JPH07174609A - Instrument and method for measuring weight - Google Patents

Abstract

PURPOSE:To shorten a time difference for preventing simultaneous feeding of two pieces of objects to be weighed to a weighing conveyor so as to improve the throughput of the conveyor by providing transferring time difference forming gaps before the leading edge of one object to be measured reaches downstream conveyors from upstream conveyors. CONSTITUTION:Gaps having lengths A and B which are required for forming fixed time differences (transferring time differences) before the leading edge of an object 5 to be weight reaches downstream conveyors from upstream conveyors are provided as transferring time forming means among a supply conveyor 1, discharge conveyor 3, and weighing conveyor 2. When the gaps are provided in such a way, the simultaneous feeding preventing time difference T2 becomes shorter because the difference T2 becomes the quotient of the apparent length of the conveyor minus the lengths A and B of the gaps divided by the carrying speed of the conveyor 2. Therefore, the supplying time difference between the object 5 and its succeeding object 5' to be measured is shortened and the throughput of the conveyor 2 is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a weighing device having a weighing conveyor incorporating weight measuring means such as a load cell.

[0002]

2. Description of the Related Art In a product manufacturing line or the like, a weighing device for automatically measuring the weight of a product and checking the weight of the product may be provided. This weighing device is composed of a weighing conveyor incorporating weight measuring means such as a load cell, a supply conveyor arranged upstream of the weighing conveyor, and a discharge conveyor arranged downstream of the weighing conveyor. The weighing object supplied from is weighed by the weight measuring means when passing through the weighing conveyor, and then discharged onto the carry-out conveyor.

When measuring the weight on the weighing conveyor, the entire weight of the object to be weighed must be loaded on the weighing conveyor. That is, as shown in FIG. 9, when the weighing object (5) straddles between the weighing conveyor (2) and another conveyor, for example, the supply conveyor (1), the weight of the weighing object (5) is increased. Accurate weighing cannot be performed because they are dispersed on both conveyors (1) and (2). Therefore, in the weighing work, as shown in FIG. 5, the rear end of the weighing object (5) rides on the weighing conveyor (2) and then the leading end of the weighing object (5) rides on the discharge conveyor (3). It must be performed within the time T ₁ '(hereinafter referred to as the measurement timing) until immediately before. This weighing timing T ₁ 'is calculated in advance by the equation T ₁ ' = (weighing conveyor length-weighing object length) / conveying speed of the weighing conveyor = (X-L / V ... It is stored in the control unit.

A sensor (6) including a light emitting element and a light receiving element is arranged at the upstream end of the weighing conveyor (2). When the sensor (6) detects the passage of the weighing object (5), the control unit of the device starts counting, and when the stored weighing timing T ₁ 'is reached after a certain period of time, the weighing value of the weight measuring means is reached. Read. If the measured value is excessive or insufficient with respect to the target value, the control unit outputs a distribution signal and activates a distribution device (not shown) arranged on the downstream side to convey the defective measured object. Discharge outside the route.

In addition to this, in the weighing device, in addition to the weighing timing T ₁ ′, it is necessary to perform the weighing operation while sequentially measuring the following two types of time differences.

(A) Double-carrying prevention time difference When the succeeding weighing object (5) moves onto the weighing conveyor (2) during weighing, the weight of the succeeding weighing object is added to the weighing value,
Accurate weighing work cannot be performed. Therefore, as shown in FIG. 6, between the weighing object (5) and the succeeding weighing object (5), T ₂ '= length of the weighing conveyor / transport speed of the weighing conveyor = X / V. .. It is necessary to secure the supply time difference T ₂ '(hereinafter referred to as the double-carrying prevention time difference) calculated by the following formula. The two-seat prevention time difference T ₂ 'is calculated in advance by the above-described arithmetic expression in the initial setting stage, and is actually calculated between the object (5) detected by the sensor (6) and the subsequent object (5'). Supply time difference
When it is smaller than the calculated two-seat prevention time difference T ₂ ',
A sorting signal is sent to the sorting device, and the front weighing object (5) is discharged to the outside of the transport path.

