JP3635421B2 - Weighing device preload device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
An object of the present invention is to alleviate vibrations peculiar to an elastic body when an article is loaded in a weighing device whose balance mechanism is mainly composed of an elastic body (such as a helical spring and a parallelogram type load cell), and to shorten the weighing time. It relates to the weighing device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, a measuring device using an elastic body as an equilibrium mechanism has a configuration as shown in FIG. This weighing apparatus uses a parallelogram type load cell as an equilibrium mechanism, and the entire apparatus is for quantitatively weighing powder particles. The general operation is as follows. Therefore, the parts having the same functions as those in the embodiment of FIG. In FIG. 3, it is assumed that the same raw materials 30a and 30b are sufficiently prepared in the raw material tanks 25a and 25b, respectively. Now, the target value is set by the setting device 15 and the operation is started. The raw material A is put into the weighing hopper 22 from the raw material tank 25a by the raw material supply feeder 24a. In such a quantitative weighing device, a plurality of supply devices having different capacities are often used in order to shorten the weighing time. That is, a large-feed feeder and a small-feed feeder. These feeders usually have a feed capacity of 1:20 or less. In the case of FIG. 3, the raw material supply feeder 24a is a large input feeder and 24b is a small input feeder. Therefore, the target value is set by the 100% setter 16, and then the value supplied by the large-feed feeder 24a is set by the cut value setter 17 as 90% of the target value (referred to as the large-cut cut value). The percentage of the cut value depends on the properties of the raw material. The weighing hopper 22 is weighed by the balancing mechanism 2 while the raw material is being charged. In order to shorten the weighing time, when the supply amount to the weighing hopper 22, which is simply referred to as “large charging”, “rough charging”, or “90% charging”, reaches 90%, the control device 14 supplies the small feeding feeder 24 b. The operation is switched, and the remaining 10% is put in a small amount with a small capacity, and when the target value is reached, this charging is also stopped. When the series of supply is completed, the discharge gate 23 of the weighing hopper 4 is opened, and the measured raw material is discharged in the next process (not shown). This completes one quantitative measurement. Actually, a head correction is performed to increase the weighing accuracy, but details are omitted. As described above, in such a system, the measuring ability is improved by properly determining the timing of switching between large input and small input in consideration of the properties of the raw material. However, a large input cannot be expected to be quantitative due to the large fluctuations in the supply amount and poor cutability. Therefore, it is considered difficult to obtain a target value only by large input, and this is considered to be due to instability of switching timing between large input and small input.
[0003]
[Problems to be solved by the invention]
If the timing of switching between large input and small input becomes unstable, the measurement time cannot be determined, and there is a problem that the control of the entire system is hindered especially when there is a packaging system or the like in the subsequent stage. For example, if the large input fluctuates significantly, the weighing signal being input also varies, and as a result of capturing the above switching timing with the peak value of the fluctuation, the large input is completed where the actual value is less than the preset cut value. It ends up switching to small input. Then, since the small input is originally a small capacity, it takes more time than expected to reach the target value, and the measurement time is extended. Conversely, a large input value may be supplied in excess of the set value. In other words, it is a result that is captured below the peak of the fluctuation, and when switching from large input to small input, the actual value is input more than the preset cut value, and the small input time becomes extremely short. In some cases, there may be a case where there is no time for small input, and there is a case where a fixed amount is reached with a large input variation value, and the measurement accuracy may be remarkably deteriorated. The present invention solves such problems of the prior art, and provides a weighing device that shortens the weighing time by minimizing the fluctuation of the weighing time even if there is some fluctuation in the large input. .
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the first invention is a scale for measuring the weight of an article. When a target value of an article to be weighed is determined, a value smaller than the target value is set. A value equal to or close to the first weighing stage in a weighing device composed of a first weighing stage for weighing and a second weighing stage for weighing to the target value beyond the first weighing stage Thus, the preload device of the weighing device is characterized in that the preload is applied from a fixed portion different from the scale.
