JP5060706B2 - Combination scale - Google Patents

Description

  The present invention relates to a combination weigher. More specifically, the present invention relates to a combination weigher in which it is determined whether or not each weighing hopper is difficult to select, and the weighing hopper determined to be difficult to select is re-loaded.

  The combination weigher includes a number of weighing hoppers greater than the integer M, and puts an object to be weighed into each weighing hopper with a weight obtained by dividing the combined target weight X by M, that is, X / M. As a result, the weight of the objects to be weighed in each weighing hopper (hereinafter, weighed weight) is approximately X / M. Next, for each combination when taking out the M weighing hoppers from all the weighing hoppers, the total of the weighing weights of the weighing hoppers participating in each combination (hereinafter, combination weight) is calculated. Furthermore, among all combinations, a combination that is within an allowable range determined on the basis of the combination target weight and that corresponds to the combination weight closest to the combination target weight (hereinafter referred to as an optimal combination) is adopted. The input amount of the object to be weighed into the weighing hopper is adjusted by the opening time or opening degree of the cut gate upstream of the weighing hopper. However, in the adjustment based on the opening time, the opening degree, and the like, the non-uniformity of the object to be measured itself, turbulence, and the like cause an error in the input amount (hereinafter referred to as an input error).

  Here, the technical feature of the combination weigher is that if weigh each weighing hopper alone, a weighted object with a positive or negative charging error is added, but by combining a plurality of weighing hoppers, The charging error can be canceled, and the weight of the object to be weighed finally into the container or the like can be accurately adjusted to the vicinity of the target weight. For this reason, the accuracy and efficiency of measurement increase as the number of combinations (hereinafter, combination candidates) that are candidates for the optimal combination increases.

  However, for example, when an insertion error is accidentally increased for a certain weighing hopper, the weighing weight of the weighing hopper greatly deviates from the originally targeted weight (X / M). Since there is a low probability of such an input error canceling such a large error, a weighing hopper greatly deviating from X / M is difficult to select. When a weighing hopper that is difficult to select is generated, there is a problem that the number of combination candidates is substantially reduced and the accuracy and efficiency of weighing are lowered. In addition, if the specific weighing hopper is left unselected, there is a problem that an object to be weighed in the weighing hopper deteriorates or the bulk density increases and clogging occurs.

  As a means to make it easier to select a weighing hopper that is difficult to select, a sub-weighing hopper is provided, and an insertion error is detected for the remaining weighing hopper, and an input amount to the sub-weighing hopper is determined so as to cancel it. There is a combination scale (Patent Document 1).

In addition, depending on how the input error is generated, the optimum combination may not be found. If there is no optimal combination, processing such as emptying all the weighing hoppers once as defective discharge is necessary, and the efficiency of operation decreases. As means for efficiently eliminating the state where there is no optimal combination, a combination weigher has been proposed in which the number of items of one or a plurality of weighing machines is increased or decreased and the combination calculation is performed again (Patent Document 2).
JP 58-124918 A JP-A-57-46217

  However, in the combination weigher of Patent Document 1, at least one of the remaining weighing hoppers is used as a sub-weighing hopper in order to select a weighing hopper that has become difficult to select. Therefore, at least two weighing hoppers need to participate in the optimal combination. Therefore, in practice, the number of combination candidates decreases, and the accuracy and efficiency of measurement may be reduced. In addition, when a sub-weighing hopper is provided separately from the main weighing hopper, the size of the apparatus increases correspondingly, and the control system tends to be complicated.

  Further, in the combination weigher of Patent Document 2, it is unclear how much the product is increased or decreased to obtain the optimum combination, and it is not always easy to obtain the optimum combination.

  The present invention has been made in order to solve the above-described problems. It is determined whether or not each weighing hopper is difficult to select, and an object to be weighed is re-entered into the weighing hopper determined to be difficult to select. The purpose is to provide a combination weigher.

  In the present invention, the principle for solving the above problems will be described below.

  In a combination weigher, the insertion error when putting an object to be weighed into each weighing hopper often shows a single-peak distribution around zero. In this case, the greater the insertion error, the lower the probability that such a large insertion error will occur. When a weighing hopper happens to be loaded with an amount of an object to be weighed that includes a large loading error, a large reverse error will not occur to the extent that the loading error is canceled, so it is difficult to select the weighing hopper. Become. A weighing hopper that is difficult to select is hereinafter referred to as a specific weighing hopper.

  Here, it is not always necessary to select a specific weighing hopper when the insertion error is large. Depending on the error generation pattern, it may be difficult to select a weighing hopper having a specific error. There may be cases. In the present invention, any cause may be selected that is difficult to select. In the following, description will be made by taking as an example a case where the insertion error shows a single-peak distribution centering on zero, that is, the probability that such an error will decrease as the insertion error increases.

  When a specific weighing hopper is generated, the number of weighing hoppers that can participate in the optimum combination is substantially reduced. As a result, the number of combination candidates is reduced, and the accuracy and efficiency of measurement are reduced. In some cases, the optimum combination cannot be found due to the presence of the specific weighing hopper. It is generally difficult to efficiently resolve such a situation. This is because the efficiency of operation is reduced by measures such as stopping the device and performing the return operation by the operator, or emptying the weighing hopper once as defective discharge.

  Therefore, in the present invention, for each weighing hopper, it is determined whether or not it is difficult to select, and for the weighing hopper that is difficult to select, the weight of an object to be weighed in each weighing hopper (hereinafter referred to as the weighing hopper) , The measured weight) is an integral multiple of X / M, that is, the target value is determined and the object to be weighed is recharged so that the loading error is canceled in the weighing hopper. By re-feeding, the feeding error that is difficult to select is positively eliminated, and the weighing hopper that has been difficult to select is easily selected. Even when there is no optimal combination before re-injection, there is a possibility that an optimum combination will be found by recalculation after re-injection. If the optimum combination is generated by re-charging, the operation can be continued without wasting the objects to be weighed once.

