JP2002104637A - Belt conveyor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt conveyor device capable of reliably conveying a powdery, granular, or a small lump-form object to be conveyed at a comparatively low cost without needing so wide installation space. SOLUTION: First and second belt conveying mechanisms 10 and 10 are vertically situated. By frictional contact of an under surface 13b of a main conveyance belt 13 and an upper surface 23a of an auxiliary conveyance belt 23 with each other, the two belts 13 and 23 are synchronously driven. An under surface 23b of the auxiliary conveyance belt 23 is positioned opposite to and in parallel to a bottom wall (a supporting surface) of a support chute 30. During operation, even when sands reach a position situated downstream, a part of sands S not separated from the main conveyance belt 13 and continuously adhered thereto is returned to a position situated upper stream once, but conveyed gain toward a position situated downstream as the sands slip and roll over the bottom wall 31 through operation of the auxiliary conveyance belt 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt conveyor for conveying powdery, granular, or small objects to be conveyed from an upstream position to a downstream position in a conveying direction.

[0002]

2. Description of the Related Art In a foundry, for example, a belt conveyor is generally used to carry foundry sand for making a mold. An alternative to a belt conveyor is an oscillating conveyor (oscillating conveyor), which is mechanically complex and expensive and is difficult to adopt for general use.

[0003] A belt conveyor is generally constructed by endlessly spanning a rubber flat belt between a pair of front and rear pulleys. When at least one of the pair of pulleys is driven by a drive motor, the flat belt runs endlessly in one direction. At this time, the belt surface located on the upper side of the traveling track serves as a transport surface, and the upper belt surface travels with the molding sand as the object to be transported, so that the molding sand moves from the upstream position in the transport direction to the downstream position. Conveyed toward. On the other hand, the belt surface located on the lower side of the traveling track travels in the opposite direction (return direction) to the transport surface, and changes direction by the pulley at the upstream position in the transport direction to become the next transport surface. In addition, since the conveyance distance of the molding sand by the belt conveyor is generally long, a plurality of rollers are provided at predetermined intervals below each belt surface. In particular, the roller that slides on the lower belt surface (return surface) traveling in the return direction is
It is called a return roller.

[0004]

In this belt conveyor, when the upper belt surface of the running track changes direction with the pulley at the downstream position (destination) in the transport direction, all of the foundry sand is removed from the belt surface. If it falls off cleanly, there is no problem. However, in reality, even after the belt surface on which the casting sand has been loaded changes its running direction with a pulley at the downstream position and becomes a return surface, it remains on the return surface (lower belt surface) facing the floor surface (or the ground). In a small amount, the foundry sand continues to adhere against gravity. Causes of this adhesion include, for example, the influence of moisture contained in foundry sand, electrostatic attraction,
Sand particles are trapped in the scratches and cracks produced on the rubber belt. And every time the downward facing return surface gets over each individual return roller,
Since the foundry sand adhering to the return surface is scraped off by the roller, it is inevitable that sand gradually accumulates between the return surface and the floor surface. Such a situation deteriorates the environment in the factory and is not preferable for safety and hygiene. In addition, if spilled sand is piled up under the belt conveyor, the movement of the return roller and the belt may be hindered and a failure may occur.

[0005] Under such circumstances, various measures have been attempted to prevent the accumulation of spilled sand on the lower side of the belt conveyor. One is to install a scraper (contact type scraping plate) in the vicinity of the pulley at the downstream position in the transport direction, thereby completely removing the sand adhered to the belt surface. However, this countermeasure has not only the disadvantage that the scraper gradually wears due to long-time operation and loses the scraping effect, but also has the disadvantage of accelerating the wear and deterioration of the conveyor belt. In particular, sand particles that have entered the scratches and cracks caused by belt deterioration are difficult to scrape off with a scraper, but they cause a considerable amount of spillage when passing through a return roller. Can not be.

On the other hand, there is a measure to install a mechanism for re-collecting sand spilled from the belt conveyor.
For example, a sludge conveyor to which a large number of recovery blades are attached is installed under a belt conveyor, and the spilled sand is conveyed and collected. However, in this case, a large installation space for the sludge conveyor is required under the belt conveyor, and there is a difficulty in installation in a factory where installation space for machinery is generally limited. In addition, since a drive source and a control device for the sludge conveyor are separately required, there is a problem that the cost for measures is high.

