GB2189416A - Pallet transfer apparatus - Google Patents

Abstract

A wire-guided cart system used in a flexible manufacturing system has a pallet transport (34) with pallet guideways 40, 41 and a locking pin 42. Upon arrival of the cart at a docking station, the transport is lowered onto locating means 72 or station a support rails, downward movement releasing the transport from the top deck of the cart and releasing the pallet 3 locking pin 42 to allow transfer of the pallet onto A receiving ways 67 at the station. <IMAGE>

Description

SPECIFICATION Apparatus for moving a workpiece into a working station Description of Invention This invention relates generally to machinery utilis ing interchangeable pallets providing machine tooling and/orworkpieceswith a common registering base.

More specifically, one aspect of the invention relates to the interchange of pallets in a system which utilises motorised parts for the automatic change of pallets between stations.

It swell known in machinetoolartstosecure workpieces to pallet bases which have common registering means for interchange on a machine tool.

Palletised workpieces are implemented in simple two pallet systems wherein one palletcarriedworkpiece is shuttled into the mach ine working zone while the other pallet is serviced by an operatorforfixing anotherworkpieceto the pallet. In multipallet systems, pallets may be moved by a conveyor, for example, between varieties of machinetools having a common registering means for accepting the pal lets.

Recent developments in the machine tool arts have sought to exploit a manufacturing cell comprised of selected machine tools grouped for a particular manufacturer's needs. To service these machining cells, manufacturers have developed a flexible manufacturing system (FMS)fortransferring pallets between machine stations, which does away with the hardware associated with convention conveyors. The present day FMS employs unmanned motorised carts which drive on the machine floor and follow the path of wire embedded in the floor. Radio frequency signal is used to communicate between the floor wire and the cart.

Wire-guided carts are available from a variety of commercial suppliers, for example Eaton Corp. In the United States and AGC Division of Volvo, in Sweden.

The carts typically have an internal elevating mechanism for raising and lowering the top deck of the cart.

The user must affix part-specifictooling to the top deck ofthe cart. In certain wire-guided cart applications, not related to precision machine tools, the cart may be positioned solely in response to the signal received from the wire. The stopping or positioning accuracy of the cart is typically within +.200 inch, or 5 millimetres. This accuracy is sufficient for grosslyposition objects such as boxes and the like which are to be utilised in packaging systems etc. However, in precision machine tool applications, it is necessary to registerthe to-be-interchanged pallet precisely with respectto a machine station. Therefore, supplemental registering means forthe cart must be employed.A common positioning means used in machine systems for positioning wire-guided carts isto equip the cart with at least one detent socket, and to have a precisely positioned detent pin positioned in the machine floor proximal the machine site. When the cart is grossly positioned through its inherent stopping accu racy, the detent pin is fired into the detent socket ofthe cart and servestopullthecartintoanaligned position.

Thereafter, the precisely aligned pallet on the cart may be successfully interchanged with the machine station. Here it should be noted thatthe elevational capability of the cart is utilised to bring the pallet precisely into a vertical alignment with the machine station for interchange. Also, it should be noted that the pallet leaves the part-specific tooling completely intact on the cart. Typically, the cart will remain atthe machine site until a pallet is loaded onto the cart.

Several problems are inherent in the prior art usage of wire-guided carts: the detent pin extending from the floor serves as a collection site for swarf, grit and other deleterious matter; the pin encounters great forces as it attempts to move the combined weight of the pallet, pallettooling, and cart intocorrectalign- mentwith the machine; and, the cart is generally tied up at the machine site during the machine working time because of the detent assembly required to locate and fix the cart.

According to the invention, there is provided apparatusfortransferring pal lets from one station to another and comprising a transport housing, a pallet guideway on the housing, a movable pallet locking pin in the housing and proximal to the guideway, a stationary docking station having a railforsupporting the transport housing, locating means for locating the transport housing relative to the rail in horizontal and vertical directions, means for reversibly moving the transport housing in vertical directions and means for moving the pallet locking pin in response to vertical movement of the housing.