As a specific example, let us calculate the number of combination candidates when the total number of weighing hoppers is 10 and M = 4. First, approximately X / 4 objects to be weighed are put into each weighing hopper. Normally, all weighing hoppers can participate in the optimal combination, so the number of combination candidates is
₁₀ C ₄ = 210
It becomes.

Here, when a large throwing error occurs in one of the ten weighing hoppers and an excessive amount of objects to be weighed is thrown, the combination including the weighing hopper cannot be an optimum combination. Therefore, the weighing hopper is not selected and becomes a specific weighing hopper. That is, the number of weighing hoppers that may be selected is substantially 9, and the number of combination candidates is
₉ C ₄ = 126
It becomes. Thus, when a specific weighing hopper is generated, the number of combination candidates is greatly reduced. Here, the specific weighing hopper is recharged so that the weighing weight becomes twice X / 4, that is, X / 2. This makes it easier to select the weighing hopper that has been difficult to select.

At this time, in addition to the original combination candidates made with 9 pieces that have not been re-introduced, one weighing hopper that has been re-introduced and 2 out of the 9 weighing hoppers that have not been re-introduced The combination candidates to be extracted are added,
₉ C ₄ + ₉ C ₂ = 126 + 36 = 162
It becomes. That is, the number of combination candidates increases by 36. Therefore, even when there is no optimal combination before re-introduction, if there is an optimal combination among the increased combination candidates, the operation can be continued without wasting already-on objects to be weighed. This increases the accuracy and efficiency of weighing. Moreover, it becomes possible to make it easy to select the weighing hopper which has been difficult to select. As a result, problems such as clogging due to deterioration of the object to be weighed and increase in bulk density are solved.

Further, when a large throwing error occurs in two of the ten weighing hoppers, the two weighing hoppers are not selected and become specific weighing hoppers. At this time, the number of weighing hoppers that may be selected is substantially 8, and the number of combination candidates is
₈ C ₄ = 70
It becomes. Thus, when a plurality of specific weighing hoppers are generated, the number of combination candidates is greatly reduced. Here, the one of the specific weighing hoppers is recharged so that the weighing weight is twice X / 4, that is, X / 2. This makes it easier to select one of the weighing hoppers that has been difficult to select.

At this time, the number of combination candidates is one of the re-loaded weighing hoppers and 2 of the 8 weighing hoppers not re-filled, in addition to the original combination candidates made up of 8 re-loaded. The combination candidates to be extracted are added,
₈ C ₄ + ₈ C ₂ = 70 + 28 = 98
It becomes. That is, the number of combination candidates increases by 28.

When re-loading is performed on both of the specific weighing hoppers, combination candidates for taking out one weighing hopper that has been re-filled and two weighing hoppers that have not been re-filled, and re-charging Because the combination candidate to take out the two weighing hoppers that have been
₈ C ₄ + 2 · ₈ C ₂ + 1 = 70 + 56 + 1 = 127
It becomes. That is, the number of combination candidates increases by 57. As described above, when a plurality of specific weighing hoppers are generated, recharging can be performed on one or two of the specific weighing hoppers. As a result, even if there is no optimal combination before the re-input, if there is an optimal combination among the increased combination candidates, the operation can be continued without wasting the input object to be weighed. This increases the accuracy and efficiency of weighing. Moreover, it becomes possible to make it easy to select the weighing hopper which has been difficult to select. As a result, problems such as clogging due to deterioration of the object to be weighed and increase in bulk density are solved.

  Here, in the present invention, conditions for determining whether or not the weighing hopper is a specific weighing hopper are roughly divided into the following three groups.

  1) Before calculating the combined weight, a weighing hopper whose weighing weight satisfies a specific condition is determined to be a specific weighing hopper.

  2) If the optimum combination is not found even after calculating the combination weight, the weighing hopper that satisfies the specific condition is determined to be a specific weighing hopper.

  3) A weighing hopper that has not been selected even after a certain time or a certain number of selections is determined to be a specific weighing hopper.

  More specifically, a weighing hopper that satisfies one or more of the following conditions is determined to be a specific weighing hopper.

  1: The measured weight is more than a certain weight away from X / M.

  2: The measured weight is more than a certain rate away from X / M.

  3: When the optimum combination is not found, the weighing weight is the largest among all weighing hoppers.

  4: When the optimum combination is not found, the weighing weight is the smallest among all weighing hoppers.

  Immediately after the weighing hopper was recharged according to 5: 3, when the optimum combination was not found, the weighing weight was the second largest among all weighing hoppers just before the recharging was performed.

  Immediately after the weighing hopper was recharged according to 6: 3, when the optimum combination was not found, the weighing weight was the smallest among all weighing hoppers just before the recharging was performed.

  Immediately after the weighing hopper was recharged according to 7: 4, when the optimum combination was not found, the weighing weight was the second smallest among all weighing hoppers just before the recharging was performed.

  Immediately after the weighing hopper according to 8: 4 was recharged, if the optimum combination was not found, the weighing weight was the largest among all weighing hoppers just before the recharging was performed.

  9: Even if selection was performed for a certain period of time, it was not selected even during that time.

  10: Even if selection was performed for a certain number of times, it was never selected during that time.

  Here, the conditions 1 and 2 correspond to the group 1), the conditions 3 to 8 correspond to the group 2), and the conditions 9 and 10 correspond to the group 3). In actual control, various combinations and orders using the following conditions are conceivable. In the present invention, as long as no logical contradiction occurs, the determination may be performed in any combination and order using the following conditions.

