JPH078730U - Mass measuring device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Speed up mass measurement by devising the platform and adopting the measurement method that utilizes its features. [Structure] The object to be weighed 1 is put into a tray 2 attached to a conveyor chain 4, transferred from left to right, and discharged. The conveyor is a motor 5 with a reducer that drives the conveyor.
Along with it, it is attached to the conveyor mount 7. Load cell 8
One end of supports the conveyor mount 7, and the other end is fixed to the load cell support 9. After the weight of the object to be weighed on the platform is converted into a voltage by the load cell 8 and amplified by the amplifier, the high frequency component of the signal is removed by the low-pass filter and input to the A / D converter. The output signal of the A / D converter is taken into a calculation device and used as a mass signal for calculating the mass of the object to be weighed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the structure and measuring method of an apparatus for measuring mass (or weight) in various industrial fields.

[0002]

[Prior art]

 When performing mass measurement while transferring the object to be weighed, in the conventional measurement method, first one object to be weighed is placed on a platform, measured, and then discharged, and the same is performed for the next object to be weighed. It was a measurement method that performs the operation of.

[0003]

[Problems to be solved by the device]

 When the conventional mass measuring device is speeded up to improve the throughput of the object to be weighed, the following problems occur. For example, in the case of a conveyor type table, the conveyor speed increases in proportion to the number of units processed per unit time, forcing a harsh condition on the mechanical part, which causes mechanical disturbance that adversely affects the measurement accuracy. The impact will also increase. The present invention provides a newly devised measuring device equipped with a mounting base with a measuring method different from the conventional one, which is applied to a measuring device equipped with a mounting base, which has a severe load imposed on a mechanical part of the mounting base when a measuring device based on the conventional measuring method is speeded up and an adverse effect resulting therefrom. By adopting this, it is intended to significantly reduce the power consumption and to achieve performance exceeding the processing capacity of conventional equipment.

[0004]

[Means for Solving the Problems]

 A specific example of the solving means is the following (1) or (2). The only difference between (1) and (2) is the model of the platform (see Figures 1, 2 and 3). (1) A plurality of trays 2 are attached to the conveyor chain 4 to form a conveyor-type platform, and the objects to be weighed 1 are sequentially loaded into the tray one by one, and each time one is loaded, the object to be weighed on the platform is loaded. The entire mass is measured by the load cell 8, and the mass of each of the objects to be weighed is continuously measured by calculation using the value. At that time, the objects to be weighed on the mounting table are discharged from the mounting table in order from the previously measured objects, leaving a predetermined number. In addition, the input and the discharge will be performed almost at the same time. The above measurement and control are performed by the digital signal processing measurement system in FIG. (2) Two rotary plates 13 having a plurality of cutouts at the periphery and driven to rotate are used as a mounting table, and the objects to be weighed 12 are sequentially put into the cutouts 2 one by one. Each time, the mass of the entire object to be weighed on the platform is measured by the load cell 17, and the mass of each object to be weighed is continuously measured by calculation using the value. At this time, the objects to be weighed on the platform are discharged from the platform sequentially from the previously measured ones, leaving a certain number. The above measurement and control are performed by the digital signal processing measurement system of FIG. In the case of Fig. 2, the two rotating plates rotate in the vertical plane and support two points of the object to be weighed, but the method is to put it on one horizontal in-plane rotating plate without notches. May be

[0005]

[Action]

In the case of the above solution means (1), its action will be described focusing on the mass signal. Fig. 4 is a schematic diagram in which the timing of inputting / discharging and signal level measurement is entered in the time change diagram of the mass signal (signal obtained by converting the output signal of the A / D converter to mass) when there are four pans. is there. T _i (i = 1, 2, 3, ...) Is the settling time of the mass signal for each loading of the object to be weighed. _Assuming that the signal level at this time is L _{i and the mass value of each measured object is M i} , L _i = M _i + M _i−1 , M ₀ = 0, (i = 1, 2, 3, …) Therefore, M _i = L _i −M _i−1 , M ₀ = 0, (i = 1, 2, 3, ...) Is obtained. From this formula, L _i is measured and is substituted in the above formula together with the known amount M _i−1 , whereby the mass value M _i of each object to be weighed is obtained.

[0006]

【Example】

 Here, the structure and operation of the embodiment will be described with reference to FIGS. FIG. 1 shows an example in which the present invention is carried out on a conveyor type mounting table. The object 1 to be weighed is put into a tray 2 attached to a conveyor chain 4, transferred from left to right, and discharged. The conveyor is attached to the conveyor mount 7 together with the motor 5 with a reducer that drives the conveyor. One end of the load cell 8 supports the conveyor mount 7, and the other end is fixed to the load cell support portion 9. The weight of the object to be weighed on the platform is converted into a voltage by the load cell 8, amplified by the amplifier 20, and then the high-frequency component of the signal is removed by the low-pass filter 21 and input to the A / D converter 22. The output signal of the A / D converter 22 is taken into the arithmetic unit 22 and used as a mass signal for the mass calculation calculation of the object to be weighed. The mass value thus obtained is displayed on the display unit 24 and stored in the arithmetic unit for use in controlling the equipment in the next step. The loading time of the object to be weighed and the mass detection time (settling time) are determined with reference to the ON / OFF signal obtained by the optoelectronic switch 10. FIG. 2 shows an example in which the present invention is carried out on a rotary plate type table. The object to be weighed 12 is put into the notch at the uppermost position of the rotary plate 13 and discharged at a fixed position while rotating clockwise. The rotating plate 13 is attached to the rotating plate mount 16 together with the motor 14 with a reducer that drives the rotating plate 13. One end of the load cell 17 supports the rotary plate mount 16, and the other end is fixed to the load cell support portion 18. The signal processing after the weight of the object to be weighed on the platform is converted into the voltage by the load cell 17 is the same as in the above-mentioned embodiment.