An object of the present invention is to provide a belt conveyor device which is relatively inexpensive and does not require much installation space, and which can surely convey a powdery, granular or small lump object from an upstream position to a downstream position in the conveying direction. To provide.

[0008]

According to the present invention, there is provided a belt conveyor device for conveying a powdery, granular, or small object to be conveyed from an upstream position to a downstream position in a conveying direction. A first belt transport mechanism having a main transport belt that can be driven endlessly; and a second belt transport mechanism that is disposed immediately below the first belt transport mechanism and has a sub-transport belt that can be driven endlessly. The sub-transport belt has an upper surface facing the lower surface of the main transport belt and a lower surface facing substantially parallel to a receiving surface located below the second belt transport mechanism. The first and second belt transport mechanisms are driven so that the lower side of the sub-transport belt can travel in the same direction as the transport direction as the upper side travels in the transport direction. .

In this belt conveyor device, the first and second belt conveying mechanisms are arranged vertically above the receiving surface.
It has a story structure. According to this configuration, the upper surface of the uppermost main transport belt functions as a main transport surface on which the powdery, granular, or small lump transported object is placed and transported in a predetermined transport direction. The main transport belt is configured to be able to be driven endlessly, and the traveling direction is reversed at the downstream position in the transport direction during operation of the apparatus. That is, as the upper side of the main conveyor belt travels in the transport direction, the lower side of the main transport belt travels in the opposite return direction. On the other hand, the sub-transport belt is also configured to be endlessly driven and its lower surface runs in the same transport direction as the upper surface of the main transport belt,
During operation of the apparatus, the upper surface of the sub-transport belt travels in the same return direction as the lower surface of the main transport belt. For this reason, even if the conveyed object that has adhered to the lower side of the main conveyor belt is separated from the lower side during operation, the conveyed object is received by the upper side of the sub-conveyor belt and temporarily moved to the upstream position in the conveying direction. Will be returned. Even if the transported object is temporarily returned to the upstream position and may temporarily accumulate at the upstream position of the receiving surface, the transported object deposited there may be moved by the lower side surface of the sub-transport belt traveling in the transport direction. It is dragged between the lower surface and the receiving surface. Then, due to the transport action of the lower surface of the sub-transport belt, the powdery, granular or small lump transported object is re-transported to the downstream position in the transport direction while sliding or rolling on the receiving surface. As described above, according to the belt conveyor device, even if the transported object attached to the surface of the main transport belt may separate from the surface of the main transport belt and fall off, the cooperation between the sub-transport belt and the receiving surface can be achieved. It is reliably transported to the downstream position (destination) in the transport direction, and does not accumulate unlimitedly along the transport path.

According to a second aspect of the present invention, in the belt conveyor device according to the first aspect, the lower surface of the main transport belt and the upper surface of the sub-transport belt are brought into frictional contact with each other so that the first and second belts are brought into contact with each other. The belt transport mechanism is operatively connected.

According to this configuration, power can be transmitted from one belt to the other belt due to frictional contact between the main transport belt and the auxiliary transport belt. That is, if one belt is driven by a drive source such as a motor, the other belt is driven in synchronization with the movement of the one belt. According to such an operational connection, a drive source may be assigned to either one of the first and second belt transport mechanisms, and the apparatus can be simplified. Further, since the first and second belt transport mechanisms can be brought close to each other, the installation space for the apparatus can be reduced.

According to a third aspect of the present invention, in the belt conveyor device according to the first or second aspect, the second belt transport mechanism has a roller for supporting an upper surface of the sub-transport belt. Features.

According to this configuration, since the upper surface of the sub-transport belt is supported by the rollers, it is possible to extend the overall length of the belt and extend the transport distance. In particular, in a configuration in which the lower surface of the main transport belt and the upper surface of the sub-transport belt are in frictional contact, the roller supports not only the upper surface of the sub-transport belt but also the lower surface of the main transport belt. In this case, the transfer of the conveyed object attached to the lower surface of the main transport belt to the upper surface of the sub-transport belt is promoted by the rollers, so that the effectiveness of the re-transport operation by the sub-transport belt is enhanced. That is, according to this configuration, it is possible to increase the transport distance of the transported object by the device while avoiding the transported object from being deposited in the middle of the transport path.

