JPH0248850B2 - MASATSURYOKUKENSHUTSUROODOSERU - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a friction force detection load cell for a friction tester using a rotating wheel.

A friction tester normally presses a sample perpendicular to the direction of motion of a moving body and detects the frictional force that occurs perpendicular to the direction of the press. For this reason, a device for detecting force in a direction perpendicular to the force transmitting element is required, which inevitably makes the mechanism complex, large and expensive.

The present invention eliminates this drawback and provides a compact and compact load cell for transmitting pressing force and detecting frictional force, which transmits pressing force and detects only the frictional force perpendicular to the pressing force.

The device is a friction testing machine that applies pressure from above to a sample that is cut at the apex of the vertical axis of a rotating wheel. A horizontal bottom side that projects a cantilevered load cell having a flexible portion and a strain gauge on a solid base that is vertically upward facing upstream, and a horizontal top side that projects a cantilevered load cell of the same shape that is vertically downwardly adjacent to the downstream side in the rotational direction. and a vertical side having integral vertically symmetrical flexible parts at both left and right ends of the horizontal top and bottom sides. A friction force detection load cell is provided in which both cantilever load cells are engaged by a horizontal screw which is horizontally fixed at a center height and contacts the other one with a spherical tip.

In other words, as shown in Figure 1, the vertical pressing force is transmitted to the sample through the vertical sides at both ends of the parallelogram beam, while the frictional force perpendicular to this pressing force is transmitted parallel to the vertical sides but at the tip. It is detected as a horizontal pressing of two cantilever load cells that are free and protrude vertically without connecting their horizontal top and bottom sides. For this purpose, two identical T-shaped vertical cantilever load cells protruding upward and downward from the top and bottom sides of the parallelogram beam are provided upstream and downstream of the frictional force that the bottom side receives, respectively, so that they are in adjacent contact even when no load is applied. As the frictional force is generated, the frictional force is transmitted from upstream to downstream in the horizontal direction, and since displacement is free in the vertical direction, only the horizontal frictional force is detected by the deformation due to the pressing of both cantilever load cells, regardless of the pressing force. At this time, since the upper and lower cantilever load cells have the same shape, the bending due to the horizontal frictional force is relatively opposite and symmetrical, so the force can be accurately detected with an electric bridge that has separate diagonal sides for tension and compression. Furthermore, by using a material with a large elastic modulus E as the strain gauge force detection load cell, force can be detected without displacement, so if such a strong cantilever load cell is used, the top and bottom horizontal sides of the parallelogram beam will be free from friction. Since the applied force is detected without any displacement even if it occurs, the vertical sides at both ends of the parallelogram beam always remain almost vertical. Only cantilever load cells are detected by it.

However, since the above-mentioned cantilever load cell is freely displaceable in the vertical direction, it is insensitive to the vertical pressure force and detects only the frictional force, and the pressure force is bypassed by the vertical sides on both sides of the parallelogram beam, so the pressure force is reduced. Frictional force can be detected as well as transmitted.

According to this device, the parallelogram beam with a cantilevered load cell is shown in Fig. 1 with extra space for the sake of explanation, but in reality it can be constructed compactly and compactly, and the entire friction tester can be Since it is small and inexpensive, statistical true values can be obtained by arranging multiple unit testing machines in parallel as shown in Figure 2 and simultaneously conducting many friction tests with low reproducibility.

