JPH08247828A - Weighing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a weighing device capable of easily performing highly accurate weighing irrespective of a change in the conveying speed of a weighing conveyor. A processing timing determination means 31 processes a weighing signal based on a moving distance of an article M on a weighing conveyor 2 and a length L2 of the weighing conveyor 2 in a carrying direction and a length L1 of the article in a carrying direction. Since the timing is determined, the calculation of each processing timing is simplified and the accuracy is improved, and it is not necessary to input the filtering required time corresponding to the transport speed V of the weighing conveyor 2, and the operation is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weighing device in which a weight detector (load cell) is loaded with a weighing conveyor and articles are weighed while being conveyed on the weighing conveyor.

[0002]

2. Description of the Related Art Generally, when a large number of articles produced in a factory are continuously weighed, a take-in conveyor, a weighing conveyor,
And a metering device with a discharge conveyor is used. The articles taken in from the take-in conveyor are conveyed while being placed on the weighing conveyor, weighed by the weight detector (load cell) of the weighing conveyor, and then discharged from the discharge conveyor.

The weighing operation in the weighing conveyor is performed as follows. First, the tip of the article sent from the take-in conveyor to the weighing conveyor is detected by the detection sensor provided between the take-in conveyor and the weighing conveyor. After that, the article is transferred from the take-in conveyor to the weighing conveyor, and weighing is started at the timing when the entire article is transferred to the weighing conveyor (weighing start timing), and the weighing signal after this timing is adopted.

Further, since this measurement signal contains a vibration component caused by the vibration of the belt conveyor, it is necessary to remove this vibration component by a filter. Therefore, after the weighing is started and the vibration component is removed by the filter, the weighing data is determined (weighing timing), and the weighing data at this timing is adopted as the accurate weight value of the article.

The above processing timing is calculated on the basis of the length L1 of the article in the conveying direction, the length L2 of the measuring conveyor in the conveying direction, the conveying speed V of the measuring conveyor, and the filtering required time t as input parameters. To be done. The measurement start timing is L1 / V time after the tip of the article is detected by the detection sensor. In addition, the weighing timing is the transport speed V from this weighing start timing.
After the required filtering time t set in accordance with Usually, this time t is preferably as long as possible in order to remove the vibration component, so that the time when the entire article is on the weighing conveyor, that is, (L2-L1) / V
Is set to As described above, Japanese Patent Application No. 3-14 discloses a conventional device for weighing articles at a predetermined timing based on time.
There is a weighing device disclosed in Japanese Patent No. 1161.

[0006]

However, in the above-mentioned conventional apparatus, when the carrying speed V of the weighing conveyor is changed to improve productivity, the above-mentioned weighing start timing and weighing timing are set to the carrying speed. Since it is necessary to recalculate according to V and it is necessary to input the filtering required time t according to the transport speed V, there is a problem that it is complicated.

Further, depending on the capacity of the motor that drives the weighing conveyor, the rotation speed of the motor changes when the load changes, and the input transfer speed and the actual transfer speed deviate, causing the processing timing to deviate. There was also a problem that high-accuracy weighing could not be achieved.

An object of the present invention is to solve the above-mentioned problems and to provide a weighing device capable of easily performing highly accurate weighing regardless of the change in the conveying speed of the weighing conveyor.

[0009]

