JP3011561U - Center of gravity adjustment mechanism for electronic balance - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a center-of-gravity adjustment mechanism for electronic balances that improves space efficiency and can be easily adjusted from the outside. [Structure] The center-of-gravity adjusting mechanism 10 includes a center-of-gravity lever 14, a prismatic weight 16, a pair of adjusting screws 18, and a pair of coil springs 20, and one end of the center-of-gravity lever 14 is coupled to a weighing lever. The prismatic weight 16 is provided with a pair of threaded screw holes 16a. The adjusting screws 18 are respectively screwed into the screw holes 16a of the prismatic weight 16, and the lower ends thereof are rotatably attached to the through holes 14d of the gravity center lever 14. The coil spring 20 is on the outer circumference of each adjusting screw 18, and the upper and lower ends thereof are on the lower surface of the prismatic weight 16 and the center of gravity lever 1.
4 are arranged so as to abut on the upper surface of 4, respectively. By turning the adjusting screw 18, the prismatic weight 16 and the center of gravity lever 1
The positional relationship between the measuring levers 4 and 4 is changed, and this change makes it possible to adjust the position of the center of gravity of the weighing lever.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a center-of-gravity adjusting mechanism for an electronic balance, and more particularly to a center-of-gravity adjusting mechanism for reducing a tilt error of an electromagnetic balance type electronic balance.

[0002]

[Prior art]

 An electromagnetic balance-type electronic balance is known as a type of precision load measuring device.This type of electronic balance is usually connected to one end with a Roberval mechanism for supporting the load and the other end with an electromagnetic coil. It has a weighing lever that is equipped with an electromagnetic balance unit consisting of a magnet and a magnet, and the weighing lever is adjusted to a balanced state in advance, and the imbalance when a load is placed is supplied to the electromagnetic coil with current. Therefore, the load is measured by balancing and determining the magnitude of the supply current at this time.

By the way, in this kind of electronic balance, when the main body is tilted, if the position of the center of gravity is vertically separated from the weighing lever, there is a problem that the load measurement error becomes large, and this error is due to the tilt error. It is called. Such tilt error can be eliminated by adjusting the position of the center of gravity of the weighing lever. Therefore, conventionally, a center-of-gravity adjusting mechanism as described below has been provided. In the conventional center-of-gravity adjusting mechanism, a columnar weight is attached to a screw screwed to a weighing lever, and the weight is rotated to move the weight closer to or away from the weighing lever to adjust the position of the center of gravity of the weighing lever.

However, the conventional center-of-gravity adjusting mechanism having such a structure has the technical problems described below.

[0005]

[Problems to be solved by the device]

 That is, the center-of-gravity adjusting mechanism having the above-mentioned configuration is often used for analytical and general-purpose balances with relatively small weighing and high resolution, but for example, for electronic weighing scales with a weighing of about 20 to 30 kg. Was rarely adopted. The reason is that in an electronic balance with a small weighing amount, the weight of a load measuring system such as a weighing lever is also small, and the position of the center of gravity can be adjusted with a relatively small weight, but in a heavy weight electronic balance, the weight of the load measuring system is large. This is because the weight for adjusting the center of gravity becomes large as a result, and it becomes difficult to secure the installation space.

Therefore, it is difficult to eliminate the tilt error in the conventional heavy weight electronic balance. Further, in the conventional center-of-gravity adjusting mechanism having the above-described configuration, the weight is usually formed in a column shape because it is necessary to have a shape in which the zero point change is small when the weight is rotated. However, the one in which a cylindrical weight is installed on the weighing lever has a problem that the space efficiency is extremely deteriorated because the height is increased and the diameter is increased.

Further, since the adjusting screw uses a relatively long screw, there is a problem that the movement of the screw directly contacts other parts. The present invention has been made in view of such conventional problems, and an object of the present invention is to improve the space efficiency of an electronic balance that can be easily adjusted from the outside. It is to provide a center-of-gravity adjusting mechanism.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention comprises a weighing lever provided with an electromagnetic balance section composed of an electromagnetic coil and a magnet, and an electronic device for supplying a current to the electromagnetic coil so that the weighing lever is in a balanced state. The center-of-gravity adjusting mechanism for a balance is characterized by having a prismatic weight supported by a pair of adjusting screws so as to be able to approach and separate so as to be substantially parallel to the surface of the weighing lever. The prismatic weight has a pair of screw holes that are screwed into the adjusting screw, and the adjusting screw is screwed into the prismatic weight and is rotatably attached to the weighing lever. There is no vertical movement of the adjusting screw, and only the prismatic weight can be moved toward and away from the prismatic weight. The prismatic weight has a pair of through-holes through which the adjusting screw is inserted, and between the prismatic weight and the weighing lever, a bar that biases the weight in a direction separating from the weighing lever. One end of the adjusting screw is rotatably attached to the measuring lever, and an adjusting nut is screwed on the other end of the adjusting screw to resist the urging force of the spring to prevent the adjustment of the prismatic shape. The weight can be closely spaced from the weighing lever.