An example of apparatus in accordancewiththe present invention will now be described, with reference to the accompanying drawings, wherein:~ FIGURE 1 is a side elevation of a known wire-guided cart assembly, FIGURE 2 is a perspective view of a known pallet, FIGURE 3 is a side elevation of a wire-guided cart and pallet transport assembly embodying the present invention, FIGURE 4 is a perspective view of the cart offigure 3, showing the top deck;; FIGURES is a cross-section through a ball castor and locating pin ofthe top deck ofthe cart of figure 3, taken along the line 5-5 offigure 4, FIGURE 6 is a section through the ball castor assembly along the line 6-6 of figure 5, FIGURE 7 is a perspective view from the front of the pallet transport assembly entering a docking station, FIGURE 8 is a perspectiveviewfrom the front of the elements offigure 7, after the pallet transport has been lowered onto locating pads ofthe docking station, FIGURE 9 is a perspective view of the elements of the docking station, shown in Figure 7 in the absence of the pallet transport, FIGURE 10 is a side elevation ofthe docking station, as viewed in the direction of arrow 10 offigure 8, FIGURE 11 is a front elevation showing the pallet transport crank in a fully raised and in a fully lowered position, as viewed along the line 11-11 of figure 10.

FIGURE 12 is a section through the pallettransport crankshaft along the line 1 2-1 2 of figure 10, FIGURE 13 is a section through the crank and crankshaft along the line 13-13 offigure 12, FIGURE 14 is a front elevation of the docking station, FIGURE 15 is a plan view of the pallettransport, FIGURE 16 is a section through the crankshaft and movable socket of the pallettransportalong the line 16-160ffigure 15, FIGURES 17,17a and 17b are sections in a transverse planethrough the movable socketand a hardened ball wear pad of the pallettransport in the positions: transportfully down atthe docking station; transport initial contactwith raising ball castor; and transportfully raised position atthe docking station; respectively, FIGURES 1 8,18a and 1 8b are sections through the pallet locking pin ofthepallettransportinthe positions: pallettransportfully down atthe docking station; transport initial contact with the raising ball castor and transport in thefully raised position at the docking station; respectively, and FIGURES 19,19a and 1 9b are sections in a fore-andafter plane through the docking station locating pin and transport guide bushing showing the pallet transport in the following positions: transport fully down atthe docking station; transport initial contact with raising ball castorandtransportfully raised atthe docking station; respectively.

Referring to the drawings, figure 1 depicts a guided cart system 10 of the prior art, wherein a wheeled unmanned cart 11 has a top deck 12 which is movable in vertical directions, and a pallet 13 is carried on specifictooling 14 mounted to the top deck 12 ofthe cart 11.The pallet 13 is transported to a machine station (not shown). At the machine station, a tapered locating pin 15 which is mounted in the floor is powered up into a companion socket 16 in the cart 11, to provide accurate horizonal positioning ofthe cart 11 for the interchange of pallets 13 with the machine station. An elevating assemblywithin the cart 11 provides the vertical accuracy of position forthe pallet interchangetotake place.

Figure2 depicts a typical pallet 13. The pallet 13 is a generally rectangularblockofcast iron, having a series of "T"-slots 17 machined in its upper surface 18, for mounting tooling and/orworkpieces. The bottom surface 19 ofthe pallet has large "T"-slot 20 machined throughout, so that a rectangularway system is created for sliding the pallet 13, and the "T"-slot facilitates pal let clamping at a machine station One end 21 ofthe pallet 13 is fitted with a stud 22 having a stem 23 and an outboard enlarged head 24. The machine station is provided with a push-pull rod 25, having a birfurcated end plate 26 which is ableto trap the head of the pallet stud 22, as the pallet 13 is lowered.In suchfashion,the rod 25thereforecan move the pallet 13 into, or out of, a machine station at interchange time.

Theelevational viewoffigure3 illustrates the present invention, wherein a wire-guided cart 27 i.e.

an unmanned wheeled vehicle guidedfrom a signal wire 28 embedded in thefloor29, has an elevatable top deck 30, which is fitted with a unique deck plate 31.

The deck plate 31 has a plurality of ball castors 32 secured thereto, and a pair oftapered locating pins 33 are also secured to the deck plate 31. The ball castors 32 support a separate pallettransport34 comprised, in part, of a housing 35 having an enclosed box structure 36 (which is fabricate weldment), welded to a bottom plate 37. A plurality of stiffening ribs or gussets 38,39 are welded to the sides of the box structure 36 and the plate 37 and a pair of hardened "T"-shaped, rails 40,41 are affixed to the top side of the transport housing 35.

