US 3718246 A
Description (OCR text may contain errors)
Feb. 27,, 1973 E.J DARDAINE ET 3,713,246
MULTIPURPOSE GROUPING DEVICE FOR AN ENCASING-UNCASING MACHINE Filed Feb. 24, 1971 5 Sheets-Sheet 1 8 V 7 am w FTOfiA EKS Feb. 27, 1973 E. J. DARDAINE ET 1 MUL'IIPURPOSE GROUI'ING DLVICE FOR AN-ENCASIiiG-UNCASING MACHINE" 5 Sheets$heet 5 I 7 /N1/E/vraAl5 Filed Feb. 24. 1971 AgmAA/EVJ Feb. 27,1973 E.J DARDAINE E1 AL 3,713,246
MULTlFURPOSE GROUPING DLVICE FOR AN ENCASIKGUNCASING MACHINE 5 Sheets-Sheet 4 Filed Feb. 24, 1971 fiw g A 7704/1/95 Feb. 27, 1973 E, J DARDMNE ET AL 3,718,246
MULTUURPOSE GROJIING DLVICE FOR AN ENCASLJG-UNCASING MACHINE 5 Sheets-Sheet 5 Filed Feb. 24, 1971 wyaw 54,
United States Patent us. or. 19s--34 7 Claims ABSTRACT OF THE DISCLOSURE Device for grouping bottles to be gripped by gripping heads comprising a conveyor travelling at a constant speed higher than that of the heads, a guiding device provided with retaining members arranged equidistantly with a pitch L equal to that of the gripping heads and adapted to move at a speed V equal to that of the gripping heads and selecting means arranged upstream of the said guiding device and provided with retaining members arranged equidistantly with a pitch 1 and adapted to move at a speed The present invention relates essentially to a device for grouping objects such as, for instance, bottles or the like, in order that they may be seized by an encasing-uncasing machine comprising equidistantly arranged gripping heads provided with rows of gripping members and adapted to move along at least one rectilinear path element at a constant speed, the said device being of the type comprising a horizontal conveyor adapted to move under the said path element at a contant speed higher than that of the heads and formed of separate elements mounted on a rotary drive system and each adapted to receive a row of bottles, a bottle guiding device arranged straight under the said rectilinear path element and provided with retaining members arranged equidistantly with a pitch L equal to that of the gripping heads and adapted to move at a speed V equal to that of the gripping heads, and selecting means arranged upstream of the said guiding device in order to select a given number of bottles in each row.
The bottles distributed in any manner whatsoever on the conveyor elements are first gathered together and divided into homogeneous groups by the said selecting means, and then each group of bottles, after being freed from the said selecting means is received by the guiding device which guides them under the gripping heads so as to enable them to be gripped by the latter.
Selecting means for gripping devices are known which temporarily stop the flow of bottles or the like, i.e. cause a discontinuity in their displacement, resulting in impacts and, therefore, risks of breakage and limiting the hamdling capacity of such grouping devices. Movable select ing means are also known which are adapted to move at a speed lower than that of the conveyor and to brake the bottles. However, the mechanical interconnections between the selecting means and the guiding means following them have not beeen defined. As a result, they hinder optimum operation of the grouping devices with which they are associated.
One of the purposes of the present invention is to enable the grouping devices of the aforementioned type to be optimized. The grouping device according to the invention is characterized in that the said selecting means Patented Feb. 21, 1973 are provided with retaining members arranged equidistantly with a pitch 1 and adapted to move at a speed The retaining members of the selecting means are thus adapted to move at a speed proportional to that of the retaining members of the guiding device and to the ratio of the respective pitches of the said retaining members, thus ensuring strict synchronism, minimum slowing down of the bottles .or the like and, therefore, optimum operation of the grouping device.
According to another characteristic feature of the invention, the said selecting means comprise several independent selecting devices arranged under the said conveyor one after another, the sets of equidistant stops of each selecting device being arranged with a given pitch la, lb, lc, etc., differing in each device from the pitches in the other devices, and adapted to move at a given speed etc.
Owing to the said stops being distributed on each selecting device-with a given pitch, the provision of several selecting devices enables several pitches to be available, i.e. allows to form groups of bottles differing from one another as far as the number of bottles and their diameter are concerned.
