JPH0643009A - Weight measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain an apparatus for measuring the weight of an object while transferring in a short time with simple constitution. CONSTITUTION:The weight measuring apparatus comprises a load detection sensor 24 interposed between a transferring means and a fixed side and producing a detection signal corresponding to the load applied to the transferring means, and a low-pass filter 36 blocking such components of detection signal as exceeding the frequency corresponding to the number of revolutions of a drive roller. The weight measuring apparatus further includes a sensor 6 detecting an object being carried into the transferring means and commanding an integration A/D converter to calculate the weight upon elapse of a predetermined time, and the integration A/D converter 38 integrating signals from a low-pass filter 36 corresponding to one period of the number of revolutions of a roller and calculating the weight of an object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight measuring device for measuring the weight of an object to be measured while conveying the object to be measured.

[0002]

2. Description of the Related Art Conventionally, an apparatus for measuring the weight of an object to be measured is provided in an automated line in order to process the object to be measured. For example, a fish body with a similar shape and a substantially uniform composition can be estimated from its weight, regardless of the size of the object to be measured. An apparatus for measuring the weight of an object to be cut in order to cut it into pieces of a predetermined weight is known (Japanese Patent Publication No. 4-8195).

Further, in such an apparatus, the object to be measured is placed on a load cell or the like for weight measurement, the weight is measured in a stationary state, and then the conveyor or the like is driven to measure the object to be measured. Was being transported. Alternatively, the object to be measured is conveyed on the load cell by the conveyor, the conveyor is once stopped, the weight is measured in a stationary state, and then the object to be measured is conveyed.

[0004]

However, in such a conventional device, the conveyance of the object to be measured is temporarily stopped, and
Since the measurement must be performed in a stationary state, the measurement time becomes long. Further, if an attempt is made to carry out the measurement while being conveyed, the measurement accuracy will be deteriorated due to the influence of vibration due to the imbalance of the rotating portion of the conveyor or the like. Therefore, it is possible to filter the detection signal from the load cell etc. to remove the influence of vibration, but the rotation speed of the rotating part is small, so
The frequency of vibration is also low. If you try to filter this, you need to lower the cutoff frequency, and if you lower it, the time constant of the filtering will increase and the response will be delayed. There was a problem that the time would be long.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a weight measuring device which can measure the weight of an object to be measured while it is being transported and has a simple structure and a short measuring time.

[0006]

In order to achieve such an object, the present invention has the following constitution as means for solving the problem. That is, as illustrated in FIG. 1, in a weight measuring device for measuring the weight of the object to be measured M1 while conveying the object to be measured M2 by the conveying means M2 for conveying the object to be measured M1 by the rotation of the roller rotated by the rotary drive source. , Load detecting means M3 arranged between the transporting means M2 and the fixed side and outputting a detection signal according to the load applied to the transporting means M2.
And a signal from the low-pass filter M4 corresponding to one cycle of the number of rotations of the roller, and a low-pass filter M4 for blocking a component exceeding the frequency corresponding to the number of rotations of the roller in the detection signal from the load detection means M3. Is calculated to calculate the weight of the object to be measured M1 on the conveying means M2, the carry-in detecting means M6 to detect the carry-in of the object to be measured M1 into the carrying means M2, and the carry-in. This is the configuration of the weight measuring device characterized in that it comprises a measurement instructing means M7 for instructing the calculation of the weight by the calculating means M5 after a lapse of a predetermined time after the detection of the carry-in by the detecting means M6.

[0007]

The weight measuring device having the above-described structure has the conveying means M.
Reference numeral 2 conveys the object to be measured M1 by the rotation of the roller rotated by the rotary drive source, and the load detecting means M3 outputs a detection signal corresponding to the load applied to the conveying means M2. Further, the low-pass filter M4 cuts off a component of the detection signal exceeding a frequency corresponding to the rotation speed of the roller.