According to a fourth aspect of the present invention, in the belt conveyor device according to any one of the first to third aspects, the first
And a receiving chute disposed below the second belt conveying mechanism, wherein the receiving surface is provided by a bottom wall of the receiving chute.

By arranging the receiving chute, the conveyed objects spilled from the belt can be collected in the receiving chute without receiving. And since the bottom wall of the receiving chute functions as a receiving surface that cooperates with the lower surface of the sub-transport belt,
The transported objects collected in the receiving chute are reliably transported to the downstream position in the transport direction by the sub-transport belt.

According to a fifth aspect of the present invention, in the belt conveyor device according to any one of the first to fourth aspects, the distance between the receiving surface and the lower surface of the sub-transport belt is 0 to 50 m.
m.

This limits the preferred range of the distance between the receiving surface and the lower surface of the sub-transport belt. The interval is 0
Even in the case of mm, by forming the sub-transport belt from an elastic material such as rubber, a transport action in cooperation with the receiving surface can be exhibited. When the interval exceeds 50 mm, not only the transport action by the cooperation of the receiving surface and the sub-transport belt decreases, but also the accumulation amount of the transported object on the receiving surface becomes nonnegligible. It is not preferable to exceed 50 mm.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a belt conveyor according to the present invention will be described below with reference to FIGS. As shown in FIG. 1, the belt conveyor device is configured to transfer a powdery, granular, or lumpy conveyed object from a supply hopper H1 provided at an upstream position in a conveyance direction to a collection hopper H2 provided at a downstream position in the conveyance direction. It is provided indoors or outdoors to transport S (eg, foundry sand) by belt. This apparatus includes a first belt transport mechanism 10 and a second belt transport mechanism 20, which are disposed substantially horizontally between a supply hopper H1 and a recovery hopper H2, and a transport mechanism disposed below the transport mechanisms 10, 20. A receiving chute 30 is provided.

The first belt transport mechanism 10 includes a first head pulley 11 at a downstream position in the transport direction, a first tail pulley 12 at an upstream position in the transport direction, and a main transport stretched between the pulleys 11 and 12 so as to be driven endlessly. The belt 13 is provided. The first head pulley 11 is operatively connected to a motor 15 via a chain 14. When the first head pulley 11 is rotated counterclockwise by the motor 15, the upper surface 13a of the main transport belt 13 travels in the transport direction and the lower surface 13b of the main transport belt 13 moves in the direction opposite to the transport direction ( Travel in the direction of return). Also, the main transport belt 13
, The first tail pulley 12 is also driven counterclockwise. The upper side surface 13a of the main transport belt 13 running in the transport direction functions as a main transport surface on which the transported object S is mounted and moves. For this reason, a plurality of rollers 16 that guide the running of the main transport belt 13 while supporting the load applied to the upper side surface 13a are provided directly below the upper side surface 13a of the main transport belt.

The second belt transport mechanism 20 is disposed immediately below the first belt transport mechanism 10 along the transport direction. The second belt transport mechanism 20 includes a second head pulley 21 at a downstream position in the transport direction, a second tail pulley 22 at an upstream position in the transport direction, and a sub-transport belt 23 stretched between the pulleys 21 and 22 so as to be driven endlessly. Have. Immediately below the upper side surface 23a of the sub-transport belt 23, the belt 23 is supported while supporting the load applied to the upper side surface 23a.
A plurality of rollers 24 (referred to as return rollers) for guiding the traveling of the vehicle are provided. These return rollers 2
Reference numeral 4 also has a function as a pressing unit or an urging unit for bringing the sub-transport belt upper surface 23a into frictional contact (or close contact) with the main transport belt lower surface 13b. In other words, the sub-transport belt 23 is sandwiched between the group of return rollers 24 and the main transport belt 13. By this group of return rollers 24, power transmission between the two belts 13 and 23 by friction contact between the lower side surface 13b of the main transport belt and the upper side surface 23a of the sub-transport belt is ensured, and the main transport belt 1
The sub-transport belt 23 is driven in synchronization with the driving of the third belt. That is, with the driving of the main transport belt 13, the sub-transport belt 23
The upper side surface 23a travels in the return direction, and the lower side surface 23b of the sub-transport belt 23 travels in the direction opposite to the return direction (transport direction). At this time, the second head pulley 21 and the second tail pulley 22 follow clockwise.

