JP2002168683A - Load cell balance with calibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load cell balance, equipped with a calibrator in which the leverage of a force increasing lever can be stabilized and calibrated accurately, and accurate weighting is ensured, by preventing the force increasing lever from interfering with the load cell at the time of weighing. SOLUTION: A calibration weight 22 is secured integrally to one end side of a force increasing lever 21, and at calibration time, a load-acting part 29a engages with a load receiving part 30a to couple the force increasing lever 21 with a load cell 11. Through the action of the weight load in the direction of gravity, increased force of the load of the weight 22 is generated at the engaging point P6 of the load acting part 29a and the load-receiving part 30a formed between the weight 22 and a fulcrum P4, i.e., the other end side of the force increasing lever 21, and is transmitted to the load cell 11. At non- calibration time, the load acting part 29a is disengaged from the load receiving part 30a, to uncouple the force increasing lever 21 from the load cell 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load cell type balance equipped with a calibration device for increasing the load of a built-in weight by using an intensifying lever and causing the load to act on a load cell to perform calibration or eliminate a tare load.

[0002]

2. Description of the Related Art Conventionally, there is a load cell type balance with a calibration device which has a built-in weight and applies a load of the weight to a load cell to adjust the span (sensitivity) of the balance. As a result, variations in measured values due to differences in gravitational acceleration for each region in which it is used are corrected, and span drift due to a temporal change such as age hardening of a strain generating body constituting a load cell is corrected.

[0003] However, many load cell scales have a large weighing capacity (maximum mass that can be safely and correctly measured by the scale). In this case, if the built-in weight is increased in weight according to the weighing capacity, the weight of the entire scale will increase. For this reason, in Japanese Patent Application Laid-Open No. 11-108740, by using a lever to apply a larger load to the load cell than the actual load of the weight, the weight of the weight in a scale having a large weighing capacity that requires a large calibration weight is required. The weight is reduced.

FIG. 21 shows the construction of the scale. One end of the lever 2 is connected to the scale body or the like to form a fulcrum P1, and the other end is a built-in weight load section (important point) on which the built-in weight 3 is loaded. P2. One end of a connection member 4 such as a leaf spring attached to the load cell 1 at one end is connected to an intensifying point P3 between the fulcrum P1 and the important point P2. Lever 2
Is a boost lever acting on the boost point P3 by increasing the force acting on the important point P2.

[0005] Assuming that the distance between P1 and P3 is a and the distance between P1 and P2 is b, when the load of the weight 3 is applied to the important point P2 during calibration, the weight of the weight x (b / a) ) Force acts. This force is applied to the load cell 1 via the connection member 4.

[0006]

However, Japanese Patent Laid-Open No.
In JP-A-1-108740, the lever 2 is always at the intensifying point P3.
And is connected to the load cell 1 via the connection member 4. Therefore, when the load on the object to be weighed placed on the mounting table 1a is being measured by the load cell 1, the lever 2 vibrates and the force acting on the boost point P3 fluctuates. When the load cell 1 is transmitted to the load cell 1 via the load cell, a load from an object other than the object to be weighed is applied to the load cell 1 and accurate weighing of the object to be weighed cannot be performed.

[0007] The force applied to the load cell 1 at the time of calibration or non-calibration is applied by placing or lifting the weight 3 on the lever 2.
The weight P3 shifts due to a shift (eccentricity error) of the position where the weight 3 is placed, and the lever ratio (b / a) becomes unstable. Therefore, at the time of calibration, the load applied to the load cell 1 does not become constant every time calibration is performed, and accurate calibration cannot be performed. In order to cope with this, in the above-mentioned publication, the eccentric error absorbing means (Robarbal member) is provided at the portion where the weight 3 is loaded.
Is provided. However, the provision of such an eccentric error absorbing means causes an increase in cost, and also requires time and effort such as installation and adjustment of the amount of distortion of the roberval member.

Conventionally, a tare subtraction process has been performed. This is not to remove the tare load applied to the load cell itself, but to detect the load cell while the tare load is still applied. Resets the value to zero. Therefore, if the tare load occupies a significant proportion of the effective load detection capability of the load cell, the load range of the object to be weighed that can be detected by the load cell becomes narrow, and the load cell cannot fully demonstrate its ability. Would.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a simple structure for increasing the leverage to stabilize the leverage ratio and perform accurate calibration. An object of the present invention is to provide a load cell type balance with a calibration device which can perform weighing and can eliminate a tare load without narrowing an effective load detection range of the load cell.

[0010]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, the calibration weight is boosted and fixed integrally to one end thereof. Engage the load acting portion on which the applied load acts, and the load receiving portion of the load receiving member fixed to the load cell,
The load cell is connected to the load cell, and the weight is applied to the load in the direction of gravity, so that the load is applied to the load receiving portion and the load receiving portion formed between the fulcrum and the weight with the other end serving as a fulcrum. Generate a force that increases the weight of the weight at the joint point and transmit it to the load cell.When not calibrating, release the engagement between the load application section and the load receiving section, and release the connection with the load cell. Thus, load fluctuation due to vibration from the lever side is prevented from being applied to the load cell.

According to such a configuration, at the time of weighing, only the load from the object to be weighed acts on the load cell, so that accurate weighing can be performed. In addition, since the weight is integrally fixed to the booster lever, the weight does not change during calibration, and a stable lever ratio can be obtained.

According to the second or third aspect of the present invention, the engagement / disengagement between the load acting portion and the load receiving portion is performed by a blade member having a sharp tip and a V-shaped groove receiving the tip. Is performed by engagement / disengagement with the blade receiving member formed with
The displacement at the point of engagement between the load acting portion and the load receiving portion can be prevented.

According to the fourth aspect of the present invention, since the vertical displacement of the load receiving portion when receiving the load of the calibration load is minimized, there is no movement of the engagement point between the load acting portion and the load receiving portion. Therefore, stable calibration can be always performed by preventing the deviation.

According to a fifth aspect of the present invention, there is provided a load cell, a calibration weight, and a force for increasing the weight of the weight in a direction opposite to the direction of gravity on the load cell to cancel the tare load. In addition, the tare load itself applied to the load cell by the leverage is eliminated.