(B) Time difference for zero adjustment For example, when the object to be weighed is a sticky substance, a part of the object to be weighed adheres to the belt of the weighing conveyor due to long-term operation, whereby the zero point of the weight measuring means is changed. There is a case in which accurate measurement cannot be performed due to deviation. Therefore, during operation of the device, the zero point must be adjusted as appropriate to cancel the weight of the deposit. However, this zero point adjustment can be performed only after the weighed objects have been completely discharged from the weighing conveyor (2) as shown in FIG. Further, the zero point adjustment requires a certain time T ₅ (hereinafter, referred to as zero point return time). Therefore, zero point adjustment, 'between the two ride prevention time difference T ₂ weighed (5) (5)' in addition to, weighed (5) entirely to possess on discharge conveyor (3) of It can be performed only when the time T ₄ 'and the zero point return time T ₅ are secured. That, T ₃ '= (length of the length + weighed weighing conveyor) / Weighing conveyor transport speed + zero return time of = (X + L) / V + T 5 ···· comprising time difference T ₃ which is calculated by the formula '(Hereinafter, referred to as a zero point adjustment time difference) is ensured between the objects (5) and (5'), and the zero point adjustment can be performed.

[0008] In an actual apparatus, it weighed (5) (5 ') to supply the time difference in places artificially predetermined zero point adjustment time difference T ₃ between' or more, or a large supply time difference accidentally occur It is used to perform zero adjustment work.

By the way, in the above-mentioned weighing device, especially when the length of the weighing object (5) is long, the weighing timing T ₁ '
In order to secure sufficient time, as shown in FIG. 8, gaps (9) (9) (9) (9) are provided between the weighing conveyor (2) and the supply conveyor (1) and between the weighing conveyor (2) and the discharge conveyor (3). )
Is provided.

In this case, conventionally, the transport conveyor length X is grasped as the sum of the actual conveyor length Y and the gap amounts A and B at both ends of the measuring conveyor (2) (X = Y + A + B), and this apparent transport conveyor length is calculated. The length X (indicated by a broken line) was substituted in each of the above-mentioned calculation formulas for obtaining the measurement timing T ₁ ′, the double-ride prevention time difference T ₂ ′, and the zero point adjustment time difference T ₃ ′. That is, the actual length Y of the weighing conveyor (2) was regarded as equivalent to the apparent length X of the conveyor shown by the broken line in FIG. 8, and this apparent length X was substituted into each arithmetic expression. .

[0011]

However, when handled in this manner, the two-seater prevention time difference T ₂ 'and the zero point adjustment time difference are treated.
T ₃ 'can only obtain a value equal to that shown in FIGS. For this reason, the interval between the front and rear weighing objects (5) is unavoidably longer than the apparent length X, and there is a problem that the throughput of the weighing conveyor per unit time is reduced.

[0012] Therefore, an object of the present invention is to improve the processing capacity per unit time of the weighing conveyor by shortening the two-car-riding prevention time difference in the above case.

[0013]

[Means for Solving the Problems] To achieve the above object,
In the device of the present invention, a supply conveyor and a discharge conveyor are arranged at both ends of a weighing conveyor incorporating weight measuring means, and the difference in the feeding time between the weighing object and the subsequent weighing object is detected and the detection value is preset. In a weighing device that weighs a weighing object supplied on the weighing conveyor from the supply conveyor while comparing with the two-carrying prevention time difference,
Between the supply conveyor and the discharge conveyor and the weighing conveyor, there is provided a transition time difference forming means for forming a transition time difference until the leading end of the weighing object reaches from the upstream conveyor to the downstream conveyor, and A calculation unit for calculating the double-carrying prevention time difference by including the transition time difference as one of the parameters is provided.

Further, a supply conveyor and a discharge conveyor are arranged at both ends of the weighing conveyor incorporating the weight measuring means, and a difference in feeding time between the weighing object and a succeeding weighing object is detected and the detection value is preset. In a weighing device that weighs the weighing object supplied from the supply conveyor onto the weighing conveyor by comparing the two-carrying prevention time difference and the zero point adjustment time difference, the supply conveyor, the discharge conveyor, and the measurement conveyor. In the meantime, a transition time difference forming means for forming a transition time difference from the upstream end of the weighing object to the downstream conveyor is provided.
In addition, a calculation unit that includes the transition time difference as one of the parameters and calculates the double-ride prevention time difference and the zero point adjustment time difference is provided.

As the transition time difference forming means, it is preferable to provide a gap between the conveyors.

Concretely, the two-carrying prevention time difference T ₂ is calculated by the following equation: T ₂ = (apparent length of measuring conveyor-length of gap) / conveying speed of measuring conveyor.

