JPS59132323A - Power measuring transducer for electronic weighing machine and similar meter and its manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for measuring the strain in the surface layer of a loaded measuring body, which is measured in a manner known per se using resistive strain meter technology, in which the resistance of the strain gauge is measured by means of a resistive bridge. Concerning force-measuring transducers for electronic scales and the like, based on compression.

There are a large number of measuring bodies or load cells of various shapes known as force-measuring transducers of this type.

However, in addition to being very expensive, load cells are associated with certain drawbacks. For example, when a cylindrical measuring object is loaded in the longitudinal direction, surface tension is generated in various directions, and it is necessary to use the resistance strain gauge in various directions, and the arrangement is not always necessary. It's not the best thing to do. US Patent Specification 298693
There are also diagonally loaded long-tube strain gauge cells, such as the device according to No. 1 (73-141). However, apart from being relatively expensive, this strain gauge cell has the disadvantage that its rectangular sides are subjected to tensile tension and compression as well as bending. The measuring body according to the invention is characterized, inter alia, by the thin sides, i.e. the measuring sides of the oblique parallelogram, which form an angle of 90° with the diagonal measuring line and which are subjected to fairly pure bending. Different from cell.

The main aim of the invention is to achieve a particularly inexpensive and accurate, ie competitive, load cell. An inexpensive way to make a load cell is to cut a bow-shaped metal section into appropriate pieces according to the desired measurement range to make the cell or measuring body. No profile extraction tools are required. The features of the present invention are:
It consists of a force-measuring transducer made of an essentially oblique parallelogram body that is loaded diagonally, the two opposite sides of which are thick and relatively inflexible, while the other The so-called measuring side, on which the strain gauges are placed, is thin and forms an angle of 90° with the load line, so as to form two surfaces that serve as overload protection for the measuring body when necessary. The surfaces can be shaped and contact each other to limit deformation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A few embodiments of the present invention will be described below with reference to drawings that represent the principles of the present invention.

The transducer according to the invention can be used for both compressive and tensile loads. FIG. 1 shows a greatly exaggerated view of how the unloaded conversion cell on the left is deformed by compressive and tensile loads. For overload protection during compression, parallel planes l perpendicular to the load lines are provided in the center of the cell, which in case of overload touch each other and the thin sides 2 Prevent it from further bending and breaking. Of course, overload limits can and should be established to prevent permanent deformation from occurring on the thin sides.

Of course, in the case of tensile loads, it is not possible to use such a single overload protection means, and overloads must be prevented by other means.

The structure of a transducer measurement body or cell according to the invention is further illustrated in FIG. In addition to the aforementioned midplane 1 and the thin sides 2 of the oblique parallelogram, there are thick, substantially inflexible sides 3 of the parallelogram.

Between the planes 1, spacing pieces 4 can be used as overload protection means. At both ends of the cell (e.g. top and bottom) there are planes 5 perpendicular to the load line and thus parallel to plane 1, in the center of which a tightening screw hole 6 is provided in the direction of the load line. . As already mentioned, the cells are made by cutting pieces at right angles from drawn metal sections of suitable thickness depending on the desired measuring range. The thickness of the cell can also be varied by cutting along the dashed line 7 in FIG. It is advantageous to arrange the resistive strain gauges 8 at the locations shown in FIG. 2, but they can also be located at other locations on the thin edge or on both sides thereof.

FIG. 3 schematically shows a cell with the aforementioned central plane 1 but without a spacing piece 4. FIG. Although FIG. 4 shows cells without a center plane, they cannot of course be used for tensile loads. FIG. 5 shows a cell with a diagonal parallelogram with curved thick sides, which cell is provided with a flat surface for the spacer. Figure 6 shows the top of the cell where the thin edge has no pinch, Figure 7 shows the thin edge with one pinch, and Figure 8 shows the thin edge with two narrow edges. Show the sides. These pincers are mostly used with small loads when it is necessary to obtain relatively high sensitivity from the cell. FIG. 9 shows a cell where the thin side is at an angle of 90' with the load line. In FIG. 10 the corresponding angle is 1200 and in FIG. 11 it is 60°. However, the two latter cases should be avoided since the further away from 90° the more inaccurate the transducer becomes. FIG. 12 shows how the spacing piece 4 of the overload protection means can possibly be arranged preferably in a cell according to FIG.

