JP4623601B2 - Combination scale - Google Patents

Description

  The present invention relates to a combination weigher.

  Conventional weight-type filling machines include those disclosed in Patent Documents 1 and 2.

JP-A-62-230527 JP-A-10-288544

  The technique of Patent Document 1 relates to an input weighing device that stops supply of an article when the weight of the article supplied to the weighing hopper reaches a predetermined value. A supply hopper is provided above the weighing hopper. The supply hopper is provided with a gate whose opening degree can be changed. This gate is controlled based on the measured value in the weighing hopper. At the start of the supply of the article, a large input is performed to supply the article with a predetermined first opening degree of the gate. When the weight of the article in the weighing hopper reaches a predetermined value, the opening degree of the gate moves toward a predetermined second opening degree (an opening degree smaller than the first opening degree) according to the change of the weighing value. The inside is gradually reduced. When the second opening degree is reached, the second opening degree is maintained until the measured value reaches a predetermined value, and then the small opening is performed in which the gate is closed.

  In the technique of Patent Document 2, when the weight of an article supplied to the weighing hopper reaches a predetermined value, an input weighing device that stops the supply of the article, discharges the article from the weighing hopper, and stores the remaining article in the weighing hopper. A discharge weighing device is provided that stops the discharge of articles from the weighing hopper when the amount reaches a predetermined value. In the weighing hopper, large throwing and medium throwing are performed in the same manner as in Patent Document 1, and an article corresponding to a deviation between the weight of the article supplied to the weighing hopper and a predetermined filling target weight is placed in the weighing hopper. Discharged from the discharge metering device. That is, the small input is performed by the discharge metering device.

  In the technique of Patent Document 1, since the middle input is performed by a method of gradually reducing the opening degree, an overshoot does not occur in the measurement value, and a short measurement time and high measurement accuracy can be ensured. However, although small flow rate is small, there is a limit to further increase the weighing accuracy because there is a drop amount and the weighing while applying the drop impact of the article to the weighing hopper.

  In the technique of Patent Document 2, since the small input is performed by discharge weighing, the weighing accuracy can be improved as compared with the technique of Patent Document 1. However, a meter is used in the input metering device, and a meter is also used in the discharge metering device. That is, since two measuring instruments are used, the cost increases. In addition, the measurement value of each measuring instrument includes an error based on the surrounding environment and the like, and the measurement accuracy cannot be further increased.

  An object of the present invention is to provide a combination weigher that can maintain higher weighing accuracy at low cost.

The combination weigher according to one aspect of the present invention variously combines the weights of articles weighed by a plurality of weighing means, and selects a combination from which the total weight is equal to or close to a predetermined target weight. The combination weigher is provided corresponding to each of the weighing means, and stores the article therein, and supplies the article to the corresponding weighing means at a flow rate corresponding to a supply flow rate control value. And control means for outputting the supply flow rate control value to the article supply means corresponding to the empty measurement means when any of the measurement means is empty. The control means has a second value that is determined to be greater than the first weight and smaller than the constant weight after the measurement value of the measurement means has increased to a first weight that is smaller than a predetermined constant weight. In the process of controlling the supply flow rate control value, at least the rate of change of the supply flow rate control value with respect to the measurement value of the measurement unit is equal to the measurement value of the measurement unit. The supply flow rate control value is gradually decreased from a value when the measurement value of the measuring means reaches the first weight so as to include a control process that gradually increases in accordance with the increase, and the supply flow rate control value gradually decreases. When the measured value of the measuring means reaches the second weight in the control process, the supply flow rate control value is immediately set to zero.

The combination weigher according to another aspect of the present invention also variously combines the weights of articles weighed by a plurality of weighing means, and selects a combination in which the total weight is equal to or close to a predetermined target weight. Article supply means and control means. The control means controls the supply flow rate control value from a first time at which a predetermined time has elapsed from the time when the supply of the article to the weighing means is started to a predetermined second time. The supply flow rate control value at the first time so that at least the rate of change of the supply flow rate control value with respect to time gradually increases as time increases. When the second time is reached in the control process in which the supply flow rate control value gradually decreases, the supply flow rate control value is immediately set to zero.