Then, the carry-in detecting means M6 is replaced by the carrying means M.
2 is detected, and measurement instruction means M7 is detected.
However, after the carry-in detection means M6 detects the carry-in, a predetermined time elapses, and then the calculation means M5 is instructed to calculate the weight.
The calculating means M5 integrates the signal from the low-pass filter corresponding to one cycle of the rotation speed of the roller to calculate the weight of the object to be measured M1 on the conveying means M2.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is an overall layout diagram of a cutting line using a weight measuring device according to an embodiment of the present invention. Reference numeral 1 is a weight measuring device, and a loading conveyor 2 is arranged in front of the weight measuring device 1. The fish body or the half body thereof is conveyed to the weight measuring device 1.

A carry-in detection sensor 6 as a carry-in detection means M6 using a photoelectric sensor for detecting the object 4 to be measured is provided between the weight measuring device 1 and the feeding conveyor 2.
Further, a cutting device 8 is arranged behind the weight measuring device 1, and the cutting device 8 cuts the object to be measured 4 into a piece of constant weight and a cutter based on the weight measured by the weight measuring device 1. It is cut by 10.

As shown in FIG. 3, the weight measuring device 1 includes a drive roller 1 rotatably supported at both ends of a frame 12.
4 and a driven roller 16, and a belt 18 is stretched between the rollers 14 and 16. Also, the frame 12
A rotary drive source 20 using a motor with a speed reducer is attached to the rotary drive source 20, and the rotation of the rotary drive source 20 is transmitted to the drive roller 14 by a timing belt 22.

In this embodiment, the rotation speed n of the drive roller 14
Is configured to be 480 rpm (= 8 rps). Moreover, the rotation speed of the output shaft of the rotary drive source 20,
The ratio with the rotation speed n of the drive roller 14 is 1: 1 and the reduction ratio of the reduction gear is set to an integer.
In the present embodiment, the rotation speed of each rotating portion is determined by the driving roller 14
It is configured to be an integral multiple of the rotation speed n. As a result, the frequency generated by the rotation becomes an integral multiple due to the unbalanced amount of each rotating portion.

In this embodiment, the frame 12, the driving roller 14, the driven roller 16, the belt 18 and the rotary drive source 2 are used.
No. 0, the timing belt 22 constitutes the transporting means M2. On the other hand, the frame 12 is fixed to one end of a load detection sensor 24 as a load detection means M3 using a load cell, and the other end of the load detection sensor 24 is the base 2.
It is fixed at 6. The load cell of the present embodiment uses a strain gauge and outputs a detection signal according to the applied load.

In this embodiment, the arm 30 is swingably supported by the fulcrum pin 28 on the base 26.
The balance weight 32 is fixed to one end of the arm 30, and the other end of the arm 30 is rotatably engaged with the frame 12. The balance weight 32 may be provided as needed, and the balance weight 32 can be implemented without providing it.

The load detection sensor 24 is connected to an amplifier 34 as shown in FIG.
It is configured to be input to the low pass filter 36. The low-pass filter 36 blocks a component exceeding a frequency corresponding to the rotation speed of the drive roller 14,
In this embodiment, the cutoff frequency is set to 7 Hz.

The reason why the rotation speed of the drive roller 14 (8 rps) is set slightly lower is that even if the cutoff frequency is set to 7 Hz, it is not completely cut off in the vicinity of 7 Hz.
Any component that blocks frequency components exceeding 8 Hz may be used. Then, the low-pass filter 36 is connected to an integrating type analog-digital converter 38 as the calculating means M5. As shown in FIGS. 5 and 8, the integration type analog-digital converter 38 receives the signal VIN from the low-pass filter 36 via the first switch S1 and the resistor R, and
The reference voltage Vref having the opposite polarity to the signal VIN is applied to the second switch S.
2. The capacitor C is connected to the integrator 40 in parallel via the resistor R. The integrator 40 is also connected to the control circuit 44 via the comparator 42, and the control circuit 44 is connected to the counter 46.

When the first switch S1 is short-circuited, the signal VIN is integrated for a preset fixed time T1. The output VOUT of the integrator 40 at this time is given by the following equation (1). VOUT = (VIN / R) × (T1 / C) (1) Next, after the elapse of a certain time T1, the first switch S1 is opened,
The second switch S2 is short-circuited, and the reference voltage Vref having the opposite polarity to the signal VIN is applied. Then, the comparator 42 detects that the integrator 40 has become 0 V, and obtains the time T2. At the time T2, the following expression (2) is established.

