GB1587118A

GB1587118A - Manufacture of nailed frame assemblies eg for pallets

Info

Publication number: GB1587118A
Application number: GB406276A
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) MANUFACTURE OF NAILED FRAME ASSEMBLIES, E.G. FOR PALLETS (71) We, OSBORNE STEVENS GROUP LIMITED, a British Company 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, usually of wood. The invention is particularly applicable to the manufacture of sub-assembly frames as a stage in the manufacture of wooden pallets, and will be hereinafter described in relation to such manufacture although it will be understood that it is equally applicable to the manufacture of other nailed frame assemblies.

Pallets of the so-called four-way-entry kind comprise a wooden bottom frame onto which are nailed rectangular spacer blocks positioned normally at the corners and centre of the frame and at the mid-points of its side members. Onto the tops of these blocks are nailed stringer boards, and the decking is nailed cross-wire 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 four-way-entry pallets the spacing 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, together with the boards and blocks is advanced stepwise on a carrier to successive positions beneath a nailing machine by which the boards are then nailed to the blocks. The nailed sub-assembly of bottom frame and spacer blocks is then withdrawn from the nailing machine and inverted, and the stringer boards and decking are nailed on it in a separate operation. One application of the present invention is the provision of equipment for mechanically assembling and nailing together the bottom boards and spacer blocks to form the bottom frame sub-assemblies as a stage in the automated manufacture of four-way-entry pallets.

According to the present invention, apparatus for manufacturing frame assemblies of boards nailed to spacer blocks, for example bottom frame sub-assemblies of wooden pallets of the four-way-entry kind, comprises a conveyor having an endless flexible conveyor member of the chain, belt or cable kind and carrying a series of jig assemblies mounted on and spaced apart along the length of the flexible conveyor, each jig assembly affording supports for supporting and locating a set of spacer blocks for a single frame assembly on the jig assembly in spaced horizontal rows extending at right angles to the direction of travel of the flexible conveyor member and 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 the flexible conveyor member and the jig assemblies carried thereby in steps of predetermined length past the nailing machine, block feeding mechanism mounted above the flexible conveyor member and extending across it upstream of the nailing machine with respect to the direction of travel of the upper run of the flexible conveyor member, the lengths of the successive steps of movement of the flexible conveyor member being such as to bring each jig assembly in turn first into successive positions beneath the block feeding mechanism to receive the rows of blocks in turn therefrom and, in subsequent steps, into successive positions beneath the nailing heads for nailing in turn into the rows of blocks supported thereon, the block feeding mechanism being operable in the intervals between stepwise movements of the conveyor belt to place mechanically each row of spacer blocks in turn in its required position on the respective support of a jig assembly held stationary in its respective position below the block feeding mechanism, and the nailing machine being operable in the intervals between subsequent stepwise movements of the flexible conveyor member when the jig assembly is held stationary in its suc cessivc positions beneath the nailing heads, whereby frame boards previously placed on the upper surfaces of the spacer blocks supported by the jig assembly can be nailed to the repective rows of blocks.

in this way, complete bottom frame subassemblies of wooden pallets can be manufactured semi-automatically, the blocks being mechanically positioned on each jig assembly in turn in their required rows by means of the block feeding mechanism, whereupon the longitudinal and transverse bottom frame boards can be placed on the blocks, manually or by a mechanical device, and located by fittings on the jig assembly, before the conveyor advances the loaded jig assembly to the successive nailing positions beneath the nailing machine. On completion of the nailing of the final row of blocks, the conveyor advances the complete subassembly through and beyond the nailing machine to a position where it is taken up and removed for addition of the stringers and decking.

For example, a set of skids may be provided beyond the nailing machine to engage beneath and lift each completed frame assembly from its supporting jig assembly for removal, as it approaches the far end of the conveyor.

The block feeding mechanism may comprise a row of spaced feeder devices of the construction which forms the subject of our co-pending patent application No. 4050/76 (Serial No. 1 587 117).

The nailing machine may have its nailing heads arranged in two rows extending side by side across the width of the flexible conveyor member, both rows of nailing heads being operable simultaneously or successively and being close enough together to nail into a single row of the spacing blocks.