According to a sixth aspect of the present invention, there is provided an inclining means for inclining the lever by means of the intensifying lever about the fulcrum, and the inclining force by the inclining means causes the lever to act on the load cell in a direction opposite to the direction of gravity. In the calibration, the force in the direction opposite to the gravity direction is reduced or set to zero, and the calibration is performed by applying the tare load to the load cell as the calibration load. That is, the cancellation of the tare load applied to the load cell is adjusted by one weight and the booster, so that the tare load erasure and the calibration load can be switched and used.

According to a seventh aspect of the present invention, the load cell receives the load from the mounting table via a plurality of one-stage reduction levers, and the load cell has a large mounting area and exceeds the effective load detecting capability of the load cell itself. The calibration device according to the present invention is assembled on a scale that can weigh an object to be weighed. That is, one load cell can measure a large weight without using a plurality of costly load cells. Further, since the adjustment of the accuracy may be performed only for one load cell, fine adjustment can be performed, which leads to an improvement in the accuracy of the balance.

[0017] According to an eighth aspect of the present invention, a detected value of a load cell obtained by applying a calibration load to a load cell at a location where span adjustment is performed, and a calibration load is applied to the load cell at the installation location after the balance is installed. Determining means for determining a difference from the detected value of the load cell obtained by the calculation and determining whether the difference is caused only by a change in the gravitational acceleration. If the difference occurs more than due to a change in gravitational acceleration, it can be considered that the calibration device itself has some abnormality.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 schematically shows a load cell type balance 10 with a calibration device according to the first embodiment of the present invention.
A fixed portion side of the load cell 11 formed by attaching a plurality of strain gauges to the strain body is fixed on a base 13 via a bracket 12. A load receiving plate 15 is fixed to the movable portion side of the load cell 11 via a bracket 14. A mounting table 17 is fixed on the load receiving plate 15 via a mounting arm 16.

A calibration load from a calibration device to be described later is directly applied to the load receiving plate 15 at the time of calibration without passing through the mounting table 17.

Next, the calibration device will be described with reference to FIGS. FIG. 1 is a plan view of the calibration apparatus 20, and FIGS. 2 and 3 are longitudinal sectional views thereof. FIG. 2 shows a state at the time of calibration, and FIG. 3 shows a state at the time of non-calibration. 4 is a sectional view taken along the line [4]-[4] in FIG. 2, FIG. 5 is a sectional view taken along the line [5]-[5] in FIG. 2, and FIG. [6] A sectional view in the line direction is shown.

As shown in FIG. 1, on the side of the load cell 11, a booster lever 21 is disposed extending in a direction perpendicular to the longitudinal direction of the load cell 11. The booster lever 21 includes two plate members 21a and 21b extending in parallel.
A calibration weight 22 is fixed to one end of each of 1a and 21b. The calibration weight 22 is a first weight 2 sandwiching the plate 21a.
2a, a second weight 22b, and a third weight 22c sandwiching the plate 21b together with the second weight 22b.
The third weights 22a to 22c are two bolts 23 screwed from a direction perpendicular to the longitudinal direction of the plate members 21a and 21b,
24, they are integrally fixed to the plate members 21a and 21b.

Referring also to FIG. 2, a blade member 25 having a rhombic cross section is fixed to the other end side of the lever 21 by press-fitting both ends into two plate members 21a and 21b. The portion 25a is in contact with the V-shaped groove of the blade receiving member 27 fixed to the intermediate base 26.

Above the other end of the lever 21, two load receiving levers 28 extending in a direction parallel to the lever 21.
a, 28b are provided, and these load receiving levers 2 are provided.
One end of each of 8a and 28b is fixed to the load receiving plate 15. At the other ends of the load receiving levers 28a and 28b, a blade member (second force point blade) 30 having a rhombic cross section is press-fitted at both ends and fixed. These load receiving plate 15, load receiving levers 28a and 28b, and second force point blade 30 constitute a load receiving member.

In the calibration state shown in FIG. 2, the force transmitting member 29 has an upper blade receiving member 29a formed thereon.
The V-shaped groove is pressed against the upper end portion 30a of the second power point blade 30 to press the second power point blade 30 downward.

A first power point blade 31 having a rhombic cross section and having both ends press-fitted is fixed to a portion of the force-intensifying lever 21 corresponding to a portion below the second power point blade 30. First force point blade 31
Makes the second diagonal line in the vertical direction coincide with the second power point blade 30.

The lower end portion 31a of the first power point blade 31 is connected to a lower blade receiving member 29b formed below the force transmitting member 29.
In the calibration state shown in FIG. 2, the force transmission member 29 is pressed downward.

A bearing member 32 is erected on the intermediate base 26 on the side of the weight 22 side of the force transmitting member 29, and a pin 33 penetrates the upper end thereof and is supported by the bearing member 32. . As shown in FIG. 1, both ends of a pin 33 protruding from the bearing member 32 pass through two horizontal arm portions 34 a of the rotation lever 34, and the rotation lever 34
3 is rotatable about a rotation axis.

As shown in FIG. 6, a U-shaped notch 35 is formed at the lower end of the vertical arm portion 34b of the rotating lever 34, and the U-shaped notch 35 is screwed into one end of a feed screw 36. The combined nut member 37 is engaged. The nut member 37 includes a small diameter portion 37a and flange portions 37b formed at both ends in the axial direction. The nut member 37 is fitted so that the outer periphery of the small diameter portion 37a is in contact with the inner wall portion of the U-shaped notch 35, and the contact portion of the outer periphery of the small diameter portion is formed vertically along the inner wall portion of the U-shaped notch. The rotation of the feed screw 36 prevents the rotation of the nut member 37. The diameter of the flange portion 37 b of the nut member 37 is formed larger than the width of the U-shaped notch 35.