A pallet locking pin 42 is shown extending upward from the transport housing 35 and engaging the pallet 1 3 during thetime of transport. Thepallet 1 3 is therefore locked in position on the "T"-shaped ways 40,41 until interchange time when the pallet locking pin 42 is retracted into the housing 35. Thetapered locating pin 33 of the cart deck plate is shown engaging a movable socket i.e. a tapered socket 43 formed in a cylindrical socket rod 44 extending from the bottom plate 37 of the transport housing 35, thus preventing relative movement between the cart 27 and transport 34 during transportation. The crankshaft 45 and the crank 46 shown at the end of the pallet transport 34 are spring-biased in a clockwise direction tothepositionshown i.e. apprnximately30 belowthe horizontal.When the crank46 is relatively moved in a counterclockwise direction with respecttothetrans- port housing 35 (see figures 7 and 9), the pallet locking pin 42 and socket rod 44 will retract into the housing 35.

The perspective view of figure 4 shows the cart 27 of figure 3 with the pallet transport 34 removed to show the deck plate 31. The four ball castors 32 are shown in a squared pattern, and the two tapered locating pins 33 are secured to the deck plate 31 between the castors 32. The sectional view offigure 5 depicts in enlarged fashion, the locating elements of figure 4,wherein the ball castor 32 is comprised of a short cylindrical housing 47 having a pilot diameter 48 received in a locating pilot hole 49 in the deck plate 31. A clearance-drilled hole 50 is provided in the top 51 of the housing 47, and a plurality of rollers 52 are received on horizontal pins 53 locked in the housing 47 by set screws 54 (see figure 6).As figure 6 depicts, the three rollers 52 are equally spaced around the ball 55, and are contained from side movement by clearance slots 56 cut through the housing 47. The rollers 52 have a concave groove 57 to conform to the ball 55. As shown in figure 5,the ball 55 is seated in the rollers grooves 57 and is prevented from outward movement by a cover 58 which is received on the castor housing 47 and secured by screw 59. The cover 58 has a cylindrical skirt 60 welded thereto which extends along the cylindrical body ofthe housing 47. The cover 58 has a clearance hole 61 drilled from its underneath side to such depth that the tapered drill point will not breakthrough, and the resulting diameter in the top of the cover 58 will clearthe exposed ball surface, yet prevent the ball 55 from escaping. Mounting screws 62 are provided through the castor housing 47 to secure the assembly to the deck plate 31.

The tapered locating pin 33 hasshortstraight pin section 63 with a conical point 64 at the top, and a flange diameter 64 is provided at the bottom for mounting against the deck plate 31. A plurality of screws 65 passing through the flange diameter 54 secure the locating pin 33 in position on the deck plate 31.

Referring to figure 7, a machine station 66 is shown having pallet-receiving machine ways 67 extending from the machine 68. Here it may be noted that the machine station 66 may comprise any station with pallet-receiving ways 67, a metal cutting machine; inspection machine; a washing machine; and pallet storage mechanism, etc. A pallettransportdocking station 69 is shown, generally comprising spaced apart rail brackets 70,71. A plurality offlat, hardened, locating pads 72 are mounted to the brackets 70,71 to provide vertical location for the pallet transport 34, while a plurality of fixed tapered locating pins 73 are used to provide horizontal location for the transport 34.As figure 7 depicts, the cart 27 has the deck plate 31 elevated to the topmost position, i.e. normally used when the cart 27 is cruising through a machine system. The pallet transport 34 is shown supporting a pallet 13 (in phantom) on its "T"-shaped ways 40,41 .A cam support bracket 74 is mounted to one decking station bracket 71, and the cam bracket 74 supports a hardened cam plate 75 which is essentially a horizontal plate having lead-in ramp surfaces 76 at each end.

As will be discussed further in conjunction with figure 9 there are two cam plates 75 used, but the lower one depicted in figure 7 is actively used to actuate the transport release machanism. The crank 46 shown in figure7 is in the "normallydown", spring-biased position relative to the transport housing 35. The crank 46 has an anti-friction cam follower77 extending into proximitywiththecam plate 75.