VOUT = − (− Vref / R) × (T2 / C) (2) From the above equations (1) and (2), the following equation (3) is established. (VIN / R) × (T1 / C) = (− Vref / R) × (T2 / C) VIN = − (T1 / T2) × Vref (3) Therefore, the signal VIN is the time of T1 and T2. It is determined by the ratio and the reference voltage Vref, and the error of the integration constants R and C does not affect the accuracy.

In this way, when the control circuit 44 receives the instruction signal, the integral type analog-digital converter 38
During the preset fixed time T1, the low-pass filter 3
The signal VIN that has passed through 6 is integrated, and converted into a digital signal by the control circuit 44 and the counter 46 and output.

The preset constant time T1 corresponds to one cycle of the rotation speed n of the driving roller 14, and the constant time T1 = 1 / n. The integration type analog-digital converter 38 is connected to an electronic control circuit 50. The electronic control circuit 50 mainly includes a well-known CPU 52, a ROM 54 that stores a control program and data in advance, and a readable / writable RAM 56. It is configured as a logical operation circuit, and the input / output circuit 58 and the drive circuit 60 are connected to each other via a common bus 62 to perform input / output with the outside.

Then, the CPU 52 inputs signals from the integration type analog-digital converter 38 and the carry-in detection sensor 6 via the input / output circuit 58, and these signals, R
Based on the programs and data in the OM 54 and RAM 56, the CPU 52 outputs a signal to the integral type analog-digital converter 38 via the input / output circuit 58 and to the rotary drive source 20 via the drive circuit 60. ing.

Next, the operation of the weight measuring apparatus of this embodiment will be described with reference to the flow chart of FIG. First,
A signal is output to the rotary drive source 20 via the drive circuit 60, and the rotary drive source 20 is rotationally driven. Along with that, the drive roller 14 is rotated via the timing belt 22, and the belt 18 is driven.

The object 4 to be measured is placed on the feeding conveyor 2, conveyed on the feeding conveyor 2, and transferred from the feeding conveyor 2 to the belt 18 of the weighing device 1. Then, the DUT 4 is conveyed by the belt 18. Along with the transportation of the DUT 4, the measurement control process shown in FIG. 6 is executed, and it is determined whether or not the DUT 4 has been detected as having passed the carry-in detection sensor 6 by the transportation of the DUT 4. (Step 100). This control process is repeatedly executed until the carry-in detection sensor 6 determines that the object to be measured 4 has passed. When the carry-in detection sensor 6 detects the passage, whether or not a predetermined time t has elapsed after the passage. It is judged (step 110).

The predetermined time t is a time that allows for a preset time corresponding to the time constant of the low-pass filter 36. After the predetermined time t, the filtering process of the low-pass filter 36 becomes a steady state. Judge that it has become. This control process is repeatedly executed until the predetermined time t has elapsed, and when the predetermined time t has elapsed, a measurement start instruction signal is output to the integration type analog-digital converter 38 via the input / output circuit 58 (step 120).

In this embodiment, execution of the measurement control process works as the measurement instructing means M7. As shown in FIG. 7A, the detection signal from the load detection sensor 24 increases in level as the DUT 4 is placed on the belt 18, and the detection signal includes the drive roller 14 and the driven roller. 1
Under the influence of vibration due to the unbalance amount of 6, in the present embodiment, signals of the frequency component of 8 Hz and other components are superimposed.

The driving roller 14 and the driven roller 16 have the lowest number of rotations and the largest weight, and generate vibrations of large amplitude due to the rotational imbalance. The load detection sensor 24 detects this vibration and outputs a detection signal superimposed as noise. And, the frequency component based on this vibration, among the components superposed on this detection signal,
The lowest frequency is 8 Hz in this embodiment.

If this low frequency noise is reliably filtered and removed, the time constant becomes very large, and if the weight of the DUT 4 is measured by filtering, it takes a long time to perform the measurement. Requires. The low-pass filter 36 blocks components exceeding this frequency, and the signal that has passed through the low-pass filter 36 is affected by the vibration due to the unbalanced amount of the driving roller 14 and the driven roller 16 as shown in FIG. Further, the signal VIN has a frequency component of 8 Hz superimposed. Further, since the frequency components lower than that are not cut off, the time constant becomes small and the filtering time is short.

