JPS6061628A - Load indication of suspension scale - Google Patents

Abstract

PURPOSE:To effect rapid measurement and display of an actual load in a simple manner, by, in a frequency cycle of a suspended load, obtaining maximum and minimum values applid to a load cell and computing and displaying an actual load from these values. CONSTITUTION:An output signal from a load cell 2 is converted to a digital signal Si by an A/D convertor 5 located in an apparatus 3. A frequency of this A/D convertor is determined generally as approx. from 10/sec through several tens/ sec. This digital signal Si is applied to RAM7 through CPU6 and judgement as to their magnitudes is made on the digital signal Si+1 by the CPU6. Namely, from a train of positive and negative values of difference DELTAi of the continuously introduced digital signals Si-1, Si, maximum value Tmax and minimum value Tmin are determined by the CPU6. By employment of neighboring maximum value Tmax and minimum value Tmin, the following arithmetic computation is made by the CPU6 and the signal is applied to a display device 4 for display of the actual load m of the suspended load 1. mg=1/3(Tmax+2Tmin).

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for displaying a load on a hanging scale that measures and displays a load in a hanging scale using a load cell.

(Prior Art) FIG. 1 shows a normal crane scale, in which the force of a suspended load 1, that is, the displayed value, fluctuates. In order to prevent this, it is necessary to wait until the suspended load 1 becomes stable, or to apply force manually to stabilize the suspended load 1.

However, with this method of stabilizing the suspended load 1,
In the case of hanging scales such as crane scales that have low vibration damping, efficient measurement and display cannot be performed, and it is troublesome to manually apply force to stabilize the scale.

Another method, as shown in Japanese Patent Publication No. 49-47868, is to incorporate a so-called "real model" into the device and perform correction by dividing the measured value of the "measured object" by the measured value of this real model. There is also a method of apparently compensating for the vibration of the suspended load by performing calculations.

However, this method requires a real model, which makes the equipment complicated and expensive, and has the disadvantage that it requires a large space.

(Objective of the Invention) Therefore, the object of the present invention is to provide a hanging scale with low vibration damping using a simple device and relatively simple calculations.
To provide a load display method for a hanging scale capable of quickly measuring and displaying the final, ie, true, load despite vibrations of a suspended load.

(Structure of the Invention) In order to achieve the above object, the load display method for a hanging scale according to the present invention is such that the load display method for a hanging scale of the present invention is such that the fluctuation of the force applied to the V-dossel that detects the load of the hanging load is caused by the fluctuation of the force in the vibration period of the hanging load. Calculate the maximum value (T+oax) and minimum value (T m 111), calculate the true weight based on this maximum value (T 1Oax ) and minimum value (Tmin), and calculate the true weight determined by this calculation. The feature is that it displays the load.

(Example) Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

First, the rationale for this method will be explained.

In FIG. 1, the force applied to the load cell 2 varies periodically mainly due to the vibration of the suspended load 1. In FIG.

Now, r is the length from the fixed point O to the center of gravity of the suspended load 1, B is the gravitational acceleration, the sheath is the mass of the suspended load 1, t is time, and e is the suspended load 1.
Let fixed point O be the angle between the Jζ straight line and the vertical line. When an equation of motion is established for the suspended load 1, it becomes as follows, e ``eo S!IIωt (1).

It has a large angle of inclination. However, this θ. can have different values for each period due to attenuation.

When the suspended load 1 vibrates as shown in equation (1), the force T exerted on the load cell 2 is as follows.

The second term in equation (2) is centrifugal force. When cos θ is expanded into an integer series, where e is small, the second term from θ4 can be ignored, so equation (2) can be replaced.

Then, equation (3) becomes 1...(4) 1) From this, ωt-π11. θ=0. In other words, when the suspended load 1 is suspended on the vertical line, the tension ゛r takes the maximum value 1'max, and ωL = 11 + θ = 1゜, that is, the minimum value when the suspended load 1 is most inclined from the vertical line. T m
Take in. That is, Tmax = 111g (
1+θo2 )...(5) From equations (4) and (5), the following can be obtained.

