Conveyor belt and belt constituent members

A conveyor belt (11) is formed by coupling multiple chain links 15 aligned in a conveyance direction X. The chain link (15) is provided with multiple recess parts (15a) and first hinge parts (21) protruding in the conveyance direction X from positions between which each of the recess parts (15a) is placed. If some object hits on an outer end of the conveyor belt (11) to apply force to the first hinge part (21), a section including the first hinge part (21) and a bulging part (30) pivots about a fulcrum at an outer base end of the first hinge part (21) to deform this section. In this invention, a point of action where force acts on the conveyor belt (11) and the center of pivotal motion of the first hinge part (21) and the bulging part (30) are determined to be spaced by a relatively short distance.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a conveyor belt and belt constituent members.

BACKGROUND OF THE INVENTION

A conveyor belt is used in a belt conveying device to convey an item. A conveyor belt such as a modular belt disclosed in patent documents 1 to 5 includes multiple balls (free balls) arranged in a vertical direction and a horizontal direction. The multiple balls are attached to the conveyor belt while protruding from a surface of the belt.

FIG. 7shows an example of a conventional conveyor belt with balls. A conveyor belt81includes a belt part84. The belt part84is formed of multiple chain links82each provided as an example of belt component. The multiple chain links82are aligned in the longitudinal direction of the belt parallel to a conveyance direction X. Each chain link82is arranged in a manner such that the longitudinal direction of the chain link82agrees with a width direction Y crossing the conveyance direction X. The belt part84is formed by coupling the multiple chain links82through a pin83in a manner that allows pivotal motion of the chain links82. Each chain link82is provided with multiple recess parts82aspaced at substantially constant intervals in the longitudinal direction of the chain link82. The recess part82ais formed in a manner such that an opening end of the recess part82ais pointed toward a downstream side of the conveyance direction X. A ball unit86that holds a ball85in a manner that allows rotation of the ball85is attached to the recess part82a. For example, a conveying device is formed by placing the conveyor belt81with balls on a driving mechanism that controls rotation of the ball85. This conveying device has the function of conveying an item at double speed and the function of changing a direction of conveyance of an item that are carried out by controlling the rotation of the ball85with the driving mechanism.

The chain link82has one first hinge part87on each of opposite lateral sides of the recess part82a. Each first hinge part87extends in a direction opposite to the direction in which the recess part82ais recessed, specifically, in the conveyance direction X. The chain link82is provided with multiple second hinge parts88at its rear edge to be spaced at substantially constant intervals in the longitudinal direction of the chain link82. Each second hinge part88protrudes from a position corresponding to the recess part82aof the chain link82.

Two adjacent chain links82are attached to each other while the second hinge part88is inserted between a pair of first hinge parts87. The two adjacent chain links82are pivotally coupled to each other through the pin83inserted in respective pin holes of these chain links82.

A first hinge part87among the multiple first hinge parts87placed an end portion of the chain link82is narrower than the other first hinge parts87. This is done with the intention of placing the first hinge parts87adjacent to each other in the width direction Y at an interval the same as an interval between the other adjacent first hinge parts87.

PRIOR ART DOCUMENTS

Patent Documents

DISCLOSURE OF THE INVENTION

While the conveyor belt81is moving, an external force applying object to apply some kind of external force may hit on an end portion of the conveyor belt81. The external force applying object may be an item to be conveyed, a foreign matter on or outside the belt part, a worker, or an object belonging to the worker, for example.

FIGS. 8(a) and 8(b)show a state where an external force applying object hits on an end portion of the conveyor belt81in the width direction while the conveyor belt81is moving. In this case, external force F is applied to the tip of a first hinge part87at the outermost position of the chain link82to deform a periphery of this first hinge part87.

As shown inFIG. 8(a), force is first applied to the tip of the first hinge part87from outside to expand the opening of the recess part. Then, as shown inFIG. 8(b), a section including the first hinge part87and an outer wall of the recess part82apivots about a fulcrum O1at an outer base end of the second hinge part88in an arrow direction ofFIG. 8(b), thereby deforming this section. This expands the opening of the recess part82a, causing the risk of detachment of the pin83from the first hinge part87. This further causes the risk of detachment of the ball unit86from the recess part82a.

The aforementioned problems are generally common to a conveyor belt including a belt component such as a chain link with a recess part that receives a unit member attached to the recess part that is not limited to a ball unit but may be a roller unit, a guide unit, or a scraper unit, for example.