  Next, the configuration of the present invention based on the above principle, that is, means for solving the above problems will be described below.

The combination weigher according to the present invention includes a plurality of weighing hoppers for detecting a weighing weight that is a weight of an input object to be weighed, and the weighing weight is 1 / M (M is an integer) of a combination target weight. In this way, an object to be weighed is put into the empty weighing hopper, and, for the combination of the weighing hoppers, a combined weight that is the sum of the weighing weights of the weighing hoppers participating in the combination is calculated, and the combined weight is a combination target weight. In a combination weigher that selects a weighing hopper that participates in an optimal combination that is within the allowable range determined based on the above and that is closest to the combination target weight, and discharges an object to be weighed from the selected weighing hopper Determining whether there is a specific weighing hopper that satisfies a predetermined criterion for determining difficulty of being selected, and at least one of the specific weighing hoppers is present Weighing the weight of the specific weighing hopper is such that said combination is an integral multiple of the target weight of 1 / M, again turning on the objects to be weighed the to at least one specific weighing hoppers (claim 1).

  Thus, it is determined whether or not each weighing hopper is difficult to select, and for a specific weighing hopper determined to be difficult to select, the weighing weight is set to be an integral multiple of 1 / M of the combination target weight. The sample is reloaded. As a result, it becomes easy to select the weighing hopper that has been difficult to select, and the number of combination candidates can be substantially increased. Therefore, the accuracy and efficiency of measurement are improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

Further, when the combination target weight is X and the weighing weights of the individual weighing hoppers before and after re-feeding are W ₁ and W ₂ respectively,
K · X / M ≦ W ₁ <(K + 1) · X / M
For an integer K (K = 0, 1, 2,... (M-2), (M-1))
W ₂ = (K + 1) · X / M
In such a case, the object to be weighed may be reintroduced into the specific weighing hopper (Claim 2).

  As a result, the weighing weight of the weighing hopper, which has become difficult to select, can be made an integral multiple of X / M with the smallest amount of recharging. As a result, as many times as possible can be secured for the same weighing hopper as many times as possible. Therefore, the accuracy and efficiency of measurement are improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

  Moreover, M = 3, 4 or 5 may be sufficient (claim 3).

  As a result, in a standard combination weigher having a total number of weighing hoppers of 10, it is determined whether or not the weighing hopper is a specific weighing hopper even when the value of M that can secure a large number of combination candidates is adopted. And re-injection. As a result, measurement accuracy and efficiency are improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

  Further, the reference may be that a certain number of times or a certain time has not been selected.

  As a result, the weighing hopper that is not actually selected can be determined as a specific weighing hopper and re-inserted. As a result, the number of weighing hoppers that are not selected can be reliably reduced. Therefore, the accuracy and efficiency of measurement are improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

  Further, the predetermined number of times or the predetermined time may be settable (Claim 5).

  Thereby, the determination conditions can be changed according to the operation status of the apparatus and the accuracy and efficiency of the intended measurement.

  Further, the reference may be a certain weight or more or a certain proportion or more away from the nearest value among integer multiples of 1 / M of the combination target weight.

  Thereby, when a larger error is less likely to occur, it can be determined whether or not each weighing hopper is difficult to select based on the magnitude of the error. As a result, measurement accuracy and efficiency are improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

  The constant weight or the constant ratio may be settable (Claim 7).

  Thereby, the determination conditions can be changed according to the operation status of the apparatus and the accuracy and efficiency of the intended measurement.

  Further, the reference may be that the weighing weight is the maximum when any combination weight does not fall between the upper limit value and the lower limit value set based on the combination target weight. 8). Alternatively, the criterion may be that the weighing weight is the minimum when any combination weight does not fall between the upper limit value and the lower limit value set based on the combination target weight. 9).

  Thereby, even when the optimum combination cannot be obtained, the operation can be continued without using inefficient means such as forced discharge or operation stop. Therefore, the accuracy and efficiency of measurement are improved.

  Further, the lower limit value may be the combination target weight (claim 10).

  As a result, the object to be weighed always exceeds the combination target weight. Therefore, even when it is necessary to input an object to be weighed having a specific weight or more in packaging of goods or the like, the accuracy and efficiency of weighing can be improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

  In addition, the determination may be performed immediately when an object to be weighed is put into the weighing hopper and the detected value of the weighing weight is first stabilized (claim 11).

  Thereby, it is possible to determine whether or not each weighing hopper is a specific weighing hopper even before the combination weight is calculated. As a result, when a specific weighing hopper occurs, it can be recharged earlier. Therefore, the accuracy and efficiency of measurement are improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

  In addition, when all the combination weights were calculated for the first time after re-introduction, again, any combination weight did not fall between the upper limit value and the lower limit value set based on the combination target weight. In some cases, the weighing weight may be the second largest or the weighing weight may be minimal immediately before re-introduction (claim 12). Alternatively, when all of the combination weights are calculated for the first time after re-inputting, again none of the combination weights falls between the upper limit value and the lower limit value set based on the combination target weight. In some cases, the weighing weight may be the second smallest or the weighing weight may be the maximum immediately before re-introduction (claim 13).

  As a result, even when reintroduction is performed, even when the optimum combination still does not exist, reintroduction into another weighing hopper can be performed. As a result, if the optimum combination is found again by calculating the combination weight, the operation can be continued as it is. Therefore, the accuracy and efficiency of measurement are improved.

  Further, the object to be weighed may be a granular material (claim 14).

  Thereby, in the measurement of the granular material in which a large charging error is unlikely to occur, the charging error can be positively canceled when a large charging error that occurs very rarely occurs. As a result, a weighing hopper that is difficult to select due to a large throwing error is easily selected. Therefore, the accuracy and efficiency of measurement are improved. In addition, since there is no weighing hopper left unselected, problems such as deterioration of an object to be weighed and clogging due to an increase in bulk density can be solved.

