JPH06100489B2 - Metering method and device - Google Patents

Description

Detailed Description of the Invention Technical Field: This invention relates to a weighing method and weighing device in which a weighing belt conveyor is loaded onto a load cell, an object to be weighed is received from an input belt conveyor, and the weight of the object is measured while being transferred to an output belt conveyor.

BACKGROUND ART For example, when inspecting the weight of an object to be weighed, such as a pre-weighed packaged product, a weighing device is used in which a weighing belt conveyor is loaded onto a load cell, which is a weight detection means. An inlet belt conveyor is placed at one end of the weighing belt conveyor, while an outlet belt conveyor is placed at the other end. The packaged products are sent from the inlet belt conveyor to the weighing belt conveyor, and after their weight has been measured, they are discharged onto the outlet belt conveyor, and a sorting device is operated as necessary.

However, as mentioned above, this type of weighing device measures the weight of the objects while they are moving on the weighing belt conveyor, so there is a problem in that weighing errors occur due to aerodynamic forces such as buoyancy caused by the speed difference between the objects and the surrounding air. In particular, the higher the conveying speed of the weighing belt conveyor, the larger the weighing error becomes.

One proposed solution to this problem is to measure the weight of the sample to be weighed both when stationary and while moving, and then correct the weighing error that occurs while the object is actually moving at the data level. However, differences in the packaging shape of the object to be measured and the spacing between the objects change the air flow, which in turn changes the magnitude of the aerodynamic force. This results in the problem of weighing errors.

Another method has been proposed in which air is blown in the same direction as the transport direction of the objects to be weighed, in order to minimize the difference in speed between the objects and the surrounding air.
Since it is extremely difficult to make the air flow uniform, wind pressure is applied to the objects to be weighed and the weighing belt conveyor, which causes a problem of inconsistency in the measurement results.

This invention has been made in consideration of these problems, and aims to provide a weighing method and weighing device that can reduce weighing errors caused by aerodynamic forces such as buoyancy that occur during transportation, regardless of the transport speed of the weighing belt conveyor, the size and packaging shape of the objects to be weighed, etc.

DISCLOSURE OF THE INVENTION In order to achieve the above object, the weighing method of the present invention uses a weighing device that loads a weighing belt conveyor onto a weight detection means, places objects to be weighed on the belt, and measures the weight of the objects while transporting them.Each time an object is transported, the aerodynamic force that corresponds to the weight component of the aerodynamic force acting on the object during transport is measured, and the weight of the object is corrected using this measured value.

In this weighing method, the aerodynamic force acting on the objects being transported is measured each time the objects are transported, and therefore it is possible to accurately measure aerodynamic forces such as buoyancy even if they change due to the transport speed, packaging shape, etc. Therefore, by correcting the weight of the objects using the measured aerodynamic force, it is possible to accurately measure the true weight of the objects.

In addition, the weighing device of the present invention has a weighing belt conveyor that conveys the objects to be weighed loaded on a weight detection means, and
The belt conveyor device includes a correction means for correcting the weight of the object to be weighed by receiving an air force corresponding to the weight component of the air force acting on the object to be weighed while being transported by the belt conveyor device including the weighing belt conveyor.

In this weighing device, the correction means receives the aerodynamic force acting on the object to be weighed during transport, which corresponds to the weight component, and corrects the weight by taking this aerodynamic force into account.
Therefore, it is also possible to reduce the measurement error caused by aerodynamic forces such as buoyancy.

In a preferred embodiment of the present invention, the correction means comprises:
The weighing device further comprises an aerodynamic force acting member positioned at least above the objects being weighed while being transported on the weighing belt conveyor, and means for applying a load to the weight detecting means with the aerodynamic force acting member.

