JPH0538535U - Electronic scale overload protection mechanism - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an overload protection mechanism for an electronic scale, which can protect a load cell from overload by simple adjustment. [Arrangement] One end of the movable column is fixed to the balance base, the other end is supported by the base through an adjusting screw, and has a ridge extending in a direction orthogonal to the beam direction of the load cell. A regulating member having a convex curved surface is provided, and the gap between the ridge and the bottom of the movable column is changed by the rotation of the adjusting screw.

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overload prevention mechanism for an electronic balance using a double beam load cell as a load sensor.

[0002]

2. Description of the Related Art Generally, an electronic balance using a double beam type load cell has a structure in which one end of the load cell is fixed to the base of the balance and the other end is a free end, and a disc bearing shaft is attached to the other end. Take. In such electronic scales, in order to protect the load cell from overload, the displacement of the load cell is usually kept below a certain amount by facing the bottom surface of the free end side of the load cell (called movable column). A stopper for regulating is provided. This stopper is generally composed of a cylindrical protrusion integrally formed with the base of the electronic balance.

[0003]

By the way, in the double beam type load cell, even if the maximum load in the measuring range is applied, the displacement amount is as small as 0.2 mm to 0.3 mm at the most, and Even if a displacement of about 0.2 to 0.3 mm occurs from the state in which the maximum load is applied, it will be damaged. In order to protect the load cell from overload, it is necessary to regulate the maximum displacement of the movable column within 1.5 times to at most 2 times the displacement under the maximum load condition.

In the above-mentioned conventional protection mechanism, although the maximum displacement amount of the movable column is designed to be within the above range, the maximum displacement amount is accurately regulated for all products without variation. It is hard to say that overloading may damage the load cell. Further, in the conventional protection mechanism, the load cell may be damaged due to the action of overload although the maximum displacement amount is accurately regulated within the above range.

The present invention has been made in view of such circumstances, and an object thereof is to provide a mechanism capable of reliably protecting the load cell from overload by simple adjustment.

[0006]

[Means for Solving the Problems] In order to achieve the above object, in the protection mechanism of the present invention, the double beam type load cell extends in a direction orthogonal to the beam direction of the load cell facing the bottom surface of the movable column. A restricting member with an upward convex curved surface having a ridge is arranged, and this regulating member has one end fixed to the base of the scale so that the ridge of the convex curved surface intersects with the substantial axis of the dish receiving shaft. In addition, the other end is supported by a scale base via an adjusting screw, and the gap between the ridge of the convex curved surface and the bottom of the movable column is changed by the rotation of the adjusting screw.

[0007]

[Operation] The vertical position of the ridge of the convex curved surface of the regulating member is higher than the vertical displacement of the adjusting screw screwed or unscrewed by the rotation of the adjusting screw provided at the end. Get smaller. For example, if the position of the ridge is the central portion, the amount of displacement of the ridge will be 1/2 of the amount of vertical movement of the adjusting screw, and fine position adjustment is possible.

Further, the cause of the load cell being damaged despite the fact that the maximum displacement amount of the movable column is set correctly in the conventional protection mechanism is that in the double beam type load cell, the movable columns are supported by beams parallel to each other. However, because it has a so-called Roberval mechanism, its displacement direction is restricted only to the vertical direction, but in reality it may be displaced with a slight inclination. Even if it is arranged so that it is on the same axis as the axis of the receiving shaft, since the shape is cylindrical, the movable column comes into contact with the end of the upper surface of the stopper. This is because a load is applied on the line and a moment acts on the movable column, causing it to twist.

In the restricting member of the present invention, the surface facing the movable column is a convex curved surface that extends in the direction perpendicular to the beam direction of the load cell and has a ridge that passes through substantially the axis of the dish receiving shaft. Even if the column comes into contact with the regulating member in a tilted state, the movable column comes into contact with the regulating member substantially on the axis of the dish receiving shaft, and no moment acts.

[0010]

Embodiment FIG. 1 is a front view of a main part of an internal structure of an electronic balance according to an embodiment of the present invention, and FIG. 2 is a plan view of a regulating member 5 thereof. A double-beam type load cell 1 having a movable column 14 supported by beams 12 and 13 parallel to the fixed column 11 is fixed to a base 2 at the bottom of the fixed column 11. A dish receiving shaft 4 for supporting the dish 3 is fixed to the upper surface of the movable column 14.