[0005]
In the second invention, a load cell type scale for measuring the weight of an article, comprising at least two stages of supply means of large input and small input, wherein the large input supply means is a value less than a target value. The small input supply means starts supply when the supply as the first measurement value by the large input supply means is completed, or operates the large input supply means. In the weighing device configured to continue when it is operated at the same time, supply the second measured value up to the target value, and stop the supply when the target value is reached, it is equal to or close to the first measured value A preload is applied to the load cell type balance from a fixed part separate from the scale until the value is reached, and when the large input supply means is operated, the large input supply means is stopped from a value exceeding the preload and the small value is reduced. Making input and supply means The is characterized in that it has to be supplied until reaching the desired value.
[0006]
In a third aspect of the invention, the means for applying the preload includes a worm gear 6 driven by a motor 9 and a worm wheel 7 and a pressing shaft 5 helically fitted at the center of the worm wheel 7. It is characterized in that the pressing load can be added or removed by forward / reverse driving.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
A case where a quantitative weighing apparatus is implemented according to the present invention will be described. The metering device is usually a load cell type scale equipped with a large input device and a small input device. First, the target weight is set by a predetermined amount setting device so that the most efficient measurement can be performed. The cut value before the predetermined amount, that is, the amount of large input is determined based on the properties of the article. When the large input amount is determined, the setting of the large input amount that is set so that the remainder obtained by subtracting the large input amount from the target weight automatically becomes the small input amount is completed, and an instruction for setting a preload is issued. This instruction is normally started manually, but may be automatically started when the setting of the large input amount is completed, and the preload is applied to the load cell by any method. According to the present invention, the preload is set to a value equal to or close to the large input amount when the large input amount is determined, and the load cell is electrically driven by the preload setting start command. Applied to the load end. This applied value is immediately displayed on the display. Normally, the metering operation is started from this stage. A large input is started from a large input storage tank by a large input supply device. Even if there is a change in the supply state at the beginning of operation, the measured value during this period does not appear as a change value. In this embodiment, since a large input amount or its equivalent amount is forcibly loaded in advance on the load cell, the load fluctuation during the large input is not easily shown in the measured value. Therefore, the time point when the large input ends is also stable and can be switched to the small input at an accurate timing. When the small injection is completed, the quantity is determined and the supply device is stopped, and the quantitative weighing operation is completed. Although not shown, if there is a discharge instruction from the next step, the hopper gate attached to the weighing hopper is opened, the metered article is discharged, and one operation is completed. However, it may be removed only when checking the zero point of the load cell and checking the span or the like.
[0008]
【Example】
The operation of each part of the quantitative weighing apparatus according to the present invention will be described with reference to FIG. 1 showing the overall configuration and the enlarged perspective view 2 of the balancing mechanism 1. First, reference numeral 1 denotes a hopper type weighing device including a mechanism for applying a preload, and reference numeral 2 denotes a balance mechanism, which is a load detection load cell. A hopper mounting bracket 3 is mounted, and a pressing load is applied by pressing the pressing shaft 5 against the preload application upper surface 4 of the bracket. As for the pressing load, the pressing shaft 5 is displaced in the direction of the arrow 8 by the forward / reverse rotation of the worm gear 6 and the worm wheel 7 driven by the pulse motor 9, and the pressing load is added or removed. The measurement signal 10 of the load detection load cell 2 which is a balance mechanism enters an amplifier 11 and enters a control device 14 through a filter 12 and an A / D converter 13. On the other hand, the target value (target weight value) is set by the target value setting unit 16 using various setting devices. Further, the large input amount value is set by the setting device 17. These set values are temporarily stored in a storage device (not shown) and input to the control device 14. The set value is displayed on the display device 21. The various setting devices 15 include a command value push button switch 18 for applying a preload to the load detection load cell 2 in addition to a target value and a large input amount value setting device. When the push button switch is pressed, the command signal 26 is It is output to the pulse motor 9. Further, the setter 15 is provided with a push button switch 19 for starting operation and a push button switch 20 for stopping operation. Further, the weighing hopper 22 has a discharge gate 23 for discharging a fixed quantity article, which can be opened and closed by a signal 27 from the control device 14 and can be discharged to the next process. A raw material tank 25 having a large charging supply device 24a and a small charging supply device 24b is provided at the upper part of the weighing hopper, and the raw material 30 is stored.