In this embodiment, when the objects to be weighed are conveyed, a speed difference occurs between the objects and the surrounding air, and the pressure on the top surface of the objects to be weighed becomes lower than the pressure of the surrounding air. The aerodynamic force caused by this pressure difference acts on the top surface of the objects to be weighed and the bottom surface of the aerodynamic member. Therefore, this aerodynamic force is expressed as follows:
Since the aerodynamic forces act in opposite directions on the object to be weighed and the aerodynamic force acting member, respectively, by loading the aerodynamic force acting member onto the weight detecting means, the aerodynamic forces are cancelled out,
As a result, it is possible to reduce measurement errors caused by aerodynamic forces such as buoyancy.

In a preferred embodiment of the present invention, the aerodynamic member is supported on the weighing belt conveyor via a support portion.

In a preferred embodiment of the present invention, the aerodynamic force acting member is formed in the shape of a tunnel through which the objects to be weighed pass.

In another preferred embodiment, the aerodynamic member comprises:
It is formed into a plate, sheet or cloth shape.

In still another preferred embodiment, a height adjusting device is provided for freely adjusting the height of the aerodynamic member from the measuring belt conveyor.

In this embodiment, the height of the aerodynamic force acting member from the belt conveyor is freely adjustable, so that the aerodynamic force acting member can be brought close to the object to be weighed to an optimum position where aerodynamic force can be easily detected, in accordance with the height of the object to be weighed, thereby further reducing weighing errors.

If necessary, it is preferable to provide a drive unit for driving the height adjusting device and a control unit for controlling the drive unit in accordance with the height of the object to be weighed.

This allows the aerodynamic force acting member to be automatically brought closer to the object to be weighed in accordance with the height of the object, making the weighing operation easier.

In an embodiment of the present invention, the correcting means
The apparatus includes an aerodynamic force acting member positioned above the objects being transported by a belt conveyor including the weighing belt conveyor, another weight detecting means for detecting the aerodynamic force acting on the aerodynamic force acting member, and a computing unit, which calculates the true weight of the objects based on weight signals from both the weight detecting means.

In this embodiment, while the objects to be weighed are being transported by a belt conveyor device including a weighing belt conveyor, the air such as buoyancy acting on the objects to be weighed is detected by another weight detection means via an aerodynamic member, and a calculator calculates the true weight of the objects to be weighed based on the weight signals from both weight detection means, thereby making it possible to accurately determine the true weight.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a weighing device showing a first embodiment of the present invention, Fig. 2 is a cross-sectional view showing the main part of the present invention, Fig. 3 is a perspective view of the main part of an aerodynamic member of the present invention, with a part cut away, Fig. 4 is a perspective view of an aerodynamic member etc. showing a second embodiment, Fig. 5 is a perspective view of an aerodynamic member etc. showing a third embodiment, Fig. 6 is a cross-sectional view showing the left end of the link, Fig. 7 is a cross-sectional view of the left end of the link, Fig.
The figure is a front view showing a modified example of the aerodynamic member, FIG. 8 is a schematic diagram showing the fourth embodiment, FIG. 9 is a schematic diagram showing the fifth embodiment, FIG. 10 is a table showing data input to the control device, FIG. 11 is a schematic diagram showing the sixth embodiment, and FIG. 12 is a schematic diagram showing the seventh embodiment.

Best Mode for Carrying Out the Invention An embodiment of the present invention will now be described with reference to the accompanying drawings.

1 to 3 show a first embodiment of the present invention.

In Fig. 1, an inlet belt conveyor 2 for feeding in the object A (Fig. 2) is arranged on the inlet side of the weighing device main body 1, while an outlet belt conveyor 4 equipped with a sorting unit 3 is arranged in a straight line on the outlet side. The control device 6 has a keyboard 7 for inputting measurement conditions,
A display 8 is provided to display the measurement results.

FIG. 2 shows an example of the weighing device main body 1.

In this figure, the weighing belt conveyor 10 is
The frame 12 is fixed to a weight detection device (weight detection means) 11 and is loaded on the weight detection device 11. A drive roller 14 connected to a motor 13 is provided at one end of the frame 12, and an idle roller 15 is provided at the other end. A belt 16 is stretched between these rollers 14, 15.

