WO2005046977A1

WO2005046977A1 - A crushing apparatus

Info

Publication number: WO2005046977A1
Application number: PCT/IB2004/052365
Authority: WO
Inventors: Peter B Dugmore; Anthony E Bull; Stanford W G Reynolds
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-12
Filing date: 2004-11-10
Publication date: 2005-05-26
Anticipated expiration: 2006-05-12

Abstract

The invention provides a crushing apparatus (10.1) including a compression ram (30.1) defining a movable crushing surface mounted for reciprocal linear motion within a framework (11.1) having at least one end wall (14.1) defining a fixed crushing surface (28.1). The framework (11.1) is defined by two pairs of spaced apart rack formations (16.1/22.1 and 18.1/20.1) joining first and second end walls (12.1,14.1), each pair being coplanar with a drive pinion formation (42.1) and an idler pinion formation (52.1) mounted on drive and idler shaft assemblies, respectively. Each rack and each pinion formation carries two adjacent sets of gear teeth, each set being offset from its neighbour by one half pitch. The drive and idler shaft assemblies serve as a moving tie bar so as to hold the rack formations (16.1/22.1 and 18.1/20.1) in parallel spaced relationship where they interengage the pinion formations.

Description

Description A CRUSHING APPARATUS

[1] FIELD OF THE INVENTION

[2] THIS INVENTION relates to a crushing apparatus, with particular reference to a can crushing apparatus.

[3] BACKGROUND OF THE INVENTION

[4] Various different types of crushing apparatus particularly those having applicability to the crushing of cans have been proposed. These vary from relatively complicated motor-driven to relatively simple lever-based or geared shaft manually operated devices. An example of the latter is provided in US patent 4,414,891 to Kitzman.

[5] Motor-driven can crushing devices are normally not portable, and are relatively expensive to manufacture. Whilst a number of their manually-operated counterparts are portable and are cheaper to manufacture than motor driven crushers, the lever or geared drive shaft mechanisms associated with such counterparts generally occupy significant space to provide the requisite mechanical advantage and/or to accommodate both the compaction and retrieval stroke of the piston, thereby proscribing a number of potential applications where space is at a premium, as well as increasing the costs of packaging, warehousing and transport. In many instances, such devices also need to be particularly securely mounted to counter the force exerted by the lever arm. Moreover, most fulcrum-based or lever-actuated can crushing devices are potentially hazardous, in that the moving linkages tend to provide a number of potential digit crushing zones, especially in the case of young children. Manually operable crushing mechanisms also either tend to be over-engineered, on the one hand, or substantially under-engineered on the other in order to minimize the cost of materials. Most manual devices require the compaction mechanism to be reset between each compaction stroke. They are moreover normally characterized by a lack of any ready manner of distinguishing between or separating aluminium and steel or tin-plated cans.

[6] SUMMARY OF THE INVENTION

[7] According to a first aspect of the invention there is provided a crushing apparatus comprising: a framework having a first end wall defining a first fixed crushing surface; a compression ram mounted for reciprocal motion within the framework and defining a first movable crushing surface; a rotary-to-linear crawl mechanism including at least one toothed rack formation and a complementally toothed pinion formation carried on the rack formation; and drive means for crawling the mechanism in a first linear direction so as to crush an object placed between the first movable and fixed surfaces.

[8] In a preferred form of the invention, the framework includes a second opposed end wall defining a second fixed crushing surface, and the compression ram defines a second movable crushing surface opposite the first movable crushing surface, with the toothed rack formation extending between the first and second end walls, whereby the drive means is arranged to crawl the pinion formation along the rack formation in a second opposed linear direction to crush an object placed between the second movable and fixed surfaces.

[9] Advantageously, continued reciprocating motion of the compression ram is arranged alternatively to crush objects placed successively between the first fixed and movable crushing surfaces and the second fixed and movable crushing surfaces respectively.

[10] The drive means may comprise an electrical or similar motor. Typically, it may comprise a manually operable crank arm and handle, or the like.

[11] Advantageously, the toothed rack formation comprises a plurality of rack plates in an adjacently stacked arrangement, each rack plate carrying a substantially identical row of teeth; and the complementally toothed pinion formation comprises a matching number of pinion gears in a co-operating adjacently stacked arrangement.

[12] Preferably, rows of teeth on adjacent rack plates and co-operating pinion gears are offset by a matching degree. Conveniently, the degree of offset may be one half pitch.

[13] Alternatively, the toothed rack and pinion formations may comprise a common rack or pinion base member respectively, on which are cut one or more mutually offset and adjacent sets of teeth.

[14] In the case of a conventional gear train utilizing substantially identical com- plemental teeth and tooth spaces with minimum gear slippage, the gear train will tend to wear and become sloppy. Advantageously, in the present invention, controlled gear slippage means may be effected by providing a special profile of the intermeshing gear teeth, whereby negligible clearance between the respective addenda and dedenda of the mating teeth of the respective pinion and rack formations is provided. By arranging for the true motion transfer to occur tangentially to the pitch circle diameter of the gear members and not on either the addenda or the dedenda, slippage is thereby introduced on the addenda and dedenda surfaces, significantly decreasing wear on the gear train.

