elongate spacer bearers at appropriate spacings along the flexible conveyor member, for jig assemblies each adapted to locate a set of the spacer blocks in rows at the same spacings as the rows of bearers, or at different

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. a separate guide jig placed temporarily over the set of boards the guide jig having spacing dividers which are interposed between the boards. As before, with the bearers and boards positioned and located as a set by a set of the dogs 241 upstream of the nailing machine B, the conveyor can be advanced stepwise under the control of the control system, to place each of the three bearers 246 in turn beneath the row of nailing heads and to hold the bearers and boards stationary in that position, with the respective bearer in engagement with the plungers 146 of the stop rams 147, whilst the nailing machine is operated to nail the bottom boards to that bearer; and then the conveyor advances through a further step. When the boards have been nailed in this way to the third and rearmost bearer 246 of a set, the completed bottom frame subassembly is advanced past the nailing machine to the outfeed skids 260 which lift it clear of the dogs 241 and deposit it onto the delivery power conveyor G1. The outfeed skids 260 are shown in detail in Figure 12, and it will be seen that they are slightly different from the skids 160, having straight, continuously inclined upper ramp surfaces which engage beneath the bearers 246. The set of skids 260 is substituted for the set of skids 160 as a further step in the process of converting the machine 10 for manufacture of two-way entry bottom frame sub-assemblies. The dogs 241 will be positioned at spacings along the chains 136 determined by the particular dimensions of the pallets to be manufactured, and the settings of their plates 244 adjusted correspondingly. Thus it will be seen that the machine 10 is capable of being set up for manufacture of pallets of a wide range of dimensions, the guide rails 145 being adjustable to accommodate different pallet widths. For conversion of the machine 10 back to its condition for making sub-assemblies of four-way-entry pallets, it is only necessary to remove the dogs 241 from the conveyor chains, and to replace the three jig plates 1 35A at spacings determined by the pallet dimensions, and to change the skids 260 for the skids 160, and to replace the block feeder devices D, E and F and the nail 101 if they have been removed. Normally only two sizes of four-way-entry wooden pallet will be required, namely the imperial size 48 x 40 inches, and the metric size 1200 x 1000 mm. When the machine 10 shown in Figures 1 to 8 is to be converted for two-way-entry assembly work, the rail 101 with the three block feeder devices D, E and F may be removed as a complete assembly if required, (and is shown in that condition in Figure 10), although this is not strictly necessary as there is ample room for placing the sets of bearers and bottom boards by hand in their positions located by the dogs 241 upstream of the nailing machine, even with the feeder devices D, E, and F still in position. WHAT WE CLAIM IS:

1. A machine for manufacturing pallet bottom frame sub-assemblies of the kind specified, which comprises a conveyor having an endless flexible conveyor member of the chain, belt or cable kind carrying a series of jig assemblies mounted on and spaced apart along the length of the flexible conveyor member, each jig assembly affording means for locating a set of spacer members for a single pallet supported on the flexible conveyor member in relative positions corresponding to their required positions in a finished sub-assembly, a nailing machine having at least one row of nailing heads extending across the upper run of the flexible conveyor member at right angles thereto, means for driving the conveyor intermittently to advance the upper run of its flexible conveyor member and the jig assemblies carried by it in steps of predetermined length past the nailing machine, the lengths of the successive steps of movement of the flexible conveyor member being such as to bring each jig assembly in turn into successive positions beneath the nailing heads, and the nailing machine being operable during the intervals between the stepwise movements of the flexible conveyor member and with the jig assembly stationary in the said successive positions, to nail spaced rows of nails into a set of spacer members located by the jig assembly, and thereby to nail to the spacer members a set of bottom frame boards previously placed on the spacer members, and in which the machine is convertible for use in making bottom sub-frame assemblies either of twoway-entry pallets or alternatively of fourway-entry pallets, the conversion being effected by changing the jig assemblies to locate in the one case sets of elongate spacer bearers supported horizontally on the flex- ible conveyor member and extending across it at right angles to its direction of movement, and in the other case sets of spacer blocks supported in spaced horizontal rows extending at right angles to the direction of movement of the flexible conveyor member.

spacings, as required, and vice versa, the machine being provided with alternative sets of the two kinds of jig assembly for this purpose.

3. A machine as claimed in Claim 1 or Claim 2, which is provided at the delivery end of the conveyor beyond the nailing machine with a set of fixed skids constructed and arranged to engage beneath and lift each completed sub-assembly from its supporting jig assembly for removal, and in which conversion of the machine also involves exchanging a set of skids adapted to engage beneath and lift one of the two kinds of sub-assemblies for a set of skids adapted to engage beneath and lift the other kind of sub-assembly from the respective jig assemblies.

4. A machine as claimed in any one of the preceding Claims which, for the manufacture of bottom frame sub-assemblies of four-way-entry pallets, is provided with block feeding mechanism mounted above the flexible conveyor member and upstream of the nailing machine with respect to the direction of movement of the upper run of the conveyor member, the block feeding mechanism being operable during the intervals between the stepwise movements of the flexible conveyor member to place spacer blocks mechanically, a row at a time, their required positions on the flexible conveyor member in which they are located by the respective jig assemblies.

5. A machine as claimed in Claim 4, in which the block feeding mechanism is removable as a step in the conversion of the machine for manufacture of sub-assemblies of two-way-entry pallets.

6. A machine as claimed in Claim 4 or Claim 5, in which the block feeding mechanism comprises a set of the feeding devices claimed in any one of Claims 1 to 5 of our co-pending patent application No.

4050/76 (Serial No. 1587117).

7. A machine as claimed in Claim 2, or in any one of Claims 3 to 6 when dependent on Claim 2 which, for the manufacture of sub-assemblies of four-way-entry pallets, is provided with jig assemblies each comprising a set of rigid plates which in use are detachably secured to the flexible conveyor member and extend across it at right angles to its direction of movement, in spaced parallel relationship to one another, the plates being provided on their upper surfaces with formations for locating the spacer blocks in their required relative positions, one row of blocks per plate,

8. A machine as claimed in Claim 7 in which the jig plates are also provided with formations for locating certain of the bottom frame boards in their required positions on and relative to the spacer blocks.

9. A machine as claimed in Claim 2, or in any one of Claims 3 to 8 when dependent on Claim 2, which for the manufacture of sub-assemblies of two-way-entry pallets, is provided with jig assemblies each comprising a set of pairs of locating dogs which in use are detachably secured to the flexible conveyor member, to protrude outwardly therefrom, for locating the elongate spacer bearers in their required positions each between the spaced dogs of two pairs.

10. A machine as claimed in Claim 9 in which the flexible conveyor member comprises a pair of spaced endless chains, the dogs of each pair being separately secured to the respective chain at positions spaced apart along the length of the chain and being provided with a pair of slidablymounted contact plates whose positions on the respective dogs can be adjusted towards and away from one another for adjusting the effective spacing between the dogs in accordance with the width of a spacer bearer.

11. A machine for manufacturing wooden pallet bottom frame sub-assemblies, substantially as specifically described herein with reference to the accompanying drawings.