The combination weigher according to another aspect of the present invention also variously combines the weights of articles weighed by a plurality of weighing means, and selects a combination in which the total weight is equal to or close to a predetermined target weight. Article supply means and control means. The control means includes at least the supply flow rate control value during the control process of the supply flow rate control value from a first time when a predetermined time has elapsed from the start of supply of the article to the weighing means. The rate of change of the measuring means with respect to the measured value includes a control process in which the rate of change gradually increases with an increase in the measured value of the measuring means. In the control process in which the supply flow rate control value gradually decreases, the supply flow rate control value is immediately set to zero when the measurement value of the measuring means reaches a predetermined weight.

  As shown in FIG. 1, the weight type filling machine as the first reference form of the present invention has a weighing means, for example, a weighing hopper 2. The weighing hopper 2 has a hopper 3 that is open at the top, and a weighing signal generating means, for example, a load cell 5 is attached to the hopper 3. The load cell 5 generates an analog weighing signal that represents the weight of the article accommodated in the hopper 3. This analog weighing signal is amplified by the amplifier 4, an unnecessary noise component is removed by the filter 6, converted into a digital weighing signal at a predetermined sampling period by the A / D converter 8, and controlled via the input / output unit 10. Means are supplied to the CPU 12, for example.

  An article discharge opening is formed in the lower part of the hopper 3. An article discharge means, for example, a discharge gate 14 is provided in the article discharge opening. The opening degree of the discharge gate 14 is adjusted by gate driving means, for example, a motor 16. By adjusting the opening degree, the discharge flow rate of articles from the hopper 3 is controlled. The motor 16 is controlled so that the opening degree of the discharge gate 14 becomes the opening degree proportional to the discharge flow rate control value generated by the gate control means, for example, the motor control unit 18. The motor control unit 18 outputs a discharge flow rate control value to the motor 16 based on a control signal supplied from the CPU 12 via the input / output unit 10. Although not shown, a packaging container that stores articles discharged from the hopper 3 is disposed below the hopper 3.

  An article storage means, for example, a supply hopper 20 is disposed above the weighing hopper 2. Articles are supplied to the supply hopper 20 by a conveyance supply device (not shown). An opening is provided in the lower portion of the supply hopper 20, and an article supply means, for example, a supply gate 22 is provided in the opening. The opening degree of the supply gate 22 is adjusted by gate driving means, for example, a motor 24. The supply flow rate of articles from the supply hopper 20 is controlled by adjusting the opening degree. The motor 24 is controlled so that the opening degree of the supply gate 22 becomes the opening degree proportional to the supply flow rate control value generated by the gate control means, for example, the motor control unit 26. The motor control unit 26 outputs a supply flow rate control value to the motor 24 based on a control signal supplied from the CPU 12 via the input / output unit 10.

  The CPU 12 adjusts the supply flow rate control value and the discharge flow rate control value according to the change of the digital weighing signal according to the storage means, for example, the program stored in the memory 28, and supplies and weighs articles to the weighing hopper 2. The discharge of the articles from the hopper 2 is controlled. Reference numeral 30 denotes an operation unit, for example, a setting operation key. Reference numeral 32 denotes a display unit, for example, a display device such as an LCD. By these, various parameters used for control in the CPU 12, such as the opening of the discharge gate 14 and the supply gate 22 are displayed. The weight value and the like for changing the degree are set.

  In this weight-type filling machine, one weighing hopper 2 has both input and discharge weighing functions. The target filling weight with which the packaging container is filled is defined as Wt. First, the weighing hopper 2 repeats a regular filling cycle in principle. Before entering this cycle, the preparation hopper weighing mode 1 in which the weighing hopper 2 is filled with the article of the initial weight Wi by weighing-in is set to 1. Run only once.

  The input weighing in the preparation charging mode is performed by the method disclosed in Patent Document 1. The initial weight Wi is the maximum negative filling error that can occur when an article having a target weight Wt is almost charged into the weighing hopper 2 by the input weighing in the above filling cycle, and when the weight type filling machine is operated for a long time. The value is selected to be larger than the sum of the maximum accumulated error of the zero point shift of the weighing hopper 2.

