JPH04294221A - Electronic balance with mechanism for absorbing swinging of weighing saucer - Google Patents

Abstract

PURPOSE:To protect a supporting line which is stretched in a beam of an electronic balance and works as a point of application of the beam. CONSTITUTION:A damper line 8 having the total length larger than a supporting line 3 is extended with respect to a lower plate 7 of a damper member 4 suspended by the supporting line 3 via a load line 9. A load transmission member 14 with a hook 15 is mounted at the center of the damper line 8. The swing of a weighing tray secured by the hook 15 is absorbed as the twist of the damper 8 the changing amount of which is set large because of the large total length, thereby obstructing the transmission of the swing to the supporting line 3. Accordingly, the measuring accuracy of the balance is prevented from being deteriorated as a result of the error of the mounting position of the supporting line 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic scales, and more particularly to an electromagnetic balance type electronic scale with an improved load transmitting section.

0002

[Prior Art] Electromagnetic balance type weighing devices, commonly known as electronic balances, have high weighing accuracy and are theoretically capable of measuring extremely small amounts of weight, but the mechanism that responds to this small amount of weight is fragile. Therefore, it is also easy to cause errors.

FIG. 5 is a conceptual diagram showing the operating principle of an electromagnetic balance type weighing device (hereinafter referred to as "electronic balance"). A weighing plate 52 is suspended from one end of a beam 50 that is swingably supported around a fulcrum P1 fixed to the apparatus main body side via a hanging mechanism 51.
The beam connection part of is the point of action P2. An electromagnetic section 5 is located at the end of the beam opposite to the point of action P2 via the fulcrum P1.
3 is arranged, and the load of the object to be weighed placed on the weighing pan 52 is measured by generating a force that is balanced with the inclination of the beam 50 corresponding to the load of the object to be weighed placed on the weighing pan 52. There is.

In this device, the weighing pan 52 suspends and supports a weighing pan body 52a by two hanging wires 52b (see also FIG. 2(A) showing an embodiment of the present invention). reference). This facilitates the work of adding and removing objects to be weighed, and even if the weighing plate comes into contact with the weighing plate when adding or removing it, the weighing plate will swing back and forth (X-Y direction in FIG. 5), and the hook portion 51a of the hanging mechanism 51 will Designed to absorb vibrations.

[0005] However, the absorption of rocking motion at the hook part is not 100%, and when the minimum measurable weight is extremely small, such as several mmg or a fraction of a millimeter, even if a slight rocking motion is transmitted, the measurement accuracy may be affected. This requires a more complicated vibration absorption mechanism.

[0006]

3 and 4 show the structure of the beam application point in a conventional electronic balance.

A threaded rod 54 is connected to the upper end of the load transmission member 53 having a hook 52a for suspending the weighing pan 52, and this threaded rod 54 is formed at the center of a beam portion 55a of the support indicated by an arrow 55. It is inserted vertically through the vertical opening. Reference numeral 56 denotes a vibration absorbing member fixed to the threaded rod 54, and is arranged parallel to the beam portion 55a.
Pivot receivers 58, 58 are formed at positions corresponding to a pair of pivots 57, 57 protruding from each other, and by engaging these pair of pivots 57 and pivot receivers 58, the weight on the load transmission member 53 side is reduced. It is supported by this support body 55 via a swing absorbing member 56. In the illustrated configuration, arms for locking the internal weight 61 of the load transmission member 53 extend out on both sides.

On the other hand, the tip of the beam 50 is divided into two roughly Y-shaped parts, and a thin metal wire (usually platinum wire) 59 is attached to this Y-shaped part.
is being extended as a support line. Further, thin metal wires similar to the support wires 59 are extended as load lines 60 to the open ends of a pair of substantially V-shaped support arms 55b arranged perpendicular to the beam portions 55a of the support body 55. The support line 59 and the load line 60 are fixed by a connector 61 so as to be perpendicular to each other. With this configuration, the weight of the weighed object transferred to the support 55 as described above is further transferred to the beam 5 via the load line 60 and the support line 59.
0. That is, the support line 59 becomes the point of action P2 of the beam 50.

