Patent Publication Number: US-2022234321-A1

Title: Supply apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2021-008965, filed Jan. 22, 2021. The contents of that application are incorporated by reference herein in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a supply apparatus. 
     BACKGROUND ART 
     In the prior art, apparatuses that make, pack, and seal boxes are known, as is disclosed in Japanese Laid-open Patent Publication No. 2019-147582. It is conceivable that such an apparatus would be equipped with a supply apparatus that supplies a plurality of stacked corrugated cardboard sheets to a box-making section. In some cases, supply apparatuses include a photoelectric sensor for sensing the total quantity of the plurality of stacked corrugated cardboard sheets. 
     BRIEF SUMMARY 
     When an expensive sensor is employed as the photoelectric sensor included in the supply apparatus, the cost of manufacturing the supply apparatus may increase. 
     It is an object of the present invention to provide, at low cost, a supply apparatus that can estimate the total quantity of the plurality of stacked corrugated cardboard sheets. 
     A supply apparatus according to a first aspect of the present invention is a supply apparatus that supplies corrugated cardboard sheets to a supply position in a box-making apparatus that opens folded corrugated cardboard sheets and makes boxes. The supply apparatus comprises a conveying unit, a drive unit, and a control unit. The conveying unit conveys a plurality of the corrugated cardboard sheets to the supply position with the corrugated cardboard sheets stacked. The drive unit drives the conveying unit. The control unit estimates the total quantity of the plurality of stacked corrugated cardboard sheets on a conveying surface of the conveying unit. The control unit acquires a value pertaining to the drive force of the drive unit when the drive unit drives the conveying unit, and estimates the total quantity of the plurality of stacked corrugated cardboard sheets on the basis of the acquired value. 
     The inventors associated with the present application have discovered that the total quantity of the plurality of stacked corrugated cardboard sheets on the conveying surface of the conveying unit can be estimated on the basis of the value pertaining to the drive force of the drive unit driving the conveying unit. 
     In the supply apparatus according to the first aspect, the control unit estimates the total quantity of the plurality of stacked corrugated cardboard sheets on the basis of the value pertaining to the drive force of the drive unit. Therefore, in the supply apparatus according to the first aspect, the total quantity of the plurality of stacked corrugated cardboard sheets can be estimated by means of an inexpensive configuration. 
     A supply apparatus according to a second aspect of the present invention is a supply apparatus that supplies corrugated cardboard sheets to a supply position in a box-making apparatus that opens folded corrugated cardboard sheets and makes boxes. The supply apparatus comprises a weighing unit and a control unit. The weighing unit measures the weight of the plurality of stacked corrugated cardboard sheets. The control unit estimates the total quantity of the plurality of stacked corrugated cardboard sheets. The control unit estimates the total quantity of the plurality of stacked corrugated cardboard sheets on the basis of the value measured by the weighing unit. 
     In the supply apparatus according to the second aspect, the control unit estimates the total quantity of the plurality of stacked corrugated cardboard sheets on the basis of the value measured by the weighing unit. Therefore, in the supply apparatus according to the second aspect, the total quantity of the plurality of stacked corrugated cardboard sheets can be estimated by means of an inexpensive configuration. 
     A supply apparatus according to a third aspect is the supply apparatus according to the first or second aspect, wherein the control unit, on the basis of the estimated total quantity of the plurality of corrugated cardboard sheets, performs a process relating to automatically or manually replenishing the corrugated cardboard sheets. 
     In the supply apparatus according to the third aspect, a process relating to manually replenishing the corrugated cardboard sheets is performed when, for example, the total quantity of corrugated cardboard sheets is less than a predetermined value. 
     In the supply apparatus according to the third aspect, the operator of the supply apparatus will not have to monitor the supply apparatus any more than necessary. Therefore, with the supply apparatus according to the third aspect, operator labor is reduced. 
     A supply apparatus according to a fourth aspect, is the supply apparatus according to the third aspect, further comprising a notification unit. The notification unit issues a notification of information prompting replenishing of the corrugated cardboard sheets. The control unit performs, as said process, a process of causing the notification unit to issue a notification. 
     In the supply apparatus according to the fourth aspect, the operator of the supply apparatus will not have to monitor the supply apparatus any more than necessary. Therefore, with the supply apparatus according to the fourth aspect, operator labor is reduced. 
     A supply apparatus according to a fifth aspect is the supply apparatus according to the third aspect, wherein the control unit performs, as said process, a process of transmitting a signal to cause an action of automatically replenishing the corrugated cardboard sheets in the supply apparatus. 
     In the supply apparatus according to the fifth aspect, the control unit performs a process of transmitting a signal to cause an action of automatically replenishing the corrugated cardboard sheets in the supply apparatus as the process relating to automatically or manually replenishing the corrugated cardboard sheets. With this configuration, corrugated cardboard sheets are automatically replenished in the supply apparatus. Therefore, with the supply apparatus according to the fifth aspect, operator labor is reduced. 
     A supply apparatus according to a sixth aspect is the supply apparatus according to the first aspect, wherein the control unit estimates the total quantity of the plurality of stacked corrugated cardboard sheets on the basis of a relational expression between the value pertaining to the drive force of the drive unit and the total quantity of the plurality of stacked corrugated cardboard sheets. 
     A supply apparatus according to a seventh aspect is the supply apparatus according to any one of the first through sixth aspects, wherein the plurality of stacked corrugated cardboard sheets is placed on the conveying surface so as to be inclined relative to horizontal. The plurality of stacked corrugated cardboard sheets is conveyed while the lower ends of the plurality of corrugated cardboard sheets are in contact with the conveying surface. 