[15] Adjacent sets of teeth may also or alternatively be provided with complementary rolling formations to further reduce wear on the gear train. Conveniently, the rolling formations may comprise side- or spacer- plates running respectively contiguous to or interposed between adjacent rack plates, the side- or spacer- plates being designed to guide complemental rollers arranged to be mounted for rolling movement beside, or within gaps defined between, adjacent, complemental pinion gears.

[ 16] The roller diameter may conveniently correspond to the pitch circle diameter of the pinion gears and rack plates.

[17] At least one idler shaft carrying two or more idler pinion formations and at least one drive shaft carrying two or more drive pinion formations for driving the idler pinion formations may typically be journalled within the compression ram, with the framework advantageously defined by two pairs of spaced apart rack formations joining the first and second end walls, each pair being coplanar with a drive pinion formation and an idler pinion formation.

[18] By offsetting the rack plates and pinion gears in the manner described above, so that the teeth are self-aligning, any sideways movement of the teeth is prevented in that the inner surfaces of all of the intermeshing plates and gears are in contact with one another at the point of intermeshing, the drive and idler shaft assemblies serving as a moving tie bar when travelling reciprocally along the rack formations, so as to hold the rack formations in parallel spaced relationship where they interengage the pinion formations.

[19] Conveniently, the ram may include a magnetic circuit for selectively attracting ferromagnetic cans, and the crushing apparatus may comprise at least one outer opening adjacent the first end wall for discharging non-ferromagnetic cans and at least one central opening for discharging ferromagnetic cans.

[20] Advantageously, the magnetic circuit includes a central magnet, a pair of pole pieces on the opposed first and second moving faces of the ram, and a toggle mechanism for moving the magnet between the first and second pole pieces for selectively attracting cans to and releasing cans from the first and second moving faces of the ram.

[21] According to a second aspect of the invention there is provided a crawl mechanism assembly, comprising: a mechanism containment formation; a rotary-to-linear crawl mechanism; and drive means for crawling the mechanism linearly within the containment formation.

[22] The containment formation may advantageously comprise a framework.

[23] Conveniently, the linear motion within the framework will be reciprocal.

[24] Preferably, the mechanism will comprise at least one toothed rack formation and a_* complementally toothed pinion formation carried on the rack formation, the pinion formation defining an axis of rotation.

[25] Each of the rack and pinion formations may comprise one or more adjacent sets of teeth, each set of teeth being mutually offset from an adjacent set of teeth in a plane perpendicular to the axis of rotation, whereby the mutually offset sets of teeth on the rack and pinion formations respectively are arranged to intermesh to prevent sideways displacement of the teeth relative to one another.

[26] Preferably, the crawl mechanism includes a pair of parallel spaced apart rack formations and a corresponding pair of spaced apart pinion formations arranged to travel along the rack formations, with the mutually offset interengaging rows of teeth on both the rack formations and the pinion formations serving to ensure that the rack formations are maintained in a parallel configuration at their moving points of contact with the pinion formations.

[27] Typically, the crawl mechanism assembly will drive a compression ram, a skip or similar carrier or container formation or conveyance, or the like.

[28] According to a third aspect of the invention, there is provided a method of manu- facturing and assembling a crushing apparatus according to the first aspect of the invention, above, comprising the particular application of a can crusher, wherein: each of the rack formations of the crushing apparatus is formed from a pair of rack plates of identical length which are fine blanked from a single strip of sheet metal (advantageously a relatively thin gauge mild steel) in such manner that the profiles of the teeth of a first rack plate form the matching profiles of the tooth spaces between the teeth of a second rack plate. By placing first and second rack plates adjacently back-to-back with one another, a rack formation is defined having two adjacent and identical sets of teeth, each set of teeth being offset from the other by half a pitch;

• four of such rack formations are then welded in opposing pairs to first and second rectangular opposed end plates spaced apart by the rack formations so as to provide a parallelopipedal framework, with the teeth of each pair of rack formations inwardly opposing one another;

• the framework thus formed is then treated against corrosion, preferably by tin- dipping. The use of tin is preferred firstly because it acts as a solder flux which in its molten state penetrates even the smallest gaps defined between the rack plates, effectively solder-bonding them together as an integral rack formation as the tin cools; and secondly because of its superior resistance to the corrosive effects of residual cold drink beverages which could be spilled when a beverage can is crushed;

• a housing for the crushing apparatus is formed out of a number of nominally planar, interlocking components, preferably injection moulded out of a polymer such as glass-filled nylon. By defining the housing in this manner, the alternative costs of moulding an integral housing (involving high moulding tonnages and deep-draw moulds) are significantly reduced;

• four idler pinion gears and four drive pinion gears per crushing apparatus are pressed out of sheet metal, advantageously a relatively thin gauge mild steel plate, and the pinion gears are then case-hardened;

• the drive shaft assembly is then formed by affixing two pairs of drive pinion gears in spaced apart arrangement on the drive shaft, with the adjacent teeth on each pair of gears being mutually offset by half a pitch. Preferably, the gears are affixed to the shaft using high current silver soldering;