  Next, the original filling cycle is started, and the opening degree of the supply gate 22 is controlled so that the article with the target filling weight Wt is put into the weighing hopper 2. This input weighing is not aimed at high accuracy in dynamic weighing, but is performed as fast as possible so that a static weighing value can be obtained with high accuracy. Even if the dynamic weighing accuracy is lower than that of the technique of Patent Document 2, as a weighing method in which a static weighing value can be accurately obtained in as short a time as possible, a method that performs only large charging and medium charging is used. This input measurement method will be described later.

  Since this dosing weighing method is adopted, there is a possibility that only the Wt-We articles that allow for the maximum error We from the target filling weight Wt are supplied to the weighing hopper 2. Here, the maximum error We may be several tens of percent of the target filling weight Wt. In anticipation of this error We, the weighing hopper 2 is prefilled with an article having an initial weight Wi. Therefore, if the stationary weighing value of the article in the weighing hopper 2 after the completion of the input weighing is Wa, Wa = Wt−We + Wi> Wt, and an article having a weight more than the target filling weight Wt is accommodated in the weighing hopper 2. Therefore, it is possible to discharge and weigh the article having the target filling weight Wt from the weighing hopper 2.

  When the input weighing is completed, the stationary weighing value Wa of the article in the weighing hopper 2 is measured in anticipation of the stabilization time, and then the discharge weighing mode is executed. Wt is given as a target value for discharge weighing, the discharge gate 14 of the weighing hopper 2 is opened, and discharge weighing is started. The opening degree of the discharge gate 14 is controlled based on the measured measurement value so that the discharge measurement is completed in as short a time as possible and high measurement accuracy is obtained. Details of this discharge metering will also be described later.

  When the article is discharged from the weighing hopper 2 by the target weight Wt, that is, when the weighing value Wb of the weighing hopper 2 satisfies Wa−Wb ≧ Wt, the discharge gate 14 is completely closed and the discharge weighing is stopped. Let By this discharge weighing, an article having a predetermined weight Wt is discharged from the weighing hopper 2 to the packaging container.

  After the discharge weighing, the weight value Wc of the remaining article in the weighing hopper 2 is measured by looking at the stabilization time. Since there was an error We in the previous input weighing, the weight value Wc of the remaining article after weighing and weighing Wt from the weight Wa before starting discharge weighing is Wc = Wa−Wt = Wi−We.

  Next, the charging weighing mode is executed again, but the target weight Wf of the article to be loaded into the weighing hopper 2 this time is not Wt but Wf = Wt + Wi−Wc. Here, since Wf is equal to Wt + We, by inserting an article of Wf, We is compensated and no error is accumulated. Such a change in the weight of the weighing hopper 2 is shown in FIG. Strictly speaking, the error in the discharge weighing is added to the above-mentioned error, but the increase or decrease in the initial charging weight Wi due to the error generated as a result of the previous charging weighing, including this error, is also measured at the next charging weighing. It is compensated by changing the input weighing target value.

  In this way, in this weight type filling machine, since the next input target value is set and input weighing is performed so as to compensate for the error caused by the previous input weighing, articles that are always accommodated in the weighing hopper 2 The weight is slightly larger than the target filling weight for the packaging container. Therefore, there is no need to make the hopper 3 of the weighing hopper 2 large and the load cell 5 have a large capacity. In addition, even if there is some zero point drift in the measured value, the situation in which the articles in the weighing hopper 2 are insufficient for the target filling weight does not occur.

  Input weighing in this gravimetric filling machine is performed as follows. First, the opening degree of the supply gate 22 is set to a predetermined G1. When the measurement is started, as shown in FIG. 3A, the opening degree of the supply gate 22 quickly becomes G1. As a result, the article is fed from the supply hopper 20 into the weighing hopper 2. However, since there is a drop between the weighing hopper 2 and the supply hopper 20, the measured value Wx does not rise immediately as shown in FIG. Eventually, when the article reaches the weighing hopper 2, a large load and impact load are applied to the weighing hopper 2, and the measured value Wx rises rapidly and eventually reaches a first set weight W1 set in advance. A section until the first set weight W1 is reached is a so-called large charging section. As described above, since the target filling weight Wf in the input metering mode changes every time, the first set weight W1 is determined by subtracting a predetermined deviation weight wm from the target filling weight Wf.