Each jig assembly may comprise a set of spaced, parallel, rigid plates extending across and secured to the flexible conveyor member, means and provided on their upper surfaces with formations for locating a row of the spacer blocks, and preferably also the frame boards, in their required relative positions. Fixed longitudinal runners may underlie the upper run of the flexible conveyor member, to support the central portions of the jig plates. Moreover, beneath the lower run of the flexible conveyor member one or more longitudinal rows of rollers may be mounted to support the returning jig plates carried by the lower run of the flexible conveyor member and thereby to reduce the tension loading of the conveyor member.

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 four-way-entry pallets; Figure 2 is a perspective view of one of the jig assemblies on the conveyor chains of the machine of 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 subassembly about to engage the skids; Figure 8 is a sectional view on the line VIII-VIII of Figure 1; and Figure 9 shows the apparatus of Figures 1 to 8 incorporated in a complete prdduc- tion line.

In the illustrated embodiment, a machine 10 for making nailed bottom frame subassemblies for four-way-entry pallets is shown in Figures 1 and 8, and comprises a power-driven conveyor A having an endless flexible conveyor 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 of the conveyor chains 136 and carrying the nailing heads, which are arranged in one or 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 and secured to the conveyor 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 locator brackets 137 and transverse locator brackets 138 positioned to define three support areas a, b and c each dimensioned to receive one of the wooden spacer blocks 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 end 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.

1 587 117). Thus each of the feeders D, E 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-members 104, the side rails 102 having out-turned 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 chutes 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 shoes 119 mounted on opposite sides of 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 frictionallygripped 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 thrustng 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 arm 120.

The three block feeding devices D, E and F are 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 plates 135A each of jig assembly 135 beneath the open lower ends of the chutes 110 of the three feed devices, in the exect 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 trans fcr 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 posi tioned on a jig assembly 135 consisting of a set of three plates 135A, the conveyor A then advances the jig assembly of the feed ing 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 L35 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 146 are then automatically retracted, and the conveyor A automatically advances the jig assembly 135 to bring its next plate 135A 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. During this time the next jig assembly 135 on the chains 136 is brought forward by the conveyor, supplied with its set of blocks by the feeder devices, and moved forward for board application and subsequent nailing, as described.

Each completed bottom frame subassembly is delivered at the out-feed end of the conveyor A onto a set of skids 160 shown in detail in 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 sub-assembly as the jig assembly moves down round the out-feed end sprockets Al of the conveyor. From the skids 160 the containers may be removed in any desired manner for storage but preferably they are 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 blockto-base machine 10 forms one end of a continuous production line containing, in order, a power-driven roller conveyor G1, a power-driven turner unit H for inverting each sub-frame assembly so that its blocks 106 lie uppermost, a further power-driven conveyor G2, 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 G4 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 longitudinal rails 165 are mounted beneath the upper run of the conveyor chains 136 between the chains as shown in Figure 8. These rails are of steel covered on at least their upper faces with bearing strips or coatings of polytetrafluorethylene or other low-friction plastics material, the jig plates 135A resting on the bearing strips of the three rails.

Moreover, to support the inverted returning jig plates 135A carried by lower runs of the conveyor chains 136, two rows of rollers 166 are mounted beneath the conveyor on 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.

Our copending patent Application No.

18099/77 (Serial No. 1587119) describes the 'conversion of the equipment shown in Figures 1 to 8 for use in manufacturer of two-way-entry wooden pallets, by removal of the jig plates 135A and substitution of jigs suitable for locating elongate spacer bearers on the flexible conveyor member in place of the rows of spacer blocks.

WHAT WE CLAIM IS: 1. A machine for manufacturing frame assemblies comprising frame boards nailed to spacer blocks, for example bottom frame sub-assemblies of wooden pallets of the fourway-entry kind, which comprises a conveyor having an endless flexible conveyor member of the chain, belt or cable kind and carrying a series of jig assemblies mounted on and spaced apart along the length of the flexible conveyor member, each jig assembly affording supports for supporting and locating a set of spacer blocks for a single frame assembly on the jig assembly in spaced horizontal rows extending at right angles to the direction of travel of the flexible conveyor member and in relative positions corresponding to their required positions in the finished frame 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 member and the jig assemblies carried thereby in steps of predetermined length past the nailing machine, block feeding mechanism mounted above the flexible conveyor member and extending across it in-a position upstream of the nailing machine with respect to the direction of travel of the upper run of the flexible conveyor member, the lengths of the successive steps of movement of the flexible conveyor member being such as to bring each jig assembly in turn first into successive positions beneath the block feeding mechanism to receive the rows of blocks in turn therefrom and, in subsequent steps, into successive positions beneath the nailing heads for nailing in turn into the rows of blocks supported thereon, the block feeding mechanism being operable in the intervals between stepwise movements of the conveyor belt to place mechanically each row of spacer blocks in turn in its required position on the respective support of a jig assembly held stationary in its respective position below the block feeding mechanism, and the nailing machine being operable in the intervals between subsequent stepwise movements of the flexible conveyor member when the jig assembly is held stationary in its successive positions beneath the nailing heads, whereby frame boards previously placed on the upper surfaces of the spacer blocks supported by the jig assembly can be nailed to the respective rows of blocks.

