AU588877B2 - Combination weigher - Google Patents

Description

DESCRIPTION COMBINATORIAL WEIGHING SYSTEM Techincal Field

The present invention relates to a combinatorial weighing system and, more particularly, to a combina¬ torial weighing system which operates by distributing articles to be weighed to a plurality of weighing machines, combining the weights measured by the respec¬ tive weighing machines to select an optimum added weight combination within a prescribed allowable error range, discharging the articles from the weighing machines selected to give the optimum weight combina¬ tion, and collecting and conveying the discharged arti¬ cles to a packaging unit. Background Art

In a circulation market such as a supermarket, as is well known in the art, there appear on the market many kinds of numerous commodities, the packaged ones of which, for example, are labelled for sale to indi- cate their measured weights.

The weights of those various and numerous commodi¬ ties or articles should naturally be measured fully automatically and precisely. For these measurements, a variety of the so-called "combinatorial weighing sys- terns" combining the theories of probability and statis¬ tics and the arithmetic function of a microcomputer having highly progressed in recent years are developed and adopted widely in the circulation market. Fig. 5 is a schematic side elevation showing the combinatorial weighing system, which will be described in the following with reference to Fig. 5.

The combinatorial weighing system 1 is constructed of: a distributive or dispersive supply unit 3 composed of a distributive or dispersive table 4 arranged above the center of an upper frame 2 and a plurality of radial supply troughs 6 arranged in a circular pattern around the dispersive table 4; weighing heads 5 having a plurality of weighing machines composed of a plurali¬ ty of article pooling hoppers 7 arranged in a circular pattern below the respective leading ends of the radial troughs 6 , a plurality of weighing hoppers 9 arranged below the article pooling hoppers 7, respectively, and a plurality of load cells 8 supporting the weighing hoppers 9, respectively; a collection unit composed of a collection chute 12 arranged below the weighing hop¬ pers 9, and a timing hopper 13 arranged at the lower end of the collection chute 12; and a hopper actuating unit 11' arranged on the lower side of the upper frame 2 for actuating those individual hoppers .

In the combinatorial weighing system thus con¬ structed, the articles to be weighed or commodities are supplied onto the dispersive table 4. The commodities are then distributed or dispersed as evenly as possible to the outer circumference of the dispersive table 4 by the three-dimentional vibrations of the table 4 until they are supplied to the radial troughs 6. The com- modifies are then carried to the leading ends of the radial troughs 6 by the radial vibrations of the troughs 6 until they are charged onto the respectively corresponding article pooling hoppers 9 and further onto the respectively corresponding weighing hoppers 9. The load cells 8 of the weighing machines respectively supporting the weighing hoppers 9 charged with the commodities send signals indicating the weights of the charged commodities to a not-shown control unit com- posed of a microcomputer or the like. The not-shown control unit performs the combinatorial weighing process based on the weight signals coming from the respective weighing machines to select an optimum added weight combination which is equal to or closest to a target weight within the prescribed allowable error range, and controls the hopper actuating unit 11' thereby to open the covers 91 of the weighing hoppers 9 of the weighing machines in the combination selected. Thus, when the covers of the weighing hoppers of the weighing machines selected in the optimum combination are opened, the commodities are allowed to drop from the respective weighing hoppers 9 into the underlying collection chute 12 until they are conveyed through the timing hopper 13 to a packaging unit or the like for a subsequent step. In this meanwhile, the weighing hop¬ pers 9 having been selected in the optimum combination to discharge the commodities are recharged with new commodities when the covers of the article pooling hoppers 7 are opened by the hopper actuating unit 11 ' under the control of the control unit.

In this combinatorial weighing system 1, the flow of the commodities to be supplied to the center of the dispersive supply unit 3 and discharged from the lower¬ most timing hopper 13 to the subsequent step comprises the steps of dispersing the commodities circumferen¬ tially of the dispersive table 4 to the respective weighing heads 5, combinatorially weighing the dis- persed commodities circumferentially by the respective weighing hoppers 9, and collecting the weighed com¬ modities and discharging the same. Thus, the com¬ modities are subjected in the horizontal direction to the concentration, dispersion and collection and in the vertical direction to the downward slide by the gravity.