Until the measured value Wx reaches the second set weight W2 from the first set weight W1, the gate opening degree Gx is
Gx = (G1-G2) * {(W2-Wx) / (W2-W1)} ^A + G2
Controlled by. The second set weight W2 is a value close to the target fill weight Wt, and is also set by subtracting a predetermined deviation weight wn from the target fill weight Wf, similarly to the first set weight W2. G2 is a gate opening degree when an article having a weight equal to the set weight W2 is put into the weighing hopper 2, and G1> G2. A is a coefficient. Thus, the supply flow rate is decreased as the weight of the articles supplied to the weighing hopper 2 increases. However, since an impact load is applied to the weighing value Wx in the input weighing in addition to the weight of the article, the weighing value Wx is larger than the article weight actually stored in the weighing hopper 2. Therefore, if the gate opening degree Gx is reduced in proportion to the measured value Wx, the opening degree is reduced too quickly, and the supply flow rate is reduced too early for the actual article weight in the weighing hopper 2, The time required to fill the article to the target weight is increased. Therefore, as shown in FIG. 4, the coefficient A is appropriately selected, and the aperture of the gate opening degree Gx is reduced for the measurement value Wx, so that the arrival at W2 is accelerated. Until the measured value Wx reaches the second set weight W2 from the first set weight W1, it is the medium throw-in. When the charging is completed, the supply gate 22 is immediately closed. That is, a small input is not performed.

  As described above, in this charging measurement, the opening degree of the supply gate 22 is set to a constant value G1 when the charging is large, and the opening degree of the supplying gate 22 is gradually decreased according to the gradual increase of the weighing value when the charging is medium. The supply is stopped when the measured value Wx reaches a predetermined weight W2 so as not to cause overshoot. By performing input weighing in this manner, articles can be input within a certain range of measurement accuracy, and a static measurement value can be obtained earlier than when only large input is performed.

  In the weighing hopper 2, since more articles than the weight of articles to be discharged by discharge weighing are to be thrown in by input weighing, the accuracy of the input weighing may be lower than that of the discharge weighing. However, it is desired that the static weighing value of the input article can be measured with high accuracy. Therefore, when an overshoot occurs in the measurement value Wx, the opening degree of the supply gate 22 based on the measurement value is not correctly controlled, and it takes time until the measurement value is stabilized after the input measurement. Therefore, the supply flow rate is reduced so that a too large overshoot does not occur. Moreover, the time required for charging is shortened by not performing small charging. If the coefficient A is set to 0.3 or less, for example, 0.2, the input metering is performed while maintaining the large supply flow rate by slowing down the gate opening degree Gx for the magnitude of the measurement value Wx. Time can be shortened.

  In the above charging metering, the opening degree of the supply gate 22 is set to a constant value G1 in the large charging, but the supply flow rate is increased by increasing the gate opening degree at a constant speed or constant acceleration from the start of charging. When the measured value Wx reaches W2, the gate opening degree can be gradually decreased by the above formula. In this case, an amount larger than W2 is accommodated due to a response delay of the gate.

  Discharge measurement is performed as follows. After completion of the input weighing, after waiting for a stable time, the weight Wa of the article in the weighing hopper 2 is measured. It is assumed that the input measured value is Wa = W3 after waiting for stability. When this measurement is completed, discharge weighing is performed with the target discharge weight as Wt. First, the article is discharged with the opening degree of the discharge gate 14 set to G3 which is set in advance. This discharge continues until the measured value Wx reaches the third set weight W4. That is, a large input is performed. The third set weight W4 is set to a value obtained by subtracting a predetermined weight Wp from the static weighing value Wa. The weight Wp is set to, for example, about 95% of the target filling weight Wt.

When the measured value Wx reaches the third set weight W4, the opening degree of the discharge gate 14 is gradually decreased until the measured value Wx reaches the fourth set weight W5. That is, the middle throw is performed. The fourth set weight W5 is a value obtained by subtracting a predetermined weight Wq from the static weighing value Wa. The weight Wq is set to, for example, about 98% of the target filling weight Wt. The gradual decrease in the opening degree of the discharge gate 14 is as follows. When the opening degree of the discharge gate 14 is Gxx and the gate opening degree corresponding to the fourth set weight W5 is G4,
Gxx = (G3-G4) * {(W5-Wx) / (W5-W4)} ^A + G4
Determined by.