An aerodynamic member 17 is disposed above the weighing belt conveyor 10. The aerodynamic member 17 is positioned above the objects A being transported by the weighing belt conveyor 10, covers the objects A, and, as will be described later,
Of the aerodynamic forces acting on the objects A being transported by the weighing belt conveyor 10, the objects A are subjected to an aerodynamic force that corresponds to (cancels) the weight component.
The length La of the aerodynamic force acting member 17 is set to, for example, approximately the same as the length Lc of the weighing belt conveyor 10.

In FIG. 3, the aerodynamic force acting member 17 is
The conveyor is formed in a tunnel shape through which the conveyor passes, and is fixed to the frame 12 of the weighing belt conveyor 10 via the support part 18.
The weight detector 11 (FIG. 2) is loaded with the air force acting member 17. In this embodiment, as shown in FIG.
The weighing device is covered with a windshield 5. The windshield 5 prevents the air (wind) flowing in the room where the weighing device is installed from passing through the aerodynamic force acting member 17.
As shown in FIG. 2, the length Lg of the aerodynamic member 17 is set to be longer than the length La of the aerodynamic member 17 and the length Lc of the weighing belt conveyor 10.

In this embodiment, the aerodynamic force acting member
17, and a support portion 18 as means for applying the aerodynamic force received by the aerodynamic force acting member 17 to the weight detecting device 11.
A correction means is provided to correct the weight of the object A to be weighed.

Next, the principle of the present invention will be explained.

When the object A is transported by the belt 16, a speed difference occurs between the object A and the surrounding air, and the pressure on the top surface of the object A becomes lower than the pressure of the surrounding air. As a result, an air force, such as a buoyancy Fu, acts on the object A, reducing the apparent weight of the object A.
Since the aerodynamic force acting member 17 is disposed close to the top surface of the object A to be weighed, a buoyant force Fu that pulls the object A upward is generated.
The aerodynamic force acting member 17 receives a force Fd of the same magnitude as that of the aerodynamic force acting member 17, which pulls the aerodynamic force acting member 17 downward. This force acting on the aerodynamic force acting member 17 acts on the weight detecting device 11 via the support portion 18 (FIG. 3) and the frame body 12. Therefore, the weight detecting device 11 receives the weight of the object A to be weighed (Fu) and the aerodynamic force acting member 17.
The weight increase (Fd) of 17 acts through the frame 12, and the weight detection device 11 measures a weight equal to the weight of the object A in a stationary state.

In the above configuration, the weight component of the aerodynamic force acting on the object A is measured each time the object A is transported, so even if the moving speed or external shape of the object A changes and the magnitude of the buoyant force Fu acting on the object A changes, the same load acts on the aerodynamic force acting member 17, so it is possible to cancel out the buoyant force Fu acting on the object A. Therefore, it is possible to reduce weighing errors caused by aerodynamic forces such as buoyancy occurring during transportation.

When the weight of the object A to be weighed was measured without the aerodynamic member 17 attached, an error of 0.71 grams occurred on the negative side compared to the weight in a stationary state. On the other hand, when the weight of the same object A was measured with the aerodynamic member 17 attached, an error of 0.01 grams occurred on the negative side. This demonstrates that the aerodynamic member 17 has a significant effect in reducing errors, and is extremely effective for weighing devices that require measurements with an accuracy of around 0.1 grams.

In this embodiment, since the windshield 5 is provided, even if there is an air flow from the lateral direction relative to the conveying direction of the weighing belt conveyor 10 in the room, this air flow is blocked by the windshield 5.
However, it goes without saying that the windshield 5 is not always necessary.

Other embodiments will be described below with reference to FIGS. 4 to 12.

The following embodiments are basically the same as the first embodiment, and the same or corresponding parts are denoted by the same reference numerals.
Only the differences will be explained.