2. A machine as claimed in Claim 1, which includes a set of skids positioned beyond the nailing machine to engage beneath and lift each completed frameassembly from its supporting jig assembly for removal, as it approaches the far end of the conveyor.

3. A machine as claimed in Claim 1 or Claim 2, in which each jig assembly comprises a set of spaced, parallel rigid plates extending across and secured to the flexible conveyor member, and provided on their upper surfaces with formations for locating a row of the spacer blocks, and preferably also the frame boards, in their required relative positions.

4. A machine as claimed in Claim 3 including fixed longitudinal runners which underlie the upper run of the flexible conveyor member to support the central portions of the jig plates.

5. A machine as claimed in Claim 4 including one or more longitudinal rows of rollers mounted beneath the lower run of the flexible conveyor member to support the returning jig plates carried by the lower run of the conveyor member and thereby to reduce the tension loading of the conveyor member.

6. A machine as claimed in any one of the preceding claims, in which the nailing machine has its nailing heads arranged in two rows extending side by side across the width of the flexible conveyor member, both rows of nailing heads being operable simultaneously or successively and being close enough to each other to nail into a single row of the spacing blocks.

7. A machine as claimed in any one of the preceding claims, in which the block feeding mechanism comprises, for positioning a row of the spacer blocks at a time, a corresponding number of block feeder devices each comprising a first guide chute open at one end to receive a supply of the blocks and hold them supported in a row which is biassed by gravity or other means towards the second and closed end of the guide chute, a second guide chute mounted alongside the second end of the first guide chute with a portion of the length of the

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

Claims

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

Moreover, to support the inverted returning jig plates 135A carried by lower runs of the conveyor chains 136, two rows of rollers 166 are mounted beneath the conveyor on 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.

Our copending patent Application No.

18099/77 (Serial No. 1587119) describes the 'conversion of the equipment shown in Figures 1 to 8 for use in manufacturer of two-way-entry wooden pallets, by removal of the jig plates 135A and substitution of jigs suitable for locating elongate spacer bearers on the flexible conveyor member in place of the rows of spacer blocks.

WHAT WE CLAIM IS: 1. A machine for manufacturing frame assemblies comprising frame boards nailed to spacer blocks, for example bottom frame sub-assemblies of wooden pallets of the fourway-entry kind, which comprises a conveyor having an endless flexible conveyor member of the chain, belt or cable kind and carrying a series of jig assemblies mounted on and spaced apart along the length of the flexible conveyor member, each jig assembly affording supports for supporting and locating a set of spacer blocks for a single frame assembly on the jig assembly in spaced horizontal rows extending at right angles to the direction of travel of the flexible conveyor member and in relative positions corresponding to their required positions in the finished frame 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 member and the jig assemblies carried thereby in steps of predetermined length past the nailing machine, block feeding mechanism mounted above the flexible conveyor member and extending across it in-a position upstream of the nailing machine with respect to the direction of travel of the upper run of the flexible conveyor member, the lengths of the successive steps of movement of the flexible conveyor member being such as to bring each jig assembly in turn first into successive positions beneath the block feeding mechanism to receive the rows of blocks in turn therefrom and, in subsequent steps, into successive positions beneath the nailing heads for nailing in turn into the rows of blocks supported thereon, the block feeding mechanism being operable in the intervals between stepwise movements of the conveyor belt to place mechanically each row of spacer blocks in turn in its required position on the respective support of a jig assembly held stationary in its respective position below the block feeding mechanism, and the nailing machine being operable in the intervals between subsequent stepwise movements of the flexible conveyor member when the jig assembly is held stationary in its successive positions beneath the nailing heads, whereby frame boards previously placed on the upper surfaces of the spacer blocks supported by the jig assembly can be nailed to the respective rows of blocks.
2. A machine as claimed in Claim 1, which includes a set of skids positioned beyond the nailing machine to engage beneath and lift each completed frameassembly from its supporting jig assembly for removal, as it approaches the far end of the conveyor.
3. A machine as claimed in Claim 1 or Claim 2, in which each jig assembly comprises a set of spaced, parallel rigid plates extending across and secured to the flexible conveyor member, and provided on their upper surfaces with formations for locating a row of the spacer blocks, and preferably also the frame boards, in their required relative positions.
4. A machine as claimed in Claim 3 including fixed longitudinal runners which underlie the upper run of the flexible conveyor member to support the central portions of the jig plates.
5. A machine as claimed in Claim 4 including one or more longitudinal rows of rollers mounted beneath the lower run of the flexible conveyor member to support the returning jig plates carried by the lower run of the conveyor member and thereby to reduce the tension loading of the conveyor member.
6. A machine as claimed in any one of the preceding claims, in which the nailing machine has its nailing heads arranged in two rows extending side by side across the width of the flexible conveyor member, both rows of nailing heads being operable simultaneously or successively and being close enough to each other to nail into a single row of the spacing blocks.
7. A machine as claimed in any one of the preceding claims, in which the block feeding mechanism comprises, for positioning a row of the spacer blocks at a time, a corresponding number of block feeder devices each comprising a first guide chute open at one end to receive a supply of the blocks and hold them supported in a row which is biassed by gravity or other means towards the second and closed end of the guide chute, a second guide chute mounted alongside the second end of the first guide chute with a portion of the length of the