  When the measured value Wx matches the fourth set weight W5, the opening degree G4 is maintained until the measured value Wx reaches the fifth set weight W6, and then the discharge gate 14 is immediately closed. That is, a small input is performed. The fifth set weight W6 is set to a value obtained by subtracting the target filling weight Wt from the static weight Wa and adding a drop weight Wg after the discharge gate 14 is closed to the value. This drop weight Wg is not as large as the drop weight at the time of input weighing, and is not affected by the chevron shape of the surface of the article stored in the packaging container, so it is more constant than the drop weight at the time of input weighing. The discharge weighing can be made with higher weighing accuracy than the input weighing.

  In this weight-type filling machine, the packaging container is filled with the article having the target filling weight Wt accurately by discharge weighing. Therefore, the weight of the article accommodated in the weighing hopper 2 is the target filling weight Wt. As long as it is carried out so that the value is larger than that, the weighing accuracy is not necessary. Therefore, in the input weighing, the small input is removed in order to shorten the time until the measured value of the article weighed in from the start of charging becomes stable and can be statically metered with high accuracy as much as possible.

  If an error exceeding the initial weight Wi occurs during the input weighing, the discharge weighing cannot be performed. Therefore, a target filling weight Wt is set, and a supply gate is set so that articles substantially equal to the target filling weight Wt are supplied to the weighing hopper 2. The opening degree of 22 is gradually reduced. The supply gate 22 is closed at the end of the middle charging. The small input is not performed because it is performed to bring the static weighing value closer to the target weight value Wt. It is possible to set the initial input weight Wi to 10 to 20% of the target filling weight Wt, and an error in the input weighing is allowed within this range. Therefore, the weighing accuracy of the input weighing can be relaxed by one digit or more as compared with the small weighing.

In the first reference embodiment, the supply gate 14 and the discharge gate 22 are used as the article supply and discharge means, and the gate opening degree is used as the supply flow rate control value and the discharge flow rate control value. It is also possible to use a screw feeder, a vibration feeder or the like, and use the screw rotation speed or the amplitude of the electromagnetic feeder as the supply flow rate control value and the discharge flow rate control value. In addition, the hopper 3 of the weighing hopper 2 is of a size that can accommodate an article having a weight that is a multiple of the target filling weight, and after the single input weighing is performed, the discharge weighing is continuously performed a plurality of times. Good. In this case, the target filling weight at the time of input weighing is set to nWt + (Wi−Wc) when the discharge weighing is performed n times.

As shown in FIG. 5, the weight-type filling machine of the second reference form of the present invention is intended to fill the packaging container with a higher speed and higher accuracy than the weight-type filling machine of the first reference form. To do. This weight type filling machine has two weighing hoppers 2a and 2b. These weighing hoppers 2a and 2b have hoppers 3a and 3b and load cells 5a and 5b. The weighing hoppers 2a and 2b are provided with discharge gates 14a and 14b, and the opening degrees of these gates are adjusted by the motors 16a and 16b.

  A supply hopper 20 is provided above the weighing hoppers 2a and 2b, and supply gates 22a and 22b are provided so as to correspond to the respective weighing hoppers 2a and 2b. The opening degree of these is adjusted by the motors 24a and 24b. .

  Although not shown, analog weighing signals from the load cells 5a and 5b are converted into digital weighing signals and supplied to the CPU. The CPU controls the motors 16a, 16b, 22a and 22b via the motor control unit. Thus, the opening degrees of the discharge gates 14a and 14b and the supply gates 22a and 22b are controlled.

  Below each weighing hopper 2a, 2b, temporary storage means for temporarily storing articles discharged via the discharge gates 14a, 14b, for example, timing hoppers 34a, 34b are provided. The articles stored in the timing hoppers 34 a and 34 b are accommodated in the packaging container via the collecting chute 36.

  The weighing hopper 22a, the timing hopper 34a, etc. constitute a measuring device 38a with a discharge flow rate control device, and the weighing hopper 22b, the timing hopper 34b, etc. constitute a weighing device 38b with a discharge flow rate control device.