Following on to figure 8, the transport 34 is shown immediately after the deck plate 31 is lowered in the direction ofthe broad arrow, to such position where the transport 34 is vertically positioned on the hardened, flat locating pads 72 and is horizontally positioned by the tapered locating pins 73 sothatthe "T"-shaped transportways 40,41 are in line with the machine ways 67 and the pallet may successfully slide into the machine station 66. As can be seen in figure 8, the cam follower77 ofthe crank46 is shown in contact with the cam plate 75, and the lowering ofthe crank shaft 45 about the cam followed 77 (due to the weight of the pallet transport 34) causes the crank46 to relatively move ina counterclockwise direction, overcoming the internal spring-biased force.Thus, the pallet locking pin 42 and the socket rod 44(nowt shown but extending from the bottom of the pallet transport housing) are retracted.

Turning now to the perspective view offigure 9, the docking station 69 is shown with the pallettransport removed for clarity, and the station is comprised of two independent parallel brackets 70,71 which are fabricated from square hollow structural steel tubing.

One bracket70 has single rail 78 extending along its top surface, and the other bracket has double rails 79,80 extending along its top surface. The single rail bracket 70 is positioned alongside the machine station 66 (see figure 7)so that the machine ways 67 may be brought as close as possible to the pallet transport 34.

The double rail bracket 71 provides supportforthe cam bracket 74 which subtends the two rails 79,80.

The cam bracket 74 is a fabrication affixed to a plate 81 welded to the two rails 79, 80 and the cam bracket 74 has a facial slot 82formed in the side disposed toward the opposite station bracket 70. The slot 82 contains the two identical cam plates 75, which are fastened with screws 83 to the cam bracket 74. The lead-in ramp surface 76 of the cam plates 75 serves to provide a smooth entry for the cam follower77 due to any positioning misalignments ofthe crank46 (see Figure 7 and 8) with respectto the docking station 69. The double rail bracket 71 has a pair of hardened locating pads 72 spaced apart along its inside rail 79, and the pads 72 are fastened to a plate 84 which is welded to the inside rail 79.The locating pad 72 has a small hole 85 drilled in its top surface, and a horizontal hole 86 is drilled and pipe-tapped in one side of to interconnect with the vertical hole 85. All locating pads 72 are connected to an air pressure line 87 which in turn, has a pressure switch 88 to sense when the airflow from an air source 89 is closed off, therefore, signalling when a pallet transport 34 is "fully down " and positively located on the pads 72. A proximity switch 90 is threadably received through the rail plate 91 supporting the rear locating pad 72 ofthe inside rail 79. The proximity switch 90 is adjustably held in position by a locknut 92, and serves to indicate the presence of a pallettransport34.The single rail bracket 70 likewise supports corresponding locating pads 72, and the front pad plate 93 has a proximity switch 90threadablyreceivedtherethrough and secured with a locknut 92 in a similar fashion to that of the double rail bracket 71. In addition to front and rear locating pads 72, a pair of hardened tapered locating pins 73 having rectangular bases extend vertically from the rail plates 93,94 of the single rail bracket 70.

The conical locating pins 73 serve to provide horizontal positioning forthe pallettransport34. Flow of air through the holes 85 cleans the mutually facing surfaces fo the locating pads as these approach one another. Use ofthe pressure switch 88to provide a "fully down " signal is optional. The proximity switches 90 are alternatives to the pressure switch 88 but may be used in addition thereto.

The docking station brackets 70,71 have sideextending shelves 95 weldedto the bottom, and each shelf 95 contains a pair of levelling screws 96which are used to adjust the vertical position of the brackets 70,71. Once the brackets 70,71 are precisely located in a vertical direction, a central screw97 passing through the hollow levelling screw 96 serves to lag the assembly down tight to the floor in a conventional manner. The double rail bracket 71 need only be positioned accurately in a vertical direction, but the single rail bracket 70 must be positioned in a horizontal direction as well since itcarriesthe conical locating pins 73 which positively locate the transport 34 with respectto a machine station 66.Therefore, a pair of "U"-shaped brackets 98 are provided on the floor adjacent the single rail bracket 70 and horizontal screws 99 received through the "U"-shaped bracket 98 react against a welded tang 100 extending from each shelf 95 of the single-rail bracket 70 to provide horizontal adjustment.

Figure 10 depicts an end view ofthe docking station 69, showing the pallet transport 34 supported in the "fully down" position on the single rail and double rail brackets 70,71. The bottom plate 37 ofthe transport housing 34 has a plurality of welded plates 101,102 which, in turn, carry hardened locating pads 103 to mate with the locating pads 72 of the brackets 70,71.