In order to achieve the above object, a weighing device of the present invention drives a conveyor by a drive motor to convey articles and weighs articles, and a weighing conveyor for conveying the articles. A weighing device comprising a data input means for inputting a length and a length of an article in a conveying direction, and a filtering means for filtering a weighing signal of an article from the weighing conveyor, the weighing conveyor being based on a rotation amount of a drive motor. Moving distance detecting means for detecting the moving distance of the article, a processing for determining the processing timing of the weighing signal based on the moving distance, the length in the carrying direction of the weighing conveyor and the length in the carrying direction of the article. A timing determining means is provided. According to the above configuration, the processing timing determination means determines the processing timing of the weighing signal based on the moving distance of the article on the weighing conveyor, the length of the weighing conveyor in the transport direction and the length of the article in the transport direction. . Therefore, since the processing timing of the weighing signal is determined by the moving distance of the article, it is not necessary to recalculate each processing timing according to the change of the conveyance speed, so that the calculation of each processing timing is simplified and the accuracy is improved. At the same time, it is not necessary to input the required filtering time according to the conveying speed of the weighing conveyor, which facilitates the operation. Here, the processing timing of the weighing signal refers to timing related to execution of processing necessary for obtaining a weighing value from the weighing signal, such as weighing start timing and weighing timing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a weighing device according to an embodiment of the present invention. This apparatus comprises a conveyor C driven by a drive motor M1 and a weighing conveyor 2 including a weight detector (load cell) 8 for detecting the weight of the article M on the conveyor C while conveying the article M,
Rotation amount detecting means 18 for detecting the rotation amount of the drive motor M1
A take-in conveyor 4 that takes in the articles M and sends them to the weighing conveyor 2, a discharge conveyor 6 that discharges the articles M sent from the weighing conveyor 2, a take-in conveyor 4 and a weighing conveyor 2
The detection sensor 10 disposed on the boundary between the sensor M, the length of the article M in the transport direction (hereinafter referred to as “article length”) L1 and the length of the weighing conveyor 2 in the transport direction (hereinafter referred to as “conveyor length”) L2 The data input means 22 for inputting the data and the control unit 20 for controlling this device are provided.

The weighing conveyor 2 loads a weight detector (load cell) 8 via a frame F with a conveyor C composed of a conveyor belt B which is wound around a driving roller J1 connected to a driving motor M1 and a driven roller J2. It was done.
A rotation amount detector 18, which generates a pulse signal P with rotation, is attached to the drive motor M1 like an encoder. The moving distance detecting means 30 is composed of a counter that counts the pulse signal P, starts counting from the timing when the tip of the article M is detected by the detection sensor 10, and counts the moving distance of the article M on the weighing conveyor 2. Output as value P1.

A detection sensor 10 is arranged between the take-in conveyor 4 and the weighing conveyor 2, and optically detects the leading end of the article M passing between them. This detection sensor 10 is
For example, it is configured by a transmissive or reflective optical sensor including a light projecting element and a light receiving element, and outputs a detection signal S when the light emitted from the light emitting element is blocked by the article M. This signal S is input to the counter clear generation unit 28, and the value of the counter 30 is cleared to zero.

The control unit 20 includes a filtering unit 24, a motor speed control unit 26, and a counter clear generation unit 2.
8, counter 30, and processing timing determination means 31
It has.

The filtering means 24 filters the weighing signal by numerical calculation, and is a weight detector 8
The analog weight signal output from is input to the A / D converter 16 via the amplifier 14, and the weighing signal W digitally converted therein is input and filtered. As a result,
The vibration component due to the vibration of the belt conveyor included in the weighing signal W is removed, and the weighing data corresponding to the weight of the article M is output.

The motor speed control unit 26 is provided for the weighing conveyor 2
Control the rotational speed of the drive motor M1. The pulse signal P from the rotation amount detector 18 is the motor speed control unit 26.
The speed is controlled based on the number of pulses per unit time. The processing timing determination means 31 has timing determination means composed of comparators 32 and 33, and determines the weighing start timing for starting the acquisition of the weighing signal of the article M and the weighing timing for determining the weight of the article M.

Here, in this apparatus, the weighing start timing and the weighing timing of the processing timing determining means 31 are based on the position of the article M on the weighing conveyor 2.
It is determined as follows. FIG. 2 shows the processing timing.

The measurement start timing is the time when the article M is completely transferred from the take-in conveyor 4 to the weigh conveyor 2, and the detection sensor 10 causes the take-in conveyor 4 and the weigh conveyor 2 to move.
When the tip of the article M is detected between them and the detection signal S is output,
From that point, the counter 30 starts counting the pulse signal P, and when the count value reaches the count value corresponding to the length of the article length L1, the weighing start timing comes.

The measuring timing is the filtering means 2
4 is the timing for ending the filtering process and determining the weight of the article M. The timing is, after the leading edge of the article M has passed the upstream end of the weighing conveyor 2,
Is the time when the front end of the reaches the downstream end of the weighing conveyor 2. That is, the tip of the article M is at a position moved by the length of the conveyor length L2 from the upstream end of the weighing conveyor 2 (see FIG. 1).
02). Therefore, when the count value of the counter 30 reaches the count value corresponding to the length of the conveyor length L2, the measurement timing is reached. It should be noted that L2 does not have to be the same as the conveyor length, and can be a constant length shorter than the conveyor length (for example, 0.9 times the conveyor length) with reference to the conveyor length.