The spacing piece 4 can be glued to the lower end and replaced when necessary. In the case according to FIG. 13, a spacing piece is not necessary, but since the central planes of the cells are already close to each other, they already act as an overload protection measure. FIG. 14 shows how the spacing pieces 4 can be arranged in a cell according to FIG.

When the cell is loaded, deformation occurs on both thin sides in exactly the same way. When both ends of the thin side are fixed to the thick side (see Figure 1), when the cell is loaded, the thin side bends into an S-shape as shown in Figure 1, in which case it is difficult to measure the deformation. is easy. 1st, 2.6.7. and 8
The figure gives an example of arranging resistive strain gauges.

Compared to previous solutions, the invention offers the following advantages:

Diagonal parallelograms give very accurate values when the thin sides are located at right angles to the load line. In the cell according to the invention it is easy to obtain return load protection measures. The production of the cells is particularly economical in that they are produced by cutting the cells into suitable pieces from drawn metal sections.

[Brief explanation of the drawing]

Figure 1 is a diagram roughly showing the deformation of an unloaded cell, a compressively loaded cell, and a tensile loaded cell; Figure 2 is a diagram showing a practical example of a cell using the axonometric projection method; , 4 and 5 are diagrams showing three different practical examples of the cell; Figures 6, 7 and 8 are diagrams representing the top of the cell in which zero, one and two pinches are made on the thin sides; Figures 9.10 and 11 represent the top of the cell with the thin sides forming different angles with the load line; Figures 12.13 and 14 show different arrangements of the overload protection basins. . 1... Two surfaces 2... Measuring side 3... Thick side 4... Spacing side 8... Strain meter Figure 2 51 Procedure amendment L (, jt) Showa Tazo July Otsu Patent Office Director 'Kazuo Wakasugi 1, Showa Da 8 Patent Application No. t8j? ! ; No. 17 No. 3, Relationship with the case of the person making the amendment Applicant 4, Agent Investigator 6, Supplementary Null family +-[ ,-” miscellaneous

Claims (6)

[Claims] (1) Electronic measuring instruments based on measuring the strain or compression in the surface layer of a loaded measuring body in a manner known per se using resistive strain meter technology, in which the resistance of the strain meter is measured by means of a resistive bridge. Force-measuring transducers for and the like consist of a diagonally loaded, essentially oblique, parallelogram body whose two opposite sides are thick (relatively inflexible). while the other side, the so-called measurement side (2), where the strain gauge (8) is placed
is thin and makes an angle of 90° with the load line, and forms two surfaces (1) that serve as overload protection and limit deformation of the measuring body when necessary and in contact with each other to limit deformation. A force measuring transducer characterized in that it can be shaped to look like this. 2. A transducer according to claim 1, wherein the direction of the measuring side (2) relative to the load line deviates slightly from 900, but by no more than 30° in both directions. (3) The transducer according to claim 1, wherein the thick side (3) of the oblique parallelogram is curved. (4) The transducer according to claim 1, wherein the measurement side (2) is provided with one or two narrow portions. (5) Two planes perpendicular to the load line (
1) so that these planes are forced towards each other in case of overload and serve as overload protection means, or a separate spacing piece (4) can be arranged between these two planes. A converter according to claim 1, wherein (6) Electronic weighing instruments based on measuring the strain compression in the surface layer of a loaded measuring body in a manner known per se using resistive strain meter technology, in which the resistance of the strain gauge is measured by means of a resistive bridge. and the like, comprising a diagonally loaded, essentially oblique, parallelogram body, the opposite sides of which are thick and relatively inflexible; On the other hand, the other side, the so-called measurement side (2) on which the strain gauge (8) is placed, is thin and makes an angle of 90° with the load line, and when necessary, the measurement object can be In a method for manufacturing a force-measuring transducer, which can be shaped to form two surfaces (1) that serve as overload protection and limit deformation in contact with each other, a drawn metal profile is A method characterized in that the measurement object is shaped so that it can be easily manufactured by cutting it into appropriate pieces according to the range.