As a result, the commodities passing through the individual mechanisms are subjected to the horizontal distribution and collection and to the vertical sliding drop.

As shown, the combinatorial weighing system 1 has its radial troughs 6, article pooling hoppers 7 and weighing hoppers 9 arranged in the circular patterns and its actuating unit 11' arranged at the center, and the pooling hoppers 7 and the weighing hoppers 9 are equipped with not only link mechanisms for the covers 91 but also detectors, electromagnetic actuating units and so on. This imposes restrictions on reduction in the diametrical extension of the weighing system 1 so that the overall diameter of the weighing system 1 cannot but be enlarged. In order to effect a sliding speed exceeding the relative friction between the com- modifies and the respective mechanisms of the system, these individual mechanisms have to be slanted consid¬ erably highly. In order that especially the slanting angle of the collection chute 12 for collecting the commodities , which have been selected for the combi- natorial weighing process and discharged from the indi¬ vidual weighing hoppers 9, to the timing hopper 13 or the subsequent packaging step may be held at a pre¬ scribed value, the collection chute 12 must be designed to have a remarkably large size, as shown. For this design, as shown in Fig. 5, the combi¬ natorial weighing system 1 has its center of gravity raised because the collection chute 12 disposed in the lower position is large-sized although its individual mechanisms are concentrated in the upper portion. As a result, the weighing system 1 rising above the pack¬ aging unit is encountered by a difficulty that it is highly instable. Moreover, the lower collection chute 12 has to be large-sized so that the weighing system 1 is accompanied by serious troubles in its maintenance and inspection.

Notwithstanding an earnest desire of processing the combinatorial weighing system 1 promptly, moreover, the speed dominating the prompt processing is limited by the aforementioned sliding drop of the commodities. If the timings at which the respective covers of the pooling hoppers 7 and weighing hoppers 9 are opened or closed are accelerated to the extremities of cycles so as to retain the allowable dropping speed, there arises a defect that the individual cycles of the commodities approaching are entangled below the collection chute 12. In the vicinity of the timing hopper, moreover, the commodities collide against one another to invite a diadvantage that butter peanut, for example, is broken to drop its market value.

In view of these, on the contrary, the collection chute 12 is equipped with means for dropping the sliding speed, such as a stopper or a shutter, which in turn raises another difficulty that the speediness of the combinatorial weighing system 1 is degraded. If the slanting angle of the collection chute 12 so as to descend the center of gravity, on the other hand, this leads to another disadvantage that the commodities are not allowed to slide downward smoothly on the collec¬ tion chute 12. Disclosure of Invention

An object of the present invention is to provide an excellent combinatorial weighing system which has its height reduced in its entirety to drop its center of gravity, which can facilitate not only its construc¬ tion and installation but also its maintenance and inspection without deteriorating its combinatorially weighing function and which can be constructed and run at a low cost so that it can benefit the weighing technical field in the circulation industry.

Another object of the present invention is to provide an excellent combinatorial weighing system which is enabled to avoid mutual collisions of the commodities and to shorten the time period required for collecting the commodities in each combinatorial selec¬ ting and discharging cycle by forcibly collecting the commodities having been combinatorially selected and discharged.

Still another object of the present invention is to provide an excellent combinatorial weighing system which is enabled to avoid the mutual collisions of the commodities and to shorten the time period required for collecting the commodities in each combinatorial selec¬ ting and discharging cycle by pooling or storing a plurality of batches of the commodities, which have been combinatorially selected and discharged, upon each combinatorial selection and discharge in the course to a packing step and by forcibly collecting the com¬ modities immediately before they are discharged to the packaging step.