As shown in FIGS. 1 and 2, the feed screw 36
A bearing member 38 fixed to the base 13 rotatably supports, and a pulley 39 is attached to the other end.
A motor 40 is provided on the base 13, and a pulley 41 is attached to a rotating shaft 40 a of the motor 40.
A belt 42 is stretched between 1 and the pulley 39 on the feed screw side.

The load cell type balance with the calibration device according to the present embodiment is configured as described above, and its operation will be described below.

FIG. 2 shows a state at the time of calibration.
The intensifying lever 21 is weighted by the weight 22, and a force rotating counterclockwise in the drawing acts on the contact point between the blade member 25 and the blade receiving member 27 as a fulcrum P4, and the first power point blade 31 and the lower blade A force that increases the load of the weight 22 is applied downward to the contact point P5 with the receiving member 29b. As a result, the force transmitting member 29 is pushed down, and the upper blade receiving member 2 is pressed.
The V-shaped groove as a load acting portion formed in 9 a is brought into contact with and engaged with an upper end portion 30 a as a load receiving portion of the second power point blade 30. Therefore, the same force as that applied to P5 is transmitted to the engagement point P6. Thus, the load of the weight 22 is increased and applied to the load cell 11 via the load receiving levers 28 a and 28 b and the load receiving plate 15. At this time, since the emphasis of the lever 21 is the center of gravity P7 of the weight 22 fixed to one end of the lever 21, the emphasis position is stable, and accurate calibration can be performed with a stable lever ratio. Further, by arranging P5 and P6 on the same vertical line, the transmission of the force from P5 to P6 is performed accurately.

At the time of non-calibration, the state shown in FIG. 3 is taken. FIG.
In the transition from the state of FIG. 3 to the state of FIG.
2. Transmission to the feed screw 36 via the pulley 39 to rotate the feed screw 36 to move the nut member 37 rightward in FIG.

By the movement of the nut member 37, the flange portion 37b on the left end thereof comes into contact with the lower end of the vertical arm portion 34b of the rotating lever 34, and pushes the lower end to the right to rotate as shown in FIG. The moving lever 34 rotates around the pin 33. By this rotation, the horizontal arm portion 34a of the rotation lever 34 comes into contact with the pin 43 attached to the upper blade receiving member 29a of the force transmission member 29, and lifts the pin 43 upward.

As a result, the force transmitting member 29 is lifted upward, the upper blade receiving member 29a is separated from the second force point blade 30, and the connection between the load cell 11 and the lever 21 is released. Since no load is applied from the intensifying lever 21, accurate measurement of the object to be weighed on the mounting table can be performed. At this time, as the force transmitting member 29 rises, the force-intensifying lever 21 is lifted with its first power point blade 31 supported by the lower blade receiving member 29b of the force transmitting member 29, and is tilted upward about P4 as a fulcrum. You.

When the nut member 37 is fed rightward by the rotation of the feed screw 36 and reaches the position shown in FIG. 3, for example, a flange portion 37b is attached to a limit switch (not shown) provided on the base 13. In contact therewith, the limit switch is operated, and upon receiving this operation signal, the rotation of the motor 40 is stopped. As a result, the nut member 37 is fixed to the feed screw 36 at that position, and the rotation lever 34 is restricted from rotating clockwise by the flange portion 37 b of the nut member 37, and the force transmission member 29 The raised position as shown is held.

Similarly, when shifting from the state shown in FIG. 3 to the state shown in FIG. 2 at the time of calibration, the nut member 37 is sent to the left by the reverse rotation of the feed screw 36 at the time of non-calibration, and the position shown in FIG. Is reached, the limit switch is operated to stop the rotation of the motor 40. As a result, the nut member 37 is fixed to the feed screw 36 at the position shown in FIG. 2, and the rotating lever 34 is held in the illustrated position by the flange portion 37 b of the nut member 37, and is positioned below the force transmitting member 29. Does not prevent movement to

Further, since the calibration device 20 is covered with the cover 67, it prevents moisture and dust from adhering to the weight 22, and prevents the blade member and the blade receiving member from being clogged with dust and the like.

After the balance is manufactured at a factory or the like, various adjustments such as span adjustment are performed at the place where the scale is manufactured, and the scale is shipped to the place of use. Then, at the place of use, the calibration is first performed by operating the calibration device at the time of installation. After installation,
In order to maintain the accuracy of the balance, calibration is performed by operating the calibration device periodically or irregularly. Next, the specific procedure will be described with reference to the flowcharts of FIGS.

First, as step S1, span adjustment is performed at the scale manufacturing site (factory). For example, weighing 10
In the case of a 00 kg scale, a 1000 kg weight is placed on the mounting table, and at this time, the detected value (digital value) of the load cell is set to, for example, "100,000" as a rated value corresponding to 1000 kg. Specifically, a span coefficient S that should be equal to the detected value of the load cell × S = 100000 is obtained. This span coefficient S is stored in the memory.

Next, in step S2, the calibrating device 20 described above is operated at the manufacturing site where the span adjustment has been performed, and the load cell is loaded with, for example, about 1/3 of the weighed 1000 kg.
Calibration load is applied. If the detected value of the load cell at this time is, for example, "35005", this value is stored in the memory as a reference value. In addition, it is assumed that the production site is located in 10 wards according to the old measurement law, and the reference value is 350.
05 is stored in association with the value of the calibration result in the tenth ward.

Next, as step S3, the scale is shipped from the factory and installed at the place of use (installation place). After the installation, the first calibration at the installation location is performed.

First, after visually confirming that there is no load on the mounting table and that the indicated mass value displayed on the indicator is 0 (step S4), the zero reset button is pressed.
By pressing the zero reset button, a switch 91 shown in FIG. 20 is turned on, and the detected value W1 of the load cell at this time is captured and stored in the memory 92. And
In the comparator 93, W1- (W1 stored in the memory) is calculated, and as a result, the detected value of the load cell is W2 = 0.
(Step S5). By pressing the zero reset button, the indicated mass value (displayed as 0.0 kg) displayed on the indicator is erased and switched to the "under calibration" display.

Then, after a while, the current date is displayed on the display unit of the indicator (the scale has a built-in auto calendar). If the display is correct, press the calibration start button. If they are different, correct the date with the setting button and then press the calibration start button. Then, the display switches again to the “under calibration” display.