  The present invention has a configuration as described above, and it is determined whether or not each weighing hopper is difficult to select, and a combination weigher that re-injects an object to be weighed into a weighing hopper that is determined to be difficult to select. There is an effect that it can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment)
FIG. 1 is a diagram illustrating an example of a schematic configuration when a combination weigher according to an embodiment of the present invention is cut in a vertical section. The arrow in the figure indicates the moving direction of the object to be weighed. Hereinafter, the schematic configuration of the combination weigher according to the present embodiment will be described with reference to FIG. This combination weigher has a feeding hopper 1 at its upper end. The lower portion of the charging hopper 1 is branched into a plurality of paths toward the lower outer periphery. The bottom surface of the charging hopper 1 has a gentle conical surface convex upward in the vertical direction so that an object to be weighed falls on the path according to gravity. An outlet is provided at the lower end of the path. Cut gates 2 and 2 are disposed at the outlet. The cut gates 2 and 2 have doors whose opening and opening time can be adjusted so that the amount of the object to be weighed discharged from the outlet can be adjusted. Below the cut gates 2, 2, weighing hoppers 3, 3 are arranged at positions where the objects to be weighed discharged from the outlet can be received. Each weighing hopper 3, 3 is connected to a weight sensor 4, 4 that detects the weighing weight of the weighing hopper 3, 3. The weighing hoppers 3 and 3 have doors so as to hold and discharge the objects to be weighed introduced from the path as needed. Below the weighing hoppers 3 and 3, a collecting chute 5 for collecting and discharging the objects to be weighed discharged from the weighing hoppers 3 and 3 is disposed. The collective chute 5 is formed in a hollow truncated cone shape whose radius decreases downward, and has an outlet at the lower end. A wrapping machine (not shown) is provided below the collecting chute 5 so as to receive and package the objects to be weighed discharged from the outlet. The center portion of the charging hopper 1 is supported by a hollow center column 11 extending in the vertical direction. The center column 11 has a leg portion 11a for grounding at a lower portion thereof. The weight sensors 4 and 4 are accommodated in the center column 11.

  FIG. 2 is a block diagram showing an example of the hardware configuration of the combination weigher according to the embodiment of the present invention. FIG. 3 is a block diagram showing an example of the configuration of the control system of the combination weigher according to the embodiment of the present invention. Hereinafter, the hardware and control system of the combination weigher according to the present embodiment will be described with reference to FIGS. 2 and 3.

First, the hardware will be described below. As shown in FIG. 2, the hardware of the combination weigher according to the present embodiment includes a charging hopper 1 that divides the flow of an object to be weighed from the upstream into N pieces and discharges it downstream, and a load that is discharged from the charging hopper 1. N cut gates 2 ₁ to 2 _N that allow the weighed material to pass downstream by an input amount, and N weighing hoppers that receive and weigh the material to be weighed from the cut gates 2 ₁ to 2 _N , and then discharge them downstream. 3 _{1 to} 3 _N and a collecting chute 5 that collects the objects to be weighed discharged from the weighing hoppers 3 _{1 to} 3 _N and puts them into a packaging machine (not shown). In addition, the arrow in a figure shows the direction through which a to-be-measured object flows.

In this embodiment, hopper 1 has one inlet and N outlets, the cut gate 2 ₁ to 2 _N is provided in each outlet. Each of the cut gates 2 _{1 to} 2 _N is provided with a door so that the opening degree and the opening time can be individually adjusted. The weighing hoppers 3 _{1 to} 3 _N are each provided with a door so that only selected ones can send an object to be measured downstream.

Next, the control system will be described below. As shown in FIG. 3, the control system of the combination weigher according to the present embodiment includes N weight sensors 4 ₁ to 4 _N that detect the weighing weights of the weighing hoppers 3 _{1 to} 3 _N , a control board 6, Input means 7 and output means 8 are provided. The control board 6 can also transmit signals to the cut gates 2 ₁ to 2 _N and the weighing hoppers 3 _{1 to} 3 _N. In addition, the arrow in a figure shows the direction where a signal is transmitted.

In the present embodiment, for example, load cells are used for the weight sensors 4 ₁ to 4 _N. For example, a microcomputer is used for the control board 6. As the input means 7, for example, a keyboard or the like is used. As the output means 8, for example, a liquid crystal display or the like is used.

Hereinafter, the configuration of the control board 6 will be described. FIG. 4 is a block diagram showing a schematic configuration of the control board 6. The control board 6 includes a control unit 9 and a storage unit 10. For example, a CPU is used as the control unit 9. For the storage unit 10, for example, an internal memory is used. The control unit 9 and the storage unit 10 are connected to each other. Further, the control unit 9 receives signals from the weight sensors 4 ₁ to 4 _N and the input means 7 and transmits signals to the cut gates 2 ₁ to 2 _N and the weighing hoppers 3 _{1 to} 3 _N. In addition, the arrow in a figure shows the direction where each signal is transmitted.

Next, the operation of the control board 6 will be described with reference to FIG. Parameters indicating the combination target weight, conditions used for determination, a program used for calculation, and the like are input from the input unit 7 to the control unit 9. The control unit 9 stores the received parameters, programs, and the like in the storage unit 10. The stored parameters, programs, and the like are displayed on the output unit 8 as necessary and confirmed by the operator. The control unit 9 receives weight detection signals from the weight sensors 4 ₁ to 4 _N. The control unit 9 processes the received detection signal using software stored in the storage unit 10, and controls the cut gates 2 ₁ to 2 _N and the weighing hoppers 3 _{1 to} 3 _N based on the result. Send a signal. By the above operation, the control board 6 detects the weight of the objects to be weighed which cut gate 2 ₁ to 2 _N and weighing hoppers 3 ₁ to 3 _N turns on and discharge, and controls, to operate the combination weigher.