In addition, the presently known grouping devices are designed to receive a predetermined number of rows of bottles having a given diameter and to so gather them together as to form groups, each of which comprises a given number of said bottles. Therefore, such devices may be used only with gripping heads of a given type, i.e. gripping heads comprising a given number of rows of gripping members, the said rows being arranged in given spaced relationship (depending on the diameter of the bottles) and each comprising a predetermined number of gripping members. Therefore, the field of application of such devices is quite limited, whereas there exists a great number of types of gripping heads adapted for all types of bottles, racks, etc., so that, up to the present, the flexibility in use of the encasing-uncasing machines was limited precisely by the said devices.
The grouping device according to the invention has also for its purpose to enable the bottles to be grouped and guided in order to be handled by encasing-uncasing machines adapted to handle any number of bottles having any diameter, i.e. equipped with gripping heads which may comprise any number of rows of gripping members, arranged in any spaced relationship and comprising anynumber of such gripping members in each row.
The grouping device according to the invention is also characterized in that the elements forming the said conveyor are adjustable in number and in position with respect to one another, and in that the said retaining members are constituted by interchangeable sets of stops, removably mounted, on the one hand, on the said guiding device and, on the other hand, on the said selecting means.
The conveyor in the grouping device according to the invention may therefore be provided with a number of elements equal to the number of rows of gripping members of the gripping heads and the spacing of which corresponds to the spacing of the said rows of gripping members; on the other hand, owing to the fact that the retaining members of the selecting means and of the guiding device are interchangeable, the said selecting means as well as the said guiding device may be provided with a set of retaining members adapted to the number of conveyor elements and to their relative spacing. Moreover, the retaining members of the said selecting means maybe adapted to the number of gripping members in each row of gripping members of the gripping heads and to the diameter of the bottles.
In contradistinction to the presently known gripping devices, the gripping device according to the invention allows the handling of any number of rows of bottles having any dimensions, i.e. the universality of its use is altogether identical with that of the presently known gripping heads and it is no longer a source of limitation of the capacity and flexibility in use of the encasing-uncasing machines.
According to another characteristic feature of the invention, the elements forming the said conveyor are supported by two slotted drums or rolls, the axes of which are in parallel relationship and which are arranged in one and the said horizontal plane, the length of the said drums or rolls being greater than the useful width of the conveyor, so that the said elements are adapted, by moving in lateral translation, to take various positions with respect to the said drums or rolls and with respect to one another. 7
According to still another characteristic feature of the invention, each selector as well as the said guiding device comprises two vertical parallel endless chains driven by two pinions keyed on a common drive shaft, each removable set of stops being mounted on a support arranged between the said chains and solid with the latter.
The invention will be better understood and other objects, characteristics and advantages thereof will appear as the following description proceeds, with reference to the appended drawings given solely by way of example illustrating one form of embodiment of the invention and wherein: 1
FIG. 1 is a diagrammatic perspective view showing a gripping device according to one form of embodiment of the invention, associated with an encasing-uncasing machine;
FIG. 2 diagrammatically illustrates the operation of the device of FIG. 1;
FIG. 3 is a partial top view of the conveyor ofthe grouping device according to the invention, wherein the elements forming. the said conveyor are in a first position;
" FIG. 4 is a view identical with FIG. 3, wherein the elements constituting the conveyor are in a second position;
FIG. 5 is a partial sectional view upon the line VV of FIG. 3;
FIG. 6 is a sectional view upon the line VIVI of FIG. 3;
FIG. 7 is a diagrammatic perspective view of the guiding means of the grouping device according to the invention; I I 1 FIG. 8 is a detailed view illustrating the mounting of the sets of stops and the said guiding device;
' FIG. 9 is a detailed perspective view of a set of stops used with the guiding device of FIG. 7;
FIG. .10 is an exploded perspective view showing the members driving the guiding device of FIG. 7.
FIG. 1 shows a grouping device according to the invention, indicated generally by 20, associated with a bottle encasing-uncasing machine indicated generally by10. 7 Y
The encasing-uncasing machine 10 comprises a plurality of gripping heads 11 (only two of which are shown) arranged with a pitch L and provided with gripping members 12, each of the said members being adapted to seize a bottle by its neck. In the case illustrated, the
' gripping members 12-are distributed in three rows of four the said pairs, 15a being driven in rotation by a motor 1 6 through the medium of a transmission member 17. The gripping heads 11 are driven in closed circuit at a constant translation speed V along a path comprising, between the two pairs of pinions 15a and 15b, two rectilinear portions, one of the said portions, namely the front portion, being located above the grouping device 20, whereas the other portion, namely the rear portion is located above a conveyor belt or the like (not shown) for conveying the cases.