It is an object of this invention to provide a conveyor belt and a belt component with a recess part receiving a unit member attached to the recess part capable of limiting an expansion amount of the recess part to a small amount on the occurrence of application of external force to an end portion of the belt component in the longitudinal direction thereof.

To solve the aforementioned problem, a first aspect of this invention provides a conveyor belt including a belt part and a unit member. The belt part includes multiple belt components. The belt part is formed by coupling adjacent belt components through a hinge part in a manner that allows the adjacent belt components to pivot freely. Each of the belt components is provided with a recess part having an opening pointed in a short-side direction of the belt. The unit member is attached to the recess part of each of the belt components. The hinge part includes multiple first hinge parts and multiple second hinge parts. The first hinge parts protrude from positions between which recess parts of each of the belt components are placed. The second hinge parts protrude toward a side opposite the first hinge parts. A belt component among the multiple belt components placed at an end portion of the belt part in a width direction has an end portion provided with a bulging part that protrudes in the width direction. The bulging part has a restricting part that protrudes in the same direction as the first hinge parts or the second hinge parts. The restricting part faces an end portion of a belt component in the width direction adjacent to the bulging part.

An end portion of the conveyor belt may hit on some external force applying object while the conveyor belt is moving. In this case, the belt component pivots in an area around the portion having hit on the external force applying object in a direction where the recess part is expanded, thereby deforming the belt component. In this regard, in this invention, the restricting part is provided in the bulging part along a short-side direction of the belt component to protrude in the same direction as the first hinge parts or the second hinge parts. Thus, if collision with the external force applying object causes displacement of the bulging part, the restricting part abuts on the end portion of the belt component in the width direction adjacent to the bulging part. This suppresses further deformation of the belt component. This can make it unlikely that the unit member will be detached from the recess part or excessive fatigue will be caused due to the deformation.

In the aforementioned conveyor belt, it is preferred that the restricting part protrude in the same direction as the second hinge parts and the first hinge part of the belt component adjacent to the bulging part is inserted between the restricting part and the second hinge part.

In this structure, if the belt component pivots in an area around a portion having hit on an external force applying object in the direction where the recess part is expanded, the restricting part abuts on the first hinge part. This restricts further deformation of the belt component. In this case, as a result of the presence of the bulging part, the center of pivotal motion of the belt component is set near the first hinge part. This limits the amount of displacement in the direction where the opening of the recess part is expanded to a relatively small amount.

In the aforementioned conveyor belt, it is preferred that the restricting part protrudes further than tips of the first hinge parts in the same direction as the first hinge parts.

An end portion of the conveyor belt may hit on some external force applying object while the conveyor belt is moving. In this case, the belt component pivots in an area around the portion having hit on the external force applying object in the direction where the recess part is expanded, thereby deforming the belt component. At this time, a part of the bulging part abuts on the restricting part of the belt component adjacent to the bulging part. This restricts further pivotal motion of the belt component.

In the aforementioned conveyor belt, it is preferred that the restricting part holds the first hinge part between the restricting part and the second hinge part, the restricting part, the first hinge part, and the second hinge part form the hinge part together, and a common pin passes through the hinge part.

In this structure, the restricting part forms the hinge part. This allows coupling of the belt components while the narrowest first hinge part at the outermost position of the belt component is held between the second hinge part and the restricting part. Thus, the first hinge part at the outermost position having a relatively small width and low strength can be protected.

In the aforementioned conveyor belt, it is preferred that the bulging part has a sloping surface that rises up from a position outside the width direction of the belt part toward a position inside the width direction.

In this structure, as a result of the provision of the bulging part at the end portion of the belt component in the width direction, the end portion of the belt component can be relatively wide. Further, forming the sloping surface of the bulging part that rises up from a position outside the surface of the bulging part toward a position inside the surface can prevent strength reduction that is to be caused by thinning of an area around the recess part. Additionally, a relatively large area of the sloping surface is ensured. This allows an item to be transferred onto the conveyor belt smoothly.

In the aforementioned conveyor belt, it is preferred that the unit member is at least one of a ball unit, a roller unit, a guide unit, and a scraper unit.