[0009] Here, if the minimum measurable weight becomes a very small amount such as several mmg or a fraction of a mmg, the measurement accuracy will be reduced even if the point of action P moves in units of microns. That is, it is necessary to prevent this point of action from moving by applying as little special force as possible to the support line 59, which is the point of action P, other than the weight of the object to be weighed. In particular, if shaking in the X-Y direction on the weighing pan side is transmitted to the support line 59, the support line 59 may be twisted, causing a slight change in the attachment position on the beam 50, and the point of action may change. There is. In consideration of this point, the illustrated configuration absorbs the shaking on the weighing pan side as the shaking of the shaking absorber 56 by engaging the pivots 57, 57 and the pivot receivers 58, 58, and the shaking is absorbed by the support 55. I'm trying to keep it out of reach.

However, the following problems have been pointed out with the above-mentioned conventional mechanism, and a solution to these problems is desired.

First, as shown in the drawings, the structure of the vibration absorbing mechanism is complex, requiring a great deal of effort to assemble the device, and due to its complexity, very delicate adjustments are required in the arrangement of various parts.

[0012]Also, the rocking movement of the weighing pan side is absorbed by the engaging part between the pivot and the pivot holder, but if the machining accuracy of both is low, the smooth movement of the pivot will be hindered, and the rocking movement will be affected. A part of it is transmitted to the pivot side. That is, very high processing precision is required for this engaging portion, resulting in an increase in the unit cost of the entire device. Furthermore, since the engaging portion wears out over time, it is difficult to maintain a high ability to absorb rocking motion at all times.

Furthermore, if a shock is applied to the load transmission mechanism, such as by accidentally dropping an object to be weighed onto the weighing pan, the engagement between the pivot and the pivot holder is insufficient to absorb this shock. A significant portion of is transmitted to the support line 59,
There is also a fear that the position of the point of action may be misaligned due to this.

[0014]

[Means for Solving the Problems] The present invention has been constructed in view of the above-mentioned problems, and a wire rod having the same effect as the support wire is provided between the support wire extended to the beam and the load transmission member. It is stretched so that it is located almost vertically below and parallel to the support line, and this wire prevents the shaking of the weighing pan side.
It is characterized by being configured to absorb impact.

[0015]

[Operation] The wire rod stretched between the support line stretched on the beam and the load transmission member located almost vertically below the support line absorbs the swinging motion of the weighing pan as its own torsional deformation. It prevents the vibration from being transmitted to the support wire side, and when an impact is applied to the weighing pan side due to a falling object, etc., the impact is absorbed by deformation based on the elasticity and malleability of this wire material. .

[0016]

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 is a beam of an electronic balance, and 2a and 2b are parts that support the beam 1 and serve as the center of swing of the beam 1, that is, fulcrums. Fulcrum 2
An electromagnetic part M is attached to one end of the beam 1 centered on a and 2b, and a load transmission mechanism for transmitting the load of the weighing object placed on the weighing pan to this beam is attached to the other end. .

The end of the beam on the side where the load transmission mechanism is attached is branched into a substantially Y-shaped plane, and a support wire 3 made of, for example, a platinum wire is stretched across this branch portion 1a. Arrow 4 indicates a damper member that is suspended and supported by this support line 3 via a load line that will be described later. This damper member 4 is connected to the upper plate 5 via spacers 6a and 6b.
The lower plate 7 is arranged and fixed in parallel to the lower plate 7. The side shape of the upper plate 5 in the width direction is approximately V.
Arms 5a, 5a are exposed in the shape of a letter, and these arms 5a,
5a is a load line 9 made of the same material as the support line 3.
is expanded, and the load line 9 is connected and fixed to the support line 3 via a connector 10 so as to be perpendicular to the support line 3. Further, the total length of the tamper member 4 is preferably longer than the total length of the support line 3, for example, about twice the total length of the support line 3.