• the drive shaft assembly is then treated against corrosion, preferably by tin dipping, before being introduced into the framework through the gap defined by the two opposing pairs of rack formation, with the drive pinion gears intermeshing, in the manner previously described, with the upwardly projecting teeth of the lower pair of rack formations; in the event that the drive shaft assembly includes a manual crank handle, the drive shaft assembly is introduced into the framework at a precisely determined point along the rack formation, and at a pre-determined angle of the crank arm relative to the longitudinal axis of the framework. This ensures that when the drive shaft assembly is at the extreme of its travel relative to the first or second end plate of the framework, the crank handle will lie in co- planar orientation to the longitudinal axis of the framework as an aid to effective packaging; the diameter of the holes in the centre of the idler pinion gears is smaller than the outside diameter of the idler shaft. After tin plating, the four idler pinion gears are introduced as offset adjacent pairs into the framework, in a manner such that the teeth at the bottom of the idler gears intermesh with the teeth at the top of the corresponding drive gears, and the teeth at the top of the idler gears intermesh with the corresponding downwardly depending teeth of the upper rack formations. • the idler shaft is then introduced between the centres of the opposing pairs of idler pinion gears, and a screw is passed through the centre holes of the gears and then tightened into a pre-threaded hole in each end of the idler shaft. The upper pair of rack formations are therefore spaced and held precisely apart by the idler shaft assembly, the lower pair of rack formations are similarly spaced and held precisely apart by the drive shaft assembly, and each of the vertically opposed pairs of rack formation are spaced apart by the drive shaft and idler shaft assemblies acting perpendicularly in concert with one another; • mating halves of the compression ram, or tup, are then journalled and fixed around the drive and idler shafts in the spaces defined between opposing pairs of pinion gears; cradle members for holding an empty beverage can in the crushing apparatus prior to being crushed are screwed into the framework; and finally inwardly projecting moulded studs on the panels comprising the housing of the apparatus are passed through complemental fixing apertures in the framework and then welded thermally or electronically into rivet heads thereby securely affixing the panel/s to the framework. [29] The steps of the method above described should be seen as exemplary rather than prescriptive. The precise sequence of the steps listed may, of course, be varied, and individual steps may be combined, separated or omitted, without affecting the overarching principle of the method. The method should be construed accordingly. [30] The general operation and characteristics of the crushing apparatus of the present invention will now be described, by way of non-limiting example, with reference to two embodiments of a can crushing apparatus. [31] BRIEF DESCRIPTION OF THE DRAWINGS

[32] In the drawings:

[33] Figure 1 shows a partly exploded perspective view of a first embodiment of a crushing apparatus of the invention in the particular application of a can crushing apparatus; [34] Figure 2 shows a top plan view of the can crushing apparatus of Figure 1;

[35] Figure 3 shows a side view of the can crushing apparatus of Figures 1 and 2;

[36] Figure 4 shows a cross-sectional view of a compression ram along the lines 4-4 of Figure 2; [37] Figure 5 shows a cross-sectional side view of a first embodiment of a ram along the lines 5-5 of Figure 3; [38] Figure 6 shows a cross-sectional side view of a second embodiment of a ram;

[39] Figure 7 shows a detailed side view of part of the crawl mechanism of the invention; [40] Figure 8 shows a perspective view of a second embodiment of a can crushing apparatus of the invention without its housing; [41] Figure 9 shows a top plan view of the can crushing apparatus of Figure 8;

[42] Figure 10 shows a side view of the can crushing apparatus of Figures 8 and 9;

[43] Figure 11 shows a detailed side view of part of the crawl mechanism of the can crushing apparatus of Figures 8 to 10 illustrating a protective finger shield; [44] Figure 12 shows a block diagram schematic view of a method of manufacturing and assembling the can crushing apparatus of Figures 8 to 11; [45] Figures 13 A and B show respectively a plan view of the cutting profiles for the rack plates, and the die cut rack plates, referred to in Step 1 of the method of Figure 12; [46] Figure 14 shows a perspective view of the framework cage produced according to Step 2 of the method of Figure 12; [47] Figure 15 shows an exploded perspective view of the components forming the housing of the can crushing apparatus of Figure 8, moulded according to Step.4 of the method of Figure 12; [48] Figure 16 shows the drive shaft assembly formed in accordance with Step 6 of the method of Figure 12; [49] Figure 17 shows a detailed perspective view of the assembled crawl mechanism introduced into the framework cage according to Step 10 of the method of Figure 12; [50] Figure 18 shows a perspective view of the can crushing apparatus of Figure 8 prior to assembly of the housing onto the framework according to Step 12 of the method of Figure 12; and [51] Figure 19 shows a detailed perspective view of a part of the assembled can crusher to illustrate the countersunk plastic rivet heads formed in accordance with Step 13 of the method of Figure 12. [52] DETAILED DESCRIPTION OF THE DRAWINGS

[53] REFERRING first to Figures 1 to3, a crushing apparatus 10 of the invention comprises a can crushing apparatus having a framework 11 in the form of first and second rectangular opposed end plates 12 and 14 spaced apart by four rack formations 16, 18, 20 and 22 which are welded to the end plates 12 and 14 so as to provide a parallelopipedal framework. The end plates 12 and 14 are formed with apertured flanges 24 for mounting the can crushing apparatus to a suitable fixture such as a wall, or for receiving mounting brackets such that the apparatus may be mounted to a pole, a vehicle, a shopping trolley or the like. The end plate 12 defines a first fixed crushing surface 26 and the end plate 14 defines a second fixed crushing surface 28. A housing indicated in chain outline at 29 covers the framework.