Further, the time difference T ₃ for adjusting the zero point is calculated as follows: T ₃ = (apparent length of weighing conveyor-length of gap + length of weighing object) / conveying speed of weighing conveyor + zero return of weight measuring means Calculate with the formula that is time.

As the transition time difference forming means, a step may be provided between the conveyors.

[0019] The weighing object is conveyed from the supply conveyor to the discharging conveyor via the weighing conveyor, and a feeding time difference between the weighing object and a succeeding weighing object is detected, and this detected value is compared with a preset two-seat prevention time difference. However, when measuring the weighing object supplied from the supply conveyor onto the measuring conveyor by the weight measuring means provided in the measuring conveyor, a transition time difference forming means is provided between the supplying conveyor and the discharging conveyor and the measuring conveyor. Then, the weighing object is transferred from the upstream conveyor to the downstream conveyor with a transition time difference, and the transition time difference is included in one of the parameters to calculate the double-carriage prevention time difference.

In addition, the weighing object is conveyed from the supply conveyor to the discharging conveyor via the weighing conveyor, and the difference in the feeding time between the weighing object and the succeeding weighing object is detected and the detected value is set in advance to prevent double-carrying. And when comparing the time difference for zero adjustment with the weight measuring means equipped on the measuring conveyor to measure the object supplied on the measuring conveyor from the supplying conveyor, between the supplying conveyor and the discharging conveyor and the measuring conveyor. Is provided with a transition time difference forming means to move the weighing object from the upstream conveyor to the downstream conveyor with a transition time difference, and this transition time difference is included in one of the parameters to adjust the two-piece riding prevention time difference and the zero point. Calculate the operating time difference.

By providing a gap between the conveyors, a transition time difference forming means is constructed.

The above-mentioned two-piece riding prevention time difference T ₂ is calculated by the following equation: T ₂ = (apparent length of measuring conveyor-length of gap) / conveying speed of measuring conveyor.

The time difference T ₃ for adjusting the zero point is T ₃ = (apparent length of weighing conveyor-length of gap + length of weighing object) / conveying speed of the weighing conveyor + zero point returning time of the weight measuring means. Calculate with an expression.

The transition time difference forming means may be a step provided between the conveyors.

[0025]

When the transfer time difference forming means is provided between the supply conveyor and the discharge conveyor and the weighing conveyor, the actual length of the weighing conveyor (the distance between the upstream end and the downstream end of the weighing conveyor) is It is shorter than the apparent length (the distance between the downstream end of the supply conveyor and the upstream end of the discharge conveyor). From the calculation formula, the double-carriage prevention time difference is proportional to the length of the weighing conveyor, so the double-carriage prevention time difference can be shortened by including the transition time difference as one of the parameters and substituting a shorter actual conveyor length into the formula. it can. Similarly, since the time difference for zero point adjustment is also proportional to the length of the weighing conveyor from the arithmetic expression, if the time difference for zero point adjustment is calculated by including the transition time difference as a parameter, the time difference for zero point adjustment becomes short.
As a result, the difference in supply time required for performing the zero point adjustment becomes smaller, and the frequency of executing the zero point adjustment increases.

If a gap or a step is provided as the transition time difference forming means, it is possible to easily obtain the transition time difference for a fixed time.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in the figure, this weighing device is similar to the conventional device in that the supply conveyor (1), the weighing conveyor (2),
It is configured by sequentially disposing the discharge conveyor (3). A weight measuring means such as a load cell is incorporated in the weighing conveyor (2), and a sensor (6) for detecting passage of the weighing objects (5), (5 ') is provided at the upstream end of the weighing conveyor (2).
Is provided. The output of the sensor (6) is input to a control unit (not shown), and the control unit calculates the two-seat prevention time difference and the zero point adjustment time difference based on the input signal.

In the following description, for convenience of explanation, it is assumed that the feeding conveyors (1), the measuring conveyors (2), and the discharging conveyors (3) all have the same conveying speed V.

Transition time difference forming means (7a) (7b) are provided between the supply conveyor (1) and discharge conveyor (3) and the weighing conveyor (2). Here, the transition time difference forming means (7a) and (7b) form a constant time difference (transition time difference) from the time when the leading end of the weighing object (5) reaches the downstream conveyor to the upstream conveyor. FIG. 1 exemplifies a case where gaps of lengths A and B are provided as the transition time difference forming means (7a) and (7b).