By pressing the calibration start button, the motor 40 of the above-described calibration device 20 is activated, and the lever 21 is activated.
Starts to tilt slowly, and a calibration load is applied to the load cell 11. At the position where the calibration load is completely applied, the operation of the above-described limit switch stops the motor 40. Then, after waiting for the stabilization time, the detected value B of the load cell at this time is
Is stored in the memory together with the date (step S6).

Next, the motor 40 is automatically restarted, and the calibration load applied to the load cell 11 is removed. Then, the motor 40 stops at the position where the calibration load has been completely removed by the operation of the limit switch (step S7).

Next, in the judgment of step S8, if the detected value of the load cell in a state where the load for calibration is removed is 0, or +1 or -1, the detected value B stored in step S6 is set to the installation location. Is recognized as the normal detection value at the time of calibration in and stored again. If the value is other than 0, +1 or −1, it is determined that there is a change in the zero point, and step S
5 to S8 are repeated. If the detected value of the load cell does not become 0, +1 or -1 in a state where the calibration load is removed even after performing this repetition three times, for example, there is a possibility that the calibration device itself has some abnormality. "Error" is displayed on the display unit of the indicator to warn that some action is required.

If the answer is Yes in step S8,
Based on the difference between the detected value A obtained by performing the calibration at the span adjustment location in step S2 and the detection value B obtained by performing the calibration at the installation location in step S6, the installation location specifying information for specifying the installation location is obtained. It is determined by the installation location specifying means (step S9 in FIG. 18). The installation location specifying information is specifically defined as a ward which divides Japan into 16 wards in the Old Measurement Law, and for example, 10 wards are defined as wards having a gravitational acceleration of 9.797 m / s ² .

In the present embodiment, a load cell whose detected value changes by, for example, 1 / 10,000 when it changes by one section is used, and the detected value A obtained by performing calibration in 10 sections is calibrated at the installation location. By looking at the difference between the detection values B obtained by performing the above, the location area can be specified. For example, if the detected value A is 3500, the detected value B is 3505 ± 4
If (the detected value A is ± about 1 / 10,000), the installation location specifying means (CPU) calculates nine, ten, and eleven wards as the installation location identification information.

Then, the installation location specifying information is displayed on the display unit of the indicator, for example, as "9-11" (step S10). Next, in step S11, the user, the seller, the installer, and the like look at the display, and if the installation location certainly corresponds to the 9th to 11th wards, the confirmation button is pressed.

When this confirmation button is pressed, in step S12, the span coefficient S obtained at the factory in step S1 and stored in the memory is rewritten. That is, the span coefficient S is rewritten to the span coefficient S ′ obtained by S ′ = S × (detected value A / detected value B). Thereafter, the span value S 'is multiplied by the detected value of the load cell obtained by weighing at the installation location, and the span is corrected. Further, the detected value B is also stored in the memory together with the date as a reference value for future calibration at the installation location. Further, assuming that the difference between the detected value A and the detected value B is caused only by the difference in the gravitational acceleration, the gravitational acceleration at the installation location obtained from the ratio between the detected value A and the detected value B is also stored in the memory. Note that the detection value A is not erased but is kept stored with the date when it was obtained, and when the scale is moved to another location and installed, the reference value for obtaining the installation location specifying information there is required. Used as However, in the future, if the weight is placed on the mounting table and the span adjustment is performed again, it will be rewritten to the detection value obtained by operating the calibration device at this span adjustment location,
It is stored together with the installation location specifying information of the span adjustment place, and when the installation location is moved thereafter, the rewritten detection value becomes a reference value when obtaining the installation location specifying information at the moved location. .

If it is determined in step S11 that the actual installation location does not correspond to the section "9-11" displayed on the display unit, it is determined that an error has occurred (step S13). That is, in this case, it is determined that there is a difference between the detected value A and the detected value B due to, for example, an abnormality of the calibration device other than the change in the gravitational acceleration, and some action such as inspection or repair of the calibration device is performed. .

Since the calibrating device 20 uses the intensifier lever 21, the calibrating device itself may cause inaccurate calibration depending on the state of contact between the lever blade and the blade receiver. If the span coefficient is rewritten based on this incorrect calibration result, the normal scale will be changed to a crazy scale. By checking whether the detected value A and the detected value B at the time of the calibration after the installation are only due to the difference in the gravitational acceleration, it is confirmed whether or not there is any abnormality in the calibration device itself. Here, if the normality of the calibration device can be confirmed, it is recognized and the span coefficient at the installation location is obtained.

Next, with reference to FIG. 19, a description will be given of the calibration after the reference value B at the time of the installation is determined. In other words, even after the balance is installed, calibration is performed as necessary to correct the balance of the balance due to age hardening (change in Young's modulus) of the strain body constituting the load cell, and the span is set based on the calibration result. The coefficient is rewritten.

In the flowchart of FIG. 19, steps S21 to S25 are the same processing procedures as steps S4 to S8 when the balance is installed as shown in FIG. However, in step S23, the load cell detection value obtained in the calibration at this time and stored in the memory is C.

If the answer is Yes in step S25, the detected value (reference value) B obtained at the time of installation is compared with the detected value C obtained by performing the current calibration (step S26).

By comparing the detected values B and C, if the difference between them is within a predetermined difference ΔW, it is considered that the difference is within the range of a negligible variation for the accuracy of the scale, and the span coefficient S ′ is rewritten. Absent.

If the difference between the two is larger than ΔW and smaller than ΔV, it is considered that the Young's modulus of the flexure element constituting the load cell changes over time, and the detected value C obtained by performing the calibration is used. To rewrite the span coefficient S ′. That is, a new span coefficient S ″ = S × (detection value A / detection value C) is obtained and stored in the memory. The detection value C is also stored in the memory in place of B as a reference value for the subsequent calibration. You.

If the difference between the two is larger than ΔV, there is a possibility that some abnormality has occurred on the calibration device side, and steps S23 to S26 are repeated again. If the difference is still larger than ΔV, an error is displayed and a warning is issued.