[0009]
A case of driving will be described with reference to FIG. As described above, the target weight value and the large input amount value to be quantified are first set by the various setting devices 15. When the operation push button 18 is pressed, a preload is applied to the load cell 2 for the first time by a value equal to the set large input value. The applied value is always displayed on the display device 21 and is applied while being compared in the control device 14 with the large input amount value as a target. When this applied load becomes equal to the large input amount value, the application operation ends. Immediately, a large input is started. Large injection is commanded by the control device 14, and the large supply device is driven by 28 signals. As described above, since the large input has a larger supply amount than the small input, there may be fluctuations in the supply state, and when the large input is completed, the load cell 2 is inserted into the weighing hopper. It begins to equilibrate with the weight of the raw material. That is, the state is approaching the boundary point of whether or not the preload applied pressing shaft and the preload application upper surface of the load cell are separated. Eventually the large input will be completed and stopped. Then, with the stop of the large input, the small input is started. As the small throwing operation proceeds, the pressing shaft and the upper surface are surely separated from each other, and eventually reach a predetermined amount and the small throwing is stopped. This completes the quantitative weighing operation, but when a quantitative raw material supply command comes from the next step, the discharge gate 23 of the weighing hopper 22 is opened to discharge the previously weighed article. From the second time, it is possible to omit the preload application operation, and large-scale charging starts immediately after the operation is started.
[0010]
In the embodiment of the present invention, the powder particle measuring means is mentioned, but in addition to this, on a platform scale or the like, a container containing an article close to a predetermined weight is placed in advance, and then the article is added little by little by hand. It can also be applied to quantification. For example, even when a lump is loaded and unloaded, the weighing time of the scale depends on how quickly the appropriate impact value is settled, so that the technique of the present invention can be applied.
[0011]
【The invention's effect】
As described above, according to the present invention, in the weighing device using the load cell, the preload is applied as close as possible to the predetermined amount value so that the impact load during loading is erased. It has the effect of stabilizing the time scale and shortening the weighing time. In addition, when two types of powders are mixed, if there is a lot of lumps in one powder, variation occurs at the time of switching to the other powder, but the technique of the present invention is applied. By doing so, a stable switching point can be obtained, so that the mixing accuracy is improved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an embodiment according to the present invention.
FIG. 2 is an enlarged perspective view of the balancing mechanism 1 in FIG. 1 according to the embodiment of the present invention.
FIG. 3 is an overall configuration diagram according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hopper type measuring device including the mechanism which applies a pre-load 2 Load cell for load detection with a balance mechanism 3 Bracket for hopper mounting 4 Pre-load application top surface of the bracket 9 Pulse motor 11 Amplifier 14 Controller 15 Various setting devices 21 Display device 22 Weighing hopper 23 Discharge gate 24 Supply device 25 Raw material tank

Claims (3)

A scale for weighing an article, a target value of the article to be weighed is determined, and a first weighing stage for weighing a value less than the target value and the first weighing stage In a weighing device comprising a second weighing stage for weighing to a target value exceeding, a preload is applied to the balance from a fixed part separate from the scale to a value equal to or close to the first weighing stage. A preload device for a weighing device, wherein the preload device is applied. A load cell type scale for measuring the weight of an article, comprising at least two stages of supply means of large input and small input, wherein the large input supply means is configured to supply an amount of an article having a value smaller than a target value to a first value. The small input supply means starts supplying when the supply as the first measurement value by the large input supply means is completed, or continues and reaches the target value as the second measurement value. In the weighing device configured to supply and stop the supply when the target value is reached, a preload is applied to the load cell type balance from a fixed part separate from the scale up to a value equal to or close to the first measured value. When the large input supply means is operated, the large input supply means is stopped from a value exceeding the preload and is supplied until the target value is reached by the operation of the small input supply means. Made Preload device of the weighing device, characterized and. The means for applying the preload includes a worm gear 6 and a worm wheel 7 driven by a motor 9 and a pressing shaft 5 which is helically fitted in the center of the worm wheel. The preload device for a weighing device according to claim 1, wherein the pressing load can be added or removed by means of the above.

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