The weighing operation in this weight type filling machine is performed as follows. The target filling weight into the packaging container is assumed to be Wt as in the first reference embodiment. The two weighing hoppers 2a and 2b are supplied with articles having an initial weight Wi in advance. The initial weight Wi is the same value as the initial weight Wi of the first reference embodiment. The target filling weight Wff put into each weighing hopper 2a, 2b is set to Wff = 2Wt + (Wi−Wc). In other words, the articles are put into the weighing hoppers 2a and 2b so that there is a sufficient margin for filling the target filling weight Wt twice by charging. The weight value Wc at the start of the filling operation is Wc = Wi because Wc articles are charged by the initial filling, and Wff is 2 Wt. As a result, each weighing hopper 2a, 2b contains 2Wt + Wi articles. Even if an error of We occurs during the input weighing, since Wi is set to be larger than We, it is possible to discharge and weigh articles having the target filling weight Wt twice from the weighing hoppers 2a and 2b.

Control of the opening degree of the discharge gates 14a and 14b and the supply gates 22a and 22b is performed using the first to fourth set weights and the opening degrees G1 to G4, as in the first reference embodiment.

FIG. 6 is a diagram showing the operation sequence of this weight type filling machine. In the discharge weighing mode, discharge weighing and subsequent stationary weighing are executed at time T1, respectively. Performing stationary weighing. The discharge metering mode and the input metering mode are the same as the discharge metering mode and the input metering mode in the first reference mode.

  First, the meter 38a with the discharge metering control device operates, the discharge gate 14a is opened at the time P1, and the discharge metering is performed from the metering hopper 2a to the timing hopper 34a. Since articles weighing more than Wt are still stored in the weighing hopper 2a, the next discharge weighing is executed from the weighing hopper 2a at time P3 immediately after measuring the article weight value after the discharge weighing.

  On the other hand, the meter 38b with the discharge metering control device delays the phase of the operation sequence by the delay time Tc (= T1 / 2) and starts the discharge metering mode from the time P2. The delay time Tc does not need to be T1 / 2, and can be set to a time shorter than the time T1 so that the timing hoppers 34a and 34b are alternately operated at a predetermined cycle of 3T1 / 4.

  Once the discharge metering mode ends, the meter 38b enters the input metering mode from time P4. In this case, the weighing hopper 2b initially stores 2Wt + Wi, and the weight of the remaining articles in the weighing hopper 2b has changed to Wt + Wi due to the execution of one discharge weighing mode. The target weight Wff is given as Wff = 2Wt + Wi−Wc = 2Wt + Wi− (Wt + Wi) = Wt, and in the input weighing from time P4, the articles are loaded with the target filling weight Wt. Also in the weighing device 38b, the articles discharged by the discharge weighing are filled in the timing hopper 34b.

  The weigher 38a performs discharge weighing twice until time P5. Since the remaining weight Wc returns to the initial weight value Wi at time P5, 2Wt is given to the target filling weight Wff, and the weighing hopper 2a Input weighing is performed. The weighing device 38b is also charged with 2 Wt at time P10.

  As described above, the timing hoppers 34a and 34b provided in the two measuring devices 38a and 38b always collect all the articles chute 36 alternately at a constant cycle of 3T1 / 4 after expecting a predetermined phase delay Ta at the time P1. It is opened for a time Tb necessary to be discharged.

  In this way, the two weighing devices 38a and 38b can be filled four times in the three discharging or charging weighing modes, and the discharging weighing and the charging weighing are simply alternately performed by the two weighing devices 38a and 38b. Compared to the method to be performed, the filling cycle is shortened by 3/4. That is, the filling cycle consisting of two continuous discharge weighings and one charging metering is repeated in the two weighing instruments 38a and 38b, and the filling cycles of the respective weighing instruments 38a and 38b are executed in parallel while being delayed by a fixed time. I am letting. In addition, the timing hoppers 34a and 34b are provided to fill the packaging container with a cycle shorter than one discharge or weighing cycle in the filling cycle.

  In addition, since the packing container is filled with a constant cycle instead of increasing the number of times of filling the packaging container, the operation of the packaging apparatus and the transport operation of the packaging container are also positively affected.

  The filling timing hoppers 34a and 34b are provided in order to allow the articles discharged and weighed in parallel by the plurality of measuring devices 38a and 38b to be filled into the packaging container through the packaging container or packaging machine prepared in one place. This is because there are restrictions on the time interval and time length for discharging, and it is necessary to adjust the discharge timing. When packaging containers are prepared in parallel for the respective devices, the timing hoppers 34a and 34b may not be used.