The operation of this device will be described below. In FIG. 1, when the article M is transferred to the weighing conveyor 2, the signal sent from the weight detector 8 is amplified by the amplifier 14, digitally converted by the A / D converter 16, and then input to the control unit 20. In the control unit 20, the weighing signal W is filtered by the filtering unit 24 and the vibration component due to the vibration of the belt conveyor included in the weighing signal is removed.

Drive motor M1 for driving the weighing conveyor 2
Is inputted to the motor speed control unit 26, and the rotation speed of the drive motor M1 is controlled so as to match the conveyor speed set by the data input means 22.

By operating the data input means 22, the conveyor speed V of the weighing conveyor 2, the article length L1, and the conveyor length L2.
, The count value Pa corresponding to the length of the article L1 is input to the second input end of the comparator 32, and the count value Pb corresponding to the length of the conveyor length L2 is input to the comparator 33.
Is output to the second input terminal of.

The leading edge of the article M is detected by the detection sensor 10, and the detection signal S is output to the counter clear generating section 28. Upon receiving the detection signal S, the counter clear generation unit 28 sets the count value of the counter 30 to 0, and the counter 3
0 counts the pulse signal P from the rotation amount detector 18. This count value P1 is input to the first input terminals of the comparators 32 and 33. This count value corresponds to the distance traveled by the article M. For example, 2000 pulses indicate that the article M has moved by 1 m.

The comparators 32 and 33 compare the first input count value and the second input count value and, when the first input count value matches the second input count value, output a predetermined timing signal. It is designed to output. First, in the comparator 32, when the first input count value P1 from the counter 30 matches the count value Pa corresponding to the article length L1 set at the second input end, the weighing start timing signal T1 is sent to the filtering means 24. Then, the filtering of the weighing signal is started. As a result, the filtering unit 24 causes the article M after the weighing start timing.
It is possible to filter the exact weighing signal that represents the total weight of the.

Next, in the comparator 33, the counter 30
When the count value P1 from the counter coincides with the count value Pb corresponding to the conveyor length L2 set at the second input end, the weighing timing signal T2 is output to the filtering means 24 and the weighing data at that time is processed as the weighing value. To be done.

As described above, in the present apparatus, even if the conveying speed V of the weighing conveyor 2 changes, each processing timing is determined irrespective of this, and the filtering required time t according to the conveying speed V is determined. Since there is no need to input, it is possible to easily carry out highly accurate weighing regardless of changes in the transport speed V.

When a sorting device for sorting the articles M according to weight is provided downstream of the discharge conveyor 6, the distance from the upstream end of the weighing conveyor 2 to the sorting device is input to the data input means 22. The distribution timing may be detected from the comparison between this distance and the count value P1, and the distribution device may be operated at this distribution timing. As a result, accurate distribution timing can be obtained based on the moving distance of the article M, so that the distribution device operates smoothly.

[0027]

As described above, according to the present invention, the processing timing determination means is based on the moving distance of the article on the weighing conveyor, the length of the weighing conveyor in the carrying direction and the length of the article in the carrying direction. Since the processing timing of the weighing signal is determined, the calculation of each processing timing is simplified and the accuracy is improved, and it is not necessary to input the filtering required time according to the conveying speed of the weighing conveyor, and the operation is easy. . As a result, it is possible to provide a weighing device that can easily perform high-precision weighing regardless of changes in the transport speed of the weighing conveyor.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a weighing device according to an embodiment of the present invention.

FIG. 2 is a schematic view showing the weighing device.

[Explanation of symbols]

2 ... Weighing conveyor, 22 ... Data input means, 24 ... Filtering means, 30 ... Moving distance detecting means (counter), 31 ... Processing timing determining means, C ... Conveyor,
M ... article, M1 ... drive motor.

Claims (1)

[Claims] 1. A weighing conveyor that drives a conveyor by a drive motor to transport and weigh articles, and data input means for inputting the length of the weighing conveyor in the transport direction and the length of the article in the transport direction. A weighing device comprising: a filtering means for filtering a weighing signal of an article from a weighing conveyor, wherein a moving distance detecting means for detecting a moving distance of the article on the weighing conveyor from a rotation amount of a drive motor; A weighing device comprising processing timing determining means for determining processing timing of a weighing signal based on the length of the weighing conveyor in the transport direction and the length of the article in the transport direction.