[54] A compression ram 30 is mounted for reciprocal motion within the framework 11 , and is formed with a first moving crushing surface 32 and a second moving crushing surface 34. A drive shaft 38 extends through the ram, and first and second spaced apart pinion formations 40 and 42 are carried on opposite ends of the shaft 38, with the pinion formation 40 intermeshing with the teeth 45 in the rack formation 22 and the pinion formation 42 intermeshing with the teeth 44 in the rack formation 20. An idler shaft 48 also extends through the ram 30, and a pair of idler pinion formations 50 and 52 are carried on opposite ends of the idler shaft. The idler pinion formations 50 and 52 intermesh with the teeth of the respective drive pinion formations 40 and 42, and also intermesh with the teeth 54 and 56 on the respective rack formations 16 and 18.

[55] A drive means 61 is provided by a crank arm 58 extending from the drive shaft 38 and terminating in a handle 60. The rack formations 16 to 22 and the drive and idler pinion formations 40, 42, 50 and 52 in combination define a crawl mechanism 57. It can clearly be seen that rotation of the drive pinion formations 40 and 42 via the crank arm 58 will cause the intermeshing drive and idler pinion formations to travel to and fro along the toothed rack formations. A centre cradle 62 and outer cradles 64 and 66 define a pair of central openings 68 and 70 and a pair of outer openings 72 and 74 in the base of the can crusher. In operation, a can 76 is placed on the cradles 62 and 64, and the lever arm 58 is rotated clockwise so as to cause the crawl mechanism to move to the right, with the can being crushed between the first fixed crushing surface 26 and the first moving crushing surface 32.

[56] As the compression ram 30 is moved to the position indicated in Figures 2 and 3 in which the can 76 is crushed, it presents a new opening 78 behind the can for allowing the positioning of an uncrushed can 80. The lever arm 58 is then rotated in the anticlockwise direction so as to move the crawl mechanism back to a position in which the can 80 is crushed as the second moving surface 34 of the ram 30 is moved towards the second fixed surface 28 of the end plate 14.

[57] If the can is made from a non-magnetic material such as aluminium, the crushed can 76 merely drops straight through the opening 72. If however, the can has a ferromagnetic component, then, as is clear from Figures 4 and 5, the crushed can 76 will be attracted to the surface 32 of the ram 30 by a pole piece 82 which forms a magnetic circuit in conjunction with a permanent magnet 84 located within the ram. The fer- romagnetic can 76 will be conveyed to a point in which it overlies the gap 70. As the ram traverses past a centre zone overlying the cradle 62, the magnetic hold on the can 76 is temporarily released and the can is allowed to fall through the central aperture 70. The compressed cans fall through chutes beneath the cradles, which feed containers, with the non-magnetic cans being collected via outer chutes 85 A and the cans having a ferromagnetic content being collected via a central chute 85B which is fed from the central openings 68 and 70.

[58] The magnetic circuit assembly comprises the pole piece 82, the permanent magnet 84 and a pole piece 86. The permanent magnet 84 is a disc-shaped magnet which is held within a non-magnetic ring 88 which forms a cradle 90 in conjunction with a pair of laterally extending arms 92 each terminating in a pair of teeth 94. The teeth 94 intermesh with complemental teeth 96 which extend from flipper or toggle arms 98. The toggle arms 98 pivot on stub axles 100 which locate within complemental channels 101 defined within the body of the ram. The opposite ends of the toggle arms are formed with semi-circular indents 102 which are positioned to interact with corresponding protrusions 104 extending inwardly from the centre of the rack formations 16 and 18. As the ram approaches the centre position, the protrusions 104 locate within the indents 102 and cause the flipper arms to rotate in the direction of arrows 106 so as to move the cradle 90 from the Figure 5 position to a position in which the permanent magnet 84 is separated from the pole piece 82 and toggles over to the pole piece 86, with which it forms a magnetic circuit. In the event of the can 76 being ferromagnetic, this then serves to ensure that the can 76 is released as it passes over the centre opening 70.

[59] Referring now to Figure 6, an alternative version of the magnetic cradle assembly 90A is shown comprising a central rectangular permanent magnet 84A which is switched to and fro via the flipper arms 98A to define a magnetic circuit in conjunction with pole piece pairs 82 A and 86 A.

[60] Referring now to Figure 7, the crawl mechanism is shown in more detail. The rack formation 18 comprises a first outer rack plate 110 having a first row of teeth 112 having a trapezoidal profile and a second inner rack plate 114 formed with a second row of trapezoidal teeth 116 which are offset from the first row of teeth 112 by a distance 'd' which corresponds to one half of the pitch of a tooth.

[61] Similarly, the pinion formation 50 is formed from first and second pinion plates 118 and 120 which are similarly offset by one half of a tooth pitch. By offsetting the rack and pinion plates in the manner described above, the teeth are self-aligning, and sideways movement of the teeth is prevented in that the inner surfaces of all of the intermeshing plates are in contact with one another at the point of intermeshing. As a result, the ram and pinion formations serve as a moving tie bar when travelling reciprocally along the rack foπnations 16 and 18 and 20 and 22, so as to hold the rack formations in parallel spaced relationship where they interengage the pinion formations.