According to the present invention, there is pro- vided a combinatorial weighing system comprising: a dispersive supply unit for dispersively supplying arti¬ cles to be weighed; and a plurality of weighing heads arranged below said dispersive supply unit and each having a hopper, wherein the improvement comprises: a collection unit including a plurality of collection means arranged below said weighing heads, respectively, and having their outer ends opened to face the hoppers of said weighing heads, respectively; a collection hopper connected to the inner end of said collection unit; and an actuating unit for synchronously actuating said collection unit.

Other objects and features of the present inven- tion will become apparent from the following descrip¬ tion. Brief Description of Drawings

In Figs. 1 to 4 showing one embodiment of a combi¬ natorial weighing system according to the present in- vention:

Fig. 1 is a sectional view showing an essential portion of the system of the present invention;

Fig. 2 is a top plan view showing an example of the arrangement of collection conveyors to be used in the system of the present invention;

Fig. 3 is an explanatory view showing an essential portion of one of the collection conveyors; and

Fig. 4 is a schematic side elevation showing the whole structure of the system of the present invention. Fig. 5 is a schematic side elevation showing the whole structure of the combinatorial weighing system used in the prior art. Best Mode for Carrying out the Invention Next, the present invention will be described in detail in connection with the embodiment thereof with reference to the accompanying drawings.

Fig. 1 is a partially sectional view showing the embodiment of the combinatorial weighing system ac¬ cording to the present invention; Fig. 2 is, a top plan view showing an example of the arrangement of collec¬ tion conveyors acting as collection means to be used in the system of the present invention; Fig. 3 is an explanatory view showing an essential portion of one of the collection conveyors; and Fig. 4 is a schematic side elevation showing the whole structure of the sys¬ tem of the present invention. As shown in Fig. 4, a combinatorial weighing system 100 is constructed of: a distributive or dispersive supply unit 3 composed of a distributive or dispersive table 4 arranged above an upper frame 2, and a plurality of radial supply troughs 6 arranged in a circular pattern around the dispersive table 4; and weighing heads 5 composed of a plurality of article pooling hoppers 5 arranged below the radial troughs 6, respectively, and a plurality of weighing machines 80 arranged below the article pooling hoppers 7, respectively. The dispersive table 4 is supported on the center of the upper surface of the upper frame 2 through an electromagnetic vibrator 14, which is opera¬ tive to vibrate in the circumferential direction, to disperse articles to be weighed or commodities charged onto its upper surface thereby to supply the dispersed commodities to the radial troughs 6, respectively. The radial troughs 6 are supported by electromagnetic vi¬ brators 15, respectively, to supply the commodities from the dispersive table 4 to their leading ends and further to the corresponding article pooling hoppers 7 , respectively. The individual article pooling hoppers 7 release and supply the articles supplied from the re¬ spective radial troughs 6 to the corresponding weighing machines 80. Each of these weighing machines 80 is composed of a weighing hopper 9 and a load cell 8 attached to the corresponding one of later-described hopper actuating units 11 and supporting the weighing hopper 9. Each hopper actuating unit 11 is attached to the lower side of the aforementioned upper frame 2 and is controlled by a control unit composed of a not-shown microcomputer to actuate corresponding link mechanisms 92 and 72 thereby to open or close the covers 91 and 71 of the corresponding weighing hopper 9 and article pooling hopper 7, respectively. Since the structure thus far described is substan¬ tially similar to that of the prior art shown in Fig. 5, the detail description of the combinatorial weighing system 1 will be omitted here.