The cart 27 is shown in plantom, with its deck plate 31 lowered so thatthe ball castors 32 no longer contact the transport housing 35. The transport housing 35 contains a hardened, flanged bushing 104which has a central bore 105 adapted to fit closely with the tapered locating pin 73 of the single rail bracket 70. A lead-in-taper 106 is machined in the bushing 104 at the same angle as the conical pointofthe pin 73 so that misalignment ofthe transport 34 may be accomodated and overcome as the transport 34 is manoeuvred into position by the lowering deck plate 31.

The pallet 13 is pulled by the machine push/pull rod 25 onto the machine ways 67 at one end of the transport i.e. the end nearestthe single rail bracket 70 of the docking station 69. The crankshaft45 extends from the other end ofthetransport housing 35, and the antifriction cam follower77, mounted to a crank pin 107, is shown in contact with the lower cam plate 75.

The cam plates 75 are carried by the cam bracket 74 which is fixed by screws 108 to the support plate 81 of the double rail bracket 71. The phantom positions of the cam follower 77 depict that initial endwise positioning inaccuracies may be accommodated but, as the transport 34 is lowered onto the tapered locating pins 73, the transport34will be pulled into proper alignment.

Figure 1 1 is an end view of the crank46, showing (in solid) the "fully down position,wherein the crank46 is rotated ina counterclockwise direction to a position apprnximately30'abovethehonzontal line. The phantom position ofthecrank46depictsthe pallet transport 34 in the "fully raised" position wherein the internal spring-biasing force (which will be discussed in connection with figure 15) restores the crank 46 to its fully clockwise position. As can be seen in figure 11, the space between the upper and lower cam plates 75 provides clearance around the cam follower77, so that during the initial portion of a lowering motion, the crank 46 will notbe moved.

The section shown in figure 12 is taken through the crankshaft45, shown mounted in front and rear bearings 109,110which in turn, are supported in front and rear bearing caps 111,112 affixed to the box structure36 ofthetransporthousing 35.Theforward end ofthe crankshaft 45 extends from the housing 35 and supports a gear 113 within the housing 35. A woodruff key 1 serves to connect a gear 113 to the shaft 45. The gear 113 is located on a reduced diameter 115 ofthe crankshaft 45 and is shouldered againstthe large main diameter ofthe shaft 45. A spacer sleeve 117 is provided on the crankshaft 45 between the gear 113 and the bearing 109 sothatthe gear 1 ~3will not move axially.The bearing 109 is retained in the front bearing cap 111 by a front retaining ring 118 received in the bearing cap 111 and loaded againstthe inner race ofthe bearing 109. The outer race ofthe bearing 109 is shouldered againstthe end 119 of the bearing bore 120. The crank46 has a straight arm portion 121 andahubl22isweldedtothearm46a.Aborel23is providedthroughthehub 122 and arm 121.The crankshaft 45 has a pair of side flats 125 machined to provide a thin width which will fit closely in the slot 124 of the arm 121 to create a torque couple between thetwo,asshown in figure 13.Athreaded end 126 is provided on the crankshaft 45 and a washer 127 and castellated locknut 128 are provided thereon. A cotter pin 129 is received through the shaft 45 to preventthe nut 128 from backing off.The outboard end of the crank 121 arm has a hole 130 parallel to the crankshaft 45, and a crank pin 107 is mounted in the hole 130. The crank pin 107 has a pilot diameter 131 received through the hole 130 and a washer 127 and castellated locknut 128 are held by a threaded end 132 ofthe crank pin 107. A cotter pin 129 is received through the crank pin 107. The crank pin 107 has a large main diameter 133 extending from the outer face ofthe crank arm 121,andthecrankpin 107 is reduced atatapered section 1 34to a small shoulder diameter 135, extend- ing to a smaller bearing diameter 136.The bearing diameter 136 supports the antifriction cam follower 77 which is entrapped againstthe shoulder diameter 135 by a washer 127, and locknut 128, and cotter pin 129, received on the threaded outboard end 137 ofthe crank pin 107.