[0009]

[Action]

 According to the center-of-gravity adjusting mechanism for an electronic balance having the above-described configuration, the adjusting mechanism is configured by a prismatic weight supported by a pair of adjusting screws so that the adjusting mechanism can be brought close to and separated from each other so as to be substantially parallel to the weighing lever. It requires less space than the conventional structure in which is installed on the weighing lever. According to the structure of claim 2, the prismatic weight has a pair of screw holes that are screwed into the adjusting screw, and the adjusting screw is screwed into the prismatic weight and is rotatably attached to the weighing lever. The adjustment screw does not move vertically depending on its rotation, and only the prismatic weight is moved closer to and away from the fixing plate.Therefore, even if the adjustment screw is turned when adjusting the center of gravity, the end of the adjustment screw does not protrude to the outside of the fixing plate. Disappears. Further, according to the configuration of claim 3, the prismatic weight is biased by the vane so as to be separated from the weighing lever, and one end side of the adjusting screw is rotatably attached to the weighing lever. The columnar weight is moved closer to and away from the weighing lever against the biasing force of the spring by screwing, so that the position of the weight is stabilized by the elastic force of the spring.

[0010]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show an embodiment of a gravity center adjusting mechanism for an electronic balance according to the present invention. In the figure, a member formed in a substantially triangular plate shape is a weighing lever, and this weighing lever is composed of a center-of-gravity lever 14 on the left side and an electromagnetic lever 12 on the right side. It is installed.

The center-of-gravity lever 14 on the left side is provided with the center-of-gravity adjusting mechanism 10, and the electromagnetic lever 12 on the right side is provided with a known electromagnetic balance section (not shown) including an electromagnetic coil and a magnet. Also, a well-known Roberval mechanism (not shown) that supports and transmits the load is connected, and when a load is applied, a predetermined current is supplied to the electromagnetic coil so that the weighing lever balances, and this supply current is measured. By doing so, the load is weighed.

The center-of-gravity adjusting mechanism 10 includes a center-of-gravity lever 14, a prismatic weight 16, a pair of adjusting screws 18, and a pair of coil springs 20. The center of gravity lever 14 includes a main body 14a formed in a substantially trapezoidal shape, a pair of protrusions 14b formed on the right end side of the main body 14a so as to face each other, and a pair of protrusions provided below the protrusions 14b. And a circular protrusion 14c, and is attached with a screw 14c.

Further, a pair of circular through holes 14 d are formed on the left end side of the main body portion 14 a at predetermined intervals. The prismatic weight 16 is provided with a pair of threaded screw holes 16a. (The positions of the screw holes 16a are arranged symmetrically with respect to the center of gravity of the prismatic weight 16.) The adjusting screws 18 are screwed into the screw holes 16a of the prismatic weight 16, respectively. The lower end thereof is rotatably attached to the through hole 14d of the center of gravity lever 14. The coil spring 20 is arranged on the outer circumference of each adjusting screw 18 so that the upper and lower ends thereof contact the lower surface of the prismatic weight 16 and the upper surface of the gravity center lever 14, respectively.

The details of the mounting structure of the adjusting screw 18 are shown in FIG. The adjustment screw 18 shown in the figure has a structure in which the outer diameter of the shaft portion is smaller than the inner diameter of the through hole 14d, and the outer diameter of the head portion is larger than the through hole 14d, and the outer diameter is the through hole. The fixing nut 24 is larger than 14d. In order to rotatably attach the adjusting screw 18 to the center of gravity lever 14, first, with the fixing nut 24 screwed to the lower end side of the adjusting screw 18, pass the lower end edge of the adjusting screw 18 through the through hole 14d, A rotating nut 22 is screwed from the lower surface side of the gravity center lever 14 to the lower end of the adjusting screw 18, and the gravity center lever 14 is attached between the fixed nut 24 and the sliding nut 22.

In attaching the adjusting screw 18, first, a pair of adjusting screws 18 are screwed into the screw holes 16 a of the prismatic weight 16 from above to a proper length so as to project to the other end side of the prismatic weight 16. The above-mentioned mounting operation is performed by disposing the coil springs 20 on the outer periphery of the adjusting screw 18 respectively. When the prismatic weight 16 is attached to the center of gravity lever 14 as described above, the centerline in the longitudinal direction of the prismatic weight 16 becomes substantially parallel to the surface of the center of gravity lever 14 and the pair of both end sides is formed. Since the adjusting screw 18 supports the surface of the center of gravity lever 14 so as to be able to approach and separate from the surface of the center of gravity lever 14, turning the adjusting screw 18 changes the positional relationship between the prismatic weight 16 and the center of gravity lever 14. The change allows the position of the center of gravity of the weighing lever to be adjusted.