[62] The gear teeth also have a profile which is different to that of a conventional gear train. In the case of a conventional gear train utilizing substantially identical complemental teeth with minimum gear slippage, the gear train will tend to wear and become sloppy. In the present invention, there is negligible clearance between the respective addenda and dedenda of the mating teeth of the respective pinion and rack formations. As a result, a modicum of slippage is introduced on the addenda and dedenda surfaces as the true motion transfer actually occurs tangentially to the pitch circle diameter of the gear members and not on either the addenda or the dedenda. As is clear from Figure 7, at any one time there are at least three contact points, namely 122 A, 122C and 122D when the pinion 50 is turning counter-clockwise, and 122B, 122C and 122E when the pinion 50 is turning clockwise.

[63] As the velocities and the expected number of cycles in the life of the can crusher are relatively low in terms of gear design, the slippage-induced wear should not present a problem. In addition, the gears can be stamped out of relatively thin sheet material in a relatively simple but cost effective manner.

[64] Figures 8 to 11 illustrate a simpler and more compact version of the can crusher of Figures 1 to 7. Where functions or characteristics of the invention in Figures 8 to 11 are essentially the same as those previously described in Figures 1 to 7, for convenience the same numerals are used, distinguished only in the case of Figures 8 to 11 by the use of the suffix ' .1'.

[65] The can crusher 10.1 illustrated in Figures 8 to 19 differs from that described in Figure 1 in four material respects. By using a different method of mounting the framework 11.1 to the surface on which it is to be used, the overall length of the crusher 10.1 is reduced by 40 per cent, without in any way compromising its operating efficacy. A different method of forming and assembling the housing 29.1 considerably simplifies the moulding of the component parts of said housing and their assembly to the framework 11.1 of the can crusher. By dispensing with the magnetic cradle as sembly 90 of Figures 4 to 6, the number of can disposal openings and disposal chutes is reduced, with a further concomitant reduction in cost. And digit protection means in the form of a finger shield 126 are provided to obviate the possibility of digits being trapped between the teeth of the pinion formations 50.1 and 52.1, and the teeth of the intermeshing rack formations 18.1 and 20.1 respectively.

[66] The essential points of difference, only, between the can crusher of Figures 8 to 19, as compared with that of Figures 1 to 7 will now be described.

[67] Whereas framework 11 of Figures 1 and 2 is affixed to the substrate or mounting bracket on which it is to be mounted by means of apertured flanges 24, the framework 11.1 of Figures 8 and 9 is affixed to the selected mounting substrate 132 or mounting bracket through four mounting apertures 128 in rack formations 16.1 and 22.1. Apertured mounting spacer bushes 130 act as stand-offs to keep framework 11.1 suf- ficiently clear of substrate 132 to accommodate housing back plate 166 of Figure 15 and also allow sufficient free play for stub axle 134 of drive shaft 38.1 to reciprocate as compression ram 30.1 moves linearly within the framework 11.1.

[68] Access apertures 136 through rack formations 18.1 and 20.1 are arranged to sit immediately behind housing mounting access apertures 172 in front plate 168 of housing 29.1 in Figure 15, in such manner that a suitable driver can be used to drive a wall fixing, screw or the like through mounting apertures 128 in order to affix the framework 11.1 to the mounting substrate 132.

[69] Referring now to Figures 12 to 19, a method 140 of manufacturing and assembling the can crusher 10.1 of Figure 8 will now be described.

[70] In Step 1 at block 142 of method 140, rack formation 16.1 (or, equally, 18.1, 20.1, 22.1) of Figures 13A and B is formed from a pair of rack plates 16.1 A and 16. IB of identical length which are fine blanked from a single strip of thin gauge mild steel 174. By placing rack plates 16.1 A and 16. IB adjacently back-to-back with one another, as shown in Figure 13B, a rack formation 16.1 is defined having two adjacent and identical sets of teeth 56.1, each set of teeth being offset from the other by half a pitch;

[71] * In Step 2 at block 144, rack formations 16.1, 18.1, 20.1 and 22.1, formed in accordance with Step 1, are then welded in opposing pairs to first and second rectangular opposed end plates 12.1 and 14.1 spaced apart by the rack formations so as to provide the parallelopipedal cage 176 illustrated in Figure 14, with the teeth (54.1 and 45.1) and (56.1 and 44.1) of each pair of rack formations (16.1 and 22.1) and (18.1 and 20.1), respectively, inwardly opposing one another;

[72] In Step 3 at block 146, the cage 176 formed per Step 2 is then tin-dipped, thereby both treating the cage against corrosion, and tin-soldering the individual rack plates making up the rack formations 16.1, 18.1, 20.1 and 22.1, together.