The present invention is characterized in that the transition time difference is included in one of the parameters when the two-seat prevention time difference and the zero point adjustment time difference are calculated. In other words, the two-car riding prevention time difference T ₂ and the zero point adjustment time difference
T ₃ is calculated based on the actual length Y, not the apparent length X of the weighing conveyor.

That is, regarding the two-carriage prevention time difference, from the above equation, the two-carriage prevention time difference = length of metering conveyor / conveying speed of metering conveyor If the lengths A and B of the gaps are included as parameters, two riding prevent time difference T ₂ are, T ₂ = (length of the apparent weighing conveyor - length of the gap) / conveying speed of the weighing conveyor = (X- (a + B) ) / V = T 2 '- (a + B) / V Therefore, as shown in FIGS. 2A and 2B, the two-seat prevention time difference T ₂ (see FIG. 2B) becomes shorter than the conventional value T ₂ ′ (see FIG. 2A). As a result, the supply time difference between the weighing object (5) and the subsequent weighing object (5) can be shortened, and more weighing objects can be transported per unit time, and the processing capacity of the entire apparatus is improved. To do.

On the other hand, regarding the time difference T ₃ for zero point adjustment, similarly, when the length of the gap is included in the parameter, from the above equation, T ₃ = (apparent length of weighing conveyor-length of gap + length of weighing object) length) / weighing conveyor transport speed + weight zero return time measuring means = (X- (a + B) + L) / V + T 5 = T 3 '- (a + B) / V Therefore, in FIG. 3 (a) (b) As shown, the zero point adjustment time difference T ₃ (see FIG. B) becomes shorter than the conventional value T ₃ ′ (see FIG. A). As a result, it is possible to shorten the supply time difference necessary for performing zero point adjustment, increase the frequency of execution of zero point adjustment, and perform more accurate weighing.

FIG. 4 shows transition time difference forming means (7a) (7b).
As an example, a case where a step is provided between the upstream conveyor (P) and the downstream conveyor (Q) is shown. In this case as well, a transition time difference is ensured, so that the same effect as when a gap is provided can be obtained. In addition, since there is almost no need for a gap, there is an advantage that the device can be downsized as compared with the device shown in FIGS.

In the above description, the conveyor speed V of each of the conveyors (1), (2), and (3) is made constant for the sake of simplifying the arithmetic expression. However, the conveyor speeds do not necessarily have to be made constant, and different ones may be used. You may leave it.

[0036]

As described above, according to the present invention, since the transition time difference is included in one of the parameters to calculate the double-ride prevention time difference, the double-ride prevention time difference can be shortened. As a result, it is possible to shorten the supply time difference between the weighing object and the subsequent weighing object, and it is possible to convey more weighing objects per unit time, thus improving the processing capacity of the entire apparatus.

Similarly, if the transition time difference is included in one of the parameters and the zero point adjustment time difference is calculated, the zero point adjustment time difference can be shortened. As a result, it is possible to shorten the supply time difference necessary for performing zero point adjustment, increase the frequency of execution of zero point adjustment, and perform more accurate weighing.

By providing a gap or a step between the conveyors, the time difference forming means can be easily constructed. In particular, when a step is provided, the length of the entire weighing device can be suppressed and the size of the device can be reduced while shortening the two-car-riding prevention time difference and the zero point adjustment time difference.

[Brief description of drawings]

FIG. 1 is a side view of a weighing device according to the present invention.

FIG. 2 is a side view of a conventional device (FIG. 2A) and a device of the present invention (FIG. 2B) in which a gap is provided between conveyors.

FIG. 3 is a side view of a conventional device (FIG. 3A) and a device of the present invention (FIG. 3B) in which a gap is provided between conveyors.

FIG. 4 is a partial side view of the weighing device in which a step is provided between the conveyors.

FIG. 5 is a side view showing a conventional device of a type having no gap.

FIG. 6 is a side view showing a conventional device of a type having no gap.

FIG. 7 is a side view showing a conventional device of a type having no gap.

FIG. 8 is a side view showing a conventional device having a gap.

FIG. 9 is a side view showing a conventional device.