Generally denoted by reference numeral 120 is a collection unit which includes collection means charac¬ terizing the present invention. More specifically, the collection unit 120 is composed of: a plurality of screw conveyors 121 acting as collection means arranged radially to correspond to the weighing hoppers 9, re¬ spectively; a plurality of guide hoppers 17 which have their lower ends fitted in the respective outer ends of the screw conveyors 121 and their upper ends opened toward the weighing hoppers 9, respectively; a collec¬ tion hopper 19 connected to all the inner ends of the screw conveyors 121; a chute connected to the lower end of the collection hopper 19; and a conveyor actuating unit 200 for actuating the screw conveyors 121. Each screw conveyor 121 is constructed of: a cyl¬ indrical casing 122 arranged generally in a horizontal position and having its inner end connected to" the collection hopper 19; a spindle 20 arranged in the casing 122 and borne rotatably by bearings 121a and 121b; and a screw 21 formed integrally with the spindle 20 to have a prescribed pitch. Incidentally, the bearing 121b bearing the inner end of the spindle 20 is desirably protected by a suitable seal mechanism.

The conveyor actuating unit 200 is composed of: an electric motor 23 mounted on the center of the lower side of the upper frame 2; a sun gear 24 fixed on the drive shaft 231 of the motor 23; and a plurality of bevel gears 22 fixed on the respective inner ends of the spindles 20 of the screw conveyors 121 while re- spectively meshing with the sun gear 24.

In the collection unit 120 thus constructed, the eight-head screw conveyors 121 are arranged radially and equi-angularly spaced in the circumferential direc- tion, as better seen in a top plan view from Fig. 2.

The respective spindles 20 of the screw conveyors 121 are turned synchronously and at an equal speed by the single motor 23 through the bevel gears 22 and the sun gear 24 so that the spaces between each adjacent two pitches of the respective screws 21 of the screw conveyors 121 are fed synchronously inward from the outside for all the screw conveyors 121. As a result, commodities 25, which have been weighed to the optimum combination and discharged from the weighing hoppers 9, are separated from one another between the pitches of the screws 21 and then introduced precisely either in adjoining phases or. in phases spaced by several pitches depending^* upon the selected combination into the col- lection hopper 19 while being freed from any mutual mixture even they are adjacent to one another.

This limits the commodities 25, which are dis¬ charged into the central collection hopper 19 by the respective screw conveyors 121, to those which have been selected to that optimum combination and dis¬ charged from the weighing hoppers 9.

The operations of the combinatorial weighing sys¬ tem thus constructed according to the present embodi¬ ment will be described in the following. When the combinatorial weighing system 100 is run into its operative state, all the mechanisms are brought into their operative states in accordance with the program. Then, the commodities such as not-shown butter peanut are dropped and supplied as continuously as possible to the dispersive table 4 which is being vibrated three-dimentionally by the vibrator 14. By the dispersive table 4, the individual commodities are supplied in averaged amounts as much as possible to the surrounding radial troughs 6, respectively. The com¬ modities thus supplied to the respective radial troughs 6 are dropped into the respective article pooling hop¬ pers 7 from the leading ends of the corresponding radial troughs 6 being vibrated by the electromagnetic vibrators 15 until they are dropped and supplied like the mode of the prior art to the respective weighing hoppers 9 of the weighing machines 80 through the covers 71 which are to be opened or closed through the link mechanisms by the hopper actuating units 11. The weights of the commodities thus dropped into the weighing hoppers 9 are measured by the actions of the load cells 8, which in turn send their respective measurement signals to the control unit composed of the microcomputer, as has been described hereinbefore. The control unit conducts the combinatorial weighing process based upon the measurement signals to select an optimum added weight combination which is equal to or closest to a target weight within a prescribed allow- able error range, and controls the hopper actuating units 11 to open the covers 91 of the weighing hoppers 9 of the weighing machines 80 of the selected combina¬ tion. The commodities 25 in the weighing hoppers 9 are dropped into the corresponding guide hoppers 17 of the screw conveyors 121 when the weighing hoppers 9 have their covers 91 opened by the hopper actuating units 11. When the covers 71 of the article pooling hoppers

7 corresponding to the weighing hoppers 9 having their covers 91 opened are opened, the process of dropping the commodities in the pooling hoppers 7 into the corresponding weighing hoppers 9 is similar to that of the prior art mode.

