JPH0222652Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a roberval mechanism used in a weighing machine.

[Conventional technology and problems]

Figures 3 to 6 show conventional examples of this type of weighing machine. 4' and plate springs 5, 5' with bolts 15. Leaf spring 5, 5'
acts as a hinge. That is, the fixed body 2,
Movable block 3, links 4, 4', leaf spring 5,
5' constitutes a so-called roberval link mechanism. A mounting plate 7 is fixed to the upper end of the movable block 3 via a mounting member 6.

A lower end of a load transmitting member 10 is fixed to the lower end of the movable block 3 via a spacer 9. The pole 11 is supported by a fulcrum 12, one end of which passes through the opening 8 of the movable block 3, and the upper end of the load transmitting member 10 described above is fixed thereto. Further, an actuation rod 13a of a load measuring actuator 13 is pivotally attached to the other end of the rod 11. This actuator 13 is an actuating rod 13
In addition to a, it is made up of a moving coil, a magnet, a yoke, etc. (not shown), and is designed to generate a tensile force in the vertical direction due to the interaction between the current flowing through the moving coil and the magnetic flux from the magnet. This tensile force causes the actuating rod 13a to apply a counterclockwise rotational force to the rod 11 about the fulcrum 12. Although the figure shows the balanced state of the rod 11, it is assumed that means for detecting this balanced position is provided facing the left end of the rod 11, although not shown. In FIG. 5, the mounting plate 7 and the load transmitting member 10 are on the center line.

In the weighing machine 1 constructed as described above, when an object to be weighed is placed on the tray 7, the movable block 3 moves downward in accordance with the weight. At the same time, the load transmission member 10 also moves downward. That is, the rod 11 rotates clockwise around the fulcrum 12. A current flows through a coil in the actuator 13 in accordance with the amount of rotation, and a counterclockwise rotational force is applied to the rod 11 by the actuating rod 13a. The weight of the object on the plate 7 is measured based on the current value when the rod 11 is in a balanced state.

Due to the principle of the Roberval mechanism, it should be possible to accurately weigh an object no matter where it is placed on the tray 7, but for this purpose, the leaf springs 5, 5'
must all deform stably (links 4 and 4' are rigid bodies). When an object is placed on the tray 7, the upper leaf spring 5' receives a tensile force, and the lower leaf spring 5 receives a compressive force. Leaf springs used as hinges in weighing machines are generally called tapes and are extremely thin. Therefore, when subjected to a large compressive force, the central portion may bulge abnormally and buckle, making it impossible to deform stably as expected. In terms of buckling strength, this is disadvantageous compared to the leaf spring 5' which receives only the upper tensile force. Lower leaf spring 5 to increase buckling strength
It is not preferable to increase the thickness only because it reduces the accuracy of the weighing machine.

FIGS. 6A and 6B show another example 18 of the leaf spring, which is made of stainless steel and has a length of about 25 mm and a thickness of about 0.3 mm. Both end portions 18a and 18b have a substantially square shape and are fixed to the fixed body 2, movable block 3, and links 4 and 4' with bolts. The intermediate portion 18c functions as a hinge, and as shown in FIG. 6B, the central portion is made particularly thin by rounding. This can improve the accuracy of the weighing machine, but with such a shape, especially abnormal deformation occurs in response to compressive force, and the allowable load is smaller than that of the upper leaf spring.

[Purpose and structure of the invention]

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a roberval mechanism in a weighing machine that can increase the permissible load by applying tensile force to the lower leaf spring in the same way as the upper leaf spring. According to the present invention, in a roberval mechanism consisting of an upper and lower pair of links connected to a fixed side and a movable side via leaf springs, the link of the leaf spring is connected to the upper link. The inner end in the extending direction is fixed, the outer end in the extending direction of the link of the leaf spring is fixed to the fixed side and the movable side, respectively, and for the link on the lower side, An outer end of the leaf spring with respect to the extending direction of the link is fixed, and an inner end of the leaf spring with respect to the extending direction of the link is formed close to the fixed side and the movable side, respectively. A roberval mechanism in a weighing machine, characterized in that it is fixed to a protruding part that is
achieved by.

〔Example〕

Hereinafter, a Roberval weighing machine which is an embodiment of the present invention will be described with reference to FIG.

In FIG. 1, the weighing machine is generally indicated at 21, and the upper link 24' is connected to the fixed body 22 and the movable block 23 via leaf springs 25' in a conventional manner. That is, the inner end of the leaf spring 25' in the extending direction of the link 24' is fixed to the end of the link 24' by the bolt 15, and the inner end in the extending direction of the link 24' is fixed to the end of the link 24' by the bolt 15. are fixed to the fixed body 22 and the movable block 23, respectively. Note that, in this specification, the inner end and the outer end of the leaf spring refer to the inner end and the outer end, respectively, with respect to the extending direction of the link.