The grouping device 20 comprises a horizontal conveyor 21 formed of three identical separate elements 22 mounted on a rotary drive system comprising two drums or rolls 23a, 23b rotatably mounted on the frame 24 of the said grouping device, one of which, 23a, is driven at a constant speed by the motor =16 through the medium of a chain transmission system 25. The conveyor 21 is thus driven at a constant translation speed V V, each of the three elements 22 constituting the same being located straight under one of the three rows of gripping members of the gripping heads.
With the conveyor 21 are associated, on the one hand, a bottle guiding device, indicated generally by 30, located below the elements 22 straight under the said rectilinear path portion, and bottle selecting means, indicated generally by 40, arranged upstream of the said path portion.
The bottle guiding device 30 is constituted by an endless chain system 31 driven by the motor 16 through the medium of a transmission chain 32, at the speed V of the gripping heads. The chain system 31 is provided with retaining members 33 distributed equidistantly with a pitch L and arranged in the intervals between the elements 22 on either side of the said elements and projecting above the horizontal plane of the conveyor.
In the case illustrated, the bottle selecting means 40 comprise two selecting devices 40a and 40b, each of which is constituted, in the same manner as the guiding device 30, by an endless chain system 41a, 41b driven by the motor 16 through the medium of transmission chains 42a, 42b at speeds v and v lower than V and, therefore, lower than V In the example illustrated, only the device 4011 is provided with retaining members 43a identical with the retaining members 33 of the guiding device 30 and distributed in equidistant relationship with a pitch la. The retaining members 430 are arranged, in the same manner as the retaining members 33, in the intervals between the elements 22 on either side of the said elements and project above the plane of the conveyor.
In FIG. 1 there is shown a single set of retaining members 43a for the sake of clarity of the drawing.
The principle of operation of the gripping device willbe explained hereafter with reference to FIGS. 1 and 2. The bottles B are placed on the conveyor 21 in three rows corresponding to the three elements of the said conveyor, one after another, and are distributed in any manner,'i.e. with a random and variable spacing between two successive bottles. They are driven at the conveyor speed V until the first bottle meets that retaining member 43a of i the selecting device 40a, which is located above the conveyor. The said bottle as well as those following it are thus compelled to move at the speed v of the saidretaining member, which is lower than the speed V so that the bottles which are subjected to a braking effect, slide on the conveyor and are brought into contact with one another. The pitch la of the retaining members 43a of the selecting device 40a is so. chosen as to correspond to a whole number of bottles (i.e. la nD, wherein la is the number and Da the diameter of the bottles separated by the selector 40a), so that when the following retaining member in its turn arrives above the conveyor it is inserted in the interval comprised between the nth and n+1th bottles (in the case illustrated, between the 4th and the 5th bottles) and retains the bottles starting from the n+lth (starting from the 5th in the case illustrated). When the first bottle arrives at the end of he activ p0rtion of the endless chain system 41a the member retaining the same passes under the conveyor, so that the four bottles comprised between the said two retaining members are freed and therefore driven by the conveyor 21 at the speed V The bottles are therefore distributed by the selecting device 40a into distinct or separate homogeneous groups, each of which, in the case considered, comprises four bottles.
The group of four bottles moves at the speed V until it meets the retaining member 33 of the guiding device 30. The retaining members 33 move at the speed V of the gripping heads, and since each of them is located straight below the front of a gripping head during its motion on the upper side of the endless chain system 31, the group of bottles is positioned exactly under a gripping head and moves exactly at the same speed as the latter.
It is obvious that the time required for a retaining member 43a of the selecting device 40a to cover the distance la must be equal to the time required for a retaining member 33 of the guiding member 30 to cover the distance L, i.e. if v is the constant speed of translation of the retaining members 43a, then,
The evolute of the chains of a selecting device such as 40a and the number of retaining members of the said selecting device are so selected that in no case will less than one retaining member or more than two retaining members appear simultaneously in such a position as to engage the bottom of the bottles.
Owing to this fact, the pushing of the bottles is always maintained by a retaining member which disappears only when the next retaining member has appeared. It is therefore impossible for the bottles to pass without being integrated in a group of bottles. On the other hand, since the pitch of the retaining members 43a is so selected as to correspond to a whole number of bottles, a retaining member projecting above the plane of the conveyor is readily inserted behind the group of bottles which will be freed.