  Regarding the combination weigher according to the present embodiment having the above-described configuration, the operation when there is no weighing hopper 3 (hereinafter referred to as a specific weighing hopper) that is difficult to select will be schematically described.

  The combination target weight is input to the control board 6 via the input means 7 by the operator. The input combination target weight is displayed on the output means 8 and confirmed by the operator.

The object to be weighed is supplied from upstream, and an appropriate amount is secured in the charging hopper 1 by a level sensor (not shown). The objects to be weighed in the charging hopper 1 fall according to gravity along the route and are guided to N outlets. The outlet is cut gate ₂ 1 to 2 _N is provided. The opening and the opening time of the cut gates 2 ₁ to 2 _N are adjusted by the control board 6, and a substantially X / M object to be weighed is put into the weighing hoppers 3 _{1 to} 3 _N. When an object to be weighed is put into the weighing hoppers 3 _{1 to} 3 _N , the weight sensors 4 ₁ to 4 _N are passed after a predetermined time (hereinafter referred to as a stable time) required for accurate weight detection. Thus, the weighing weight of each weighing hopper 3 _{1 to} 3 _N is detected.

A detection signal indicating the weighing weight of each weighing hopper is transmitted to the control board 6. Using the transmitted detection signals, the control board 6 calculates the combined weights for all combinations that take out M pieces from the weighing hoppers 3 _{1 to} 3 _N. Next, the weighing hopper 3 participating in the optimum combination is selected based on the combination weight. A control signal for causing the selected weighing hopper 3 to discharge is transmitted from the control board 6. Upon receiving the control signal, the weighing hopper 3 opens the door and discharges the objects to be weighed to the collecting chute 5. The objects to be weighed discharged from the weighing hopper 3 are collected in the collecting chute 5 and discharged to a packaging machine (not shown).

From the control board 6, the door is opened so that the opening and the opening time are calculated so that the X / M object to be weighed is inserted into the cut gate 2 corresponding to the weighing hopper 3 that has discharged the object to be weighed. Therefore, a control signal is transmitted. An object to be weighed in an amount of approximately X / M is fed into the weighing hopper 3 from the cut gate 2 that has received the control signal. After the stabilization time has passed again, the weight sensors 4 ₁ to 4 _N detect the weights of the weighing hoppers 3 _{1 to} 3 _N. It should be noted that the weighing weight may be detected only for the weighing hopper 3 that has discharged the object to be weighed. The detected weighed weight is transmitted to the control board 6, and thereafter, by repeating the same operation as described above, an amount of an object to be weighed that satisfies a certain condition is discharged to the packaging machine.

  Next, the operation when a specific weighing hopper is generated, which is a feature of the present invention, will be described in detail below.

  At the stage of adjusting the amount of the object to be weighed from the cut gate 2 to the weighing hopper 3, the throwing amount varies due to the feeding error. For this reason, depending on the variation, a state occurs in which it becomes difficult to select a specific weighing hopper 3, that is, a specific weighing hopper. For example, in the case where the throwing error shows a single-peak distribution centered on zero, if a large throwing error occurs accidentally, the probability of such a large throwing error is low, so the throwing error is canceled. Such an input error hardly occurs. For this reason, the weighing hopper 3 into which an object to be weighed in an amount including a large loading error is likely to be a specific weighing hopper. In the present embodiment, a case will be described in which the throwing error shows a single-peak distribution centered on zero, that is, the probability that such an error will be lower as the throwing error is larger. However, in the present invention, any cause may be used that makes it difficult to select.

  When a specific weighing hopper is generated, the number of weighing hoppers 3 that can participate in the optimum combination is reduced. As a result, the number of combination candidates is substantially reduced. Therefore, the accuracy and efficiency of measurement are reduced. In some cases, the optimal combination may not exist due to the presence of the specific weighing hopper. It is generally difficult to efficiently resolve such a situation. This is because the efficiency of operation is reduced by measures such as stopping the device and performing the return operation by the operator, or if the weighing hopper 3 is once emptied as defective discharge.

  Therefore, in the present embodiment, it is determined whether or not each weighing hopper 3 is a specific weighing hopper based on the weighing weight detected by the weight sensor 4, and is determined to be a specific weighing hopper. When the weighing hopper 3 is present, the object to be weighed is re-input to the weighing hopper 3. In the present embodiment, the conditions for determining whether or not the weighing hopper is a specific weighing hopper can be broadly classified as follows: 1) Before calculating the combined weight, a weighing hopper whose weighing weight satisfies a specific condition is selected. Determine that it is a specific weighing hopper (determination 2), 2) If the optimum combination is not found even after calculating the combination weight, a weighing hopper that satisfies a specific condition is determined to be a specific weighing hopper (Decision 4 to 6), 3) Even if selection is performed for a certain time or a certain number of times, a weighing hopper that has never been selected is determined to be a specific weighing hopper (determination 7). Hereinafter, the operation of determining whether or not the weighing hopper is a specific weighing hopper and recharging the object to be weighed will be described.

FIG. 5 is a flowchart showing an example of an operation program of the control board 6 in the present embodiment. An object to be weighed is loaded from the loading hopper 1 into the empty weighing hopper 3 so that the loaded amount is X / M (step S1). After the stabilization time has elapsed, the weight sensors 4 ₁ to 4 _N detect the weights of the weighing hoppers 3 _{1 to} 3 _N (step S2). It is determined whether there is a weight exceeding the upper limit among the detected weights (determination 1: step S3).