Thus, the commodities having been discharged from the weighing hoppers 9 of the weighing machines 80 selected to the optimum added weight combination as a result of the combinatorial weighing process are sup- plied to the inside of the casing 122 by the guide hoppers 17 fitted in the outer ends of the screw con¬ veyors 121 so that they are supplied to the collection hopper 19 positioned at the center by the screws 21. In this case, the commodities 25 selected to the opti- mum weight combination are present in the spaces be¬ tween the pitches of the screws 21 while being freed from being mixed into the leading or trailing space. In the phase for which the optimum weight combination has never been selected on and before the preceding operation, on the other hand, empty spaces are present between the pitches of the screws 21.

On the other hand, those commodities 25 having been selected to the optimum weight combination, which are present in the screws 21 of the individual screw conveyors 121 arranged radially, are discharged syn¬ chronously into the central collection hopper 19 by the synchronously turning screws 21, respectively, until they are supplied to the packaging unit for the subse¬ quent step through the chute 18.

In this meanwhile, nothing but the commodities 25 selected to the optimum weight combination has to be discharged by only one step to the central collection hopper 19. Hence, the selected commodities 25 are discharged exclusively from the screw conveyors 121 and 121 having once accommodated them but not from the remaining screw conveyors 121 having the empty spaces between the pitches. This causes only the commodities having been precisely subjected to the combinatorial weighing process to be discharged.

As has been described hereinbefore, according to the present invention, the combinatorial weighing sys¬ tem has its collection means arranged below the weighing heads, respectively, for forcibly collecting the commodities having been combinatorially selected and discharged, so that it can be constructed to have a lower overall height. Inasmuch as this, the combina¬ torial weighing system has its center of gravity greatly lowered to provide an excellent effect that the system can be stabilized to have its measurements less influenced by the disturbances caused by the un¬ necessary vibrations while it is being run. Another excellent effect is to facilitate not only the instal¬ lation and assemblage but also the maintenance and inspection of the system. An additional effect is that the cost of not only the initial cost but also the maintenance cost can be dropped.

Moreover, since the system of the present inven¬ tion has its height reduced and its center of gravity dropped and is made compact, as has been described hereinbefore, it will not pick up the disturbances, even if the weighing unit such as the load cells is small-sized, to provide a further effect that the weighing accuracy can be improved. A further effect is that the excellent function of the system of having the precision despite of the compact structure can be better improved together with the speedup of the system.

In the system of the present invention, moreover, the flow of the commodities passing through the indi¬ vidual mechanisms of the system follows the concentra- tion, dispersion and collection, but the vertical sliding drop is omitted at least in the lower portion of the system. As a result, the sliding drop for those commodities by the gravity, which are to be conveyed to the subsequent step instantly after they have been weighed, is largely reduced so that the commodities can be prevented from colliding against one another to provide a further effect to prevent the market value of the commodities from being dropped by the damage or the like .

In the system of the present invention, the com¬ modities having been discharged by the weighing heads are not mixed with one another because they are sepa- rated without fail from their leading or trailing ones by using not the sliding drop but collection means such as the screw conveyors, to provide a further excellent effect that the weights of the commodities to be packaged can be measured reliably and precisely. Since the commodities selected are isolated from one another, moreover, they can conveyed at a high speed indepen¬ dently of the sliding drop due to the gravity to provide a further excellent effect that the efficiency of the combinatorial weighing system can be highly improved.

Since the transfer of the commodities caused by the sliding drop after the combinatorial weighing process to the subsequent step is eliminated, further¬ more, an excellent effect is exhibited in improvements in the flexibility or wide use of the combinatorial weighing system. For example, it is needless, as is different from the prior art, to prepare different systems for the commodities, respectively, while con¬ sidering the frictions resulting from the collection chute when the commodities of different kinds are to be weighed, and to eliminate the inconvenience that the system of the present invention cannot be elastically used for all the commodities. As a result, the system can be freely applied to any kind of commodities.