The three elements 22 forming the conveyor 21 may be constituted, as shown in FIGS. 3 to 6, by blade chains 220 mounted on guide rails 221 and meshing with both drums or rolls 23a and 2312 which are slotted along their whole length, so that the blade chains may slide laterally, i.e. in parallel relationship to the axis of rotation of the said drums, while at the same time remaining meshed with the slots. Thus, the spacing between two successive blade chains may be adjusted at will so as to adapt the said spacing to the diameter of the bottles to be handled and, of course, to the spacing between the rows of gripping members of the gripping heads. The length of the drums 23a and 23b depends of course upon the maximum number of blade chains which it is desired to place side by side to form the conveyor 21. Thus, in the case illustrated, it is seen that the drums 23a, 2312 have a length which considerably exceeds the useful width of the conveyor constituted by the three blade chains 220, thus enabling not only the said three chains to be spaced from one another to a greater extent than the one shown in the figure and, therefore, the bottles having a diameter greater than that of the bottles shown, to be conveyed, but, in addition, two or even three aditional blade chains to be added, thus enabling not only three, but five or six rows of bottles to be received by the grouping device.
The positioning of the elements 22 is carried out by means of bars or rods 26 rotatably mounted on the frame 24 and provided on their peripheries with a series of coplanar flat portions 26a and 26b arranged in perpendicular planes, the flat portions of one and the same group, for instance 2611, having a given pitch differing from the pitch of the flat portions of another group, for instance 26b. The positioning bars or rods 26 are provided to support the rails 221 of the conveying elements 22, each pair of rails 221 being located in a said fiat portion, so that the three elements 22 are positioned with the desired spacing corresponding to the selected pitch of the set of fiat portions.
Supposing the rails to be lying on the flat portions 26a (as in the case illustrated in FIG. 3), if it is desired to modify the spacing between the three elements of the conveyor 21, it is sufficient to rotate each bar or rod 26 by so as to bring the fiat portions 26b into a horizontal plane and to translate laterally the elements 22, which, as a result of the rotation of the bar or rod, are raised to a height corresponding to the depth of a flat portion and are lying on a generatrix of the said bar 26, until the rails 221 are engaged in the flat portions 26b (as in the case illustrated in FIG. 4). During this motion of translation, the blade chains 220 move on the slotted drums 23a, 23b.
=A locking system is provided to maintain the elements 22 positioned on a given series of flat portions of the positioning bar 26. This system is constituted by a bar or rod 27 provided with a flat portion 27a, mounted rotatably on the frame 24 and engaging locking members solid with the rails 221 and constituted by stops 222 secured by means of screws 223 and passing under the said locking bar 27. It is seen that according to whether the bar 27 is in the position shown in FIG. 6 or in the position resulting from rotation by the rails 221 are prevented from moving vertically, or on the contrary, they may move vertically, i.e. they are either locked or unlocked.
The guiding device 30 as well as the selecting devices 4011 and 40b are designed in the same manner, so that only the guiding device 30 will 'be described in the following by way of example.
Referring to FIG. 7, it is seen that the guiding device 30 comprises two parallel and vertical endless chains 31 meshing with two pairs of pinions 34a and 34b keyed on a shaft 35a, 35b respectively, one of which is the drive shaft (35a in the case of the guiding devices). Between the two chains 31 is secured a support 300 for the removable retaining members constituted by the stops 33 solid with a common plate 36. The support 300 comprises a cross-member 301 bracing the chains 31 and secured to the latter at both its ends and a base-member 302 rotatably mounted on the said cross-member so as to rotate about a horizontal axis. The base-member 302 is provided with a fork-shaped member 303, i.e. a member having a notch, groove or cut-out portion 303a. A guiding bar or rod 305 is also secured, at its ends, to both chains '31 in parallel relationship to the cross-member 301 and downstream of the latter in the direction of translation of the chains, indicated by the arrow F. The guiding bar 305 is provided in its medial portion with a portion of smaller diameter 305a which penetrates into the notch 303a. The plate 36 carrying the stops 33 is provided at its lower portion with two studs or the like 37 provided with notches 37a adapted to fit onto the cross-member 301. The plate 36 itself lies on the base member 302 on which it is fixed by means of a locking member constituted by a retractable pin 38 mounted slidingly in a stud 37. The pin 38 is subjected to the action of a return spring (not shown) solid with a knob or the like 39 enabling it to be retracted by making it slide against the action of the return spring, the said pin co-operating with a projection or the like 302a of the base member 302.