[0007]

[Effect of device]

For simplification of explanation, assuming that the conveyor length is 2L and the dimension of the object to be weighed is small enough to be ignored, the method of the present invention is compared with the conventional method. Will be explained. The time required to measure one object to be weighed is L / V ₁ in the conventional method and L / (2V ₂ ) in the method of the present invention having four saucers. However, V ₁ and V ₂ are belt speeds in the respective methods. Therefore, when measuring the one at the same time _{is, L / V 1 = L /} (2V 2) next, from which to obtain the _V 2 = _V 1/2. That is, in the system of the present invention, the belt speed can be reduced to half that of the conventional system without lowering the processing capacity. In general, if the number of saucers is 2N, then V ₂ = V ₁ / N. As is clear from the above description, according to the method of the present invention, the movement of the mechanism portion of the mounting table can be slowed down without decreasing the processing capacity of the conventional method. Therefore, the influence of mechanical disturbance on the measurement accuracy can be reduced, and the processing speed can be further improved by speeding up the mechanism with the method of the present invention. The same effect as above can be obtained in the other method of the present invention, that is, in the case of the rotary plate type table. However, if the rotation is in the vertical plane, the vertical component of centrifugal force must be corrected. Now, suppose that the object to be weighed with mass m is at the position of radius r and angular displacement θ of the rotating plate rotating at angular velocity ω (see FIG. 5), the vertical component F _v of the centrifugal force is F _v = − In mrω ² · cos θ, the mass corresponding to this force is F _v / g. Therefore, for the object to be weighed having the mass m at the position of θ, it suffices to add −F _v / g for correction. This correction is performed on all the objects to be weighed existing on the platform at the time when the signal level L _i is measured. Such a correction can be easily performed by an arithmetic unit using a microprocessor. The important points for making sure the effect obtained by the present invention can be described. The object to be weighed becomes unstable immediately before being discharged. The duration of this unstable state increases as the movement of the platform mechanism becomes slower. Then, if the slowing motion exceeds a certain limit, it becomes impossible to obtain the settling of the mass signal for each input of the object to be weighed. Therefore, if there is such a risk, or if you want to allow a margin for the settling time, a mechanism for forcibly discharging is installed outside the platform so that it will be discharged immediately before the object to be weighed is loaded. Quickly eliminate the objects to be discharged.

[Brief description of drawings]

FIG. 1 is an explanatory diagram when the present invention is carried out on a conveyor type table.

FIG. 2 is an explanatory view of the case where the present invention is carried out on a rotating plate type mounting table.

[Fig. 3] Schematic diagram in which timings of input / discharge and signal level measurement are entered in the mass signal

FIG. 4 is a block diagram showing a mass measurement system.

FIG. 5 is an explanatory diagram regarding correction of centrifugal force.

[Explanation of symbols]

1 ... object to be weighed 2 ... saucer 3 ...
Sprocket 4 ... Conveyor chain 5 ... Reducer motor 6 ...
Drive belt 7 ... Conveyor mount 8 ... Load cell 9 ...
Load cell support 10 Photoelectric switch 11 Photoelectric switch 12
... Weighing object 13 ... Rotating plate 14 ... Motor with reduction gear 15
Drive belt 16 Rotating plate mount 17 Load cell 18
... load cell support 19 ... mounting table 20 ... amplifier 21
... low-pass filter 22 ... A / D converter 23 ... arithmetic unit 24
... indicator L _i ... mass signal level (i = 1, 2, 3, ...) M _i ... mass of each measured object (i = 1, 2, 3, ...) T _i ... mass signal settling time ( i = 1, 2, 3, ...) F _v ... Vertical component of centrifugal force acting on the object to be weighed m ... Weight of the object to be weighed r ... Distance from the center of rotation to the center of gravity of the object to be weighed ... Rotation angle ω ... Angular velocity of rotating plate

Claims (2)

[Scope of utility model registration request] 1. A conveyor-type platform such as a chain conveyor or a belt conveyor is used as the platform, and the objects to be weighed are sequentially loaded one by one, and a predetermined number of them are left on the platform while performing a discharging operation. A mass measuring device that employs a measuring method that measures the mass of the entire object to be weighed each time it is loaded and uses the value to continuously measure the mass of each object to be weighed. 2. A rotating plate is used as a mounting table, the objects to be weighed are sequentially loaded one by one, and a predetermined number of them are left on the mounting table, and the discharging operation is sequentially performed. The mass measuring device adopting a measuring method in which the mass of the entire object is measured and the mass of each object is continuously measured by calculation using the value.