     With this configuration, dynamic friction is more accurately reflected in the value pertaining to the drive force of the drive unit. Therefore, with the supply apparatus according to the seventh aspect, the total quantity of the plurality of stacked corrugated cardboard sheets can be estimated with greater precision. 
     With an inexpensive configuration, the supply apparatus according to the present invention can estimate the total quantity of a plurality of stacked corrugated cardboard sheets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a box-packing system equipped with a supply apparatus; 
         FIG. 2  is a perspective view of the configuration of the box-packing system; 
         FIG. 3  is a perspective view of the flow of corrugated cardboard boxes and goods in the box-packing system; 
         FIG. 4  is a schematic side view of the box-packing system; 
         FIG. 5  is a schematic side view of the supply apparatus; 
         FIGS. 6A and 6B  are each a schematic side view of the supply apparatus; 
         FIG. 7  is a flow chart of the flow of actions performed in a supply process; 
         FIG. 8  is a perspective view of a supply apparatus according to a modification; 
         FIG. 9  is a block diagram of a box-packing system equipped with a supply apparatus according to a second embodiment; and 
         FIG. 10  is a schematic side view of a supply apparatus according to the prior art. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A supply apparatus  10  according to one embodiment of the present disclosure is described below with reference to the drawings. Unnecessarily detailed descriptions are sometimes omitted. For example, descriptions of matters already known and duplicate descriptions of configurations that are substantially the same are sometimes omitted. This is to avoid unnecessary redundancy in the following descriptions and to facilitate comprehension for those skilled in the art. 
     The following embodiments are specific examples and are not intended to limit the technical range of the invention; the embodiments can be changed as appropriate within a range that does not deviate from the scope of the invention. 
     The following descriptions sometimes use the expressions “upper,” “lower,” “front” (front surface), “rear” (back surface), “left,” “right,” etc., for the sake of convenience in order to describe positional relationships and orientations. Unless otherwise specified, the directions indicated by these expressions are congruous with the directions of the arrows shown in the drawings. 
     Furthermore, the following descriptions sometimes use the expressions “parallel,” “orthogonal,” “perpendicular,” “horizontal,” “vertical,” etc., but these expressions are not limited to cases in relationships such as parallel, orthogonal, perpendicular, horizontal, and vertical in the strict sense; this includes cases in relationships such as substantially parallel, orthogonal, perpendicular, horizontal, and vertical within a range in which the obtained results do not change significantly. 
     (1) Overall Configuration 
       FIG. 1  is a block diagram of a box-packing system  1  equipped with a supply apparatus  10  according to one embodiment of the present invention. The box-packing system  1  according to the present embodiment is a system for forming corrugated cardboard boxes B from corrugated cardboard sheets Z and packing a fixed number of goods G into the formed corrugated cardboard boxes B. This example is not provided by way of limitation, but in the box-packing system  1  according to the present embodiment, at most ten corrugated cardboard boxes B are packed every minute. In the present embodiment, the actions of the parts of the box-packing system  1  are controlled by a controller  40  (equivalent to the control unit described in the claims), as shown in  FIG. 1 . 
       FIG. 2  is a perspective view of the configuration of the box-packing system  1  equipped with the supply apparatus  10  according to one embodiment of the present invention, and  FIG. 3  is a perspective view of the flow of corrugated cardboard boxes B and goods G in the box-packing system  1 . 
     The box-packing system  1  packs corrugated cardboard boxes B with multiple layers of bagged goods (goods G), e.g., snack food, in fixed quantities and in an orderly arrangement, as shown in  FIGS. 2 and 3 . 
     In the box-packing system  1 , a cardboard-handling area DHA and a goods-handling area GHA are independently and separably connected to each other, as shown in  FIGS. 2 and 3 . The cardboard-handling area DHA includes three steps: a supply step P 1 , a box-making step P 2 , and a box-packing step P 4 . The goods-handling area GHA includes a goods-arranging step P 3 . 
     In other words, due to the cardboard-handling area DHA and the goods-handling area GHA being connected in the box-packing system  1 , four steps are aligned: the supply step P 1 , the box-making step P 2 , the goods-arranging step P 3 , and the box-packing step P 4 . 
     The supply step P 1  is a process in which a corrugated cardboard sheet Z is conveyed to a predetermined supply position SP, and the supply step P 1  is configured from the supply apparatus  10 . 
     The box-making step P 2  is a process in which the corrugated cardboard sheet Z is assembled into a corrugated cardboard box B and the resulting box is conveyed to a box-packing position, and is carried out by a box-making section  12  (equivalent to the box-making apparatus described in the claims), a first orientation-changing section  13 , and a box-downward-conveying unit  14 . 
     The goods-arranging step P 3  is a process in which goods G supplied from an upstream step are conveyed to a predetermined position, a fixed number of goods G are arrayed so that adjacent goods partially stack on top of each other, and the goods are conveyed to a box-packing position. The goods-arranging step P 3  is carried out by a goods-convey-in section  21 , a goods-arranging section  22 , and a goods-inserting section  23 . 
     The box-packing step P 4  is a process in which the corrugated cardboard box B conveyed from the box-making step P 2  is packed with a fixed number of goods G that have been arrayed in the goods-arranging step P 3 , and the box is closed and conveyed to a box-ejecting position. The box-packing step P 4  is carried out by a goods-receiving section  31 , a second orientation-changing section  32 , and a box-sealing section  33 . 
     The box-making step P 2 , the goods-arranging step P 3 , and the box-packing step P 4  are already known processes, and shall therefore not be described here. The supply step P 1  is described in detail below. 
     (2) Actions of Sections in Supply Step P 1   
     The supply step P 1  is described with reference to  FIGS. 4 and 5 . As described above, the supply step P 1  is a step in which a corrugated cardboard sheet Z is supplied to a predetermined supply position SP. The supply step P 1  is realized by the supply apparatus  10  acting under control by the controller  40  (see  FIG. 1 ). 