[73] In Step 4 at block 148, a housing 29.1 as illustrated in Figure 15 for the can crusher is formed out of a number of nominally planar interlocking plates 166, 168 and 170, injection moulded out of glass-filled nylon;

[74] In Step 5 at block 150 four idler pinion gears and four drive pinion gears per can crusher, as used respectively in idler pinion formations 50.1 and 52.1, and in drive pinion formations 40.1 and 42.1, are pressed out of a relatively thin gauge mild steel plate, and the gears are then case-hardened;

[75] In Step 6 at block 152 the drive shaft assembly 39 illustrated in Figure 16 as part of the crank mechanism 178 is then formed by affixing two pairs of drive pinion gears 40.1 and 42.1 in spaced apart arrangement on the drive shaft 38.1, with the adjacent teeth on each pair of gears being mutually offset by half a pitch. The gears are affixed to the shaft using high current silver soldering;

[76] In Step 7 at block 154 the drive shaft assembly 39 and crank mechanism 178 are then treated against corrosion by tin dipping, before being introduced into the cage 176 through the gap defined by the vertically opposed pairs of rack formation (18.1 and 20.1) and (16.1 and 22.1);

[77] In Step 8 at block 156 the drive shaft assembly 39 is introduced, as shown in Figure 17 into cage 176 at a pre-determined point A along rack formation 20.1, and at a predetermined angle B of crank arm 58.1, with the drive pinion gears intermeshing with the upwardly projecting teeth 44.1 and 45.1 of rack formations 20.1 and 22.1 respectively. The precise positioning of the drive shaft assembly 39 ensures that when it is at the extreme of its travel relative to the first end plate 12.1 of the cage 176, the crank handle 58.1 will lie in co-planar orientation to the longitudinal axis of the cage as an aid to effective packaging;

[78] In Step 9 at block 158, after tin plating, the four idler pinion gears are introduced as offset adjacent idler pinion formations 50.1 and 52.1 into the cage 176, in a manner such that the teeth at the bottom of the idler pinion formations 50.1 and 52.1 intermesh respectively with the teeth at the top of the corresponding drive gear formations 40.1 and 42.1, and the teeth at the top of the idler pinion formations 50.1 and 52.1 intermesh with the corresponding downwardly depending teeth 54.1 and 56.1 of the upper rack formations 16.1 and 18.1 respectively.

[79] The diameter of the holes in the centre of the idler pinion formations 50.1 and 52.1 is smaller than the outside diameter of the idler shaft 48.1. In Step 10 at block 160 idler shaft 48.1 is then introduced between the centres of the opposing pairs of idler pinion formations 50.1 and 52.1, as illustrated in Figure 17, and screws 180 are passed through the centre holes of the idler pinion formations and then tightened into a pre- threaded hole in each end of idler shaft 48.1. The upper pair of rack formations 16.1 and 18.1 are therefore spaced and held precisely apart by the idler shaft assembly, the lower pair of rack formations 20.1 and 22.1 are similarly spaced and held precisely apart by the drive shaft assembly 39, and each of the vertically opposed pairs of rack formation (16.1 and 22.1) and (18.1 and 20.1) are spaced apart by the drive shaft and idler shaft assemblies acting perpendicularly in concert with one another;

[80] In step 11 at block 162 mating halves of the compression ram, or tup, 30.1 are then journalled and fixed around the drive and idler shafts in the spaces defined between opposing pairs of pinion formations as illustrated in Figure 18;

[81] In Step 12 at block 164 cradle members 62.1 for holding an empty can in the crusher 10.1 prior to being crushed are attached to the framework 11.1 by means of screws (not illustrated) driven through apertures 182 in rack formations 20.1 and 22.1 into screw housings 184 formed in cradle members 62.1; and

[82] In Step 13 at block 165 inwardly projecting moulded studs 186 on housing back and front plates 166 and 168, respectively, are passed through complemental fixing apertures 188 in rack formations 16.1 and 18.1, and studs 187 on housing end plates 170, are passed through complemental fixing apertures 188 in framework end plates 12.1 and 14.1, and then welded thermally or electronically into countersunk plastic rivet heads 190, as illustrated in Figure 19 thereby securely affixing the housing plates 166, 168 and 170 to the framework 11.1. Each of the moulded studs 186 and 187 are provided with a spacer boss 192 to ensure that the housing plates stand off from the framework 11.1 by a precise and pre-determined amount when the housing 29.1 is assembled onto the framework 11.1.

[83] Removable plugs 194 as illustrated in Figure 15 are provided so that a suitable driver (not illustrated) may be inserted into housing mounting access apertures 172 in housing front plate 168 in order to fix can crusher 10.1 to a suitable mounting substrate, after which the plugs 194 are replaced into apertures 172 for cosmetic appeal.

[84] Handle shaft 59.1 is passed through slot 196 in front housing plate 168 before plate 168 is affixed to framework 11.1, whereafter handle 60.1 is screwed onto handle shaft 59.1.

[85] It will be apparent that while the drawings illustrate a crushing apparatus where cans are compacted along their long axis, the apparatus may also be arranged to compact cans from the side, if so preferred.

[86] While the particular crusher described is able to accommodate all known sizes of beverage cans, using a reciprocating action without the necessity of having to re-set the ram between compactions, it is no larger than a Kleenex box. This represents a significant advantage over all other known can compacters in terms of space occupied, both as it affects user convenience and range of applications, and also as it affects cost in manufacture, distribution, transport and storage.

[87] The crawl mechanism assembly, of which the can crushing apparatus is just one representative example, offers a number of functional and commercial advantages over known conventional crawl mechanisms. The most important of these is the arrangement of offset, essentially adjacent, sets of intermeshing teeth carried on the rack formations, pinion formations, or both. Used in combination with one or more drive shaft and idler shaft assemblies, this arrangement allows the crawl mechanism assembly to dispense with conventional guide means, effectively to provide a moving tie bar in order to maintain spaced apart parallel configuration of rack formations, and to provide a very high level of assurance that the crawl mechanism will not 'de-rail' off the rack formations along which it travels. The special design of the gear teeth so as to offer a planned modicum of slippage, and thereby largely avoid wear on the gear train as it rolls, is a further advantage of the invention, as is the method of constituting rack and pinion formations out of respectively a plurality of rack plates and pinion gears. This allows relatively thinner and softer metal plate to be used, which simplifies pressing and significantly reduces cost.

