JPH068742B2 - Load cell type load cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load cell type load cell configured to detect weight by a change in electrical characteristics of a detection element composed of a resistance wire strain element or a crystal oscillator or the like attached to a load receiver,
The present invention relates to a load cell type load cell in which a weight display due to an unbalanced load acting on a weighing pan is adjusted.

Conventionally, a detection element such as a strain gauge is attached to a load receiver made of an elastic body, one end of this load receiver is supported by a supporting member, and a weighing dish is attached to the movable end of the load receiver. Since the detection element is distorted corresponding to the distortion of the load receiver when the object to be weighed is placed on the weighing pan, the change in the electrical characteristics due to this distortion is detected and converted into the weight to measure the object to be weighed. A load cell type load cell that measures the weight of an object has been put into practical use.This type of load cell has a relatively simple configuration and high accuracy, and since it outputs an electric signal, It has the advantage that it can be used as it is for a typical digital display scale. Further, as described above, since the distortion of the detection element is output as an electric signal, the output of an electronic signal also increases when a plurality of detection elements are used, so recently, a plurality of detection elements are detected at different parts of the load receiver. A device with an attached element is often used.

In addition, in the case of a load meter, the object to be weighed is not always placed on the center of the weighing pan, and sometimes the object to be weighed is placed on a corner of the weighing pan that is offset. It must be possible to measure the weight accurately even in the case of an unbalanced load. However, in the case of a load cell type load cell in which a load cell is composed of one load cell, the processing accuracy of the load receiver made of an elastic body, the material and processing accuracy of a plurality of detection elements, the attachment position and attachment of each detection element Various conditions such as wearing condition, adhesive thickness and material greatly affect the measurement accuracy, and ideally it is desirable that all of the above conditions meet the manufacturing requirements at the time of manufacturing, but all of these conditions are sufficient. It is difficult to manufacture from the beginning in a filled state. And, even if some of the above conditions are deviated, the stress acting on each detection element becomes unbalanced, so that the weight display deviates especially for loads that are biased to the corners of the weighing pan. Occurs, and it is difficult to measure accurately. That is, there are two factors in the eccentric load error of the load cell in the case where the load cell is composed of one load cell, and one is the vertical downward direction of the horizontal beam due to the axial eccentric load of the horizontal beam of the load receiver. In addition to the breaking force to push down, the couple force to bend the horizontal beam, that is, the error due to the bending moment with respect to the axial unbalanced load of the load receiver, and the other one is the axis of the load receiver. Error due to a torsional moment against an eccentric load in the direction orthogonal to the axial direction of the horizontal beam of the load receiver, which is an error due to the couple force that attempts to twist the horizontal beam due to an eccentric load in the direction perpendicular to the direction The deviation of the weight display with respect to the applied load is a combination of the above two types of unbalanced load errors. These errors become so large that it cannot be neglected if the weighing pan is larger than the load cell. Therefore, in the above case, it is necessary to adjust so that the weight display for each unbalanced load is the same. No effective adjustment method was found to complexly correct the error due to bending moment and torsion moment to the body.

Therefore, if the weighing pan is large compared to the size of the load cell and there is a possibility that the four corner errors may occur and the weighing accuracy may be deteriorated, the weighing pan is supported by three or more load cells. The most common type of scale is one in which each moment is prevented from acting and the output sensitivity of each load cell is adjusted to match to reduce the four-corner error.

Also, some of the adjustments were made to remove only the bending moment among the errors due to the above moments, but since the torsional moment cannot be removed,
At least two load cells must be used, and with two load cells, if the weighing pan is easily placed, it will be overturned. If the weighing pan and the mounting surface of the movable end of the load cell deviate from each other due to impact or load, the load cells may pull horizontally or push each other to some extent and the zero point output or span may change. In addition to adjusting the error due to the bending moment of the two load cells and further causing such obstacles, rather than using the above-mentioned bending moment, it is possible to use three or more load cells without adjustment. The method I had was effective.

This invention was made to improve the above circumstances.
It is an object of the present invention to provide a load cell type load cell in which the weight display can be adjusted reliably and efficiently with respect to an unbalanced load.

The present invention will be described below with reference to embodiments shown in the drawings. In the figure, reference numeral 1 is a load cell type load cell, which will be sequentially described. As shown in FIG. 3, the load receiver 2 of the load cell 1 is formed in a rectangular shape with a predetermined thickness, and a rectangular hollow portion 3 is formed in the central portion thereof. , Both sides of the lower surface 4 are cut into arcuate concave surfaces 5, and the detection elements 7 made of strain gauges are adhered to the load receiver 2 corresponding to the concave surfaces 5 at four positions on the lower surface 6 and are also detected. The thickness (distance between the upper and lower surfaces 6 and the arcuate concave surface 5) of the adhered portion of the element 7 is finished to a predetermined dimension with high accuracy. In addition, the above 4
The detection elements 7 of one sheet are electrically connected in a bridge circuit form so that the electric signals of four detection elements 7 are combined and output. The distance between both side surfaces 8 of the load receiving body 2 is finished to a predetermined dimension, and one side surface 8 is fixed and supported by a vertical portion of an L-shaped supporting member 10 fixed on a substrate 9, and the load receiving body 2 is also supported. The lower portion of the dish mounting member 11 is fixed to the side surface 8 of the body 2 on the movable end side, and the central portion of the lower surface of the flat weighing dish 12 is fixed to the upper portion of the dish mounting member 11.