Incidentally, the main conveyor belt 13 and the sub conveyor belt 23 are preferably constituted by flat belts made of rubber. It goes without saying that the main transport belt 13 has sufficient rigidity to support the load of the transported object S, but both belts 13 and 23 also have some elasticity or flexibility.

The receiving chute 30 extends in the conveying direction immediately below the second belt conveying mechanism 20. As shown in FIG. 2, the first and second two-story structure
Conveyor frames 41 and 42 having channel-like cross sections are provided on both left and right sides of the belt transport mechanisms 10 and 20, respectively. The conveyor frames 41 and 42 are originally frames for rotatably supporting various pulleys and roller groups.
In the present device, the pair of conveyor frames 41, 42
The receiving chute 30 is provided so as to be connected to the lower side of the receiving chute. The receiving chute 30 is composed of a bottom wall 31 as a receiving surface, and a pair of side walls 32 and 33 vertically erected at both left and right ends of the bottom wall 31. These bottom wall 31 and side walls 32, 33 extend over the entire length of both belts 13, 23 in the longitudinal direction. In particular, the side walls 32 and 33 are integrated with the conveyor frames 41 and 42 and play a role of guiding the conveyed objects spilling from both sides in the width direction of the belts 13 and 23 to the bottom wall 31 while preventing them from scattering outside.

As shown in FIGS. 1 and 2, the bottom wall 31 of the receiving chute 30 faces in parallel with the lower side surface 23 b of the sub-transport belt 23 over the entire length thereof. Distance C between lower side surface 23b and bottom wall 31 of sub-transport belt 23
Is preferably set to 0 to 50 mm. Incidentally, in this embodiment, the interval C is set to approximately 0 mm, and the lower side surface 23 b of the sub-conveyor belt 23 is
It slides on top. However, since the receiving chute 30 is generally made of metal such as iron, the frictional resistance between the rubber sub-transport belt 23 and the metal receiving chute bottom wall 31 is reduced by the rubber main transport belt 13 and the sub-transport belt. It is much smaller than the frictional force between the conveyor belts 23. Therefore, the contact between the sub-transport belt 23 and the bottom wall 31 does not hinder the driving of the sub-transport belt 23 by the main transport belt 13.

During operation of the belt conveyor device, the main transport belt 13 is driven by the motor 15,
The sub-transport belt 23 is driven according to the driving of the main transport belt 13. Feed hopper H1 at upstream position
As the molding sand S is successively supplied to the upper side surface 13a of the main conveyor belt, the molding sand S is carried to the downstream position by the upper side surface 13a traveling in the conveying direction. Then, when the traveling direction of the belt surface is reversed by the first head pulley 11, most of the molding sand S placed on the upper side surface 13a of the main transport belt is transferred into the collection hopper H2. However, even after the belt surface is reversed and inverted, a part of the foundry sand S continues to adhere to the lower surface 13b of the main transport belt traveling in the return direction. This is mainly because the foundry sand S has a wide range of particle diameters, and is a mixture of powder, granules and small lumps of mixed sand that also contains moisture. By adhering to the surface.

Since the lower surface 13b of the main conveyor belt is in opposition to the upper surface 23a of the auxiliary conveyor belt, the main conveyor belt 1
The casting sand S which continues to adhere to the main conveyor belt lower surface 13
b and is transported from the downstream position to the upstream position while being sandwiched between the sub-transport belt and the upper side surface 23a. In the meantime, the molding sand S is in a state of being pressed between the two rubber belts 13 and 23, so that it does not spill laterally during the transportation. When the lower side surface 13b of the main conveyor belt and the upper side surface 23a of the auxiliary conveyor belt are separated near the upstream position, most of the molding sand S adhered to the main conveyor belt 13 moves to the upper side surface 23a of the auxiliary conveyor belt 23. Then, the second tail pulley 22
When the running direction of the belt surface is reversed by the above, part of the molding sand S attached to the upper side surface 23a of the sub-transport belt is
0, and the rest continues to adhere to the sub-transport belt 23 as it is. The casting sand S separated from the sub-transport belt 23 may temporarily accumulate at an upstream position of the receiving chute 30. However, when the sand S accumulates until it contacts the belt surface, it is conveyed by the sub-transport belt lower surface 23b traveling in the transport direction. Since it is sent out in the direction, the casting sand S does not accumulate at an upstream position of the receiving chute 30 without limitation.