The crankshaft gear 113 is enmeshed with a vertical rack portion 138 of the movable socket rod 44. The socket rod 44 is prevented from rotating by means of a headed pin 139 received in the side of the transport housing 35 and having a keying nose 140 engaged in a key slot 141 ofthe socket rod 44. A guide sleeve 142 is received around the socket rod 44 and prevented from rotating by a pilot diameter 143 of the pin 139 received in a hole 144 through the side ofthe guide sleeve 142.

The rear end ofthe crankshaft 45 is reduced from the main diameter 116, and the reduced diameter 146 extends through: a short lever 147; a spacer ring 148; and a drive gear 113.The lever 147 and gear 113 are connectedthroughwoodruffkeys 1 14to the shaft45.

Thegearmesh 113 is in mesh with a rack portion 138 of the second socket rod 44 as previously described. A spacer ring 149 is received on the shaft 45 between the gear 113 and the end bearing 110,and the assembly is locked together by an end plate 150 held to the inner race of the bearing 110 by a screw 151 received in the end of the crankshaft 45. The bearing 110 is constrained against axial movement in the rear bearing cap 112 bya shoulder 152 atthe inboard end ofthe bearing bore 153, and a retaining ring 154 provided on the bearing cap 112. A clearance bore 155 provided in the bearing cap 112 extends around the retaining plate 150 on the crankshaft 45.The crank lever 147 is engaged with a slot 156 in the side of the pallet locking pin 42 to provide vertical movement ofthe locking pin 42through its guide bushing 157.

The elevational view of figure 14 is shown looking at thetransport 34 from the side ofthe double rail bracket 71. The view is depicted with the transport 34 in the "fully down" position, i.e. with the crank46 rotated in a counterclockwise direction and having a pallet 13 ready for interchange on the transport ways 40,41. The hardened locating pads 103 of the transport 34 are shown in contact with the locating pads 72 of the brackets 70,71.

Figure 15 is a pl a n view of th e pa I I et tra nsport 34.

The crank46 and crank pin 107 are seen extending from one side of the transport housing 35. The pallet locking pin 42 is shown between the pallet support ways 40,41. The transport housing 35 contains the pair of socket rod assemblies 158 which will be more fully depicted in the sectional view offigure 16. Four hardened circular locating pads 59 are provided on the pallenttransport 34 to preventwearatthe ball casto r sites. The fou r flat locating pads 103 are shown affixed to the bottom surface of thetransport 34to provide for vertical positioning while the two pin bushings 104 are shown affixed to one side ofthe pallet transport 34forthe horizontal positioning ofthe unit.One side of the transport housing has a central relief 160, to provide clearance for machine ways 67 which may extend into close proximity with the pallet su pport ways 40.41 of the transport 34.

Figure 16 is an elevational section through the crankshaft 45 and the socket rod assemblies 158. The socket rod 44 is shown having its rack portion 138 in mesh with the crankshaft gear 113. The socket rod 44 slides in the guide sleeve 142 which extends through bores 161,162 in the top and bottom walls ofthe housing 35. Thetop oftheguide sleeve 142 has a flange 163, and screws 164 pass through a cover plate 165 and the flange 163 to secure the assembly 158 to the transport housing 35. A grease fitting 166 is provided in the side of the cover plate 165 with suitable interdrilling to introduce grease into the assembly 158. The socket rod 44 is provided with a blind clearance hole 167 drilled to approximately one-fourth ofthe overall length.A guide pin 168 affixed in the cover plate 165 extends into the clearance hole 167 approximatelyto full depth when the socket rod 44 is in thefully retracted position (shown). A preloaded spring 169 is received in the clearance hole 167, reacting against the rod 44 and cover plate 165, to normally bias the socket rod 44 downward, thus rotating the crankshaft 45 in a clockwise direction. When the socket rod 44 is in the down most extended position (in phantom) the guide pin 168 serves to keep the spring 169 from buckling.

Figure l6further shows the pallet locking pin 42 in the fully retracted position. The locking pin 42 is guided in a bushing 157 located in a cylindrical bore 170 in the housing 35. The pallet guide ways 40,41 are secured to the transport housing 35 by a plurality ofcapscrews 171.

Figures 17,18 and 19 should be viewed simultaneously, since they are related in time and space.