       FIG. 4  is a schematic side view of the box-packing system  1  equipped with the supply apparatus  10 .  FIG. 5  is an enlarged view of the area encircled by the single-dash lines in  FIG. 4 . In  FIG. 5 , a frame  20  of the box-packing system  1  is only partially depicted in order to make the description easier to comprehend. A plurality of corrugated cardboard sheets Z are placed in a stacked state on a conveying unit  50  of the supply apparatus  10  as shown in  FIGS. 4 and 5 . More specifically, a plurality of corrugated cardboard sheets Z oriented upright so that sheet surfaces ZS (outer surfaces of the corrugated cardboard sheets Z) are inclined relative to horizontal are placed in a stacked state on the conveying unit  50 . In addition, lower ends of the corrugated cardboard sheets Z constituting the plurality of stacked corrugated cardboard sheets Z is in contact with a conveying surface  53   a  as shown in  FIGS. 4 and 5 . In short, a plurality of stacked corrugated cardboard sheets Z is vertically placed in a forward incline on the conveying unit  50 . In the present embodiment, the plurality of stacked corrugated cardboard sheets Z vertically placed in a forward incline are sometimes referred to as the “plurality of stacked corrugated cardboard sheets Z.” 
     The supply apparatus  10  is provided with the conveying unit  50 , a drive unit  60 , and a notification unit  70 , as shown in  FIG. 5 . In the supply apparatus  10 , the drive unit  60  drives the conveying unit  50 , whereby the plurality of stacked corrugated cardboard sheets Z is conveyed. 
     (2-1) Conveying Unit  50   
     The conveying unit  50  is a conveyor that conveys the plurality of stacked corrugated cardboard sheets Z to the supply position SP. The conveying unit  50  according to the present embodiment also serves as an accumulation unit for accumulating the corrugated cardboard sheets Z supplied to the box-packing system  1 . 
     The conveying unit  50  is a belt conveyor including a drive roller  51 , a driven roller  52 , and an endless belt  53 , as shown in  FIG. 5 . The belt  53  is wound around the drive roller  51  and the driven roller  52 . The drive roller  51  rotates by being driven by the drive unit  60 . By rotating, the drive roller  51  drives the belt  53 . The plurality of corrugated cardboard sheets Z placed on the conveying surface  53   a  of the belt  53  are conveyed due to the belt  53  being driven. The conveying unit  50  conveys the plurality of corrugated cardboard sheets Z in a conveying direction D 1  (see the arrows in  FIGS. 4 and 5 ). An inclined surface  111  is present in the conveying direction D 1  (see  FIG. 5 ). The inclined surface  111  is a surface that is tilted relative to vertical and is disposed such that the upper side is forward (a surface tilted forward), as shown in  FIG. 5 . The movement of the plurality of corrugated cardboard sheets Z in the conveying direction D 1  is regulated by the inclined surface  111 . Therefore, when the belt  53  is driven and conveying force in the conveying direction D 1  acts on the lower parts of the plurality of corrugated cardboard sheets Z, the plurality of corrugated cardboard sheets Z stack on top of each other on the conveying surface  53   a.  Of the plurality of stacked corrugated cardboard sheets Z, several corrugated cardboard sheets Z positioned at the leading side in the conveying direction D 1  reach the supply position SP (refer to the area encircled by the double-dash lines shown in  FIG. 5 ) at this time. The several corrugated cardboard sheets Z that have reached the supply position SP are fed out to the box-making section  12  by a sheet-moving unit  118 . 
     (2-1-1) Sheet-Moving Unit  118   
     The sheet-moving unit  118  of the box-packing system  1  shall now be described. The sheet-moving unit  118  is an apparatus that takes one corrugated cardboard sheet Z from the plurality of stacked corrugated cardboard sheets Z accumulated on the conveying unit  50  and supplies that one corrugated cardboard sheet Z to the box-making section  12  (see  FIG. 3 ). For example, the sheet-moving unit  118  uses a suction cup (not shown) to hold the corrugated cardboard sheet Z accumulated on the conveying unit  50  and feeds the corrugated cardboard sheet Z out to the box-making section  12  by moving the suction cup with the sheet held thereon. Specifically, of the plurality of stacked corrugated cardboard sheets Z accumulated on the conveying unit  50 , the forwardmost corrugated cardboard sheet Z in the conveying direction D 1  is held and fed out by the sheet-moving unit  118  to the box-making section  12  located upward and forward. 
     For convenience of description below, of the plurality of stacked corrugated cardboard sheets Z, the corrugated cardboard sheet Z located at the forwardmost position in the conveying direction D 1  is sometimes referred to as the “leading corrugated cardboard sheet ZT.” In addition, the action performed by the  118  of feeding one corrugated cardboard sheet Z out to the box-making section  12  is sometimes referred to below as the “feed-out action.” 
     As described above, in the box-packing system  1  according to the present embodiment, at most ten corrugated cardboard boxes B are packed every minute. In other words, the box-packing system  1  can be set so as to operate at the setting “10 boxes/min.” When the box-packing system  1  is set so as to operate at the setting “10 boxes/min,” the sheet-moving unit  118  feeds one corrugated cardboard sheet Z out to the box-making section  12  every six seconds. 
     In the supply step P 1  according to the present embodiment, the conveying unit  50  conveys a plurality of stacked corrugated cardboard sheets Z in the conveying direction D 1  with every three feed-out actions performed by the sheet-moving unit  118 . Information is provided in greater detail further below. 
     (2-2) Drive Unit  60   
     The drive unit  60  according to the present embodiment is a motor that drives the conveying unit  50 . Due to the drive unit  60  driving the conveying unit  50 , the corrugated cardboard sheets Z are conveyed to the supply position SP. 