Since the lower surface 23b of the sub-transport belt 23 slides in contact with the bottom wall 31 of the receiving chute 30, the molding sand S transferred from the lower surface 13b of the main conveying belt to the sub-transport belt 23 and the upstream of the receiving chute 30 are provided. The casting sand S sent out from the position is slid by the rubber belt 23 between the stationary receiving chute bottom wall 31 and the sub-transport belt lower side surface 23b running in the transport direction, and is dragged or rolled. It is transported again to the downstream position. In addition,
When the sub-transport belt lower surface 23b slides while contacting the stationary receiving chute bottom wall 31, there is a secondary effect that the molding sand S adhered to the belt lower surface 23b is scraped off from the belt surface. . By the re-transporting action of the sub-transport belt lower side 23b traveling in the transport direction in this manner,
Almost all of the foundry sand S returned to the upstream position of the receiving chute 30 and the foundry sand S spilled into the receiving chute 30 from the upper side surface 13a of the main conveyor belt are reliably transported to the downstream position and sent into the collection hopper H2.

(Effects) According to the present embodiment, the following effects can be obtained. The sub-transportation of the molding sand S that has returned to the upstream position from the downstream position by adhering to the lower surface 13b of the main conveyor belt 13 and the molding sand S that has spilled into the receiving chute 30 from the upper surface 13a of the main conveyor belt 13 Due to the re-transporting action of the belt 23, it can be reliably transported to the recovery hopper H2 at the downstream position. For this reason, the casting sand S is prevented from being accumulated in the receiving chute 30 indefinitely, and the failure of the device due to the deposited sand and environmental and sanitary problems can be avoided.

The first and second belt transport mechanisms 10 and 10 are driven by frictional contact between the main transport belt 13 and the sub-transport belt 23.
20 is operatively connected. Therefore, a single motor 15
Thus, the two belts 13 and 23 can be driven simultaneously. In addition, the first and second belt transport mechanisms 10, 10 are operatively connected by frictional contact between the two belts 13, 23.
There is no need to provide a special power transmission mechanism between the two. For this reason, the structure of the belt conveyor device is simplified, and a large installation space is not required. Further, since the structure is simple, equipment costs and maintenance costs can be reduced.

The conveying capacity of the foundry sand S by the sub-conveyor belt 23 can be considerably smaller than the conveying capacity of the main conveyor belt 13, so that the diameter of the pulleys 21 and 22 constituting the second belt conveying mechanism 20 And the sub-transport belt 23 can be a thin and lightweight flat belt. Therefore, the space required for installing the second belt transport mechanism 20 can be reduced, and it becomes easy to additionally install the second belt transport mechanism 20 directly below the existing belt transport mechanism 10.

There may be a direction in which the two belts 13 and 23 are worried that the wear of both belts 13 and 23 will be accelerated due to frictional contact with each other. However, the main transport belt lower surface 13
b and the upper side surface 23a of the sub-transport belt are in surface contact over the entire longitudinal direction.
Since the belts 3 are driven synchronously, there is no relative speed difference between the belts. Therefore, abrasion due to frictional contact between the belts is reduced as much as possible, and the replacement time of the belt is not extremely advanced.

(Another Example) The embodiment of the present invention may be modified as follows. In the above-described embodiment, the power transmission from one to the other is enabled by bringing the two belts 13 and 23 into frictional contact. Instead, the first and second belt transport mechanisms 1 are used.
A mechanical power transmission mechanism may be provided between 0 and 20 and both belt transport mechanisms 10 and 20 may be operatively connected. For example, as shown in FIG. 3, a power transmission belt or chain 25 is stretched between the first head pulley 11 and the second head pulley 21 in an “8” shape, and the power of the motor 15 is applied to both heads. You may make it transmit directly to the pulleys 11 and 21. If such a power transmission configuration is adopted, a design in which the main transport belt 13 and the sub-transport belt 23 are separated from each other to make them non-contact is also possible. Alternatively, the lower surface 13 of the main conveyor belt
It is also possible to design such that a relative speed difference is generated between the sub-belt and the sub-transport belt upper side surface 23a while keeping them in contact with each other. By the rubbing effect of the relative speed difference between the two belts 13 and 23, the transfer of the conveyed object attached to the lower side surface 13b of the main conveyor belt to the upper side surface 23a of the auxiliary conveyor belt can be promoted.