As described above, even after the balance is installed, it is determined whether or not the span coefficient can be rewritten during daily use after confirming that the calibration device is normal. Like that.

Further, as a material of the flexure element constituting the load cell, for example, an aluminum alloy is used. In this case, the Young's modulus of the flexure element tends to increase with time, that is, the rated output of the load cell tends to decrease. Yes, the determination of ΔW and ΔV described above is determined according to the elapsed time from the date when the reference value B was obtained. Further, since the rated output of the load cell also changes depending on the temperature sensitivity characteristic, ΔW and ΔV are determined taking this into consideration. Thereby, the determination in step S26 can be accurately performed.

Therefore, it is desirable to periodically perform calibration in order to cope with a temporal change in the rated output of the load cell, that is, a temporal change in the span. Therefore, since the automatic calendar is built in the balance of the present embodiment, the calibration time is automatically notified. For example,
If calibration has not been performed for one year, a message "Please calibrate" will be displayed on the display to inform the user.

Next, referring to FIGS. 8 and 9, the second embodiment of the present invention will be described.
An embodiment will be described. The load cell type balance with the calibration device according to the present embodiment is obtained by incorporating the above calibration device 20 into the load cell type balance disclosed in Japanese Patent Application No. 11-074649 filed by the present applicant. FIG. 8 is a partially cutaway plan view of a load cell type balance 50 with a calibration device according to the present embodiment, and FIG. 9 is a longitudinal sectional view of a place where a reduction lever is arranged.

The load cell type balance with a calibration device 50 according to the present embodiment includes one load cell 53 formed by attaching a plurality of strain gauges to a strain body within a space surrounded by a base 51 and a mounting table 52. Are independent of each other without being connected or engaged
It includes a single reduction lever lever 54 of the book and the calibration device 20. One reduction lever 54 is composed of two plate members 5 extending in parallel.
4a and 54b.

The fixed portion side of the load cell 53 is fixed to the base 51, and the load receiving plate 55 is fixed to the movable portion side of the load cell 53. Four load receiving levers 56 extending toward the force-reducing lever 54 are fixed to the load receiving plate 55.

At four corners of the base 51, blade receiving members 57 having V-shaped grooves are provided upright. Each blade receiving member 5
7, a lower end 58a of a blade member 58 having a rhombic cross section press-fitted into one end of each of the force-reducing levers 54 is engaged from above to form a fulcrum P8.

Further, a blade member 59 having a rhombic cross section is press-fitted just to the side of the fulcrum P8 in the force-reducing lever 54, and a blade receiving member having a V-shaped groove is formed in the upper end portion 59a of the blade member 59. Numerals 60 are engaged from above to form the important point P9. The blade receiving member 60 is connected to the mounting table 52 via a lateral load relief device 61 formed by sandwiching a sphere between spherical surfaces, and the lateral load acting on the mounting table 52 is released by the lateral load relief device 61. In addition, it is configured such that no lateral load acts on the important point P9.

A blade member 62 having a rhombic cross section is press-fitted also at the other end of the force-reducing lever 54, and a blade member 63 having a rhombic cross section is press-fitted also into a load receiving lever 56 above this. Reference numerals 63 are vertically aligned with each other so that their vertical diagonal lines coincide with each other. A force transmitting member 64 is provided on the upper end portion 63 a of the blade member 63, and an upper blade receiving member 64
a of the force transmitting member 64 and the lower blade receiving member 64b of the force transmitting member 64 abuts on the lower distal end portion 62a of the blade member 62 to form the first power reducing point P1.
0.

In the above configuration, when a load is applied to the mounting table 52, this load acts on the important point P9, and the load applied to the first reduction point P10 with the load on the important point P9 (P8 to (P9 distance / P8-P10 distance) is applied. That is, the force acting on the important point P9 is reduced and acts on the first reduction point P10. This force is applied to the second reduction point P1 by pushing down the force transmission member 64.
1 and acts on the load cell 53 via the load receiving lever 56.

The above-described calibration device 20 is incorporated in the load cell type balance having this configuration. That is, FIG.
2, the load receiving levers 28a and 28b into which the second power point blade 30 is press-fitted are also attached to the load receiving plate 55 in the second embodiment to constitute a load receiving member.
At the time of calibration, the force transmitting member 29 of the calibration device 20 is engaged with the second force point blade 30, and the increased force of the weight 22 from the lever 21 is applied to the load cell 53. At the time of non-calibration, the engagement between the second force point blade 30 and the force transmitting member 29 is released, and the force from the lever 21 side does not act on the load cell 53.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 10 shows a load cell type balance 70 with a calibration device according to the third embodiment.
11 is a sectional view taken along the line [11]-[11] in FIG.

The fixed portion side of the load cell 71 is fixed to a base 73 via a bracket 72. The movable portion side of the load cell 71 is fixed to the bottom surface of the load receiving member 75 via a bracket 74. The upper surface of the load receiving member 75 is fixed to the mounting table 76.

A calibration weight 78 is integrally fixed to one end of a booster lever 77 composed of two parallel plate members 77 a and 77 b with bolts 79.

At the other end of the lever 77, a blade member 80 having a rhombic cross section is provided with two plate members 77a, 77b at both ends.
It is press-fitted and fixed. The upper end portion 80a of the blade member 80 is connected to a pair of support members 89 erected on the base 73.
a, 89b engages with a V-shaped groove formed in the blade receiving member 81 attached to the upper portion thereof to form a fulcrum P12 of the boost lever 77. The blade receiving member 81 includes two support members 89a,
The support member 89a, 89b and the blade receiving member 81 are attached to each other by pins which are sandwiched between the support members 89b.

In the lever 77, the weight 78 and the fulcrum P
A blade member 82 having a rhombic cross section is press-fitted at both ends into two plate members 77a and 77b and fixed therebetween. The lower distal end portion 82a of the blade member 82 is arranged so as to be able to engage with a V-shaped groove formed in the blade receiving member 83 attached to the pair of support members 88a and 88b erected on the load receiving member 75. I have. The blade receiving member 83 includes two support members 8.
8a and 88b, and are attached by pins passing through the support members 88a and 88b and the blade receiving member 83.