second guide chute overlapping a portion of the length of the first guide chute adjacent to its second end and communicating therewith through an aperture or passage between the adjacent side walls, the second guide having an open end and being constructed and arranged to hold at least one block or a row of two or more of the blocks, supported displaceably in its interior e.g. by friction, a first power ram mounted outside the second end of the first guide chute to act through its side wall, the first ram being arranged when operated to thrust the leading block of a row supported in the first guide chute laterally through the said aper tflre or passage into the interior of the second guide chute at a region spaced from its open end, and a second power ram associated with the second guide chute and arranged when operated to thrust the block or row of blocks supported in the second guide chute along the length of the chute so that that block, or the leading block in the row is thrust positively out through the open end of the second guide chute into a required position supported and located by one of the jig assemblies positioned below that feeder device, the feeder devices being mounted side by side in a row extending above and across the flexible conveyor member as spacings corresponding to the required spacings of the blocks on the jig assemblies.
8. A machine as claimed in Claim 7, in which the two chutes of each feeder device are straight and are mounted with their lengths parallel to one another, overlapping one another near the second end of the first guide chute which is closed.
9. A machine as claimed in Claim 8, in which the two chutes of each feeder device are vertical, the first chute being positioned at a higher level than the second chute, and the open end of the second chute being lowermost.
10. A machine as claimed in any one of Claims 7 to 9, in which the two power rams of each feeder device are provided with means for operating them in succession in cycles, in such a way that in each cycle the second ram is operated to thrust against a newly-transferred block in the second guide chute so as to thrust that block, or the leading block of a row of the blocks, out of the open end of the second chute, whereupon the first ram is operated to transfer a block laterally from the first guide chute through the aperture or passage into the second guide chute.
11. A machine as claimed in Claim 10, in which the second ram is so arranged and the stroke of its plunger is long enough to press the lowermost block positively down into its position supported on the jig assembly.
12. A machine for manufacturing bottom sub-frame assemblies of wooden pallets, substantially as specifically described herein with reference to Figures 1 to 8 of the accompanying drawings.
13. A machine as claimed in any one of the preceding claims, in combination with an inverter device positioned to receive the completed frame-assemblies from the discharge end of the conveyor and to invert them for a subsequent nailing operation.
14. The combination as claimed in Claim 13, including a second nailing machine provided with a power-driven conveyor and positioned to receive the inverted frame assemblies from the inverter device for performing a subsequent nailing operation thereon.
15. The combination claimed in Claim 14 for use in the manufacture of four-wayentry wooden pallets, in which the second nailing machine is operable to nail decking to bottom frame sub-assemblies made by the first nailing machine and inverted by the inverter device.
16. The combination claimed in Claim 15 including a stacker positioned to receive the completed pallets from the second nailing machine.
17. The combination claimed in Claim 16, in which the bottom sub-assembly manufacturing machine, the inverter, the second nailing machine and its conveyor, and the stacker are arranged in a straight line with power conveyor units interposed between them.