[88] The scope of the invention extends separately to the crawl mechanism, the magnetic circuit provided in the ram for selectively attracting ferromagnetic cans, the special design of the gear teeth in order to provide controlled slippage in the gear chain, and the design and means of affixing the housing to the framework of the can crushing apparatus described above. [89] It will further be appreciated that many variations and modifications of the invention are possible without departing from the spirit and scope of the invention.

Claims

[1] A crushing apparatus comprising: a framework having a first end wall defining a first fixed crushing surface; a compression ram mounted for reciprocal motion within the framework and defining a first movable crushing surface; a rotary- to-linear crawl mechanism; and drive means for crawling the mechanism in a first linear direction so as to crush an object placed between the first movable and first fixed crushing surfaces.

[2] A crushing apparatus as claimed in Claim 1, characterised in that the crawl mechanism includes at least one toothed rack formation and complementally toothed pinion formation carried on the rack formation.

[3] A crushing apparatus as claimed in Claim 2, characterised in that the toothed rack formation comprises a plurality of rack plates in an adjacently stacked arrangement, each rack plate carrying a substantially identical row of teeth; and the complementally toothed pinion formation comprises a matching number of pinion gears in a co-operating adjacently stacked arrangement.

[4] A crushing apparatus as claimed in Claim 2, characterised in that the toothed rack and pinion formations comprise common rack or pinion base members respectively, on which are cut one or more adjacent sets of teeth.

[5] A crushing apparatus as claimed in either of Claims 3 or 4, characterised in that adjacent rows of teeth on rack plates and co-operating pinion gears are offset by a matching degree - conveniently, one half pitch, so that the teeth are self-aligning, any sideways movement of the teeth being prevented in that the inner surfaces of all of the intermeshing plates and gears are in contact with one another at the point of intermeshing.

[6] A crushing apparatus as claimed in any of Claims 2 to 5, characterised in that controlled gear slippage means is provided between the respective addenda and dedenda of the mating teeth of the respective pinion and rack formations.

[7] A crushing apparatus as claimed in Claim 6, characterised in that the gear slippage means is provided by a special profile of the mating teeth of the respective pinion and rack formations in order to effect true motion transfer tan- gentially to the pitch circle diameter of the gear members and not onto either the addenda or the dedenda.

[8] A crushing apparatus as claimed in any of Claims 5 to 7, characterised in that the adjacent sets of teeth are provided with one or more complementary rolling formations to further reduce wear on the gear train.

[9] A crushing apparatus as claimed in Claim 8, characterised in that the rolling formations comprise side plates running contiguous to adjacent rack plates, the side plates being designed to guide complemental rollers arranged to be mounted for rolling movement beside adjacent, complemental pinion gears.

[10] A crushing apparatus as claimed in Claim 8, characterised in that the rolling formations comprise spacer plates running interposed between adjacent rack plates, the plates being designed to guide complemental rollers arranged to be mounted for rolling movement within gaps defined between adjacent, complemental pinion gears.

[11] A crushing apparatus as claimed in either of Claims 9 or 10, characterised in that the roller diameter corresponds to the pitch circle diameter of the pinion gears and rack plates.

[12] A crushing apparatus as claimed in any of Claims 1 to 11 characterised in that the drive means comprises an electrical or similar motor.

[13] A crushing apparatus as claimed in any of Claims 1 to 11 characterised in that the drive means comprises a manually operable crank arm and handle, or the like.

[14] A crushing apparatus as claimed in any of Claims 2 to 13, characterised in that the framework includes a second opposed end wall defining a second fixed crushing surface, and the compression ram defines a second movable crushing surface opposite the first movable crushing surface, with the toothed rack formation extending between the first and second end walls, whereby the drive means is arranged to crawl the pinion formation along the rack formation in a second opposed linear direction to crush an object placed between the second movable and fixed surfaces.

[15] A crushing apparatus as claimed in Claim 14 characterised in that at least one idler shaft carrying two or more idler pinion formations and at least one drive shaft carrying two or more drive pinion formations for driving the idler pinion formations are journalled within the compression ram,

[16] A crushing apparatus as claimed in Claim 15 characterised in that the framework is defined by two pairs of spaced apart rack formations joining the first and second end walls, each pair being coplanar with a drive pinion formation and an idler pinion formation.

[17] A crushing apparatus as claimed in Claim 16 characterised in that the drive and idler shaft assemblies serve as a moving tie bar when travelling reciprocally along the rack formations, so as to hold the rack formations in parallel spaced relationship where they interengage the pinion formations.

[18] A crushing apparatus as claimed in Claim 17, characterised in that continued reciprocating motion of the compression ram is arranged alternatively to crush objects placed successively between the first fixed and movable crushing surfaces and the second fixed and movable crushing surfaces respectively.

[19] A crushing apparatus as claimed in any of the previous claims characterised in that the compression ram includes a magnetic circuit for selectively attracting ferromagnetic cans.