Between the fulcrum P12 and the blade receiving member 83,
A motor 84 is provided on the base 73 and its output shaft 84
A screw is formed in a, and a nut member 85 is screwed. The nut member 85 is fixed to one end of the rotation stop member 86, and a through hole is formed at the other end of the rotation stop member 86. The through hole is formed in the guide rod 8 erected on the base 73.
7 penetrates. As a result, the rotation of the nut member 85 due to the rotation of the output shaft 84a is stopped, and the nut member 85 is allowed to move only at a constant vertical interval by a microswitch (not shown).

In the load cell type balance with a calibration device 70 constructed as described above, at the time of calibration, the nut member 85 is separated from the booster lever 77 as shown in FIG. A force rotating counterclockwise in the figure acts on the lever 77 with the fulcrum P12 as a fulcrum, and the lower end portion 82a of the blade member 82, which is a load application portion.
Engages with the V-shaped groove of the blade receiving member 83, which is a load receiving portion, to form an engagement point P13, and a force that increases the load of the weight 78 acts on the blade receiving member 83 downward. This force acts on the load cell 71 via the load receiving member 75. At this time, since the weight 78 is fixed to the booster lever 77, the focus position is stable, and a desired load acts on the load cell 71, so that accurate calibration can be performed.

At the time of non-calibration, the nut member 85 is raised by rotating the output shaft 84a of the motor 84 from the state shown in FIG.
Between the blade member 80 and the lever member 80.
The blade member 82 is separated from the blade receiving member 83 by lifting the contact point P12 between the blade receiving member 81 and the blade receiving member 81 as a fulcrum. As a result, the connection between the load cell 71 and the boost lever 77 is released, and the load cell 71 does not receive interference from the boost lever 77 due to vibration or the like, so that the object to be weighed placed on the mounting base 76 can be accurately measured.

Further, in this embodiment, assuming that the length of the hollow portion 71a of the load cell 71 in the longitudinal direction is L, the distance from the load cell fixing portion side end of the hollow portion 71a is L / 3. The engagement point P13 is located. In the direction orthogonal to the longitudinal direction, the engagement point P13 is located at the center as shown in FIG.

In the load cell 71 of the Roberval mechanism having the hollow portion 71a, it is empirically known that the vertical displacement is the minimum at the position of L / 3 (which can be accurately obtained by the finite element method). Can be). Therefore,
If the blade member 82 and the blade receiving member 83 are engaged with each other at the position of L / 3 or in the vicinity of the position at the time of calibration, the displacement between them is prevented, and an accurate calibration load is applied to the load cell 71. be able to.

Next, a fourth embodiment of the present invention will be described. FIG. 12 shows a calibration apparatus 101 according to the present embodiment.
FIG. 13 is a longitudinal sectional view of FIG. FIG.
In FIG. 2, in order to make the configuration of the main part easy to see, the mounting table is not shown, and the load receiving plate 103 fixed to the movable part side of the load cell 102 is shown by a dashed line.

As in the case of the first embodiment, a boost lever 104 is provided beside the load cell 102. The boost lever 104 is composed of two plate members 104a, 10a extending in parallel.
4b, and a calibration weight 105 is fixed to these plate members 104a and 104b. The calibration weight 105 includes a first weight 105a and a second weight 105b that sandwich the plate material 104a.
And a third weight 105c sandwiching the plate member 104b together with the second weight 105b, and the first to third weights 105a.
To 105c are integrally fixed to the plate members 104a and 104b by two bolts (not shown) screwed from a direction perpendicular to the longitudinal direction of the plate members 104a and 104b.

At the right end of the lever 104 near the load cell 102, a blade member 106 having a rhombic cross section is fixed by pressing both ends into two plate members 104a and 104b.
The upper end portion 106a is in contact with the V-shaped groove of the upper blade receiving member 108 of the force transmitting member 107.

A blade member 109 having a rhombic cross section is fixed between the blade member 106 and the weight 105 by press-fitting both ends into two plate members 104a and 104b. The part 109a is an intermediate base 1
10 comes into contact with the V-shaped groove of the blade receiving member 112 supported by the supporting member 111 erected at
0 is formed.

A pair of load receiving levers 113, 113 are fixed to the load receiving plate 103 fixed to the movable portion side of the load cell 102 so as to hang the plate members 104a, 104b therebetween. Under the load receiving levers 113, 113, a blade member 11 having a rhombic cross section is provided.
4 is press-fitted at both ends and fixed. This blade member 11
4 is a blade member 10 fixed to the plate members 104a and 104b.
6, these blade members 106, 114 are aligned in a vertical diagonal. Load receiving lever 11
3, lower end portion 11 of blade member 114 fixed to 113
4a is the V of the lower blade receiving member 115 of the force transmitting member 107.
It is in contact with the groove.

An oil damper 116 is provided below the left side of the boost lever 104 in FIG.
The vertical movement of the horizontal plate 119 fixed to the left ends of the plate members 104a and 104b via the pins 117 and the rods 118, that is, the vibration of the booster lever 104 is absorbed by the viscosity of the oil put in the oil chamber 116a of the oil damper 116. I am trying to do it.

The load of the object placed on the mounting table 17 is applied to the load receiving lever via the four single reduction levers 54 and the load receiving lever 56 in the same manner as in the second embodiment. A load acts on the load cell 102 by acting on the four corners of the plate 103.

The load cell type balance with the calibration device according to the present embodiment is configured as described above, and the operation thereof will be described below.