The bottom plate 37 ofthe transport housing 35 is common to all views and is shown therefor by a phantom lineconnectingtheviewsforeaseof understanding. The location of all elements occurs with the deck plate 31 of the cart 27 if the "fully down" position i.e. with the ball castor 32 and tapered locating pin 33 away from the pallettransport 34. The pallet transport 34 is seated on the locating pads 72 and having its bushing 104 (see figure 19) journalled on the tapered locating pin 73 ofthe single rail bracket 70. The socket rod 44 is shown in the retracted position, i.e. within the transport housing 35. The socket rod 44 has a precision socket bore 172 closely-machined to fit the locating pin 33 ofthe deck plate 31.A lead-in-taper 173 is provided at the bottom ofthe socket rod 44 so that horizontal misalignment may be accommodated between the transport 34 and the locating pin 33 when the cart 27 picks up the transport 34. The phantom positions of the pin 33 serve to show the degrees of horizontal misalignment which may be accommodated. Figure 18 shows the pallet locking pin 42 in the fully retracted position from the pallet 13 and pallet bore 174. The lever 147 ofthe crankshaft is shown rotated in the further most counterclockwise direction, thus retracting the locking pin 42. The locking pin 42 has a side slot 156 for receiving the crankshaft lever 147. A hardened replaceable nose cap 175 is received on the top of the locking pin 42. The nose cap 175 has a slighttaper.The pallet locking pin 42 isjournalled in a flanged guide bushing 157 secured to the transport housing 35. The flanged bushing 157 has a seal 176 atitstop end and a greasefitting 177 provided intheflange 178 of the bushing 157 serves to introduce lubricant to assist the pin 42 in sliding. The locking pin 42 has a small diameter straight pin 179 extending radially into a guide slot 180 in the guide bushing 157 to preventthe locking pin42from rotating.

In figures 17a, 18a and 19a, the deck plate 31 is raised to a position where the ball castor 32 contacts the locating pad 159 ofthe transport 34 and begins the initial lift. As has been explained previously,the lifting ofthe transport 34 enables the crank 46 (figure 11) to rotate in a clockwise direction underthe influence of the socket rod biasing spring 169. The socket rod 44 therefor begins its descent from the bottom plate 37 of the transport housing 35 as the locating bushing 104 of the transport 34 is leaving the locating pin 73 in figure 1 9a. Simultaneously, with the clockwise rota- tion of the crankshaft, the crank lever 147 lifts the pallet locking pin 42 into engagement with the pallet bore 174.

Continued upward motion of the deck plate 31 as shown in figures 1 7b, 18b and 1 9b, illustrates the "fully raised" position, wherein thetransport 34 is vertically positioned on the call castor 32 and horizontally positioned by virtue of the socket rod 44fully extending from the bottom plate 37 ofthe transport 35 into engagement with the deck plate locating pin 33.

Figure 18b illustrates that continued rotation ofthe crank46movestheleverl47alonga ramp 181 tangent to the circular lever path machine on the pallet locking pin 42to prevent the pin 42 from backing down. In these positions, the pallet transport 34 and pallet 13 are carried through the system on the wire guided cart 27.

It may be readilyappreciatedthatthe sequence showninfigures 17,17and 17bits reversed when the pallet transport34 enters the docking station 69 and the deck plate 31 begins to descend.

The present application is divided from application 8515143 published as GB 2,162,450A,which claims a palletised part-handling apparatus comprising pallet transport means which can remain at a docking station with a palletwhilstacarton which the pallet transportmeans has been borne to the docking station travels away from the docking station.

Claims (4)

1. Apparatus fortransferring pallets from one station to another and comprising a transport housing, a pallet guideway on the housing, a movable pallet locking pin in the housing and proximal to the guideway, a stationary docking station having a rail for supporting the transport housing, locating means for locating the transport housing relative to the rail in horizontal and vertical directions, means for reversibly moving the transport housing in vertical directions and means for moving the pallet locking pin in response to vertical movement of the housing.

2. Apparatus according to Claim 1 further com pris- ing a movable transport locking rod in said housing and means for moving said transport locking rod in response to vertical movement of said housing.

3. Apparatus according to Claim 2 wherein said meansfor moving the pallet locking pin.and said means for moving the transport locking rod include a common crank and crankshaft and wherein said crank is engageable with said stationary docking station.

4. Apparatus according to Claim 3 wherein said crank and crankshaft are normally urged in one rotary direction by a biasing spring.