At least one of a ball unit and a roller unit may be attached as the unit member to the recess part. In this case, an item on the conveyor belt can be moved by the rolling motion of a ball or a roller at a predetermined speed relative to the moving belt. As an example, the item can be conveyed at a speed twice the speed of movement of the belt. At this time, even if external force is applied to an end portion of the conveyor belt, detachment of the ball unit or the roller unit from the recess part can still be prevented. Additionally, at least one of a guide unit and a scraper unit may also be attached as the unit member to the recess part. In this case, the conveyor belt moves in a direction guided by the unit member, so that the conveyor belt is less likely to travel in a zigzag manner. Further, items can be collected with a scraper.

To solve the aforementioned problem, a second aspect of this invention provides a belt component having one end or opposite ends in a longitudinal direction of the belt component that form the end portion of the belt part in the width direction in the aforementioned conveyor belt. The belt component includes first hinge parts and second hinge parts, and a bulging part provided to either of or both of the one end or the opposite ends of the belt component. The bulging part protrudes in the longitudinal direction of the belt component. The bulging part has a restricting part that protrudes in the same direction as the first hinge parts or the second hinge parts. The restricting part faces an end portion of a belt component in the width direction adjacent to the bulging part.

In this structure, one end or opposite ends of the belt component form the end portion of the conveyor belt in the width direction, thereby obtaining the same advantages as that of the conveyor belt.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A first embodiment of this invention is described below based onFIGS. 1 to 3(b). In the first embodiment, a conveyor belt11of this invention is embodied in a conveyor belt with balls. In the following description of the conveyor belt11, a direction in which an item is conveyed is called a conveyance direction X and a direction crossing the conveyance direction X is called a belt width direction Y. The longitudinal direction of the belt is parallel to the conveyance direction X.FIG. 1shows only a part of the conveyor belt.

The conveyor belt11shown inFIG. 1is configured as an endless belt with opposite ends (not shown in the drawings) of the conveyor belt11in the longitudinal direction of the belt coupled to each other. The conveyor belt11is wrapped around multiple sprockets (not shown in the drawings) while the opposite ends of the conveyor belt11in the longitudinal direction are in meshing engagement with the corresponding sprockets. When a motor as a power source is driven by a controller not shown in the drawings, a sprocket on a driving side is rotated. This rotates the conveyor belt11around the sprockets to convey an item on the conveyor belt11in the conveyance direction X. The conveyor belt11includes a belt part12formed of a modular belt and multiple balls13exposed from a surface of the belt part12. The multiple balls13are arranged in a matrix and spaced at substantially constant intervals in a vertical direction and a horizontal direction.

As shown inFIGS. 1, 2(a), and2(b), the conveyor belt11includes multiple chain links15each provided as an example of a belt component extending in the belt width direction Y. The multiple chain links15are arranged and assembled in a designated layout pattern. The chain links15adjacent to each other in the longitudinal direction of the belt are coupled in a manner that allows these chain links15to pivot freely, thereby forming the belt part12into a shape like a band.

The chain link15includes two types of chain links of different lengths: a chain link15A and a chain link15B. The chain link15A is a comparatively long chain link including six recess parts15a. The chain link15B is a comparatively short chain link including three recess parts15a. The recess part15aof each of the chain links15A and15B receives a ball unit17attached as an example of a unit member to the recess part15a. A ball13is held in the ball unit17in a manner that allows rolling motion of the ball13. The length of the chain link15A is twice the length of the short chain link15B.

The layout pattern of the chain links15is as follows. Two chain links15B are arranged adjacent to one chain link15A in the conveyance direction X while respective end surfaces of these chain links15B in their longitudinal directions abut on each other. Specifically, the two chain links15B are arranged in a manner such that the length of these chain links15B agrees with the length of one chain link15A. This layout pattern is formed repeatedly in the longitudinal direction of the belt. The chain links15adjacent to each other in the longitudinal direction of the belt are coupled through a pin16in a manner that allows these chain links15to pivot freely. The length of the pin16is substantially the same as the width dimension of the conveyor belt11. Where appropriate, the length of the chain links15to be used, which is determined by the number of the chain links15to be aligned in the belt width direction Y and a layout pattern for these chain links15, can be changed depending on the width dimension of the conveyor belt11or required strength of the conveyor belt11, for example.