The contact point between the blade member 109 and the blade receiving member 112 is supported by the weight P
12 and 13, a counterclockwise rotating force acts in FIGS. 12 and 13, and a force that increases the load of the weight 105 is applied upward to the contact point P21 between the blade member 106 and the upper blade receiving member 108 of the force transmitting member 107. Act on. As a result, the force transmitting member 107 is pushed upward and the lower blade receiving member 115
An upward force acts on the blade member 114 of the load receiving lever 113 that comes into contact with the blade member 114. That is, a force in the direction opposite to the direction of gravity acts on the load receiving lever 113 and the load receiving plate 103,
The load receiving plate 103 is connected via the four reducing levers 54 described above.
And the tare load (in this case, the platform load) applied to the load cell 102 is canceled. The magnitude of the upward force acting on the contact point P22 is adjusted by changing the lever ratio of the lever 104 by moving the position of the weight 105 according to the magnitude of the tare load to be canceled.

With the above configuration, when no load is applied on the mounting table 17, the load acting on the load cell 102 can be substantially unloaded, and regardless of the magnitude of the tare load,
The effective load detection capability of the load cell 102 itself can be maximized.

Next, a fifth embodiment of the present invention will be described. FIG. 14 shows a calibration device 120 according to this embodiment.
15 and 16 are longitudinal sectional views, and FIG.
FIG. 5 shows a state at the time of normal weighing with the tare load eliminated.
6 shows a state at the time of calibration. The same components as those in the fourth embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, in addition to the structure of the fourth embodiment, a tilting means for tilting the lever 104 around its fulcrum P20 is provided. The configuration of the tilting means will be described below.

As shown in FIG. 14, both plate members 104a, 1
A pair of levers 121 and 122 are provided on the outer surface side of the lever 04b.
A pair of levers 121 and 122 are connected by the pin 123, and the other end is rotatable around a fixed pin 124 supported by a support member 111 supporting the blade receiving member 112. I have.

As shown in FIG. 15, an arm portion 121a extending downward is integrally fixed to one lever 121, and an engaging plate 1 is provided on a lower side surface of the arm portion 121a.
25 is fixed. The engagement plate 125 corresponds to the vertical arm portion 34b in the first embodiment, and has a U-shaped notch formed at the lower end thereof.
A nut member 127 screwed to one end of the feed screw 126 is engaged with the notch. The nut member 127 has the same configuration as that of the nut member 37 of the first embodiment, and includes a small-diameter portion and flange portions 127a and 127b formed at both ends in the axial direction. The outer periphery is fitted in such a manner as to abut on the inner wall of the U-shaped notch.

The feed screw 126 is rotatably supported by a bearing member 129 fixed to the base 128, and a pulley 130 is attached to the other end. Also base 1
28, a motor 131 is provided, and its rotating shaft 131a
A pulley 132 is attached between the pulley 132 and a belt 133 is stretched between the pulley 132 and the pulley 130 on the feed screw 126 side.

The load cell type balance with the calibration device according to the present embodiment is constituted as described above, and its operation will be described below.

At the time of normal weighing, it is in the state shown in FIG. 15, and similarly to the above-described fourth embodiment, the lever 10 is used.
4, a counterclockwise rotating force acts on the contact point between the blade member 109 and the blade receiving member 112 with the weight of the weight 105 as a fulcrum P20, and the blade member 106 and the force transmitting member 1
A force that increases the load of the weight 105 acts upward on the contact point P21 with the upper blade receiving member 108 at 07. As a result, the force transmitting member 107 is pushed upward, and an upward force acts on the blade member 114 of the load receiving lever 113 that comes into contact with the lower blade receiving member 115. That is, a force in the direction opposite to the gravitational force acts on the load receiving lever 113 and the load receiving plate 103, and the tare load applied to the load receiving plate 103 and the load cell 102 via the four reducing levers 54 described above (this In some cases, the load on the platform is negated.

At the time of calibration, the motor 131 is rotated, and this rotational force is transmitted to the feed screw 126 via the pulley 132, the belt 133, and the pulley 130, and the feed screw 1 is rotated.
26 is rotated to move the nut member 127 leftward in FIG. By the movement of the nut member 127, the flange 127b on the right end thereof abuts against the lower end of the engagement plate 125 and pushes the lower end to the left.
Rotates clockwise around the fixing pin 124. By this rotation, the pin 123 comes into contact with the lower surfaces of the plate members 104a and 104b, and as shown in FIG.
Lift b. As a result, the lever 104 is supported by the supporting point P.
20, the blade member 106 and the force transmitting member 107 suspended from the upper end portion 106a of the blade member 106 are lowered, and the blade member 114 and the lower blade receiving member at the contact point P22 are lowered. The engagement with 115 is released.
Therefore, a force in the direction to cancel the tare load does not act on the load cell 102, and the calibration is performed using the tare load applied to the load cell 102 at this time as the calibration load. In this case, the engagement at the contact point P22 was completely released, and the total tare load was used as the calibration load.
A part of the tare load may be used as the calibration load by merely reducing the upward force at the contact point P22 by adjusting the lifting amount of the boost lever 104, that is, the inclination angle.

The feed amount of the nut member 127 is detected by, for example, a limit switch (not shown) provided on the base 128, and when the state shown in FIGS. 15 and 16 is reached, the motor 131 is stopped.

As described above, in the present embodiment, 1
Since the two levers can be used for both tare load erasure and calibration, the increase in the number of parts can be suppressed, cost can be reduced, space and weight can be reduced, and maintenance can be facilitated.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited to these embodiments.
Various modifications are possible based on the technical idea of the present invention.

In the first and second embodiments, instead of rotating the feed screw 36, the nut member 37 is turned by hand or tool to move in the axial direction of the feed screw 36, The turning operation of the lever 34 may be performed.

The flow shown in FIGS. 17 to 19 is not limited to the first embodiment, but can be applied to the calibration by the calibration devices of the second, third, and fifth embodiments.

In the fifth embodiment, the tilt of the lever 104 is increased by the nut member 85 which moves up and down by the rotation of the motor 84, as in the third embodiment shown in FIG. May be carried out by raising and lowering.

[0105]

As described above, according to the present invention, at the time of weighing, the load cell is prevented from being boosted, so that the load cell is not affected at all by the boost lever, and the load cell placed on the mounting table is not affected. Accurate weighing of objects. Further, since the calibration weight is fixed to the booster lever and the emphasis is stable, accurate calibration can be performed with a stable lever ratio without providing the above-described eccentricity error absorbing means in the related art. Furthermore, the tare load can be eliminated without reducing the effective load detection capability of the load cell.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a load cell type balance with a calibration device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a state at the time of calibration.