  In the determination 1 (step S3), if there is an object exceeding the upper limit value, the control board 6 transmits a control signal to the weighing hopper 3 exceeding the upper limit value to forcibly discharge the object to be weighed. (Step S11). In the present embodiment, a value obtained by adding an allowable weight to the combination target weight is employed as the upper limit value. However, the upper limit value may be any value as long as stable operation of the apparatus can be ensured. The upper limit value or the allowable weight is input to the control board 6 via the input means 7.

  In the determination 1 (step S3), when there is nothing exceeding the upper limit value, the closest value among integer multiples of X / M is calculated for each of the detected weights, The difference from the weight is calculated. Then, a determination is made as to whether or not there is an object whose difference exceeds a certain weight (determination 2: step S4).

In the determination 2 (step S4), when there is a difference exceeding the certain weight, it is determined that the corresponding weighing hopper 3 is a specific weighing hopper. In the specific weighing hopper, when the combination target weight is X and the weighing weight of each of the specific weighing hoppers before and after re-feeding is W ₁ and W ₂ respectively,
K · X / M ≦ W ₁ <(K + 1) · X / M
For an integer K (K = 0, 1, 2,... (M-2), (M-1))
W ₂ = (K + 1) · X / M
Thus, the control board 6 calculates the re-input amount for the specific weighing hopper. The control board 6 transmits a control signal to the cut gate 2 corresponding to the specific weighing hopper so as to discharge the re-input amount. As a result, the object to be weighed is reintroduced from the cut gate 2 into the specific weighing hopper (step S12). After the recharging, the weighing weights of the weighing hoppers 3 _{1 to} 3 _N are detected (Step S2), and the determination 1 (Step S3) and the determination 2 (Step S4) are performed again. The constant weight is input to the control board 6 via the input means 7.

  In addition, since the measurement weight is always zero or more, K does not become negative. Further, when K = M, it is not discharged even though the weighing weight of the weighing hopper 3 exceeds the target weight. In the present embodiment, the upper limit value in decision 1 (step S3) and the optimum combination condition in decision 3 (step S6) are set so that such a situation does not occur.

  In the determination 2 (step S4), when there is no difference exceeding the certain weight, all combination weights are calculated using the detected weighing weight (step S5). Then, it is determined whether or not an optimal combination exists (determination 3: step S6).

  In determination 3 (step S6), when there is an optimum combination, a control signal for instructing discharge of the object to be weighed is transmitted from the control board 6 to the weighing hopper 3 participating in the optimum combination. The weighing object is discharged (step S7). The objects to be weighed discharged from the weighing hopper 3 are collected by the collecting chute 5 and discharged to the packaging machine. In the present embodiment, a combination weight that is equal to the combination target weight, or a combination that is larger than the combination target weight but has a difference from the combination target weight that is smaller than a certain weight and that produces the minimum combination weight is determined as the optimum combination. The It should be noted that parameters that define the optimum combination are input to the control board 6 via the input means 7.

In determination 3 (step S6), when the optimum combination does not exist, it is determined that the one having the largest detected weight is the specific weighing hopper. Next, an object to be weighed is recharged to the specific weighing hopper based on the same calculation method as that of recharging (step S12) performed after the determination 2 (step S4) (step S13). The weighing weights of the weighing hoppers 3 _{1 to} 3 _N are detected, and all the combined weights are recalculated (step S14). Then, it is determined whether or not an optimal combination exists (determination 4: step S15).

  In determination 4 (step S15), when there is an optimum combination, a control signal for instructing discharge of the object to be weighed from the control board 6 is transmitted to the weighing hoppers 3 participating in the optimum combination. The weighing object is discharged (step S7). The objects to be weighed discharged from the weighing hopper 3 are collected by the collecting chute 5 and discharged to the packaging machine.

In the determination 4 (step S15), when there is no optimum combination, it is determined that the specific weighing hopper is the one having the smallest weighing weight when the determination 3 (step S6) is performed. Next, an object to be weighed is recharged into the specific weighing hopper using the same calculation method as that of recharging (step S12) performed after the determination 2 (step S4) (step S16). The weighing weights of the weighing hoppers 3 _{1 to} 3 _N are detected, and all the combined weights are recalculated (step S17). Then, it is determined whether or not an optimum combination exists (determination 5: step S18).

  In determination 5 (step S18), when there is an optimum combination, a control signal for instructing discharge of the object to be weighed from the control board 6 is transmitted to the weighing hoppers 3 participating in the optimum combination. The weighing object is discharged (step S7). The objects to be weighed discharged from the weighing hopper 3 are collected by the collecting chute 5 and discharged to the packaging machine.

In determination 5 (step S18), when there is no optimum combination, it is determined that the specific weighing hopper is the one having the second largest weight when the determination 3 (step S6) is performed. Is done. Next, the object to be weighed is recharged into the specific weighing hopper using the same calculation method as that of recharging (step S12) performed after the determination 2 (step S4) (step S19). The weighing weights of the weighing hoppers 3 _{1 to} 3 _N are detected, and all the combined weights are recalculated (step S20). Then, it is determined whether or not an optimal combination exists (determination 6: step S21).

  If it is determined in decision 6 (step S21) that the optimum combination exists, a control signal for instructing discharge of the object to be weighed from the control board 6 is transmitted to the weighing hoppers 3 participating in the optimum combination. The weighing object is discharged (step S7). The objects to be weighed discharged from the weighing hopper 3 are collected by the collecting chute 5 and discharged to the packaging machine.

  When the optimum combination does not exist in the determination 6 (step S21), the control board 6 forcibly discharges the object to be weighed using the combination closest to the combination target weight among the combination weights (step S22).