Thus, the support 300' which takes its bearing, through the medium of the cross-member 301 and the guiding bar 305, on the chains 31 at two points which are relatively distant from one another, firmly holds the stops against tilting as a result of the pushing effect of the bottles. On the other hand, the fact that the base member 302 and, therefore, the stops themselves are adapted to rotate facilitates, in the case of the selecting device, the insertion of the pins between the bottles and enables their withdrawal to be accelerated when the bottles reach the end of their travel, thus improving the synchronization with the guiding device.
It is thus seen that by having available sets of stops with different characteristics, i.e. comprising a more or less considerable number of stops between which the spacings are more or less considerable, the guiding device as well as the selecting devices may be adapted to the number of elements used for the conveyor and to the relative position of the said elements.
The selecting devices 40a, 40b, etc. are provided with supports for the stops arranged with a given pitch differing in each device from the pitches in the other devices,
the sets of stops 43 being of course mounted on one and the same said selecting device, the pitch in the latter being adapted to the length of the groups of bottles which it is desired to form. Each selecting device is driven at a speed v given by the above Equation 1. A sufiicient number of selecting devices is provided to allow for all the selections required ,by the existing gripping heads and types of bottles.
It should be noted that in the case of the selectors 40a and 40b, the driving of the chains 41a, 41b is performed by the upstream pinions (as can be seen in FIG. 1), so that the upper chain side is held stretched owing to the push exerted by the bottles on the stops, the slack chain side being the lower side.
It is necessary to provide for the adjustment of the position of the sets of stops of the guiding device with respect to the gripping heads, so as to ensure a correct positioning of the bottles with respect to the said gripping heads whatever their dimensions may be, and, on the other hand, to adjust the position of the sets of stops of the selecting devices with respect to the set of stops of the guiding device, so that the bottles may reach the gate of the said guiding device immediately after the corresponding set of stops appears, and this without sliding on the blade chain.
To this end, the driving of thedriving shaft 3511 by the chain 32 connected to the motor 16 (as well as the driving of the driving shafts of the various selecting devices, which are the upstream shafts) is ensured through the medium of an adjustable keying member 310 shown in FIG. 10. The pinion 311 meshing with the chain 32 is solid with a cheek or side plate 312 provided with studs or the like 313 adapted to he slipped onto the shaft 35a. An intermediate member 314 provided with arcuate openings 315 into which the studs 313 are adapted to penetrate and with adjusting screws 316 projecting into the said openings 315, is also slipped onto the, shaft 35a. A
v first plate 317 provided with positioning holes 318 is also slipped onto the shaft 35a and secured to the intermediate member 314 by means of screws, for instance sunk head screws, 319. The pinion 311, the intermediate member 314 and the first plate 317 thus form a rigid assembly mounted on the shaft 35a. A second plate 320 provided with a central orifice 321 comprising a keying slot 322 and with two retractable studs or the like 323 subjected to the action of return springs 324, and adapted to engage into the positioning holes 318 of the first plate 317 is also slipped onto the shaft 35a and is rendered solid in rotation with the latter by means of a key 326 adapted to be inserted into the keying slot 322 and into the keying slot 327 of the shaft 35a. Therefore, by introducing one of the studs 323 into one or another positioning hole 318, the keying of the pinion 311 and, therefore, the position of the sets of stops of the endless chains 31 may be chosen at will. A a number of positioning holes 318 corresponding to the number of the desired keying positions may of course be provided in the plate 317.
It should be pointed out that the gripping heads, the conveyor, the bottle guiding device and the various selecting devices are driven by the motor 16, thus ensuring a strictly synchronous continous motion of the whole plant. The various selecting devices are permanently connected to the motor 16, thus ensuring the synchronization thereof, and are all driven in motion by the latter although only one of them is provided with sets of stops.
Of course, the invention is by no means limited to the form of embodiment described and illustrated, which has been given by way of example only. In particular, it comprises all the means constituting technical equivalents to, the means described as well as their combinations, should the latter be carried out according to the spirit of the invention.