Each chain link15is provided with multiple recess parts15asubstantially U shaped in a plan view formed on a downstream-side lateral edge of each chain link15. The multiple recess parts15aare spaced at constant intervals in the belt width direction Y. Each recess part15areceives one ball unit17attached to the recess part15a. Each ball unit17holds one ball13(free ball) in a manner that allows rotation of the ball13. The ball13is exposed from an opening at each of the front surface and the rear surface of the ball unit17. For use of the conveyor belt11, an opening end of the recess part15ais pointed toward the conveyance direction X. Thus, frictional force to be generated between the conveyor belt11and an item will not act in a direction where the ball unit17is detached from the recess part15a.

The balls13are arranged with the same pitch as the chain links15in the conveyance direction X. Further, the balls13are arranged with the same pitch as the recess parts15ain the belt width direction Y. The pitch of the balls13in the conveyance direction x and that of the balls13in the belt width direction Y are substantially the same and set at a predetermined value in a range from 10 to 60 mm, for example. The predetermined value is set to be smaller than a short-side dimension of the bottom surface of an item to be conveyed. Thus, the item is always placed on the multiple balls13while the item is being conveyed.

The conveyor belt11is used in a conveying device not shown in the drawings. For example, the conveyor belt11is placed on a driving mechanism not shown in the drawings forming the conveying device, specifically, on either of or both of a flat belt and a turn table. In the conveying device, the driving mechanism is controlled by a controller not shown in the drawings to control rotation of the balls13incorporated in the conveyor belt11. This enables conveyance of an item at a double speed and change of a direction of the item (for feed or rotation or both for feed and rotation of the item, for example). The balls13may be configured in a manner such that they can protrude and be depressed from the surface of the belt part12.

The chain link15has a substrate part20formed like an elongated plate. The substrate part20is provided with a first hinge part21extending in the conveyance direction X formed on each of opposite sides of the recess part15a. A gap between the first hinge parts21is substantially the same as the opening width of the recess part15a. The substrate part20is further provided with multiple second hinge parts22in a rear surface part of the substrate part20, specifically, on a side opposite the first hinge parts21. Each of the second hinge parts22is provided at a position shifted by a half of the pitch in the belt width direction Y from the first hinge part21. Further, each of the second hinge parts22protrudes in a direction opposite the direction in which the first hinge part21protrudes.

The width of the second hinge part22is slightly smaller than a gap between the first hinge parts21in a pair adjacent to each other, specifically, smaller than the opening width of the recess part15a. The second hinge part22is placed at a position substantially the same as the recess part15ain the longitudinal direction of the chain link15. The second hinge part22has the same width as the recess part15ain the longitudinal direction of the chain link15. The second hinge part22has a length that allows coupling to the first hinge part21of an adjacent chain link15.

The first hinge part21is provided with a pin hole21a. The second hinge part22is provided with a pin hole22a. The pin holes21aand22apenetrate the first and second hinge parts21and22respectively in respective directions perpendicular to directions in which the first and second hinge parts21and22protrude. The first hinge part21is inserted into a gap between the counterpart second hinge parts22and the second hinge part22is inserted into a gap between the counterpart first hinge parts21until their respective pin holes21aand22aagree with each other. Thus, the pin holes21aand22acommunicate with each other, and the pin16is inserted to pass through these pin holes21aand22a. In this way, each of the multiple chain links15is coupled to a different adjacent chain link15through the hinge parts21and the hinge parts22in a manner that allows these chain links15to pivot freely.

The ball unit17is substantially D shaped in a plan view. The ball unit17includes a holder25having substantially the same thickness as the chain link15. A circular opening25ais formed in each of the front surface and the rear surface of the holder25. The holder25is formed of a lower cover26and an upper cover27of substantially the same shape. With the lower cover26and the upper cover27connected to each other, a part of the ball13is exposed through the opening25ain each of the lower cover26and the upper cover27. In this state, the ball13is held in a manner that allows the ball13to rotate 360 degrees freely. The ball unit17is attached to the chain link15by being caused to slide into the recess part15a.

An attachment structure of the ball unit17to the chain link15is described next.