     The drive unit  60  according to the present embodiment performs an intermittent operation in the supply step P 1 . Specifically, the drive unit  60  drives the conveying unit  50  for 1 second with every three feed-out actions performed by the sheet-moving unit  118 . In other words, the drive unit  60  stops the driving of the conveying unit  50  while the feed-out action is being performed by the sheet-moving unit  118  (for example, for 18 seconds), and drives the conveying unit  50  for 1 seconds when the sheet-moving unit  118  feeds out the third corrugated cardboard sheet Z. 
     Due to the drive unit  60  performing an intermittent operation as described above, the lower parts of the plurality of stacked corrugated cardboard sheets Z move in the conveying direction D 1  by a distance equal to the thickness of a number of corrugated cardboard sheets Z fed out by the sheet-moving unit  118  (see  FIG. 6A  and  FIG. 6B ). The leading corrugated cardboard sheet ZT thereby comes into contact with the inclined surface  111  so as to lie along said surface (see  FIG. 6B ). An idling operation is performed by the drive unit  60  at this time. An idling operation is operation in which the drive unit  60  drives the conveying unit  50  while the leading corrugated cardboard sheet ZT is in contact with the inclined surface  111  so as to lie along said surface. In an idling operation, the drive roller  51 , the driven roller  52 , and the belt  53  remain idle while the plurality of stacked corrugated cardboard sheets Z rests on the conveying surface  53   a.  To summarize the above, in  1  second, the drive unit  60  according to the present embodiment moves the lower parts of a plurality of stacked corrugated cardboard sheets Z in the conveying direction D 1  and performs an idling operation. 
     The action of the box-packing system  1  in the supply step P 1  continues until the total quantity (remaining amount) of the plurality of stacked corrugated cardboard sheets Z carried on the conveying surface  53   a  is estimated by the controller  40  to be less than a predetermined value. The method by which the controller  40  estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z shall be described hereinafter. The controller  40  causes the notification unit  70  to issue a notification upon estimating that the total quantity of the plurality of stacked corrugated cardboard sheets Z is less than the predetermined value. 
     (2-3) Notification Unit  70   
     The notification unit  70  according to the present embodiment is a liquid crystal display  71  that can display a variety of information relating to the supply apparatus  10  (see  FIG. 4 ). The liquid crystal display  71  is not provided by way of limitation as to the configuration of the notification unit  70 ; the notification unit  70  may be an LED lamp, a speaker, etc. The liquid crystal display  71  serving as the notification unit  70  is electrically connected to the controller  40  by wire or wirelessly. The liquid crystal display  71  can therefore send and receive signals and a variety of information to and from the controller  40 . When a predetermined signal is sent from the controller  40 , the liquid crystal display  71  issues a notification of information prompting an operator of the supply apparatus  10  to replenish the corrugated cardboard sheets Z. For example, the liquid crystal display  71  displays warning text indicating the corrugated cardboard sheets Z need to be replenished as information prompting replenishment of the corrugated cardboard sheet Z. 
     (3) Controller  40   
     The configuration of the controller  40  according to the present embodiment shall now be described in detail. 
     The controller  40  controls the actions of the parts constituting the box-packing system  1  including the supply apparatus  10 , as shown in  FIG. 1 . 
     The controller  40  is electrically connected to the parts of the box-packing system  1  by wire or wirelessly so as to be capable of sending and receiving control signals, information, etc. The controller  40  is realized using a computer. The controller  40  is provided with a control computation device and a storage device. A processor such as a CPU or a GPU can be used as the control computation device. The control computation device reads a program stored in the storage device and performs a predetermined computation process in accordance with this program. Furthermore, the control computation device can, write a computation result into the storage device and read information stored in the storage device in accordance with the program. ROM, RAM, or another type of memory can be used as the storage device. The storage device stores programs for controlling the actions of the parts of the box-packing system  1 , communication protocols used when the box-packing system  1  communicates with other equipment, etc. In addition, the storage device stores a predetermined relational expression indicating a relationship between a value pertaining to the drive force of the drive unit  60  and the total quantity of the plurality of stacked corrugated cardboard sheets Z. 
       FIG. 1  shows a functional block realized by the control computation device. As shown in  FIG. 1 , the controller  40  has a function as a total quantity estimation unit  41 . The controller  40  performs a process relating to manual replenishment of the corrugated cardboard sheets Z on the basis of the total quantity of the corrugated cardboard sheets Z estimated by the function of the total quantity estimation unit  41 . For example, the controller  40  performs a process that causes the notification unit  70  to issue a notification of information prompting replenishment of the corrugated cardboard sheets Z. 
     (3-1) Total Quantity Estimation Unit  41   
     The total quantity estimation unit  41  is a functional unit that estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z on the basis of a value pertaining to the drive force of the drive unit  60 . 
     The inventors associated with the present application have discovered that the value pertaining to the drive force of the drive unit  60  has a correlation with the total quantity of the plurality of stacked corrugated cardboard sheets Z placed on the conveying surface  53   a  of the conveying unit  50 . In other words, the inventors associated with the present application have discovered that a predetermined relational expression holds between the value pertaining to the drive force of the drive unit  60  and the total quantity of the plurality of stacked corrugated cardboard sheets Z. From this matter, the inventors associated with the present application have discovered that the total quantity of the plurality of stacked corrugated cardboard sheets Z can be estimated on the basis of the value pertaining to the drive force of the drive unit  60 . Information is provided in greater detail further below. 