  In the discharge metering method, since the head amount is small, it is necessary to set the flow rate just before the supply stop to a small value, but the goods can be packaged with a predetermined accuracy without carrying out small input that continues this small value for a certain period of time. It is also possible to fill in. Therefore, the discharge gates 14a and 14b may be controlled so that the opening degree becomes 0 immediately after the middle insertion.

  One embodiment of the present invention is shown in FIG. In this embodiment, the present invention is applied to a combination weigher. In the combination weigher, articles are put into a plurality of weighing hoppers 40, each article is weighed, and each weighing value is variously combined. From these combinations, the combination whose total weight is equal to or close to the target weight is selected. The article is discharged from the weighing hopper 40 containing the selected article. Articles are supplied to the weighing hopper 40 that has discharged the articles from a supply hopper 42 provided above the weighing hopper 40. Articles are supplied to the supply hopper 42 from a vibration feeder 44 located above the supply hopper 42. The weighing hopper 40 is filled with articles by the weight determined in relation to the target weight (Wt / m when the target weight is Wt, and the number of weighing hoppers that are expected to be selected is m). Is desirable. In this way, when the article is supplied to the weighing hopper by a substantially constant weight using the vibration feeder 44, it takes a lot of time to put the article. Therefore, while weighing the articles in the weighing hopper 40 and the combination of the weighing values, the articles are put into the supply hopper 42 provided above each weighing hopper 40 by a substantially constant weight, and the weighing hopper As soon as it becomes empty, articles are supplied to the weighing hopper 40 at once from the supply hopper 42 thereabove.

  However, the supply of articles to the supply hopper 42 by the vibration feeder 44 actually takes time, and the filling cycle to the weighing hopper 40 cannot be shortened.

Therefore, in this embodiment, a method is adopted in which the supply of the article to each supply hopper is performed until the level sensor 46 provided in the supply hopper 42 detects the article, and the accuracy is lower than the conventional one, The time required for supply is shortened. Instead, a predetermined value initially the opening of the supply gate as the opening degree full flow and medium introduced was performed in the first referential embodiment of the gate 42a having the supply hopper 42, and the subsequent gradual opening degree The method to make it small is adopted. In the conventional method, since the supply gate 42a is opened all at once, an impact load is generated in the weighing hopper 40, it takes time until the weighing signal is stabilized, and it takes a long time to obtain the stationary weighing value. However, the impact load can be suppressed by gradually reducing the opening degree of the gate after the large input. In addition, it is possible to improve the combination weighing accuracy when the weight of the articles supplied to each weighing hopper 40 varies to some extent.

The method for controlling the opening degree of the supply gate 42a is similar to the first reference embodiment, in which the first and second set weights are set, and the measured value in the weighing hopper 40 becomes the first set weight. The opening degree of the supply gate 42a is set to G1, and thereafter, control is performed according to Gx = (G1-G2) * {(W2-Wx) / (W2-W1)} ^A + G2 up to G2.

Alternatively, the gate opening degree is set to G1 until time t1, and the opening degree Gx is set according to Gx = (G1-G2) * {(t2-tx) / (t2-t1)} ^A + G2 from time t1 to time t2. It can also be controlled. The reason for using time as a parameter in this way is as follows. It is desirable to control the supply flow rate based on the weight of the article put into the weighing hopper 40 as much as possible. However, if the supply flow rate is too large, the impact load applied to the weighing hopper 40 becomes large and the cedar and measurement values are actually The weight of the article supplied to the weighing hopper 40 may not be accurately represented. In this case, even if the supply gate 42a is controlled based on the measured value, the control cannot be performed correctly. Rather, more accurate supply amount control can be performed by estimating the weight of articles actually put in over time.

  Initially, the gate opening degree is set to G1, the article is supplied until time t1, the measured value W11 at time t1 is measured, and the gate opening degree is increased according to the increase of the measured value Wx from W11 to a predetermined set weight W2. Is gradually decreased from G1 to G2, and when the measured value Wx becomes W2, the gate is immediately closed, or the opening degree of the supply gate 42a is gradually increased from zero until the time t1, and predetermined from the measured value W21 at the time t1. From the gate opening degree G21 at time t1 to the gate opening degree G2 corresponding to the setting weight W2 until the set weight W2, the gate opening degree is gradually decreased corresponding to the gradual increase of the measured value Wx, and the measured value Wx becomes the set weight W2. If they are equal, a control method of closing the supply gate 42a can be adopted.