As shown inFIG. 1, the recess part15ahas two inner wall surfaces facing each other and a semicylindrical recessed curved surface. The inner wall surfaces are continuous with corresponding lateral surfaces in a pair facing each other and belonging to the first hinge parts21on opposite sides of the recess part15a. The recessed curved surface is continuous with the two inner wall surfaces at a deep position of the recess part15a. The inner wall surfaces are each provided with one guide part15blike a rectangular strip formed on each of an upper end and a lower end of the inner wall surface. The guide part15bis to guide the holder25in a manner such that the holder25can slide into the recess part15aand to engage the holder25at a position where the holder25is attached. The recess part15ais provided with a guide part15cformed of an arcuate protruding strip provided at the upper end of the recessed curved surface of the recess part15a. The guide part15cis to abut on the front upper edge of the holder25inserted in the recess part15ato restrict movement of the holder25toward the surface of the belt. The ball unit17is engaged at an attachment position that is the deepest position in the recess part15afor the ball unit17inserted in the recess part15athrough the opening end of the recess part15a. In this state, the upper end surface of the holder25is substantially flush with the upper surface of the substrate part20.

As shown inFIGS. 1, 2(a) and2(b), the width of the first hinge part21near each of opposite ends of the chain link15is smaller than that of the other first hinge parts21, more specifically, about half of the width of a first hinge part21B.

Thus, the first hinge part21at each of the opposite ends of the conveyor belt11in the width direction is comparatively narrow. Further, two first hinge parts21A are adjacent to each other in a substantially central area of the conveyor belt11. Thus, if the multiple chain links15are aligned in the belt width direction Y, the width of an area where the two first hinge parts21A abut on each other becomes substantially the same as the width of the other first hinge parts21B. As a result, the balls13are arranged in the belt width direction Y with a pitch that is constant at any position of the conveyor belt11. The two first hinge parts21A in the substantially central area of the conveyor belt11abut on each other. Thus, even if external force is applied to these first hinge parts21A, these first hinge parts21A are relatively unlikely to be deformed.

A bulging part30bulging outwardly is formed at an end portion of the chain link15in the belt width direction. The bulging part30is formed into a shape like a square pole. In this structure, if external force is applied to the bulging part30, the bulging part30and the first hinge part21A pivot about a fulcrum O2at an outer base end of the first hinge part21A in a direction where the opening of the recess part15ais expanded, as shown inFIGS. 3(a) and 3(b). This structure prevents direct application of external force F on the tip of the first hinge part21A while placing the fulcrum O2when the first hinge part21A is deformed near the first hinge part21A. This suppresses deformation of the first hinge part21A.

As shown inFIGS. 1, 2(a), and2(b), the bulging part30has a restricting part31protruding in the same direction as the second hinge part22. The restricting part31is placed at a position spaced by a gap32from the second hinge part22at the outermost position of the chain link15. The gap32is slightly larger than the width of the first hinge part21. This allows insertion of the first hinge part21in the gap32.

The restricting part31forms a hinge part and has a pin hole31a. The pin hole31ais arranged on the same axis as the pin hole22aof the second hinge part22. To assemble the conveyor belt11using the multiple chain links15, the first hinge part21is inserted first in the gap32. In this way, the first hinge part21is caught between the second hinge part22and the restricting part31. In this state, the pin16is inserted to pass through the pin holes21a,22a, and31a. The restricting part31is not always required to function as a hinge part. The restricting part31may be required only to be spaced by a slight gap from the first hinge part21inserted in the gap32.

The bulging part30is substantially the same in thickness as the first hinge part21and the substrate part20. The bulging part30is substantially the same as or larger than the first hinge part21A in width. Thus, if external force is applied to a downstream-side end surface of the bulging part30in the conveyance direction X, the bulging part30tries to pivot clockwise about the outer base end of the first hinge part21A as the fulcrum O2. At this time, the restricting part31tries to make displacement in a direction where the restricting part31approaches the second hinge part22, specifically, to the left ofFIG. 3(b). The restricting part31is spaced by a slight gap from the first hinge part21A of a different chain link15. Thus, the aforementioned displacement makes the restricting part31abut on a lateral surface of this first hinge part21A.

As shown inFIGS. 1, 2(a), and2(b), the upper surface of the bulging part30is formed as a sloping surface30athat rises up gradually from a position outside the chain link15toward a position inside the chain link15. The sloping surface30afacilitates transfer of an item to the conveyor belt11from a lateral side of the conveyor belt11. In the absence of a sloping surface, an item is likely to get snagged on a step at an end portion of a conveyor belt. This makes it difficult to transfer the item onto the conveyor belt smoothly. In this regard, in this embodiment, an item is allowed to move smoothly along the sloping surface30awhen the item is to be transferred to the conveyor belt11from a lateral side of the conveyor belt11.

The action of the aforementioned conveyor belt11is described next.