[20] A crushing apparatus as claimed in Claim 19 characterised in that the a crushing apparatus includes at least one outer opening adjacent the first end wall for discharging non-ferromagnetic cans and at least one central opening for discharging ferromagnetic cans.

[21] A crushing apparatus as claimed in either of Claims 19 or 20 characterised in that the magnetic circuit includes a central magnet, a pair of pole pieces on the opposed first and second moving faces of the ram, and a toggle mechanism for moving the magnet between the first and second pole pieces for selectively attracting cans to and releasing cans from the first and second moving faces of the ram.

[22] A can crushing embodiment of the crushing apparatus as claimed in Claim 21 characterised in that the apparatus is assembled by the steps of: forming each of the rack formations of the crushing apparatus from a pair of rack plates of identical length which are fine blanked from a single strip of sheet metal (such as a relatively thin gauge mild steel) in such manner that the profiles of the teeth of a first rack plate form the matching profiles of the tooth spaces between the teeth of a second rack plate. By placing first and second rack plates adjacently back-to-back with one another, a rack formation is defined having two adjacent and identical sets of teeth, each set of teeth being offset from the other by half a pitch; welding four of such rack formations in opposing pairs to first and second rectangular opposed end plates spaced apart by the rack formations so as to provide a parallelopipedal framework, with the teeth of each pair of rack formations inwardly opposing one another; treating the framework thus formed against corrosion, for example by tin- dipping.; forming a housing for the crushing apparatus out of a number of nominally planar, interlocking components, preferably injection moulded out of a polymer such as glass-filled nylon.; pressing four idler pinion gears and four drive pinion gears per crushing apparatus out of sheet metal, advantageously a relatively thin gauge mild steel plate, and then case-hardening the pinion gears; forming the drive shaft assembly by affixing two pairs of drive pinion gears in spaced apart arrangement on the drive shaft, with the adjacent teeth on each pair of gears being mutually offset by half a pitch, afixing the gears to the shaft using high current silver soldering; treating the drive shaft assembly against corrosion, for example by tin dipping, before introducing it into the framework through the gap defined by the two opposing pairs of rack formation, with the drive pinion gears intermeshing with the upwardly projecting teeth of the lower pair of rack formations; introducing the drive shaft assembly into the framework at a precisely determined point along the rack formation, and at a pre-determined angle of the crank arm relative to the longitudinal axis of the framework, thereby ensuring that when the drive shaft assembly is at the extreme of its travel relative to the first or second end plate of the framework, the crank handle will lie in co-planar orientation to the longitudinal axis of the framework as an aid to effective packaging; after tin plating, introducing the four idler pinion gears as offset adjacent pairs into the framework, in a manner such that the teeth at the bottom of the idler gears intermesh with the teeth at the top of the corresponding drive gears, and the teeth at the top of the idler gears intermesh with the corresponding downwardly depending teeth of the upper rack formations. introducing the idler shaft between the centres of the opposing pairs of idler pinion gears, and then tightening a screw which is passed through the centre holes of the gears into a pre-threaded hole in each end of the idler shaft, whereby the upper pair of rack formations are spaced and held precisely apart by the idler shaft assembly, the lower pair of rack formations are similarly spaced and held precisely apart by the drive shaft assembly, and each of the vertically opposed pairs of rack formation are spaced apart by the drive shaft and idler shaft assemblies acting perpendicularly in concert with one another; journalling mating halves of the compression ram and fixing them around the drive and idler shafts in the spaces defined between opposing pairs of pinion gears; screwing cradle members for holding an empty can in the crushing apparatus prior to being crushed into the framework; and finally passing inwardly projecting moulded studs on the panels comprising the housing of the crushing apparatus through complemental fixing apertures in the framework and then welding them thermally or electronically into rivet heads thereby securely affixing the panel/s to the framework.

[23] A crawl mechanism assembly, comprising: a mechanism containment formation; a rotary-to-linear crawl mechanism; and drive means for crawling the mechanism linearly within the containment formation.

[24] A crawl mechanism assembly, as claimed in Claim 22, characterised in that the crawl mechanism comprises at least one toothed rack formation and a complementally toothed pinion formation carried on the rack formation, the pinion formation defining an axis of rotation.

[25] A crawl mechanism assembly, as claimed in Claim 23, characterised in that each of the rack and pinion formations comprises one or more adjacent sets of teeth, each set of teeth being mutually offset from an adjacent set of teeth in a plane perpendicular to the axis of rotation, whereby the mutually offset sets of teeth on the rack and pinion formations respectively are arranged to intermesh to prevent sideways displacement of the teeth relative to one another.

[26] A crawl mechanism assembly, as claimed in Claim 24, characterised in that the crawl mechanism includes a pair of parallel spaced apart rack formations and a corresponding pair of spaced apart pinion formations arranged to travel along the rack formations, with the mutually offset interengaging rows of teeth on both the rack formations and the pinion formations serving to ensure that the rack formations are maintained in a parallel configuration at their moving points of contact with the pinion formations.

[27] A crawl mechanism assembly as claimed in Claim 22, characterised in that the containment formation comprises a framework.

[28] A crawl mechanism assembly, as claimed in Claim 26, characterised in that the linear motion within the framework is reciprocal.

[29] A new crushing apparatus substantially as described herein.