Although the present invention has been described in connection with the shown embodiment, it is quite natural that the present invention should not be limited to that embodiment. For example, the screw conveyors constructing the collection unit may be re¬ placed by walking beam conveyors, toothed belt con¬ veyors or pneumatic collection means. Although the collection unit may be set in the horizontal position as in the embodiment, moreover, it may be slanted uphill or downhill inward. Thus, it is possible to make free designs such as to hold the collection unit in an optimum position for the commodities or to make the overall height of the system as small as possible. It also falls within the range of design change to apply such a Teflon lining to the inner wall of the collection unit as to ensure smooth conveyance of the commodities. As the case may be, a variety of modes can be adopted including the mode of providing the collection unit with a vibrator or the mode of changing the slanting angle freely in a rocking manner.

Furthermore, each collection unit can be construc¬ ted by removing the screw 21 disposed in the screw conveyor 121 and by arranging air blow means in the vicinity of the corresponding guide hopper 17 so that the commodities dropping from the corresponding weighing hopper 9 may be abruptly blown by the air to the collection hopper 19. If the collection unit is made to have a smaller lead pitch or radius toward the center, moreover, the commodities can be discharged while being compressed, to provide a further effect that the packaging effi- ciency at the subsequent step can be enhanced. A staggered dump can be conducted depending upon the design by changing that lead pitch.

Depending upon the design, moreover, the package can be charged with the compressed commodities by such an elastic design of the pitch or the like of the screws of the collection unit that the packaging unit is directly connected to the central portion of the collection unit. Industrial Applicability The present invention can be applied not only to a combinatorial weighing system, in which the plural troughs for supplying the commodities to the weighing hoppers are arranged in the radial pattern, but also to a combinatorial weighing system of the type in which those troughs are arranged in a parallel pattern.

The present invention can also be applied to a combinatorial weighing system which can operate by temporarily pooling or storing the commodities having been weighed by weighing hoppers in article pooling hoppers, combining the weights of the commodities in the pooling hoppers to select the optimum weight combi¬ nation, and discharging the commodities from the pooling hoppers . The present invention can further be applied to weighing not only the solid articles such as butter peanut but also powdery or granular articles.

Claims (9)

CLAIMS :

1. A combinatorial weighing system comprising: a dispersive supply unit for dispersively supplying arti¬ cles to be weighed; and a plurality of weighing heads arranged below said dispersive supply unit and each having a hopper, wherein the improvement comprises : a collection unit including a plurality of collec¬ tion means arranged below said weighing heads, re- spectively, and having their outer ends opened to face the hoppers of said weighing heads, respectively; a collection hopper connected to the inner end of said collection unit; and an actuating unit for synchronously actuating said collection unit.

2. A combinatorial weighing system as set forth in Claim 1, wherein said collection unit includes a plu¬ rality of screw conveyors.

3. A combinatorial weighing system as set forth in Claim 1, wherein said collection unit includes a plu¬ rality of walking beam conveyors .

4. A combinatorial weighing system as set forth in Claim 1, wherein said collection unit includes a plu¬ rality of toothed belt conveyors.

5. A combinatorial weighing system as set forth in

Claim 1, wherein said conveyor actuating unit includes: a drive motor; a sun gear fixed on the drive shaft of said drive motor; and a plurality of gears respectively meshing with said sun gear and fixed on the respective drive shafts of the collection means of said collection unit.

6. A combinatorial weighing system as set forth in Claim 1, wherein said collection unit is arranged in a horizontal position.

7. A combinatorial weighing system as set forth in Claim 1 , wherein said collection unit is slanted inward.

8. A combinatorial weighing system as set forth in Claim 1, wherein said collection unit includes a plu¬ rality of pneumatic collection means.

9. A combinatorial weighing system as set forth in Claim 1, wherein each of said collection means is operative to store a plurality of batches of com¬ modities having been combinatorially selected and dis¬ charged.