[Explanation of symbols]

 1 Supply Conveyor 2 Measuring Conveyor 3 Discharging Conveyor 5 Measured Items 7a ・ 7b Transition Time Difference Forming Means

Claims (14)

[Claims] 1. A supply conveyor and a discharge conveyor are provided at both ends of a weighing conveyor incorporating weight measuring means, and a detection time difference between a weighing object and a succeeding weighing object is detected and the detection value is preset. In a weighing device for weighing the weighing object supplied from the supply conveyor onto the weighing conveyor by the weight measuring means while comparing with the two-carrying prevention time difference, a weighing object is provided between the supply conveyor and the discharge conveyor and the weighing conveyor. Is provided with a transition time difference forming means for forming a transition time difference between the front end of the conveyor and the downstream conveyor reaching the downstream conveyor, and the transition time difference is included in one of the parameters to prevent the double riding. A weighing device comprising a calculation unit that calculates a time difference. 2. A supply conveyor and a discharge conveyor are arranged at both ends of a weighing conveyor incorporating weight measuring means, and a supply time difference between the weighing object and a subsequent weighing object is detected and the detection value is preset. In a weighing device that weighs the weighing object supplied on the weighing conveyor from the supply conveyor by the weight measuring means while comparing the time difference for preventing two-seat and the time difference for zero point adjustment, between the supply conveyor, the discharge conveyor, and the measurement conveyor. In the meantime, a transition time difference forming means for forming a transition time difference is provided between the upstream side conveyor and the downstream side conveyor to reach the downstream side conveyor, and the transition time difference is included in one of the parameters. A weighing device comprising a calculation unit that calculates the two-seat prevention time difference and the zero point adjustment time difference. 3. The weighing device according to claim 1, wherein the transition time difference forming means is a gap provided between the conveyors. 4. The weighing device according to claim 2, wherein the transition time difference forming means is a gap provided between the conveyors. 5. The double-carrying prevention time difference T ₂ is calculated by the following equation: T ₂ = (apparent length of measuring conveyor−length of gap) / conveying speed of measuring conveyor. Item 3. A weighing device according to item 3. 6. The zero point adjusting time difference T ₃ is T ₃ = (apparent length of weighing conveyor−length of gap + length of weighing object) / conveying speed of weighing conveyor + zero return of weight measuring means. The weighing device according to claim 4, wherein the weighing device is calculated by the following formula. 7. The weighing apparatus according to claim 1, wherein the transition time difference forming means is a step provided between the conveyors. 8. A double-carrying prevention time difference in which a measured value is set in advance by conveying a measured object from a supply conveyor to a discharge conveyor on a discharge conveyor and detecting a supply time difference between the measured object and a succeeding measured object. In comparison with the above-mentioned, when measuring the weighing object supplied from the supply conveyor onto the measuring conveyor by the weight measuring means provided in the measuring conveyor, a transition time difference forming means is provided between the supplying conveyor and the discharging conveyor and the measuring conveyor. Is provided, and the weighing object is moved from the upstream conveyor to the downstream conveyor with a transition time difference, and the transition time difference is included in one of the parameters to calculate the double-carriage prevention time difference. Weighing method. 9. A double-carriage prevention time difference in which a weighing object is conveyed from a supply conveyor to a discharging conveyor via a weighing conveyor, and a feeding time difference between the weighing object and a succeeding weighing object is detected and the detected value is set in advance. And when measuring the weighing object supplied from the supply conveyor on the measuring conveyor by the weight measuring means equipped on the measuring conveyor while comparing with the time difference for zero adjustment, between the supplying conveyor and the discharging conveyor and the measuring conveyor. Is provided with a transition time difference forming means to move the weighing object from the upstream conveyor to the downstream conveyor with a transition time difference, and this transition time difference is included in one of the parameters to adjust the two-piece riding prevention time difference and the zero point. A weighing method characterized by calculating a time difference for use. 10. The weighing method according to claim 8, wherein the transition time difference forming means is a gap provided between the conveyors. 11. The weighing method according to claim 9, wherein the transition time difference forming means is a gap provided between the conveyors. 12. The double-carriage prevention time difference T ₂ is calculated by the following equation: T ₂ = (apparent length of measuring conveyor−length of gap) / conveying speed of measuring conveyor. Weighing method described in 10. 13. The zero point adjustment time difference T ₃ is calculated as follows: T ₃ = (apparent length of weighing conveyor-length of gap + length of weighing object) / conveying speed of weighing conveyor + zero return of weight measuring means 12. The weighing method according to claim 11, wherein the calculation is performed by a formula of time. 14. The weighing method according to claim 8, wherein the transition time difference forming means is a step provided between the conveyors.