  Here, discharge to the packaging machine is defined as one discharge, and the number of discharges that are not continuously selected for each weighing hopper 3 is referred to as a standby number. After the object to be weighed is discharged to the packaging machine (step S7), the number of waiting times for the selected weighing hopper 3 is reset to zero. Further, 1 is added to the number of waiting times of the weighing hopper 3 that has not been selected (step S8). The above calculation is performed by the control board 6. Next, it is determined by the control board 6 whether or not there is a weighing hopper 3 whose number of standbys exceeds a certain number (determination 7: step S9).

  If there is no waiting number exceeding the certain number, the same operation is continued after returning to the beginning (step S1). If there is a standby count exceeding a certain number, it is determined that the corresponding weighing hopper 3 is a specific weighing hopper. Next, an object to be weighed is recharged into the specific weighing hopper based on the same calculation method as that of recharging (step S12) performed after the determination 2 (step S4) (step S10). Thereafter, returning to the beginning, the same operation is continued (step S1). The predetermined number of times is input to the control board 6 through the input means 7.

With the above operation, in the combination weigher according to the present embodiment, it is determined whether or not each of the weighing hoppers 3 _{1 to} 3 _N is difficult to select, and the weighing hopper determined to be difficult to select. 3, the object to be weighed is reloaded. As a result, the weighing hopper 3 that has been difficult to select can be easily selected, the number of combination candidates can be substantially increased, and the accuracy and efficiency of weighing can be improved.

  In addition, this Embodiment has a remarkable effect especially when a to-be-measured object is a granular material. The reason is as follows. In the measurement of powder particles, the amount of input by the cut gate 2 can be adjusted with considerably high accuracy. Therefore, a large throwing error does not occur normally. However, inside the apparatus, particles of the granular material may stick to each other to grow a large lump. If such a large lump is thrown into the weighing hopper 3, a large throwing error occurs. In addition, a large charging error may occur due to clogging due to an increase in bulk density or a level fluctuation in the charging hopper 1. Whatever the cause, if such a large charging error occurs in the measurement of the granular material, a charging error that cancels this will hardly occur. This is because usually only a small throwing error occurs. Therefore, the weighing hopper 3 into which the powder containing such a large charging error is charged becomes a specific weighing hopper that is difficult to select. The present embodiment is extremely effective in eliminating such a state. That is, the specific weighing hopper in which a large throwing error has occurred is refilled so that the weighed weight is an integral multiple of 1 / M of the combined target weight. Thereby, there is a high possibility that a combination weight close to the combination target weight can be obtained by combining with another measurement hopper 3 whose measurement weight is essentially equal to 1 / M of the combination target weight. Therefore, it becomes possible to make it easy to select the weighing hopper that has been difficult to select. As a result, the number of combination candidates is substantially increased, and the accuracy and efficiency of measurement are improved. In addition, problems such as deterioration of an object to be measured and clogging due to an increase in bulk density due to generation of the weighing hopper 3 that is not selected for a long period of time can be solved.

  In the present embodiment, in the determination 2, for each of the detected weights, the closest value among integer multiples of X / M is calculated, and the difference between the value and the weight exceeds a certain weight. Was determined to be a specific weighing hopper. However, even if it is determined that a specific weighing hopper has a ratio between the difference and each weight (or the closest value among integer multiples of X / M corresponding to the weight) exceeding a certain ratio. Good. The constant ratio is input to the control board 6 via the input means 7.

  Further, in the determinations 4 to 6, it was determined that the corresponding weighing hopper 3 is a specific weighing hopper in the order of the maximum value, the minimum value, and the second largest value. However, it may be determined that the corresponding weighing hopper 3 is a specific weighing hopper in the order of the minimum value, the maximum value, and the second smallest value. Alternatively, the maximum value, the minimum value, the second largest value, and the second smallest value may be combined in any order. It may be determined that the one having the largest weighing weight is the specific weighing hopper in order from the maximum value. It may be determined that the one having the smallest weighing weight is the specific weighing hopper in order from the minimum value.

  In the determination 7, the number of standby times is calculated, and when the number of standby times exceeds a certain number, it is determined that the corresponding weighing hopper 3 is a specific weighing hopper. However, not the number of times of selection but the time of non-selection (hereinafter referred to as standby time) is calculated, and when the standby time exceeds a certain time, it is determined that the corresponding weighing hopper 3 is a specific weighing hopper. May be. The predetermined time is input to the control board 6 via the input means 7.

  Further, determination 2 and determination 7 may be combined. That is, for the weighing hopper 3 that has exceeded a certain number of times or a certain waiting time, the determination based on the weighing weight may be performed. Further, the determination condition based on the weighing weight may be varied depending on the number of standby times or the standby time. As a result, it is possible to vary the determination as to whether or not to re-input depending on the time and the number of times that the selection was not made. Therefore, even if the weighing hopper 3 having a large throwing error occurs, it can be tried whether or not the weighing hopper 3 is selected for a certain period of time. Therefore, the measurement efficiency can be improved.

In the present embodiment, after re-introduction, the weighing weight is detected again for all the weighing hoppers 3 _{1 to} 3 _N , but only the weighing hopper 3 that has been re-introduced is detected. May be performed.

  In addition, the “object to be weighed” described in the claims refers to an article to be weighed by a combination weigher, and specifically refers to, for example, potato, pepper, nail, detergent, sugar and the like. In the present invention, the item to be weighed may be any item, but the effect of the present invention is remarkably enhanced because the size of each item is smaller than that of beans. This is the case when the object is to be weighed.

  The “weighed weight” described in the claims refers to the weight of an object to be weighed that has been put into the weighing hopper 3.

  Further, the “combination weight” described in the claims means a weighing hopper taken out based on the combination when one or more weighing hoppers 3 are taken out from the plurality of weighing hoppers 3. The sum of the three weighed weights.