4, this embodiment includes an adjustment device 19 that allows the height of the aerodynamic member 17 from the belt 16 of the weighing belt conveyor 10 to be freely adjusted. That is, a pin 20 is provided on the side of the frame 12, and a plurality of locking holes 17b are provided in the vertical direction at the bottom of the side surface 17a of the aerodynamic member 17, for supporting the aerodynamic member 17 on the pins 20. According to this embodiment, by arbitrarily setting the positions of the locking holes 17b that lock onto the pins 20, the height of the aerodynamic member 17 from the weighing belt conveyor 10 can be set to, for example, three different heights. Therefore, even if the height of the object A to be weighed changes, the absolute values of the buoyant force Fu acting on the object A and the downward force Fd acting on the aerodynamic member 17 can be set to approximately the same by appropriately setting the distance between the object A and the aerodynamic member 17. Therefore, high measurement accuracy can be maintained even if the height of the object A changes.

FIG. 5 shows the main part of the third embodiment.

In this embodiment, the aerodynamic force acting member 17 is formed in a plate shape. Rails 22 having guide grooves 21 are provided on the side surfaces of the aerodynamic force acting member 17 and the frame 12. The rails 22 fixed to the frame 12 and the rails of the aerodynamic force acting member 17
A pantograph 23 (adjustment device 19) is provided between the rails 22. The right end 24a of each link 24 (support portion 18) that constitutes the pantograph 23 is fixed to one of the rails 22.
As shown in FIG. 6, the left end 24b is secured to the rail by a stepped bolt 24c.
5. Therefore, by manually operating the adjusting device 19, which is constituted by a pantograph 23 or the like shown in FIG. 5, the height of the aerodynamic member 17 can be changed steplessly.

In the above embodiment, the pneumatic force acting member 17 is plate-shaped. However, as shown in the modified example of FIG.
Furthermore, the curved shape may be in accordance with the shape of the upper surface of the
The aerodynamic force acting member 17 may be formed of a corrugated plate or the like instead of a flat plate.

FIG. 8 shows a fourth embodiment.

In this figure, a height detection device 25 is fixed to the frame (not shown) of the carry-in belt conveyor 2. The height detection device 25 is, for example, a number of photodetectors 25a, each consisting of a light emitter and a light receiver, arranged facing each other on both sides of the carry-in belt conveyor 2, spaced apart vertically.
The height of the object A to be weighed is detected by the position of the photodetector 25a that receives the light from the projector without being blocked by the object A. The control device 6 receives a height signal a from the height detection device 25 and outputs a motor rotation signal b to the drive device 26. The drive device 26 receives the motor rotation speed signal b and changes the height of the aerodynamic member 17. The drive device 26 is equipped with a pulse motor and bevel gear, not shown, and moves the left end 24b of the link 24 in Figure 5 in the horizontal direction.

According to the embodiment shown in FIG. 8, the aerodynamic member 17 can be automatically moved closer to the object A to be weighed in accordance with the height of the object A, and the vertical gap between the aerodynamic member 17 and the object A can be set to an appropriate size, which facilitates the weighing operation.

In the above embodiment, the height of the object A to be weighed is detected by the height detector 25, but it is not always necessary to detect the height of the object A. An example of this is shown in the fifth embodiment in FIG.

In FIG. 9, upstream of the weighing belt conveyor 10,
A bar code reader 27 is provided. This bar code reader 27 reads the bar code B attached to the object A to be weighed. The bar code B contains information such as the product number, and the object A to be weighed has a height corresponding to the product number, as shown in FIG. 10.
The data shown in the figure is input in advance to the control device 6 shown in Fig. 9. In this embodiment, the control device 6 uses a bar code reader.
27, the height of the pneumatic force acting member 17 is changed in accordance with the height of the object A to be weighed, in the same manner as described above.

The height recognition based on the product number may be performed in the conveying process upstream of the carry-in belt conveyor 2, and the height may be adjusted by tracking the objects A to be weighed.

In the above-described embodiments, the aerodynamic force acting member 17 is supported on the frame 12 of the weighing belt conveyor 10 as shown in FIG. 2. However, the aerodynamic force acting member 17 may be directly supported on the weight detecting device 11 and loaded thereon.