A restriction member 5 is arranged so as to face the bottom surface of the movable column 14. The regulating member 5 is made of a material having elasticity to some extent, for example, an aluminum alloy or a steel plate, has a through hole 51 at one end and a female screw 52 at the other end, and an intermediate portion thereof faces upward. A curved portion 53 having a convex curved surface is formed, and a ridge 53a of the convex curved surface extends in a direction orthogonal to the extending direction of the beams 12 and 13 of the double beam type load cell 1.

The regulating member 5 has one end fixed to the base 2 through the through hole 51 with the screw 6 at a position where the ridge 53a intersects the axis L of the dish receiving shaft 4. The adjusting screw 7 is screwed into the female screw 52 at the other end from above. The tip of the adjusting screw 7 is pressed against the surface of the base 2. Therefore, by rotating the adjusting screw 7, the other end of the regulating member 5 is vertically displaced, but at the same time, the ridge 53a is displaced by the other end. It will be displaced in the vertical direction by half the amount.

As shown in FIG. 2, the regulation member 5 has a through hole 54 formed in the center thereof, and a hook for suspending the lower plate is provided when the lower plate is mounted for measurement. It is structured so that it can pass through. In the above-described embodiment of the present invention, the gap between the bottom surface of the movable column 14 and the ridge 53a of the regulating member 5 is rotated with the adjusting screw 7 in an unloaded state or a state in which a weighing load is applied, for example, the thickness Set the size to the desired size by using a method such as using a gauge. A point to be particularly noted in this setting work is that the displacement amount of the ridge 53a of the regulating member 5 becomes 1/2 of the displacement amount of the portion where the adjusting screw 7 is arranged, which results in a small gap. It is easy to adjust the dimensions.

Further, since the regulating member 5 has a certain degree of elasticity, there is also a problem that the vertical position of the regulating member 5 is changed after once adjusted due to the rotation preventing effect of the adjusting screw 7 due to the elastic force. Does not happen. Then, after such adjustment is completed, when the dish 3 is overloaded, the bottom surface of the movable column 14 comes into contact with the regulating member 5, but since the contact position is the ridge 53a, The movable column 14 comes into contact with the regulating member 5 on the axis L of the dish receiving shaft 4, which is the line of action of the load, and no moment acts.

[0015]

As described above, according to the present invention, in the direction facing the bottom surface of the movable column, passing through the substantial axis of the dish receiving shaft and orthogonal to the beam direction of the double beam type load cell. A regulating member having a convex curved surface having an extending ridge is provided, one end of this regulating member is fixed to the base, an adjusting screw is provided at the other end, and the ridge is displaced in the vertical direction by the rotation of the adjusting screw. As a result, fine adjustment of the gap between the bottom of the movable column and the control member is possible with a very simple operation, and the accurate setting of the gap ensures that the load beam is protected from overload. became.

Further, since the displacement of the movable column is regulated substantially on the axis of the dish receiving shaft, there is no damage as in the conventional case due to the action of a moment when abutting. Moreover, since the present invention has an extremely simple structure, it does not particularly increase the cost of the electronic scale.

[Brief description of drawings]

FIG. 1 is a front view of a main part of an internal structure of an electronic scale according to an embodiment of the present invention.

FIG. 2 is a plan view of the regulating member 5.

[Explanation of symbols]

 1 ... ・ Double beam type load cell 11 ・ ・ ・ ・ ・ ・ Fixed column 12, 13 ・ ・ ・ ・ Beam 14 ・ ・ ・ ・ Movable column 2 ・ ・ ・ ・ ・ ・ Base 3 ・ ・ ・ ・ ・ ・ Plate 4 ・ ・ ・ ・ ・ ・ Plate holder Shaft 5 ・ ・ ・ ・ Regulating member 51 ・ ・ ・ ・ ・ ・ Through hole 52 ・ ・ ・ ・ Female screw 53 ・ ・ ・ ・ Curved portion 53a ・ ・ ・ ・ Ridge

Claims (1)

[Scope of utility model registration request] 1. A mechanism for protecting an electronic balance from an overload, wherein a movable plate of a double beam type load cell is provided with a dish support shaft, and the beam direction of the load cell is opposed to the bottom surface of the movable column. A regulating member having an upward convex curved surface having a ridge extending in a direction orthogonal to is provided, and the regulating member has one end so that the ridge of the convex curved surface intersects with the substantial axis of the dish receiving shaft. Is fixed to the base of the scale and the other end is supported by the base via an adjusting screw, and the gap between the ridge and the bottom surface of the movable column is changed by the rotation of the adjusting screw. An overload prevention mechanism for electronic scales.