     (3-2) Method for Estimating Number of Plurality of Stacked Corrugated Cardboard Sheets Z 
     As a premise, it is assumed in the following description that the coefficient of dynamic friction between the belt  53  of the conveying unit  50  and the corrugated cardboard sheet Z is the same. In this example, a torque value is used as the value pertaining to the drive force of the drive unit  60  (a motor or the like). As described above, the controller  40  is electrically connected by wire or wirelessly to the parts constituting the box-packing system  1  so as to be able to send and receive control signals, information, etc., to and from said parts. Therefore, the controller  40  can acquire a torque value from the drive unit  60 . 
     As previously described, the supply apparatus  10  has a conveying unit  50 . When the conveying unit  50  carrying a plurality of stacked corrugated cardboard sheets Z is actuated at a constant velocity, a dynamic friction force R received by the conveying unit  50  changes depending on a perpendicular drag force N. It is assumed that the magnitude of the perpendicular drag force N changes according to the total quantity of the plurality of stacked corrugated cardboard sheets Z placed on the conveying unit  50 . This is because the weight of the plurality of stacked corrugated cardboard sheets Z changes according to the total quantity of the plurality of stacked corrugated cardboard sheets Z. From this it is assumed that when the conveying unit  50  is driven while the conveying velocity is kept constant, the dynamic friction force R changes depending on the total quantity of the plurality of stacked corrugated cardboard sheets Z. Specifically, it is assumed that the dynamic friction force R increases if the total quantity of the plurality of stacked corrugated cardboard sheets Z increases, and the dynamic friction force R decreases if the total quantity of the plurality of stacked corrugated cardboard sheets Z decreases. The change in the dynamic friction force R is reflected in the value (a torque value in this example) pertaining to the drive force of the drive unit  60 . In particular, the dynamic friction force R is accurately reflected in the torque value because the stacked corrugated cardboard sheets Z according to the present embodiment are in contact at the lower ends with the conveying surface  53   a.    
     Thus, there is a correlation between the torque value and the total quantity of the plurality of stacked corrugated cardboard sheets Z. Therefore, the total quantity estimation unit  41  can estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z by inputting the torque value acquired by the controller  40  into a predetermined estimation expression stored in the storage device. Specifically, the total quantity estimation unit  41  can estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z within an error range of about ±5 sheets. 
     To estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z, it is preferable to acquire a torque value that more accurately reflects the dynamic friction force R. Therefore, the controller  40  preferably acquires the torque value when the idling operation is performed. 
     (4) Overall Action in Supply Step P 1   
     (4-1) 
     The overall action performed in the supply step P 1  of the box-packing system  1  shall now be described using the flowchart shown in  FIG. 7 . The box-packing system  1  provided with the supply apparatus  10  performs the supply step P 1  with a flow such as is shown in steps S 1  to S 11  in  FIG. 7 . The flow of actions shown in  FIG. 7  is one example and can be changed as appropriate. For example, the order of the steps may be changed within a consistent range, some steps may be executed in parallel with other steps, and other steps may be newly added. 
     (4-2) 
     In step S 1 , the operator lays the plurality of stacked corrugated cardboard sheets Z on the conveying surface  53   a  by hand. For example, the plurality of stacked corrugated cardboard sheets Z is placed on the conveying surface  53   a  in a posture so as to lean against the inclined surface  111  (a posture such as is shown in  FIG. 6A ). 
     In step S 2 , the plurality of stacked corrugated cardboard sheets Z is conveyed by the conveying unit  50  in the conveying direction D 1 . As a consequence, the leading corrugated cardboard sheet ZT comes into contact with the inclined surface  111  so as to lie along the inclined surface  111  (see  FIG. 6B ). At this time, several corrugated cardboard sheets Z positioned at the leading side of the plurality of stacked corrugated cardboard sheets Z reach the supply position SP. 
     In step S 3 , the idling operation is performed. 
     In step S 4 , the sheet-moving unit  118  initiates a feed-out action. 
     In step S 5 , a plurality of (three in this example) corrugated cardboard sheets Z are fed out to the box-making section  12  by the feed-out action of the sheet-moving unit  118 . The plurality of stacked corrugated cardboard sheets Z is thereby inclined so as to be in a nearly horizontal posture in relation to the conveying surface  53   a.  Specifically, the plurality of stacked corrugated cardboard sheets Z assumes a posture similar to the posture in step S 1 . 
     In step S 6 , the drive unit  60  drives the conveying unit  50 . As a consequence, the leading corrugated cardboard sheet ZT comes into contact with the inclined surface  111  so as to lie along the inclined surface  111 . At this time, the plurality of stacked corrugated cardboard sheets Z assumes a posture similar to the posture in step S 2 . 
     In step S 7 , the idling operation is performed. 
     In step S 8 , the controller  40  estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z. When the total quantity of the plurality of stacked corrugated cardboard sheets Z is equal to or greater than a predetermined value in step S 8 , the action in the supply step P 1  returns to step S 4 . When the total quantity of the plurality of stacked corrugated cardboard sheets Z is less than the predetermined value in step S 8 , the action in the supply step P 1  advances to step S 9 . 
     In step S 9 , the notification unit  70  issues to the operator of the supply apparatus  10  a notification of information prompting the operator to replenish the corrugated cardboard sheets Z. 
     In step S 10 , the operator replenishes the corrugated cardboard sheets Z. When the controller  40  has detected in step S 10  that the corrugated cardboard sheets Z have been replenished, the action in the supply step P 1  returns to step S 2 . 
     In this manner, the box-packing system  1  equipped with the supply apparatus  10  performs the supply step P 1 . The actions described above continue until the operator inputs an operation stop command to the supply apparatus  10  or the box-packing system  1 . Alternatively, the actions described above continue until the number of corrugated cardboard sheets Z supplied to the box-packing system  1  reach a target supply number stored in advance in a predetermined storage area of the storage device. 