Reference numeral 8 denotes a vibration-absorbing wire rod (hereinafter referred to as "damper wire rod") which is stretched and fixed to the lower plate 7 of the damper member 4, and FIG. 1 specifically shows its structure. It is shown enlarged. This damper wire 8 has a width W of approximately 0.
It is an extremely thin platinum wire with a substantially rectangular cross section, 2 mm thick and less than this width, and its central portion is twisted approximately 90° with respect to its both ends. As shown in FIG. 2(B), a slit 7a is formed in the longitudinal direction of the lower plate 7 of the damper member 4 to which the damper wire 8 is attached, and the load transmission member is attached along this slit 7a. The damper wire rod 8 is expanded.

That is, a pair of connecting plates 11a and 11b are fixed to the central part of the damper wire 8 with screws 12 so as to sandwich the damper wire 8, and the connecting plates 11a,
A load transmitting member 14 is attached to 11b via fixing plates 13a and 13b. In the illustrated configuration, a hook 15 formed separately from the load transmitting member 14 is attached to the load transmitting plate 14.

[0021] The damper wire rod 8 itself is fixed plates 16a and 16b.
Thus, both ends thereof are fixed to both ends of the lower plate 7, and the connection plates 11a and 11b are stretched and fixed along the slit 7a so that the attachment portions of the connecting plates 11a and 11b are located at the center of the slit 7a. Note that in place of the fixed plates 16a and 16b, upper and lower plates 5
The damper wire 8 may be directly fixed by spacers 6a and 6b arranged and fixed between the damper wire 8 and the spacers 6a and 7. Incidentally, the vibration and impact on the weighing pan side are absorbed by the deformation of the damper wire 8, but the deformation is not directly related to the mounting position of the damper wire. Therefore, unlike the prior art, the accuracy of the scale does not depend on the setting of the caulking position, the pivot accuracy, etc., so that very high accuracy is not required for attaching the damper wire 8, and assembly is easy.

[0022] Also, damper wires with a rectangular cross section, etc.
The reason why a wire rod having at least a square cross-section is used is that, compared to a wire rod having a circular cross-section, the side wall of the wire is in close contact with the object to be attached, so that displacement after attachment is less likely to occur. Furthermore, the central part is twisted by about 90 degrees to facilitate attachment of the connecting plates 11a and 11b, and by twisting the damper wire by about 90 degrees, the load is transmitted to the damper member 4 through the torsion center of the damper wire. This is to ensure that the load is accurately transmitted to the support line 3. Note that the damper member 4 is
By making the total length of the damper wire 8 approximately twice, for example, the total length of the damper wire 8 becomes approximately equal to the total length of the damper member 4. Here, when the amount of change due to twisting of the wire including the support wire 3 and damper wire 8 is Θ, the twist angle with respect to unit length of the wire is θ, and the total length of the wire is L, the following relationship holds true.

Θ=Lθ

That is, the amount of change due to twisting becomes larger as the total length of the wire is longer. In other words, when the same force is applied, a wire rod with a longer overall length is more likely to be twisted.

In the above configuration, as shown in FIG.
When a weighed object is placed on the plate main body 52a of No. 2, the load is
Suspension lines 52b, 5 provided on both sides of the weighing plate body 52a
2b, and reaches the load transmission member 14 via the hook 15. Here, the internal weight 61 is added or removed in accordance with the load of the object to be weighed, so that the load applied to the beam is within the electromagnetic measurement range. Furthermore, these loads are applied to the connecting plate 11a,
11b to the damper wire 8 extended to the lower plate 7 of the damper member 4, and then to the support line 3 via the load line 9 extended between the arms 5a, 5a of the upper plate 5 of the damper member 4.
transmitted to. Since the attachment point of the support wire 3 of the beam 1 is the point of action of the beam, the sensor detects the displacement of the beam 1 and the electromagnetic part 3 transfers the electric force used to balance the beam 1 to the weighing object. Convert to weight.