As shown inFIGS. 1, 2(a), and2(b), the conveyor belt11is configured as an endless belt and is wrapped around sprockets while being in meshing engagement with the sprockets. When the motor is driven, the conveyor belt11rotates around the sprockets to convey an item on the conveyor belt11in the conveyance direction X at a designated speed. After an item is fed from an upstream side or a lateral side of the conveyor belt11and then transferred onto the conveyor belt11, the item is conveyed in the conveyance direction X along the conveyor belt11.

As shown inFIG. 3(a), an end portion of the conveyor belt11in the width direction may hit on an external force applying object such as an item, a peripheral object, or a worker. In this embodiment, the plate-like bulging part30is formed at an end portion of the chain link15in the longitudinal direction thereof. The bulging part30bulges outwardly in the belt width direction Y. This makes the bulging part30hit on the external force applying object. At this time, the external force F applied to the bulging part30acts from a downstream side toward an upstream side of the conveyance direction X. In response, force to cause pivotal motion about the fulcrum O2at the outer base end of the first hinge part21A is applied to the chain link15, as shown inFIG. 3(b). Specifically, a section including the first hinge part21A and the bulging part30pivots in the clockwise direction ofFIG. 3(b)about the fulcrum O2that also forms a corner area between the first hinge part21A and the bulging part30. Meanwhile, as a result of the restricting part31abutting on the first hinge part21A, the pivotal motion of the section including the first hinge part21A and the bulging part30is restricted.

The aforementioned embodiment achieves the following effects.

(1) As a result of the presence of the bulging part30, direct application of external force on the tip of the first hinge part21A can be prevented easily. If the external force F is applied to the bulging part30, the section including the first hinge part21A and the bulging part30pivots about the fulcrum O2at the outer base end of the first hinge part21A. In this embodiment, the fulcrum O2is set at a position near the first hinge part21A. This limits displacement of the first hinge part21A in the direction where the opening of the recess part15ais expanded to a relatively small amount. If the section including the bulging part30pivots about the fulcrum O2at the outer base end of the first hinge part21A, the restricting part31abuts on the first hinge part21A of a chain link15adjacent to the bulging part30. This restricts further pivotal motion of the section including the bulging part30. As a result, expansion of the opening of the recess part15acan be limited to a small amount that is to occur if an end portion of the conveyor belt11in the width direction hits on an external force applying object.

(2) The restricting part31protrudes in the same direction as the second hinge part22. Thus, the bulging part30does not protrude further than the first hinge part21at any position in the conveyance direction X. Specifically, the bulging part30is shifted toward an upstream side of the conveyance direction X by the length of the protrusion of the first hinge part21A. In a structure where a restricting part protrudes in the same direction as a first hinge part, for example, the restricting part protrudes from an arcuate surface of a conveyor belt wrapped around sprockets. By contrast, this embodiment can prevent the restricting part31from protruding from the arcuate surface of the conveyor belt11.

(3) The restricting part31further functions as a hinge part. Thus, while the first hinge part21A is held by the second hinge part22and the restricting part31between one chain link15and an adjacent chain link15on an upstream side, these chain links15can be coupled with the common pin16. In this way, the restricting part31functions to protect the first hinge part21A having a relatively small width and low strength.

(4) The upper surface of the bulging part30is formed as the sloping surface30athat rises up from a position outside the belt width direction Y toward a position inside the belt width direction Y. This can form the upper surface, specifically, the sloping surface30aof the bulging part30in a relatively large area. Thus, an item can be transferred to the conveyor belt11easily from a lateral side of the conveyor belt11.

(5) The ball unit17where the ball13is held is attached to the recess part15aof the chain link15. An item on the conveyor belt11is placed on the ball13that rolls. Thus, the item can be conveyed at a speed higher than a speed of movement of the belt part12such as a speed twice the speed of movement of the belt part12, for example. By controlling rotation of the ball13, the direction of the item can be changed while the item is stopped or being moved.

Second Embodiment

A conveyor belt of a second embodiment is described next by referring toFIGS. 4(a) and 4(b).

In the first embodiment, the restricting part31protrudes in the same direction as the second hinge part22. In the second embodiment, a restricting part41protrudes in the same direction as the first hinge part21A.