     (5) Characteristics 
     Apparatuses that make, pack, and seal boxes are known in the prior art, as is disclosed in Japanese Laid-open Patent Publication No. 2019-147582. Such apparatuses are assumed to be equipped with a supply apparatus that supplies a plurality of stacked corrugated cardboard sheets to a box-making section. In some cases, the supply apparatus includes a photoelectric sensor for sensing the total quantity of the plurality of stacked corrugated cardboard sheets. 
     When an expensive sensor is employed as the photoelectric sensor included in the supply apparatus, the cost of manufacturing the supply apparatus may increase. 
     An alternative option is for the total quantity of the plurality of stacked corrugated cardboard sheets to be sensed using an inexpensive photoelectric sensor. For example, the total quantity of the plurality of stacked corrugated cardboard sheets could be sensed by means of a configuration such as is shown in  FIG. 10 .  FIG. 10  is a schematic side view of a box-packing system  1 X comprising a supply apparatus  10 X according to the prior art. The supply apparatus  10 X is provided with a first sensor  91  and a second sensor  92  as photoelectric sensors. The supply apparatus  10 X detects that there is a large amount of corrugated cardboard sheets Z when the first sensor  91  and the second sensor  92  are shielded from light. The supply apparatus  10 X detects that the total quantity of corrugated cardboard sheets Z is small when the first sensor  91  is exposed to light and the second sensor  92  shielded from light. The supply apparatus  10 X detects that the total quantity of corrugated cardboard sheets Z is exceedingly small when the first sensor  91  and the second sensor  92  are both exposed to light. However, the remaining amount of corrugated cardboard sheets Z can only be detected in increments with the configuration of the supply apparatus  10 X. Therefore, it is difficult with the supply apparatus  10 X to perform an action of, for example, prompting (notifying) the operator at the proper timing to replenish the corrugated cardboard sheets Z. Regarding this point, it is conceivable that detection precision could be improved by increasing the number of photoelectric sensors installed, but such a measure may lead to an increase in the cost of manufacturing the supply apparatus. 
     (5-1) 
     The supply apparatus  10  according to the present embodiment is a supply apparatus  10  that supplies corrugated cardboard sheets Z to a supply position SP in a box-making section  12  that opens folded corrugated cardboard sheets Z and makes boxes. The supply apparatus  10  comprises a conveying unit  50 , a drive unit  60 , and a control unit  40 . The conveying unit  50  conveys a plurality of the corrugated cardboard sheets Z to the supply position SP with the corrugated cardboard sheets Z stacked. The drive unit  60  drives the conveying unit  50 . A controller  40 , which serves as the control unit, estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z on a conveying surface  53   a  of the conveying unit  50 . The controller  40  acquires a value pertaining to the drive force of the drive unit  60  when the drive unit  60  drives the conveying unit  50 , and estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z on the basis of the acquired value. 
     In the supply apparatus  10  according to the present embodiment, the controller  40  estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z on the basis of the value pertaining to the drive force of the drive unit  60 . Thus, in the supply apparatus  10  according to the present embodiment, the total quantity of the plurality of stacked corrugated cardboard sheets Z is estimated without using a sensor. Therefore, in the supply apparatus  10  according to the present embodiment, the total quantity of the plurality of stacked corrugated cardboard sheets Z can be estimated by means of an inexpensive configuration. 
     In addition, in the supply apparatus  10  according to the present embodiment, the controller  40  can estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z more precisely than in cases of using an inexpensive photoelectric sensor. 
     (5-2) 
     In the supply apparatus  10  according to the present embodiment, the controller  40 , on the basis of the estimated total quantity of the plurality of corrugated cardboard sheets Z, performs a process relating to manually replenishing the corrugated cardboard sheets Z. 
     For example, the supply apparatus  10  performs a process relating to manually replenishing the corrugated cardboard sheets Z when the total quantity of corrugated cardboard sheets Z is less than a predetermined value. According to this configuration, the operator of the supply apparatus  10  will not have to monitor the supply apparatus  10  any more than necessary. Therefore, with the supply apparatus  10  according to the present embodiment, operator labor can be reduced. 
     (5-3) 
     The supply apparatus  10  according to the present embodiment further comprises a notification unit  70 . The notification unit  70  issues a notification of information prompting replenishing the corrugated cardboard sheets Z. The controller  40  performs a process of causing the notification unit  70  to perform notification. 
     According to this configuration, the operator of the supply apparatus  10  will not have to monitor the supply apparatus  10  any more than necessary. 
     As described above, in the supply apparatus  10  according to the present embodiment, the controller  40  can estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z more precisely than in cases of using an inexpensive photoelectric sensor. Therefore, in the supply apparatus  10  according to the present embodiment, notification to replenish the corrugated cardboard sheets Z can be issued at a precise timing. Accordingly, operator labor is reduced with the supply apparatus  10  according to the present embodiment. 
     As described above, with the supply apparatus  10  according to the present embodiment, the total quantity of corrugated cardboard sheets Z can be estimated within an error range of about ±5 sheets. Therefore, the supply apparatus  10  according to the present embodiment can notify the operator of specific information, for example, indicating “how many more corrugated cardboard sheets Z need to be replenished.” Having received the notification of this information, the operator can prepare the proper number of corrugated cardboard sheets Z. Therefore, operator labor can be reduced. 
     (5-4) 
     In the supply apparatus  10  according to the present embodiment, the controller  40  can estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z on the basis of a relational expression for the value pertaining to the drive force of the drive unit  60  and the total quantity of the plurality of stacked corrugated cardboard sheets Z. 
     In this case, the total quantity of the plurality of stacked corrugated cardboard sheets Z is estimated on the basis of an easily acquirable value; namely, the torque value of the drive unit  60 , as the value pertaining to the drive force of the drive unit  60 . In other words, the total quantity of the plurality of stacked corrugated cardboard sheets Z is estimated on the basis of a value that can be acquired without using a special sensor or the like. Accordingly, any increase in the cost of manufacturing the supply apparatus  10  is suppressed. 