According to the center-of-gravity adjusting mechanism 10 of the present embodiment configured as described above, the prismatic weight 16 has the surface of the center-of-gravity lever 14 so that the center axis is substantially parallel to the surface of the center-of-gravity lever 14. Since it is composed of a prismatic weight 16 supported by a pair of adjusting screws 18 so as to be able to come close to and away from each other, the space for the adjusting mechanism 10 is smaller than that of the structure in which the weight 16 is erected on the center of gravity lever 14. I'm done.

Therefore, the adjusting mechanism 10 of the present embodiment can be used even in a heavy-weight electronic balance, which was hardly used in the conventional adjusting mechanism in terms of space efficiency. It is possible to eliminate the tilt error of the electronic balance of the class. Further, according to the center-of-gravity adjusting mechanism 10 having the above-described configuration, the heads of the pair of adjusting screws 18 are exposed to the outside, or the heads of the screws 18 are provided with holes through which tools can be engaged, the center of gravity is adjusted. Since the position can be adjusted, it is not necessary to provide a space for the hands to be installed.

Further, according to the configuration of the present embodiment, the prismatic weight 16 has a pair of screw holes 16 a to be screwed with the adjusting screw 18, and one end of the adjusting screw 18 is rotatably attached to the center of gravity lever 14. In addition, since the spring 20 is arranged between the gravity center lever 14 and the prismatic weight 16, even if the adjusting screw 18 is turned when adjusting the center of gravity, only the weight 16 moves and the adjusting screw. The end of 18 does not project outside the center of gravity lever 14, and the elastic force of the spring 20 stabilizes the position of the weight 16.

It should be noted that in the above embodiment, the coil spring 20 is not always necessary, and even if the coil spring 20 is removed, the prismatic weight 16 is attached to the center of gravity lever by the screwing relationship between the adjusting screw 18 and the screw hole 16a. It is possible to make it close to or away from 14. FIG. 4 shows another embodiment of the present invention, and only the characteristic points will be described below. In the embodiment shown in the same figure, the mounting state of the adjusting screw 18 is reversed from that of the above embodiment, the head side thereof is fixed in the through hole 14d of the center of gravity lever 14 with the fixing nut 24, and the prismatic weight 16 Adjustment in which a through hole 16b in which a screw is not formed is bored in place of the screw hole 16a, and the spring 20 is interposed between the center-of-gravity lever 14 and the prismatic weight 16 and protrudes upward from the weight 16. A washer 26 and an adjusting nut 28 are attached to the end of the screw 18.

With the adjusting mechanism 10a configured as described above, when the adjusting nut 28 is turned, the prismatic weight 16 moves in the direction of moving toward or away from the barycentric lever 14, and the barycentric position of the weighing lever 12 can be adjusted. Also in the embodiment configured in this way, the same operational effects as those of the above-described embodiment are exhibited.

[0021]

[Effect of device]

 As described above in detail in the embodiments, according to the center-of-gravity adjusting mechanism for an electronic balance according to the present invention, the space efficiency is improved, so that it is possible to use it for a heavy-weight balance as well. The tilt error of the electronic balance can be reduced and it can be easily adjusted from the outside.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part showing an embodiment of a gravity center adjusting mechanism for an electronic balance according to the present invention.

FIG. 2 is a cross-sectional view of a main part of FIG.

FIG. 3 is an enlarged cross-sectional view of a main part of FIG.

FIG. 4 is a sectional view of an essential part showing another embodiment of the center-of-gravity adjusting mechanism for an electronic balance according to the present invention.

[Explanation of symbols]

 10, 10a Center of gravity adjusting mechanism 12 Electromagnetic lever 14 Center of gravity lever 16 Square column weight 16a Screw hole 18 Adjustment screw 20 Coil spring 22 Rotating nut 24 Fixed nut

Claims (3)

[Scope of utility model registration request] 1. A center-of-gravity adjusting mechanism for an electronic balance, which comprises a weighing lever provided with an electromagnetic balance section composed of an electromagnetic coil and a magnet, and supplies a current to the electromagnetic coil so that the weighing lever is in a balanced state. In Claim 3, there is provided a center-of-gravity adjusting mechanism for an electronic balance, which has a prismatic weight supported by a pair of adjusting screws so as to be able to approach and separate so as to be substantially parallel to the surface of the weighing lever. 2. The prismatic weight has a pair of screw holes screwed into the adjusting screw, and the adjusting screw is screwed into the prismatic weight and rotatably attached to the weighing lever. 2. The center-of-gravity adjusting mechanism for an electronic balance according to claim 1, wherein the adjusting screw does not move up and down due to its rotation, and only the prismatic weight is moved toward and away from the weight. 3. The prismatic weight has a pair of through holes into which the adjusting screws are inserted, and the weight is provided between the prismatic weight and the weighing lever in a direction in which the weight is separated from the weighing lever. An urging spring is arranged, and one end of the adjusting screw is rotatably attached to the measuring lever, and an adjusting nut is screwed on the other end of the adjusting screw to resist the urging force of the spring. 2. The center-of-gravity adjusting mechanism for an electronic balance according to claim 1, wherein the prismatic weight is closely spaced from the weighing lever.