As shown inFIGS. 4(a) and 4(b), a bulging part40is formed at an end portion of the conveyor belt11in the width direction. The bulging part40is formed at a lateral portion of the first hinge part21A. The bulging part40is provided with a restricting part41protruding in the conveyance direction X. The restricting part41protrudes further than the tip of the first hinge part21A toward a downstream side. The bulging part40is provided with a rectangular cutout42opened toward an upstream side. The cutout42receives the restricting part41of the chain link15adjacent to the bulging part40. The bulging part40has an end surface40bspaced by a slight gap from an apical surface41aof the restricting part41.

An end portion of the conveyor belt11in the width direction may hit on some external force applying object. In this case, the external force F is applied to the tip of the restricting part41at the outermost position of the chain link15. Then, a section including the first hinge part21A and the bulging part40pivots in the clockwise direction ofFIG. 4(b)about a fulcrum O3at an outer base end of the first hinge part21A. In this case, the fulcrum O3is set at a relatively narrow portion of the substrate part20, specifically, at a corner area of a recess part.

However, if the section including the first hinge part21A and the bulging part40pivots slightly, the end surface40bof the bulging part40abuts on the restricting part41of the chain link15adjacent to the bulging part40. This restricts further pivotal motion of the bulging part40. Thus, even if the external force F is applied to an end portion of the belt part12in the width direction, deformation of the first hinge part21A in the direction where the opening of the recess part15ais expanded is limited to a relatively small amount. This prevents detachment of the pin16or shift of the ball unit17from its attachment position. This can also effectively suppress fatigue of a portion where stress is applied intensively.

The aforementioned embodiments can be changed as follows.

In the first embodiment, the width of the sloping surface30aof the bulging part30is substantially the same as that in the conventional structure shown inFIGS. 7(a) to 8(b). Alternatively, as shown inFIGS. 5(a) and 5(b), the width of a sloping surface30bmay be larger than the width shown inFIG. 3(a). In this case, with the substantially same slope of the sloping surface30b, the sloping surface30bat an end portion of the bulging part30is placed at an even lower position. This increases a distance between the position of the ball13and that of an end portion of the chain link15in the longitudinal direction, specifically, a distance between the ball13and an end portion of the conveyor belt11in the width direction by the increase in the width dimension of the bulging part30. Additionally, if an item is to be transferred to the conveyor belt11from a lateral side of the conveyor belt11, the item can be conveyed along the sloping surface30bto a position near the ball13. Thus, the item can be transferred onto the conveyor belt11smoothly.

The unit member may be a unit other than the ball unit17. As shown inFIG. 6(a), the unit member may be a roller unit51with a roller, for example. In this structure, the roller unit51is attached to the recess part15aof the chain link15. The roller unit51includes a holder53having an opening53aand a roller52housed in the holder53. The roller52can be exposed partially from each of the upper surface and the lower surface of the holder53through the opening53a. The orientation of the roller52can be changed, where appropriate. Roller units51of different types including the rollers52in respective orientations may be attached to the conveyor belt11, for example. This structure may further include a selecting mechanism that can select between protrusion and depression of the rollers52. The selecting mechanism may include multiple lifting members with which rollers52in the same orientation can be lifted from the belt part12. By moving up and down the lifting members, the orientations of the rollers52to protrude can be selected. In this case, a direction where an item is to be conveyed can be changed depending on the orientations of the rollers52having been placed in their protruding positions.

As shown inFIG. 6(b), the unit member may be a guide unit61. The guide unit61is attached to the recess parts15aof the chain links15. The chain links15are pivotally coupled to each other through the pin16passing through the respective pin holes in the first and second hinge parts21and22. The guide unit61is attached to the chain links15while L-shaped guide parts62are provided to extend downward from the rear surface of the belt part12. A guide rail not shown in the drawings is provided in a section where the conveyor belt11is to be supported. On the other hand, the guide parts62are arranged on opposite ends of the conveyor belt11in the width direction. Thus, with the guide parts62engaged with the guide rail, the conveyor belt11is less likely to travel in a zigzag manner.

The unit member may be a scraper unit with a scraper. In this structure, items can be collected and conveyed.

The unit member may be attached to the recess part of the chain link15from a direction perpendicular to the front surface or the rear surface of the belt part12.

This invention is applicable to a belt conveying device in which an item is conveyed by moving a band-like conveyor belt having opposite ends back and forth in the longitudinal direction of the belt. In this case, the conveyor belt may be wound or fed on opposite sides of the conveyor belt in the longitudinal direction thereof.

REFERENCE SIGNS LIST