     (5-5) 
     In the supply apparatus  10  according to the present embodiment, the plurality of stacked corrugated cardboard sheets Z is placed on the conveying surface  53   a  in a state of being inclined relative to horizontal. The plurality of stacked corrugated cardboard sheets Z is conveyed in a state such that the lower ends of the plurality of stacked corrugated cardboard sheets Z is in contact with the conveying surface  53   a.    
     According to this configuration, the dynamic friction force R is more accurately reflected in the value pertaining to the drive force of the drive unit  60 . Therefore, in the supply apparatus  10  according to the present embodiment, the total quantity estimation unit  41  can estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z with greater precision. 
     (6) Modifications 
     The above embodiment can be modified as appropriate as shown in the following modifications. The modifications may be applied in combination with other modifications as long as there is no contradiction. The same components as those in the first embodiment are designated by the same reference numerals and are not described in detail. 
     (6-1) Modification 1A 
     A description was given in the above embodiment of the control unit  40  performing a process of manually replenishing the corrugated cardboard sheets Z on the basis of the estimated total quantity of the plurality of corrugated cardboard sheets Z. However, this example is not provided by way of limitation as to the configuration of the controller  40  according to the present invention; the controller  40  may, for example, perform a process relating to an action of automatically replenishing the corrugated cardboard sheets Z. 
     A supply apparatus  10  according to Modification 1A shall now be described with reference to  FIG. 8 . The supply apparatus  10  according to the present modification comprises a sheet supply apparatus  200  in addition to the configuration of the supply apparatus  10  described in the above embodiment. Alternatively, the sheet supply apparatus  200  may be provided in the box-packing system  1 . 
     The sheet supply apparatus  200  shown in  FIG. 8  is an apparatus that collectively supplies corrugated cardboard sheets Z to the conveying unit  50 . The sheet supply apparatus  200  is installed behind and adjacent to the conveying unit  50  (see  FIG. 8 ). The sheet supply apparatus  200  receives from the exterior a plurality of corrugated cardboard sheets Z laid down such that sheet surfaces ZS are horizontal, and supplies the corrugated cardboard sheets Z to the supply apparatus  10  after having changed the posture of the corrugated cardboard sheets Z to standing. For example, a conveyor or an unmanned conveying vehicle (not shown) supplies the corrugated cardboard sheets Z to the sheet supply apparatus  200 . 
     In the supply apparatus  10  according to the present modification, the controller  40 , on the basis of the estimated total quantity of the plurality of corrugated cardboard sheets Z, performs a process relating to an action of automatically replenishing the corrugated cardboard sheets Z. More specifically, the controller  40  transmits a control signal to the sheet supply apparatus  200  when the estimated total quantity of the plurality of corrugated cardboard sheets Z is less than a predetermined value. Having received the control signal, the sheet supply apparatus  200  supplies the corrugated cardboard sheets Z to the supply apparatus  10 . 
     With the supply apparatus  10  according to the present modification, operator labor is further reduced. 
     (6-2) Modification 1B 
     Although a description is omitted in the above embodiment, it is conceivable that there could be mechanical differences between supply apparatuses  10 . For example, it is conceivable that the tension in the belt  53  of a supply apparatus  10  used in one factory and the tension in the belt  53  of a supply apparatus  10  used in another factory could be different. Such a mechanical difference could possibly affect the torque value of the drive unit  60 , and may consequently affect the precision of the estimation made by the total quantity estimation unit  41 . Therefore, a trial operation is preferably performed before the operation of the supply apparatus  10  is started. In a trail operation, it is preferable to measure the torque value when the conveying unit  50  is driven without placing a plurality of stacked corrugated cardboard sheets Z, the torque value when the conveying unit  50  is driven without placing a plurality of stacked corrugated cardboard sheets Z, etc. By acquiring a variety of data relating to the torque value in a trial operation, the controller  40  can calculate a default value for the torque value of the supply apparatus  10 . The total quantity estimation unit  41  preferably references the default value to estimate the total quantity of the plurality of stacked corrugated cardboard sheets Z. 
     In the supply apparatus  10  according to the present modification, the total quantity of the plurality of stacked corrugated cardboard sheets Z can be precisely estimated. 
     (6-3) Modification 1C 
     Although a description is omitted in the above embodiment, the conveying unit  50  preferably includes a pusher  114  (see  FIG. 8 ). 
     The pusher  114  is a member that holds the posture of the plurality of stacked corrugated cardboard sheets Z (so that the corrugated cardboard sheets Z do not fall over rearward) accumulated on the conveying unit  50 . The pusher  114  holds down the rearmost corrugated cardboard sheets Z accumulated on the conveying unit  50 . Forward force is imparted to the pusher  114  by a force-imparting mechanism (not shown). 
     There is no limitation as to the type, but in the present modification, the force-applying mechanism is a servomotor. In the present modification, the controller  40  controls the force-applying mechanism (servomotor) so that the force that the pusher  114  exerts on the corrugated cardboard sheets Z reaches a certain predetermined value. Due to a servomotor being used as the force-applying mechanism in the present modification, the controller  40  can detect the position of the pusher  114  holding down the corrugated cardboard sheets Z on the basis of a signal from the servomotor. The controller  40  can detect the position of the rearmost corrugated cardboard sheets Z held down by the pusher  114  by detecting the position of the pusher  114  holding down the corrugated cardboard sheets Z. 
     Information on the position of the pusher  114  can be utilized to estimate the total quantity of corrugated cardboard sheets Z accumulated on the conveying unit  50 . For example, the total quantity estimation unit  41  of the controller  40  according to the present modification may refer to the torque value as well as the information on the position of the pusher  114 . 