In other words, the maximum value Tmax and the minimum value 'l''min for each period of regular load fluctuation in a suspended load j that undergoes simple vibration.
Then, calculate the exact amount of hanging load (++lli or In
) can be determined by calculating equation (7).

Next, an apparatus for carrying out this method is shown in FIG.

In this device, the output signal from the a-docell 2 is converted into a digital signal Si by the A/D converter 5 in the device 3. The frequency of this A/D conversion is generally about 10 times/second to several tens of times/second.

This digital signal Si is entered into a random access memory (RAM) 7 via a central processing unit (CI) U) 6, and the CPU 6 determines whether it is larger or smaller than the next digital signal S111. That is, the CPUG determines the maximum value Tmax and the minimum value Tll1n from a series of positive and negative values 1) of the difference Δ1 between the digital signals SL, , Si that are input one after another. That is, the difference between the digital signal S1 at a certain time and the digital signal 5i-1 immediately before that is Δ1=Si-1Si
When changes from negative to positive, the digital signal S i-1 becomes the maximum value Tmax, and conversely, when changes from positive to negative,
The digital signal 51-1 becomes the minimum value To+in.

Adjacent maximum value 'l'' + 111X obtained as above
and the minimum value T sum in, the CPU 6 performs the arithmetic operation of equation (7), and displays a signal representing the result of the operation on the display 4.
The true load amount of the suspended load 1 is displayed on the display 4.

Figure 3 shows the true load 11 when this device is actually used.
1 shows the passage of time for display No. 1.

Now, as shown in Figure 3, if the suspended load 1 is lifted at time () and the suspended load 1 is vibrating, the output signal from the load cell 2 will be as shown by the broken line in Figure 3. As shown in Fig. 2, it shows fluctuations with little attenuation.

Assume that this signal is subjected to extreme value determination as described above by the above-mentioned device, and the maximum value T+oax is obtained at time L1.

At this point, the minimum value Tl11 has not yet been determined, so the calculation of equation ('7) cannot be performed, so the display value on the display 4 shows the output of the load cell 2 as it is.

Next, when the minimum value Tm1n is reached at time t2, calculation becomes possible for the first time, and the true load (n) is determined by equation (M), and the value displayed on the display 4 is at time t2 in FIG.
suddenly changes to a value close to the true load amount. Time t
The same goes for 3+ t4+ Ls+... Using the maximum value Tmax and minimum value Tm1n for each vibration cycle, calculations of equation (7) are performed one after another, and the load update calculation results are displayed one after another on the display 4. .

Thus, the maximum value TIIIax in the oscillation period.

Since the true load is determined by calculating the minimum value T + o i n using equation (7), the true load can be quickly measured and displayed even though the suspended load is vibrating. I can do it.

There is one practical caveat here. It is the extreme value, that is, the maximum value Tmax + minimum value Tm1 in the vibration period
The problem is that the load signal undergoes slight fluctuations when calculating n. In order to eliminate this, an analog filter may be inserted before the A/D converter 5, or more practically, the value obtained after averaging by the CPU 6 may be treated as the weight signal Si.

(Effects of the Invention) As is clear from the above explanation, the load display method of the hanging scale of the present invention is based on the maximum value 'l'+IIax+ and the minimum value Ta of the force applied to the load cell during one vibration period of the suspended load.
Starting with the n-th 1, the maximum value T+oaX and the minimum value T In
Since the true load is calculated and displayed based on ill, it is possible to calculate and display the true load even though the suspended load is vibrating, using simple, inexpensive equipment and relatively simple calculations. Can be measured and displayed quickly.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a hanging scale, FIG. 2 is a block diagram of a device used in an embodiment of the present invention, and FIG. 3 is a diagram showing the output of a load cell and the true load with respect to time. 1... Hanging load, 2... Load cell, 4... Display device.

Claims (1)

[Claims] (1) In a hanging scale that detects the weight of a suspended load using a tension or compression type load cell, the maximum value (Tmax) and minimum value (Tmin) of the force in the vibration period of the suspended load can be determined from fluctuations in the force applied to the load cell. ) and calculates the true load based on the maximum value (T+nax) and minimum value (T min ), and displays the true load determined by this calculation. I) How to display the load of the suspension.