What is claimed is:
1. Device for grouping objects such as bottles or the like, in order that they may be gripped by an encasinguncasing machine comprising gripping heads arranged equidistantly wkith a pitch L, said gripping heads being provided with rows of gripping members and moving along at least one rectilinear horizontal :path element at a constant speed V, comprising a horizontal conveyor onto which said bottles are disposable in predetermined rows, said conveyor being adapted to move under the said horizontal path element at a constant speed higher than that of said gripping heads, and comprising separate conveyor members each adapted to receive a row of bottles, said conveyor members being adjustable in number and being supported by two slotted drums the axes of which are in parallel relationship and which are arranged in one and the same horizontal plane, the said drums having a length greater than the useful width of said conveyor, so that the said conveyor members may, through lateral translation, take various positions with respect to the said drums and with respect to one another, a device for guiding said bottles, disposed straight under the said rectilinear path element, and provided with removable retaining members arranged equidistantly with said pitch L and adapted to move at said speed V in a direction parallel to the direction of translation of said conveyor and a plurality of selecting devices disposed, in relation to the direction of travel of said conveyor, upstream of the said guiding device, and located under the said conveyor one after another, said selecting devices, being provided with removable stop members arranged equidistantly, the stop members of each selecting device being arranged with a pitch Ia, lb, lc, etc., and adapted to move at a speed v,,=V J1? U =V a l? 0 7? etc., said stop members being further adapted to be serted between two of said bottles so that said bottles travel at said speed v v v etc., and are distributed over the conveyor into separate homogenous groups each having a predetermined number of bottles contacting one another, whereas said retaining means are adapted to ngage said groups of bottles so that said groups travel at said speed V.
2. Device according to claim 1, wherein adjustable positioning means are provided to position said conveyor members on said drums.
3. Device according to claim 2, wherein said conveyor I members are constituted by blade chains supported and guided by rails and wherein said adjustable positioning means are constituted by at least one bar, supporting said conveyor members and provided, on its periphery, with series of coplanar flat portions arranged with different pitches and in each of which are placed the aforesaid rails supporting and guiding a blade chain, the said bar being mounted rotatably so as to provide, at a predetermined angular position, a series of flat portions corresponding to a given positioning of said blade chains on said drums.
4. Device according to claim 3, further comprising locking means adapted to lock laterally in position each rail placed in a flat portion of the said positioning bar.
5. Device according to claim 4, wherein said locking means are constituted by a rotary bar disposed under said rails and provided with a flat portion and whereinlocking stops are secured to said rails, said locking stops passing under said rotary bar and being adapted to co-operate with the latter.
6. Device for grouping objects such as bottles or the like, in order that they may be gripped by an eneasinguncasing machine comprising gripping heads arranged equidistantly with a pitch L, said gripping heads being provided with rows of gripping members and moving along at least one rectilinear horizontal path element at a constant speed V comprising a horizontal conveyor onto which said bottles are disposable in predetermined rows, said conveyor being adapted to move under the said horizontal path element at a constant speed higher than that of said gripping heads, and comprising separate conveyor members mounted on a rotary drive system and each adapted to receive a row of bottles, said conveyor members being adjustable in number and position, a device for guiding said bottles, disposed straight under the said rectilinear path element, and provided with removable retaining members arranged equidistantly with sand pitch L and adapted to move at said speed V in a direction parallel to the direction of translation of said conveyor and a plurality of selecting devices disposed, in relation to the direction of travel of said conveyor, upstream of the said guiding device, said selecting devices being provided with removable stop members arranged equidistantly, the stop members of each selecting device being arranged with a pitch la, lb, lc, etc., and adapted to move at a speed etc., said stop members being further adapted to be inserted between two of said bottles so that said bottles travel at said speed va, vb, etc., and are distributed over the conveyor into separate homogenous groups each having a predetermined number of bottles contacting one another, whereas said retaining means are adapted to engage said groups of bottles so that said groups travel at said speed V, said guiding device and each one of said selecting devices comprising two vertical parallel endless chains driven by two pinions keyed on a common driving shaft, the aforesaid retaining end stop members being carried on a base member mounted rotatably on a cross-member about a horizontal axis, said cross-member interconnecting said chains and being secured to said chains at both its ends.
7. Device according to claim 6, wherein said base member is provided with a fork-shaped element co-operating with a guiding bar arranged in parallel relationship to the said cross-member and secured at its ends to the said chains downstream of the said cross-member in the direction of translation of the chains.
References Cited UNITED STATES PATENTS Re. 25,852 9/1965 Nigrelli et al. 53-159 3,194,382 7/1965 Nigrelli et a1 l9834 2,296,201 9/1942 Carter 198-76 EVON C. BLUNK, Primary Examiner D. D. WATTS, Assistant Examiner