     In the supply apparatus  10  according to the present modification, the total quantity of the plurality of stacked corrugated cardboard sheets Z can be precisely estimated. 
     When the pusher position is not detected using the force-applying mechanism, the force-applying mechanism may be, for example, a spring or another elastic body. 
     (6-4) Modification 1D 
     In the above embodiment, an example was described in which a plurality of stacked corrugated cardboard sheets Z is placed upright on the conveying surface  53   a.  However, this example is not provided by way of limitation as to the posture of the corrugated cardboard sheets Z. For example, the corrugated cardboard sheets Z may be stacked flat on the conveying surface  53   a.    
     (6-5) Modification 1E 
     In the above embodiment, an example was described in which the storage device stores a predetermined relational expression indicating the relationship between a value pertaining to the drive force of the drive unit  60  and the total quantity of the plurality of stacked corrugated cardboard sheets Z. However, this example is not provided by way of limitation as to the information stored in the storage device. For example, a table indicating correlation between the value pertaining to the drive force of the drive unit  60  and the total quantity of the plurality of stacked corrugated cardboard sheets Z may be stored in the storage device for each type of corrugated cardboard sheet Z. 
     Second Embodiment 
     (7) Configuration of Supply Apparatus  10 S 
     A supply apparatus  10 S according to a second embodiment of the present disclosure shall next be described. In the second embodiment, only components different from those of the first embodiment shall be described, and other descriptions shall be omitted. 
     (7-1) Weighing Unit  80   
     The supply apparatus  10 S according to the present embodiment comprises a weighing unit  80  (see  FIG. 9 ). The weighing unit  80  measures the weight of the conveying unit  50  with no corrugated cardboard sheets Z placed thereon, and stores this weight. When corrugated cardboard sheets Z have been placed on the conveying unit  50 , the weighing unit  80  measures the total of the weight of the conveying unit  50  and the weight of the corrugated cardboard sheets Z. The “total of the weight of the conveying unit  50  and the weight of the corrugated cardboard sheets Z” is sometimes referred to below as the total weight. When corrugated cardboard sheets Z have been placed on the conveying unit  50 , the weighing unit  80  can measure the weight of the corrugated cardboard sheets Z by subtracting the weight of the conveying unit  50  with no corrugated cardboard sheets Z placed thereon from the total weight. 
     (7-2) Controller  40 S 
     A storage device of the controller  40 S according to the present embodiment stores the weight of one corrugated cardboard sheet Z for each type of corrugated cardboard sheet Z. In the present embodiment, the operator inputs the type of corrugated cardboard sheet Z used in the current operation to the controller  40 S before starting the operation of the supply apparatus  10 S. Having received this input, the controller  40 S refers to the storage device to confirm the weight of 1 corrugated cardboard sheet Z to be used in the current operation. On the basis of the weight of 1 corrugated cardboard sheet Z to be used in the current operation and the value measured by the weighing unit  80 , a total quantity estimation unit  41  estimates how many corrugated cardboard sheets Z constitute the plurality of stacked corrugated cardboard sheets Z placed on the conveying unit  50 . For example, when the weight of 1 corrugated cardboard sheet Z to be used in the current operation is 1 kg and the weight of the corrugated cardboard sheets Z measured by the weighing unit  80  is 30 kg, the total quantity estimation unit  41  can estimate that 30 corrugated cardboard sheets Z are placed on the conveying unit  50 . 
     (8) Characteristics 
     The supply apparatus according to the present embodiment is a supply apparatus  10 S that supplies corrugated cardboard sheets Z to a supply position SP in a box-making section  12  that opens folded corrugated cardboard sheets Z and makes boxes. The supply apparatus comprises a weighing unit  80  and a control unit  40 . The weighing unit  80  measures the weight of the plurality of stacked corrugated cardboard sheets Z. The control unit  40  estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z. The control unit  40  estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z on the basis of the value measured by the weighing unit  80 . 
     In the supply apparatus  10 S according to the present embodiment, the control unit  40  estimates the total quantity of the plurality of stacked corrugated cardboard sheets Z on the basis of the value measured by the weighing unit  80 . Therefore, in the supply apparatus  10 S according to the present embodiment, the total quantity of the plurality of stacked corrugated cardboard sheets Z can be estimated by means of an inexpensive configuration. 
     (9) Modification 2A 
     Although a description is omitted in the above embodiment, the weighing unit  80  may perform weighing continuously at least for a predetermined time or a predetermined number of times, and may calculate an average weighed value. The total quantity of the plurality of stacked corrugated cardboard sheets Z may be estimated using the average weighed value. 
     It is conceivable that a box-packing system  1 S in operation could vibrate. This is because in the processes P 1 , P 2 , P 3 , and P 4  executed by the box-packing system  1 S, a variety of equipment installed in the box-packing system  1  is constantly in action. Vibration occurring in the box-packing system  15  could possibly affect the weighing done by the weighing unit  80 . In the supply apparatus  10 S according to the present modification, the total quantity of the plurality of stacked corrugated cardboard sheets Z is estimated using the average weight value. With this configuration, the total quantity of the plurality of stacked corrugated cardboard sheets Z can be estimated according to a numerical value on which the effect of vibration is suppressed. 
     REFERENCE SIGNS LIST 
     
         
           1  Box-packing system 
           10 ,  10 S Supply apparatus 
           12  Box-making apparatus (box-making section) 
           40  Control unit (controller) 
           50  Conveying unit 
           53   a  Conveying surface 
           60  Drive unit 
           70  Notification unit 
           80  Weighing unit 
         Z Corrugated cardboard sheet(s) 
         SP Supply position