During the above measurement work, when the weighing pan etc. swings back and forth due to operations such as placing the object to be weighed on the weighing pan 52, this swinging motion is absorbed as twisting of the damper wire 8.
It is not transmitted to the load line 9 and support line 3 side. That is, as mentioned above, since the total length of the damper wire 8 is made to be, for example, about twice as long as the support wire 3, most of the swinging on the weighing pan side is absorbed by the damper wire 8, which has a large amount of deformation. In addition to or instead of forming the entire length of the damper wire 8 to be longer than the support wire 3, if the wire is made of the same material as the support wire 3, the cross-sectional area of the damper wire 8 can be made longer than the support wire 3. The amount of deformation of the damper wire 8 may be increased by making the amount of deformation smaller than that of the support wire 3, or the damper wire may be formed of a wire having a larger amount of deformation than the support wire 3.

In addition to the swinging of the weighing plate 52, the weighing plate 5
Even if a large instantaneous load is applied, such as by dropping a weighed object onto the damper wire 8, the damper wire 8, which has a large amount of deformation, will mainly deform, absorbing this instantaneous load and functioning as a damper, and absorbing the impact. is prevented from being transmitted to the support line 3 side.

[0028]

Effects of the Invention As explained above, the present invention provides a damper wire having the same effect as the support wire between the support wire extended to the beam and the load transmission member, which is located almost vertically below the support wire, and The damper wire is arranged so as to be stretched parallel to the weighing pan, and is configured to absorb vibrations on the weighing pan side and shocks through the deformation of this damper wire. Since it does not depend on the support wire, it is very easy to adjust the arrangement of parts in assembling the device while maintaining a high support line protection effect, and high measurement accuracy can be maintained at all times.

[0029] Furthermore, since this damper wire material can effectively absorb shocks caused by falling objects to be weighed, etc., there is no need for a special mechanism for shock absorption, and the overall structure of the apparatus can be simplified. .

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a load transmission mechanism section showing the configuration of the present invention.

2(A) is a front view of the mechanism shown in FIG. 1 after assembly, and FIG. 2(B) is a sectional view taken along line A-A in FIG. 2(A).

FIG. 3 is a perspective view of a conventionally configured load transmission mechanism section.

4(A) is an enlarged partial view of FIG. 3, and FIG. 4(B) is a sectional view taken along line BB in FIG.

FIG. 5 is a schematic diagram showing the mechanism of an electromagnetic parallel weighing device.

[Explanation of symbols]

1 Beam 2a, 2b fulcrum 3 Support line 4 Damper member 5 Top plate 7 Lower board 8 Damper wire rod 9 Load line 11a, 11b Connection tool 14 Load transmission member 15 Hook 52 Weighing plate

Claims (3)

[Claims] Claim 1: A member consisting of a plurality of parts and transmitting the load of the object to be weighed to the support line is suspended from a support line extended as a point of action at one end of the beam of an electromagnetic balance type weighing device, thereby transmitting the load. In an electronic scale configured such that a member that transmits the load absorbs the back and forth rocking of a weighing pan that is locked to a member that transmits the load, one of the parts constituting the member that transmits the load is A wire rod with a larger amount of deformation than the support line is stretched as a damper wire almost vertically below and parallel to this support line, and the weight of the object to be weighed is transmitted to the support line side through this damper wire. What is claimed is: 1. An electronic balance having a vibration absorbing mechanism for a weighing pan, wherein the vibration on the weighing pan side is absorbed by deformation of the damper wire. 2. The weighing pan according to claim 1, wherein the total length of the damper wire is set to be longer than the total length of the support wire, so that the amount of deformation of the damper wire is greater than that of the support wire. An electronic scale with a vibration absorption mechanism. 3. The cross section of the damper wire is approximately rectangular, and the central portion has a diameter of 90 mm with respect to the attachment portions at both ends of the damper wire.
The damper wire is twisted to a certain degree, and a member for transmitting the load from the weighing pan is attached to the center of the damper wire, so that the load from the weighing pan is applied to the center of the twist of the damper wire. An electronic balance having a mechanism for absorbing vibration of a weighing pan according to any one of claims 1 to 3.