The receiving chute 30 is provided in the above-described embodiment and another example.
The receiving chute 30 may not be provided as long as it can function as a receiving surface that faces substantially parallel to the lower side surface 23b. In other words, as the essence of the invention, what corresponds to a receiving surface capable of exhibiting the re-transporting action of the sub-transport belt 23 in cooperation with the sub-transport belt lower side surface 23b running in the transport direction is provided inside or outside the belt conveyor device. It only has to exist.

The belt conveyor device of the present invention can be used for conveying objects other than the foundry sand S. For example, flour, cement, powder or granules such as dust, coal,
Granules or small lumps such as gravel, quarry, or
It can also be used to transport mixtures of flour, granules and lumps.

[0034]

As described above in detail, according to the present invention, a part of the powdery, granular, or small lumped object adheres to the main conveyor belt, and the main conveyor belt reaches the destination. Because part of the conveyed objects that could not be conveyed can be re-conveyed to the destination by the action of the sub-conveyor belt, almost all of the conveyed objects can be reliably conveyed from the upstream position in the conveying direction to the downstream position Can be. For this reason, the transported object does not accumulate unlimitedly in the middle of the transport path, and the environment and hygiene are not degraded and the apparatus is not damaged. Further, since the belt conveyor device of the present invention has a simple structure, it can be manufactured at low cost and can be installed in a narrow installation space.

[Brief description of the drawings]

FIG. 1 is a front view showing an outline of a belt conveyor device.

FIG. 2 is a cross-sectional view of the belt conveyor device of FIG.

FIG. 3 is a partial front view showing another example of the belt conveyor device.

[Explanation of symbols]

10: first belt transport mechanism, 13: main transport belt, 1
3a: Upper side of the main conveyor belt, 13b: Lower side of the main conveyor belt, 16: Roller, 20: Second belt conveyor mechanism, 23
... sub-transport belt, 23a ... sub-transport belt upper surface, 23b
... lower side of the sub-transport belt, 24 ... return roller, 30 ...
Receiving chute, 31 ... bottom wall (receiving surface), C ... interval, S ...
Sand (transported object).

Continuing on the front page (72) Inventor Masanori Korenaga 1 Takano Shinmachi Tenno, Toyota City, Aichi Prefecture Aisin Takaoka Co., Ltd. (72) Inventor Keisuke Yabana 1 Takaoka Shinmachi Tenno 1 Toyota City, Aichi Prefecture Aisin Takaoka Corporation (72) Inventor Ito Kato 1 No. 1 Tenno, Takaokashinmachi, Toyota-shi, Aichi Prefecture F-term (reference) 3F023 AA02 AB02 BA02 BB01 BC01 EA01

Claims (5)

[Claims] 1. From the upstream position in the transport direction to the downstream position,
A belt conveyor device for transporting a powdery, granular, or small lump transported material, comprising: a first belt transport mechanism having an endlessly drivable main transport belt; and a first belt transport mechanism directly below the first belt transport mechanism. A second belt transport mechanism having a sub-transport belt disposed and capable of being driven endlessly, wherein the sub-transport belt has an upper surface facing the lower surface of the main transport belt and a lower portion of the second belt transport mechanism. Has a lower surface that faces substantially parallel to the receiving surface, and as the upper surface of the main transport belt travels in the transport direction, the lower surface of the sub-transport belt travels in the same direction as the transport direction. A belt conveyor device wherein the first and second belt transport mechanisms are driven so as to perform the operation. 2. A method according to claim 1, wherein a lower surface of said main conveyor belt and an upper surface of said sub conveyor belt come into frictional contact with each other.
The belt conveyor device according to claim 1, wherein the belt transport mechanism is operatively connected. 3. The belt conveyor device according to claim 1, wherein the second belt transport mechanism has a roller that supports an upper surface of the sub-transport belt. 4. The apparatus according to claim 1, further comprising a receiving chute disposed below said first and second belt transport mechanisms, wherein said receiving surface is provided by a bottom wall of said receiving chute. The belt conveyor device according to any one of claims 1 to 3. 5. The belt conveyor device according to claim 1, wherein an interval between the receiving surface and a lower surface of the sub-transport belt is set to 0 to 50 mm. .