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

Figure 1 10 shows a friction tester implementing the present invention.
12 is its rotating axis, 14 is its rotating wheel, 16 is the vertical axis of the rotating wheel, 18 is a sample to be cut on the top surface of the rotating wheel, and 20 is a sample 18 fixed to the horizontal base 221' of the parallelogram beam 22. In the sample holder, 221'' is the top side of the parallelogram beam 22, 222', 222'' are the vertical sides on both sides, and at each end there are stress concentration parts of the same shape as 223 and symmetrical to the center of the parallelogram. Yes, 2
24' is a cantilever load cell which protrudes upward from the horizontal base 221' in an inverted T-shape, and has a pair of strain gauges 225' glued to the left and right sides of a flexible portion at the base, and 226 is a cantilever load cell 224' from the bottom. 2 with a cantilevered load cell protruding downward from the horizontal top that is exactly the same as
25'', a pair of strain gauges 227 on top of which are fixed at the center of the height of the parallelogram beam 22 of the bottom cantilevered load cell 224', and have a spherical tip and can freely slide vertically on the top cantilevered beam. The horizontal base 221' is upstream in the rotational direction of the cutting point with the sample of the rotating wheel 12, for example, when the rotating wheel rotates clockwise, the sample flows to the right, so the horizontal base 221' is a cantilever on the left side of the upstream side. The load cell 224' is pushed to the right and the horizontal screw 227 fixed thereto is attached to the cantilevered load cell 224 at the top.
6 to the right, the lower load cell 224' and the upper load cell 226 are exactly the same, so they deform symmetrically in opposite directions, and the respective strain gauges 225' and 225'' have opposite outputs, so each of the strain gauges 224' and 226 If you make an electric bridge with separate tension and compression gauges on opposite sides, you will be able to detect only the horizontal friction force.If the rotating wheel can rotate counterclockwise, the first gauge will be placed on the right side upstream of the displacement. As shown by the dotted line in the figure, a third cantilever load cell 224'' similar to the bottom cantilever load cell 224' can be placed so that it pushes the top cantilever beam 226 to the left and similarly detects only the frictional force. . At this time, the upper and lower cantilevers pushing against each other are strong and there is almost no displacement, which is a characteristic of load cells.
In other words, if the relative displacement of the top and bottom sides is suppressed, the parallelogram will not deform and the vertical sides 222' and 222'' will remain vertical, and in the horizontal direction, the middle of the beam will be displaced due to buckling caused by the pressure, but the top will remain. Since the bottom end is not displaced, the pressurizing force is transmitted on the vertical side, and has no relation to the horizontal displacement between the cantilever load cells 224' or 224'' and 22.
6 accurately detects only the frictional force.

However, in the above example, there are 2261 cantilever load cells on the top side and 22 cantilever load cells on both sides of the bottom side.
Although it was shown that it was possible to place 4′,224″,
Conversely, one 224' may be placed at the center of the bottom and two cantilever load cells 226' and 226'' may be provided on the top on both sides, and the horizontal screw is fixed to the bottom load cell, but the top You are also free to fix it.

The load cell of the present invention takes full advantage of the load cell's ability to detect force without displacement, detects only a force in a specific direction while insulating force in a direction perpendicular to it, and at the same time has the advantage of measuring force without displacement. The compressive force is transmitted to the load cell using the vertical sides placed on both sides of the top and bottom horizontal sides, making it compact and compact, which in turn reduces the size of the friction tester itself, making it possible to create a friction tester with low reproducibility. It is also possible to statistically obtain the true value of the friction characteristics by multiplexing as shown in Fig. 2.

The above example uses a vertical axis friction tester to simplify the description, but the direction of the friction machine axis is free.

Note that the detailed structure of integrating a cantilever load cell etc. into a parallelogram beam is outside the scope of the claims and is therefore free.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram with the main parts exaggerated to explain the structure for implementing the present invention, and FIG. 2 is a layout diagram of a friction testing machine that is multiplexed to take advantage of the compact and inexpensive features of the present invention. In the figure, 10...the entire friction tester, 12...rotating shaft,
14... Rotating wheel, 16... Vertical axis of rotating wheel, 18... Sample, 20... Sample gripper, 22... Parallelogram beam, 2
21', 221''...Top and bottom horizontal sides of parallelogram beam, 2
22', 222''...both vertical sides of parallelogram beam, 2
23...Flexible parts at the upper and lower ends of the vertical sides, 224', 22
4″...Cantilevered load cell projecting upward from the bottom horizontal side, 225′, 225″…Bottom side 224′ and top side 22
A pair of strain gauges on each cantilever load cell of 6, 22
6...Cantilevered load cell at the center of the top side, 24...ramrod for pressurization, 26...ramrod fulcrum, 28...weight, 30...driving source, 227...horizontal screw.

Claims (1)

[Scope of Claims] 1. In a friction testing machine that applies pressure from above to a sample cut at the apex on the vertical axis of a rotating ring, the longitudinal axis of the sample is held parallel to the cutting point of the rotating ring. a horizontal base protruding a cantilevered load cell having a flexible portion and a strain gauge from a solid base that is vertically upward in the upstream direction of rotation, and a cantilevered load cell of the same shape that is vertically downwardly protruded downstream in the rotational direction. One of the two top-bottom cantilever load cells of a parallelogram beam constituted by a horizontal top side and a vertical side having vertically symmetrical flexible parts integrated at both left and right ends of the horizontal top-bottom side. A friction force detection load cell made by engaging both cantilever load cells with a horizontal screw that is fixed horizontally at the center height above and below and touches the other one with a spherical tip.