On the other hand, in the lower link 24, the leaf spring 25 is exactly the same as the upper leaf spring 25', but its outer end is fixed by a bolt 15 to the end of the link 24 through a spacer 26, and its inner end is fixed to the end of the link 24 through a spacer 26. The ends are the protrusion 22a of the fixed body 22 and the movable block 23, respectively.
It is fixed to the protruding portion 23a with a bolt 15.
As shown in the figure, the protrusions 22a and 23a protrude from the fixed body 22 as the fixed side and from the movable side block 23 as the movable side in a direction in which they approach each other.

The rest of the configuration is exactly the same as the conventional one, so corresponding parts are given the same reference numerals.
The explanation will be omitted.

The embodiment of the present invention is constructed as described above, and its operation and effects will be explained next.

When an object to be weighed is placed on the placing plate 7, the movable block 23 moves downward, and the weight is measured by the load measuring actuator 13 in the same way as in the conventional case. side leaf spring 2
5 is also subjected to tensile force in the same way as the upper side. That is, when the movable block 23 moves downward, the lower right leaf spring 25 engages the protrusion 23 of the movable block 23.
It deflects downward around the fixed point with a. Link 2
Since 4 and 24' are rigid bodies, the lower left leaf spring 25 is deflected upward around the point where it is fixed to the protrusion 22a of the fixed body 22 in response to the reaction force caused by the deflection of the leaf spring 25. In this way, the lower leaf spring 25 is also subjected to tensile force.

Therefore, when a heavy object is placed on the placing plate 7, there was a risk that the lower leaf spring would be abnormally deformed in the conventional weighing machine, but in this embodiment, there is no such fear at all, and the upper leaf spring is It can be handled in the same way as a leaf spring. That is, the weight accuracy can be improved by using the same leaf spring by reducing the thickness as much as possible. Also in this example, FIGS. 6A and 6
Although a leaf spring 18 can be applied as shown in Figure B,
In particular, the permissible load for such a leaf plate 18 can be made much larger than before. Further, according to this embodiment, selection of various leaf springs becomes easy.

FIG. 2 shows a weighing machine 21' according to another embodiment of the present invention.
1, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

That is, in this embodiment, a hopper/feeder assembly 7' is fixed to the movable block 23 instead of the tray 7 of the above-described embodiment. Hopper
The feeder assembly 7' includes a frame 41, a hopper 42 fixed to the frame 41, and a hopper 42 fixed to the frame 41.
It consists of a discharge feeder 43 for discharging the material inside. The discharge feeder 43 is, for example, an electromagnetic vibration feeder, and is suspended from the hopper 42 by a coil spring (not shown). In the frame 41, such a hopper feeder assembly 7'
is fixed to the movable block 23.

The weighing machine 21' as described above can measure the weight of the material in the hopper 42, that is, the amount of material discharged from the discharge feeder 43, and it is clear that the same effects as in the above embodiment can be obtained. .

Each embodiment of the present invention has been described above, but
Of course, the present invention is not limited to these, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, a Roberval mechanism was explained which consists of a pair of upper, lower, left and right links (i.e. four links) and a leaf spring, as in the conventional example, but instead of this, a Roberval mechanism which consists of a pair of upper and lower links and a leaf spring was explained. The present invention is also applicable to

Furthermore, in the above embodiments, a plate weigher and a weighing hopper have been described as weighing machines, but the present invention is also applicable to other types of weighing machines.

Further, in the above embodiments, the same type of leaf spring is used for both the upper and lower parts, but the types may be different for the upper and lower parts.

[Effect of idea]

As described above, according to the Roberval mechanism in the weighing machine of the present invention, the permissible load of the leaf spring serving as a hinge can be increased, and weighing accuracy can be improved compared to the conventional weighing machine. Furthermore, selection of various leaf springs becomes easy.

[Brief explanation of drawings]

Fig. 1 is a side view of a Roberval type weighing machine according to the first embodiment of the present invention, Fig. 2 is a side view of a Roberval type weighing machine according to the second embodiment of the present invention, and Fig. 3 is a side view of a Roberval type weighing machine according to the second embodiment of the present invention. A side view of the heavy equipment, Figure 4 is a front view of the same,
5 is a plan view of the same, FIG. 6A is a plan view of another example of the leaf spring in FIG. 3, and FIG. 6B is an enlarged sectional view in the direction of the line B-B in FIG. 6A. In the figure, 21, 21'...Roberval weighing machine, 22...fixed body, 24, 24'...link, 25, 25'...plate spring, 23...movable side block.

Claims (1)

[Scope of utility model registration request] In a Roberval mechanism consisting of an upper and lower pair of links connected to a fixed side and a movable side via leaf springs, the upper link has an inner end of the leaf spring with respect to the extending direction of the link. is fixed, the outer ends of the leaf spring in the extending direction of the link are fixed to the fixed side and the movable side, respectively, and the extension of the link of the leaf spring is fixed to the lower link. The outer end of the leaf spring in the direction of extension is fixed, and the inner end of the leaf spring in the direction of extension of the link is fixed to a protrusion formed close to the fixed side and the movable side, respectively. A Roberval mechanism in a weighing machine characterized by the following.