It is a block diagram of the weight type filling machine of the 1st reference form of the present invention. It is a figure which shows the change body of the goods of the weighing hopper in the weight type filling machine of FIG. It is a figure which shows the change state of the opening degree of a supply and discharge | emission gate in the weight type filling machine of FIG. 1, and the change state of a measured value. It is a figure which shows the relationship between the measured value which made the parameter in the formula used for control of the supply gate in the weight type filling machine of FIG. 1 a parameter, and a gate opening degree. It is a block diagram of the weight type filling machine of the 2nd reference form of the present invention. It is an operation | movement sequence diagram of the weight type filling machine of FIG. It is a schematic block diagram of the combination weigher of one embodiment of the present invention.

Explanation of symbols

2 2a 2b Weighing hopper (measuring means)
12 CPU (control means)
14 Discharge gate (Discharge flow rate control means)
20 Supply hopper (goods storage means)
22 Supply gate (supply flow rate control means)

Claims (3)

In a combination weigher that variously combines the weights of articles weighed by a plurality of weighing means and selects a combination in which the total weight is equal to or close to a predetermined target weight,
A plurality of article supply means provided corresponding to each of the weighing means, storing the article therein, and supplying the article to the corresponding weighing means at a flow rate corresponding to a supply flow rate control value;
Control means for outputting the supply flow rate control value to the article supply means corresponding to the empty measurement means when any of the measurement means is empty,
This control means comprises
When the measurement value of the measurement means increases to a first weight determined to be smaller than a predetermined constant weight, the measurement is performed to a second weight determined to be larger than the first weight and smaller than the constant weight. Until the measurement value of the means increases , during the control process of the supply flow rate control value, at least the rate of change of the supply flow rate control value with respect to the measurement value of the measurement means gradually increases according to the increase of the measurement value of the measurement means. In the control process in which the supply flow rate control value is gradually decreased from the value when the measurement value of the measuring means reaches the first weight so that the supply flow rate control value gradually decreases so as to include a control process that increases. A combination weigher that immediately sets the supply flow rate control value to zero when the weighing value of the weighing means reaches the second weight. In a combination weigher that variously combines the weights of articles weighed by a plurality of weighing means and selects a combination in which the total weight is equal to or close to a predetermined target weight,
A plurality of article supply means provided corresponding to each of the weighing means, storing the article therein, and supplying the article to the corresponding weighing means at a flow rate corresponding to a supply flow rate control value;
Control means for outputting the supply flow rate control value to the article supply means corresponding to the empty measurement means when any of the measurement means is empty,
This control means comprises
At least during the control process of the supply flow rate control value from the first time at which a predetermined time has elapsed from the time when the supply of the article to the weighing means is started to the predetermined second time. wherein as the rate of change with time of the supply flow rate control value comprises progressively larger control process in accordance with an increase in time, the supply flow rate control value, is gradually decreased from the supply flow rate control value when the first time, the A combination weigher that immediately sets the supply flow rate control value to zero when the second time comes in the control process in which the supply flow rate control value gradually decreases . In a combination weigher that variously combines the weights of articles weighed by a plurality of weighing means and selects a combination in which the total weight is equal to or close to a predetermined target weight,
A plurality of article supply means provided corresponding to each of the weighing means, storing the article therein, and supplying the article to the corresponding weighing means at a flow rate corresponding to a supply flow rate control value;
Control means for outputting the supply flow rate control value to the article supply means corresponding to the empty measurement means when any of the measurement means is empty,
This control means comprises
The metering means for at least the supply flow rate control value during the control process of the supply flow rate control value from a first time at which a predetermined time has elapsed since the supply of the article to the metering unit was started. The supply flow rate control value is gradually decreased until the measured value of the measuring means reaches a predetermined weight so that the rate of change of the measured value with respect to the measured value includes a control process that gradually increases as the measured value of the measuring means increases. A combination weigher that immediately sets the supply flow rate control value to zero when the measurement value of the measuring means reaches a predetermined weight in the control process in which the supply flow rate control value gradually decreases .

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