In the above embodiments, the aerodynamic force acting member 17 is applied to the weight detecting device 11 to which the weighing belt conveyor 10 is applied, but the aerodynamic force acting member 17 may be applied to another weight detecting device. An example of this is shown in the sixth embodiment in Fig. 11.

In Fig. 11, the pneumatic force acting member 17 is suspended from above via another weight detecting device 11A. The weight detecting device 11 is connected to the object A to be weighed and the weighing belt conveyor 10.
The weight detecting device 11A detects the aerodynamic force acting on the aerodynamic member 17 and the buoyancy acting on the object A to be weighed, while the other weight detecting device 11A detects the aerodynamic force acting on the aerodynamic member 17.
The weight sensors 11A and 11B output weight signals w1 and w2, respectively, to the calculator 28. The calculator 28 calculates the true weight of the object A to be weighed based on the weight signals w1 and w2, for example, as w1+w2=A.

In this embodiment, the aerodynamic force acting member 17, the other weight detecting device 11A, the calculator 28, and the like constitute a correcting means.

The weight detection device 11A does not necessarily have to be provided at the position of the weighing belt conveyor 10, but may be provided at the carry-in belt conveyor 2 or at the transport belt conveyor upstream of the carry-in belt conveyor 2, as in the seventh embodiment shown in FIG.
In other words, in this invention, each time an object A to be weighed is transported, the aerodynamic force corresponding to the weight component (buoyancy) of the aerodynamic force Fu acting on the object A during transport is measured at the position of the transport belt conveyor 2A, the carry-in belt conveyor 2, the weighing belt conveyor 10, or the like (belt conveyor device), and the weight of the object A to be weighed is corrected using this measured value (corresponding to signal w1).

The aerodynamic force is not limited to the buoyancy Fu, and depending on the shape of the object A to be weighed, a downward force may also act on the object A to be weighed.

INDUSTRIAL APPLICABILITY The present invention can be used as a weighing device that inspects the weight of an object to be weighed, such as a weighed and packaged product, while conveying the object on a belt conveyor.

Claims (9)

[Claims] [Claim 1] A weighing method in which the weight of an object to be weighed is measured while the object is being transported on the belt of a weighing device in which a weighing belt conveyor is loaded onto a weight detection means, characterized in that each time the object is transported, the aerodynamic force corresponding to the weight component of the aerodynamic force acting on the object to be weighed during transport is measured, and the weight of the object to be weighed is corrected using this measured value. [Claim 2] A weighing device in which a weighing belt conveyor that transports the objects to be weighed is loaded onto a weight detection means, characterized in that the weighing device is equipped with a correction means that corrects the weight of the objects to be weighed by receiving an aerodynamic force corresponding to the weight component of the aerodynamic force acting on the objects to be weighed while being transported by a belt conveyor device including the weighing belt conveyor. [Claim 3] A weighing device as described in claim 2, wherein the correction means comprises an aerodynamic force acting member positioned at least above the object to be weighed being transported on the weighing belt conveyor, and means for loading this aerodynamic force acting member onto the weight detection means. 4. A weighing device according to claim 3, wherein said aerodynamic force acting member is supported on said weighing belt conveyor via a support portion. 5. A weighing device according to claim 3, wherein said aerodynamic force acting member is formed in the shape of a tunnel through which said objects to be weighed pass. 6. A weighing device according to claim 3, wherein said aerodynamic member is formed in the shape of a plate, a sheet or a cloth. 7. A weighing device according to claim 3, further comprising a height adjusting device for freely adjusting the height of said pneumatic force acting member from said weighing belt conveyor. 8. A weighing device according to claim 7, further comprising a drive unit for driving said height adjusting device, and a control unit for controlling said drive unit in accordance with the height of said object to be weighed. [Claim 9] A weighing device as described in claim 2, wherein the correction means comprises an aerodynamic force acting member positioned above the object to be weighed being transported on a belt conveyor device including the weighing belt conveyor, another weight detection means for detecting the aerodynamic force acting on the aerodynamic force acting member, and a calculator for calculating the true weight of the object to be weighed based on weight signals from both of the weight detection means.