  In addition, the “combination target weight” described in the claims refers to a weight targeted by the combination weigher.

  The “optimal combination” described in the claims refers to a combination that is within an allowable range determined based on the combination target weight and that corresponds to the combination weight closest to the combination target weight. For the weighing hoppers 3 participating in the optimum combination, the objects to be weighed in the weighing hoppers 3 are discharged. On the other hand, for the weighing hopper 3 that does not participate in the optimum combination, the objects to be weighed in the weighing hopper 3 remain without being discharged.

  Further, the “weight sensor” described in the claims refers to a sensor that detects the weight of the weighing hopper 3, and for example, a load cell or the like is used. The detection here is not limited to the case where the weight is measured as a physical quantity with a unit, but includes the case where the weight is detected as a value such as a voltage signal and is not converted to a physical quantity with a unit. In the latter case, control is performed using the detected value directly.

  In addition, “selection” described in the claims means that the weighing hopper 3 participating in the optimum combination is selected from all the weighing hoppers 3.

  Further, the “specific weighing hopper” described in the claims refers to the weighing hopper 3 that is difficult to be selected because the weighing weight is special. Specifically, for example, since an insertion error when an object to be weighed is input to the weighing hopper 3 is extremely large, the charging error cannot be eliminated even when combined with other weighing hoppers 3 and is selected for this purpose. A weighing hopper 3 or the like that is difficult can be considered. However, depending on the occurrence pattern of the insertion error, it is not always necessary that the large insertion error is selected, and a weighing hopper including a specific insertion error may be a specific weighing hopper.

  In addition, “re-loading” described in the claims means that the weighing hopper 3 in which the object to be weighed has already been thrown in is put in the state where the object to be weighed has entered the weighing hopper 3. It means that the weighing object is added additionally.

  The combination weigher according to the present invention is effective as a combination weigher in which it is determined whether or not it is difficult to select individual weighing hoppers, and an object to be weighed is reintroduced into the weighing hopper determined to be difficult to select.

It is a figure which shows schematic structure of the combination scale which concerns on embodiment of this invention. It is a block diagram which shows schematic structure of the hardware of the combination scale which concerns on embodiment of this invention. It is a block diagram which shows schematic structure of the control system of the combination scale which concerns on embodiment of this invention. It is a block diagram which shows schematic structure of the control board 6 which concerns on embodiment of this invention. It is a flowchart which shows an example of the operation | movement program of the control board 6 which concerns on embodiment of this invention.

Explanation of symbols

1 Input hopper
2 Cut gate 3 Weighing hopper 4 Weight sensor 5 Collecting chute 6 Control board 7 Input means 8 Output means 9 Control part 10 Storage part 11 Center column 11a Leg part

Claims (14)

A plurality of weighing hoppers for detecting a weighing weight, which is the weight of an object to be weighed,
Put an object to be weighed into the empty weighing hopper so that the measured weight becomes 1 / M (M is an integer) of the combined target weight.
For the combination of weighing hoppers, calculate a combined weight that is the sum of the weighing weights of the weighing hoppers participating in the combination;
Selecting a weighing hopper that participates in an optimal combination that is within a tolerance defined based on a combination target weight and that is the closest combination to the combination target weight;
In a combination scale for discharging an object to be weighed from the selected weighing hopper,
It is determined whether there is a specific weighing hopper that meets a predetermined criterion for determining the difficulty of being selected;
In the presence of the specific weighing hopper, the weight of the at least one specific weighing hopper is applied to the at least one specific weighing hopper so that the weighing weight of the specific weighing hopper is an integral multiple of 1 / M of the combined target weight. A combination weigher that re-loads the sample. When the combination target weight is X and the weighing weights of the individual weighing hoppers before and after re-feeding are W ₁ and W ₂ respectively,
K · X / M ≦ W ₁ <(K + 1) · X / M
For an integer K (K = 0, 1, 2,... (M-2), (M-1))
W ₂ = (K + 1) · X / M
The combination weigher according to claim 1, wherein the object to be weighed is reintroduced into the specific weighing hopper so that   The combination weigher according to claim 1, wherein M = 3 or 4 or 5.   The combination weigher according to claim 1, wherein the reference is not selected a certain number of times or for a certain time.   The combination weigher according to claim 4, wherein the certain number of times or the certain time can be set.   2. The combination weigher according to claim 1, wherein the reference is a certain weight or more or a certain proportion or more away from the nearest value among integer multiples of 1 / M of the combination target weight.   The combination weigher according to claim 6, wherein the constant weight or the constant ratio can be set.   2. The combination according to claim 1, wherein the criterion is that the weight to be measured is the maximum when any combination weight does not fall between an upper limit value and a lower limit value set based on the combination target weight. Scale.   2. The combination according to claim 1, wherein the criterion is that when any combination weight does not fall between an upper limit value and a lower limit value set based on the combination target weight, the weighing weight is minimum. Scale.   The combination weigher according to claim 8 and 9, wherein the lower limit value is the combination target weight.   The combination weigher according to claim 6, wherein the determination is made immediately when the detected weight value is first stabilized after the objects to be weighed are put into the weighing hopper. Said criteria are:
When all combination weights are calculated for the first time after re-introduction, when any combination weight does not fall between the upper limit value and the lower limit value set based on the combination target weight,
9. The combination weigher according to claim 8, wherein the weighed weight was the second largest or the weighed weight was minimal immediately before recharging. Said criteria are:
When all combination weights are calculated for the first time after re-introduction, when any combination weight does not fall between the upper limit value and the lower limit value set based on the combination target weight,
10. The combination weigher according to claim 9, wherein the weighed weight was the second smallest or the weighed weight was maximum immediately before recharging. The combination weigher according to claim 1, wherein the object to be weighed is a granular material.

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