FIG. 3 is a longitudinal sectional view showing a state at the time of non-calibration.

FIG. 4 is a sectional view taken along the line [4]-[4] in FIG.

FIG. 5 is a sectional view taken along line [5]-[5] in FIG. 2;

FIG. 6 is a sectional view taken along line [6]-[6] in FIG. 2;

FIG. 7 is a diagram schematically showing a load cell type balance with a calibration device according to the first embodiment of the present invention.

FIG. 8 is a partially broken plan view of a load cell type balance with a calibration device according to a second embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of the place where the force-reducing lever is arranged.

FIG. 10 is a longitudinal sectional view of a load cell scale with a calibration device according to a third embodiment of the present invention.

11 is a sectional view taken along the line [11]-[11] in FIG.

FIG. 12 is a plan view of a main part of a load cell scale with a calibration device according to a fourth embodiment of the present invention.

FIG. 13 is a longitudinal sectional view of the same.

FIG. 14 is a plan view of a main part of a load cell scale with a calibration device according to a fifth embodiment of the present invention.

FIG. 15 is a longitudinal sectional view of the same, showing a state when a tare load is erased.

FIG. 16 is a longitudinal sectional view showing the state at the time of calibration.

FIG. 17 is a flowchart showing a flow of a calibration operation at the time of setting the balance.

FIG. 18 is a flowchart following FIG. 17;

FIG. 19 is a flowchart showing a flow of a calibration operation at the time of daily use after the balance is installed.

FIG. 20 is a circuit diagram for resetting a load cell detection value to zero.

FIG. 21 is a view showing a conventional load cell type balance with a calibration device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Load cell type balance with a calibration device 11 Load cell 20 Calibration device 21 Booster lever 22 Weight 29a Load acting part 30a Load receiving portion 50 Load cell type balance with a calibration device 53 Load cell 54 Reducer lever 70 Load cell type balance with a calibration device 71 Load cell 77 Leverage lever 78 Weight 82a Load acting part 83 Load receiving part 101 Calibration device 102 Load cell 104 Booster lever 105 Weight 120 Calibration device

Claims (9)

[Claims] 1. A load cell type balance with a calibration device, comprising: one load cell; a calibration weight; and a load for calibrating, the load of the weight being increased to be applied to the load cell as a calibration load. The weight is integrally fixed to one end side of the booster, and at the time of calibration, the load acting portion on which the load increased by the booster acts and the load receiving portion of the load receiving member fixed to the load cell Engage and connect the booster bar and the load cell, and by the action of the weight load in the direction of gravity, the booster bar is formed between the fulcrum and the weight with the other end as a fulcrum. Further, a force that increases the weight of the weight is generated at an engagement point between the load acting portion and the load receiving portion and transmitted to the load cell. To release the engagement between parts, said energizing releases the connection between the load cell that Te, scale calibration device with a load cell type load from said energizing lever in the load cell is characterized in that so as not loaded. 2. An engagement / disengagement between the load acting portion and the load receiving portion is performed by a blade member having a sharp distal end and a blade receiving member having a V-shaped groove for receiving the distal end. The load cell type balance with a calibration device according to claim 1, wherein the measurement is performed by combining / releasing. 3. The blade member comprises a first power point blade fixed to the boost lever and a second power point blade fixed to the load receiving member, and the first and second power point blades are arranged in a vertical direction. A lower blade receiving member for receiving the first power point blade, wherein the second power point blade is arranged upward, the first power point blade is positioned downward, and A force transmitting member having an upper blade receiving member engageable with the distal end of the second power point blade is provided between the first and second power point blades. In the lower blade receiving member,
By acting the increased force of the weight and pushing down the force transmitting member, the upper blade receiving member is engaged with the tip of the second power point blade, and the second power point blade is On the other hand, the increased force of the weight is applied downward, and at the time of non-calibration, the force transmitting member is raised upward, and the first blade is supported by the lower blade receiving member, and the lever is lifted. The load cell type balance with a calibration device according to claim 2, wherein the other end side is tilted and lifted, and the upper blade receiving member is separated upward from the second power point blade. 4. A force from the load acting portion at or near a position where the vertical displacement of the load receiving portion of the load receiving member fixed to the load cell when the calibration load is applied is minimized. The load cell type balance with a calibration device according to any one of claims 1 to 3, wherein 5. A load cell, a weight for calibration, and a boost lever for canceling a tare load by applying a force that increases the load of the weight in a direction opposite to the direction of gravity to the load cell. A load cell type balance with a calibration device. 6. A tilting means for tilting the boost lever around the fulcrum of the boost lever, wherein the tilt of the boost lever by the tilt means is opposite to the direction of gravity acting on the load cell from the boost lever. The magnitude of the force is adjustable, and at the time of calibration, the force in the direction opposite to the direction of gravity is reduced or set to zero, and calibration is performed by applying the tare load to the load cell as a calibration load. Claim 5
The load cell type balance with the calibration device described in. 7. A plurality of single force-reducing levers for receiving a load from a mounting table at respective emphasis points, reducing the force, and generating the force at each of the force-reducing points, wherein the load cell receives a force from the force-reducing point. The load cell type balance with a calibration device according to any one of claims 1 to 6, wherein the load cell type balance receives the load at a plurality of different force application points. 8. A detection value of the load cell obtained by applying the calibration load to the load cell at a location where the span adjustment is performed, and after installing the balance, applying the calibration load to the load cell at the installation location. 8. A method according to claim 1, further comprising determining means for obtaining a difference from the obtained detected value of the load cell and determining whether the difference is caused only by a change in gravitational acceleration. The load cell type balance with the calibration device described in. 9. The apparatus according to claim 8, wherein said determining means includes an installation location specifying means for obtaining installation location specifying information obtained based on said difference, and a display means for displaying said installation location specifying information. The load cell type balance with the calibration device described in.