When the object to be weighed is placed on the weighing pan 12, the weight of the object acts on the movable end side of the load receiver 2, so that the load receiver 2
The stress is distorted at four places of the detection element 7 adhered portion of the above (the tensile stress acts on the upper rear portion and the lower front portion, and the compressive stress acts on the upper front portion and the lower rear portion). ), Each of the four detection elements 7 attached to this portion is also distorted, and an electric signal is output according to this distortion amount.
Since the one detection element 7 is connected in a bridge circuit format, the electric signals from the four detection elements 7 are summed, enlarged and output, and the output amount of this electric signal is converted into weight and displayed. By doing so, the weight of the object to be weighed is measured.

Next, the gist of the present invention will be described. That is, since the processing dimensions and materials of the load receiver 2 and the detection element 7 or the bonding position of the detection element 7 do not match the ideal conditions at the time of manufacturing, it is possible to accurately measure when the weight display deviates from the unbalanced load. It is necessary to make adjustments because accurate measurement cannot be performed, but the method will be explained sequentially. First, a load is sequentially applied to each of the corners A, B, C, and D, which are offset portions of the weighing pan 12, to detect the unbalanced load display value at each of the A, B, C, and D parts. In addition, when the weight display is large with respect to the weight of an accurate load (for example, 1000 g), it is set to +, and when the weight display is small, it is set to −, and each part of A, B, and C is set to 1
When there is only g, 1000g + 1g = 1001g
Since the actual amount is displayed, +1 is displayed and only D part is 1g.
When the amount is small, 1000 g-1 g = 999 g is displayed, so -1 is displayed. This is because the strain amount of the part B of the load receiver 2 with respect to the D part where -1 is displayed is less than that of the other part. Therefore, if the strain amount of the load receiving body 2 is increased by scraping off the load receiving portion 2, the weight display of the D portion becomes large and changes from − to +. By scraping off a predetermined portion of the load receiver 2 corresponding to the value, adjustment is made until the displayed values of each A, B, C, D match. Then, if the display values of the respective portions of A, B, C, D match, it means that the overall balance has been achieved.
If the weight conversion circuit is adjusted in accordance with the coincident display value, the measurement error with respect to the unbalanced load is eliminated, so that the measurement can be accurately performed.

Note that the adjusting method is not limited to the above-described embodiment, and for example, when two points A and B are-displayed, the corresponding portion of the load receiver 2 is scraped off and finally each corner portion is removed. It is only necessary to adjust the unbalanced load display values in (1) and (2) so as to be adjusted, and it is needless to say that the positions of the respective corners to be detected can be appropriately selected.

As described above in detail, the present invention is formed in a rectangular shape with a predetermined thickness, and a rectangular hollow portion is provided in the center thereof to form a parallelogram, and both sides of the horizontal beam portions above and below the parallelogram are formed. The vicinity of the portion is cut into a concave shape to form one load receiver, and the detection element is attached to a position corresponding to the concave cut portion of the load receiver to form a load cell having one load receiver. , One end of the one load receiver is supported by a supporting member, and a weighing pan wider than the thickness of the load receiver is attached to the movable end of the load receiver to form a load meter, After that, the load is applied to each corner of the weighing pan to detect the eccentric load display value at each corner, and the eccentric load display value of each of these corners is matched so that the eccentric load display value corresponds to the above. The concave cutting part to which the detection element of the load receiver is attached and the predetermined part of the corner near it Shear taken simultaneously correct the errors due to bending moment and torsional moment, is characterized in that said to match the display value of the bias load of each corner. Therefore, even if the object to be weighed is placed on the corner of the weighing pan of the load cell type load meter of the present invention, the load receiver detects as described above so that the displayed values of the eccentric load at each corner of the weighing pan match. Since the concave cut portion to which the element is attached and the predetermined portion of the corner portion in the vicinity thereof are scraped off and adjusted, accurate measurement can be performed.

Further, the load cell type load meter of the present invention has an unbalanced load only by scraping off the concave cutting part to which the detection element of the load receiver is adhered and the vicinity thereof so that the unbalanced load display values of the respective corners of the weighing pan coincide with each other. Therefore, it is possible to provide a load cell capable of easily and surely adjusting an eccentric load.

[Brief description of drawings]

FIG. 1 is a perspective view of a load cell type load cell for explaining an embodiment of the present invention, FIG. 2 is a side view of the load cell, and FIG. 3 is a perspective view of a load receiver of the load cell. 1 ... Load cell type load cell, 2 ... Load receiver, 7 ...
..Detection elements, 9 ... Substrate, 10 ... Support member, 1
1 ... Plate mounting member, 12 ... Weighing pan, A, B, C,
D ... Each corner of the weighing pan, A ... Scraping part of the load receiver.

Claims (1)

[Claims] 1. A plurality of detection elements are attached to a load receiver, one end of the load receiver is supported by a support member, and
Attach a weighing pan to the movable end of the load receiver, and detect the weight of the object to be weighed by converting the change in the electrical characteristics of each detection element when the object is placed on the weighing pan into weight. In the load cell type load cell, the rectangular parallelepiped is formed with a certain thickness, and a rectangular hollow is formed in the center of the parallelogram, and both ends of the horizontal beam parts above and below the parallelogram are formed. The vicinity is cut into a concave shape to form one load receiver, and the detection element is attached to a position corresponding to the concave cut portion of the load receiver to form a load cell having one load receiver, One end of the one load receiver is supported by a support member, and a weighing pan wider than the thickness of the load receiver is attached to the movable end of the load receiver to form a load meter. , The load is applied to each corner of the weighing pan to display the unbalanced load display value at each corner. Detected, corresponding to the detected eccentric load value, the detection element of the load receiver is attached to the concave cutting portion and the corners in the vicinity thereof are scraped off to simultaneously correct the error due to the bending moment and the torsion moment, A moment type load cell characterized in that the unbalanced load display values of the respective corners are matched.