Then, in the integral type analog-digital converter 38, as shown in FIG. 7C, after the passage of the DUT 4 is detected and after a predetermined time t has elapsed, a signal is output for a predetermined time T1. VIN is integrated, converted into a digital signal, and a signal corresponding to the weight of the DUT 4 is output.

This fixed time T1 corresponds to the frequency of vibration due to the unbalanced amount of the driving roller 14 and the driven roller 16, and corresponds to one cycle of the vibration. Therefore, no matter which timing the integration start time starts, the signal VIN corresponding to one cycle is integrated, and a value corresponding to the average value of the signal VIN is measured.

Therefore, according to the weight measuring apparatus of the present embodiment, even if noise of a low frequency component due to the driving roller 14 and the driven roller 16 is superposed on the detection signal of the load detection sensor 24, the low pass filter 36 keeps this frequency. Blocks ingredients that exceed. Then, the integration type analog-digital converter 38 integrates the signal VIN for a fixed time T1 after the passage of the DUT 4 is detected and after a lapse of a predetermined time t.
It is converted into a digital signal and a signal corresponding to the weight of the DUT 4 is output.

Therefore, even if the weight of the DUT 4 is measured while being conveyed, the driving roller 14 and the driven roller 16
The low-pass filter 36 has a small time constant and a short filter processing time without being affected by a low vibration due to. Moreover, it is only necessary to integrate the signal VIN during the fixed time T1, and the accurate value can be detected in a short time even if the structure is simple.

The present invention is not limited to such embodiments as described above, and can be carried out in various modes without departing from the scope of the present invention.

[0033]

As described in detail above, the weight measuring apparatus of the present invention is not affected by low vibration even while the object to be measured is being conveyed, and the filtering time is short and the time is constant. In this way, it is possible to measure the weight of the object to be measured in a short time with a simple configuration that integrates the signal.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a basic configuration of a weight measuring device of the present invention.

FIG. 2 is an overall layout diagram of a cutting line using the weight measuring device of the present invention.

FIG. 3 is a schematic configuration diagram of a weight measuring device as one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an electric system of this embodiment.

FIG. 5 is a block diagram showing a configuration of an integral type analog-digital converter of the present embodiment.

FIG. 6 is a flowchart showing an example of measurement control processing performed in the electronic control circuit of the present embodiment.

FIG. 7 is a graph showing signals from the load detection sensor and the low pass filter of the present embodiment.

FIG. 8 is a graph illustrating an integration process of the integration type analog-digital converter of the present embodiment.

[Explanation of symbols]

M1, 4 ... Object to be measured M2 ... Conveying means
M3 ... Load detection means M4 ... Low pass filter M5 ... Calculation means
M6 ... Carry-in detection means M7 ... Measurement instruction means 1 ... Weight measuring device
2 ... Loading conveyor 6 ... Carrying-in detection sensor 8 ... Cutting device
14 ... Drive roller 16 ... Driven roller 20 ... Rotational drive source
24 ... Load detection sensor 36 ... Low pass filter 38 ... Integral type analog-digital converter 50 ... Electronic control circuit

Claims (1)

[Claims] 1. A weight measuring device for measuring the weight of an object to be measured while the object to be measured is conveyed by a conveying means that conveys the object to be measured by the rotation of a roller rotated by a rotary drive source. And a low-pass filter that cuts off a component of the detection signal from the load detection unit that exceeds a frequency corresponding to the rotation speed of the roller. A filter, a calculating unit that integrates a signal from the low-pass filter corresponding to one cycle of the number of rotations of the roller to calculate the weight of the object to be measured on the conveying unit, and the calculating unit to the conveying unit. Carry-in detection means for detecting carry-in of a measurement object; and a measurement instruction for instructing calculation of weight by the calculation means after a predetermined time has elapsed after the carry-in detection means detected carry-in. Weighing apparatus characterized by comprising: a stage, a.