JP3975611B2 - Electronic balance - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic balance, and more particularly to an electronic balance having a mechanism for protecting a mechanically fragile portion of the electronic balance during storage or transportation of the electronic balance.
[0002]
[Prior art]
Electronic balances are usually designed so that a pan on which a sample whose mass is to be measured is placed or a pan receiver having a structure for receiving the pan is inserted into an engagement portion formed in a load-sensitive portion inside the balance. During transportation, the tray is often removable to prevent the internal mechanism from being affected by the vibration of the tray. However, in electronic balances that measure large weights, the equivalent of a pan or tray holder is quite heavy, and it is fixed firmly to the load sensitive part so that it can not be easily attached and detached to reduce the error factor during measurement. There is. In such a case, every time the electronic balance is transported, it takes time and effort to remove a fairly heavy pan or tray holder and remount it after transport.
[0003]
Further, even if the electronic balance has a structure in which a dish and a dish holder can be attached and detached, in a high-precision electronic balance, it may take time to adjust the four-corner error when attaching the dish to the balance body. Furthermore, when another part such as a sample holder is attached to the plate or the plate tray, a large force may be applied to the plate during the mounting operation.
[0004]
[Problems to be solved by the invention]
The balance mechanism of an electronic balance is configured so that the weight of the sample to be measured and the electromagnetic force generated therein are balanced by a bar supported by an elastic fulcrum. Therefore, the plate on which the sample is placed can move up and down with a small force when normal measurement is performed. Therefore, when transporting the electronic balance or attaching parts to the plate, the sample is vibrated. Therefore, it is necessary to protect the specimen mounting plate from moving up and down and destroying the elastic fulcrum and other fragile parts inside the balance.
[0005]
In general, it is only necessary to remove the pan from the main body of the electronic balance and pack it separately during transportation, so that a large mass does not connect to the fragile part inside the balance, but as described above, the pan cannot be easily removed. In the case of the structure, this operation is very laborious. Even if the dish can be removed relatively easily, it is possible to save the entire work if the dish is not removed as much as possible in order to eliminate the adjustment when the dish is attached again.
[0006]
The present invention has been made in view of such circumstances, and in an electronic balance in which it is difficult to take a structure in which the sample mounting plate can be removed, or even when the sample mounting plate is not removed, during transportation or operation. An object of the present invention is to provide an electronic balance capable of easily fixing a sample mounting plate and protecting a mechanism inside the balance without damaging the electronic balance.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an electronic balance having a case with a built-in load-sensitive portion and a sample placing plate disposed above the case, and a guide shaft extending upward from the case. In the case where a slide fixing base comprising a slider movable up and down along the guide shaft and a slider fixing means for fixing the slider to the guide shaft is disposed in the case, and the load sensitive part is protected. The slider is moved upward until it touches the bottom surface of the sample mounting plate, and at that position, the slider is fixed to the guide shaft by the slider fixing means, and the sample mounting plate is fixed in that state. It comprises a dish fixing means for fixing to the dish fixing base.
[0008]
In the electronic balance of the present invention, a plate fixing base is provided on the case on the lower side of the sample mounting plate, and the sample mounting plate having a structure that cannot be easily removed is fixed to the plate fixing table during transportation. Prevents the balance mechanism from being damaged by the generated vibration. The plate fixing base includes a guide shaft extending in the vertical direction and a slider that can slide up and down along the shaft, and the slider can be fixed to the guide shaft at an arbitrary position of the guide shaft.
[0009]
When measuring the mass of the sample using the electronic balance of the present invention, the slider is lowered and fixed to the guide shaft so that there is a gap between the plate fixing table and the sample mounting plate. Keep it. In this state, since the pan fixing table does not restrain the movement of the sample mounting pan, the mass can be measured as usual. If you want to protect the internal mechanism of the balance, such as when transporting an electronic balance, move the slider upward so that it contacts the lower surface of the sample tray and place the slider at that position. Fixed against. At this time, the sample mounting pan is in contact with the pan fixing base without overloading the internal mechanism of the balance. In addition, the sample mounting pan does not vibrate up and down, and the internal mechanism of the balance is not destroyed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an electronic balance of the present invention as a longitudinal section. In the electronic balance 1 of the present invention, a balance mechanism for detecting a load and a case 11 covering the whole are fixed on a base 13 serving as a base. Two beams extend horizontally from the fixed column 2 fixed to the base 13, and the movable column 3 is connected to the end thereof. The upper beam 4 and the lower beam 5 which are two beams are parallel to each other, and a thin portion 6 is formed in the vicinity of the fixed column 2 and the movable column 3 of both beams. The Rovalval mechanism is constructed by giving it the nature. The movable column 3 can be translated only in the vertical direction by this Roberval mechanism. One end of the balance bar 7 supported from below by the elastic fulcrum 8 is connected to the movable column 3 via a connecting member 9, and an electromagnetic force generator 10 is disposed in the vicinity of the other end of the balance bar 7. A sample loading tray 20 is attached to the take-out portion 12 extending from the movable column 3.
[0011]
When a sample whose mass is to be measured is placed on the sample mounting plate 20, the load is applied to the movable column 3 via the take-out portion 12, and the force is applied to one end of the balance bar 7 (see FIG. 1) via the connecting member 9. Take the left edge. Then, the balance bar 7 tends to tilt in the direction in which the movable column 3 is lowered with the elastic fulcrum 7 as a fulcrum, but the displacement is detected by a displacement meter (not shown) and the other end of the balance bar is adjusted so that the displacement becomes zero. Control is performed so that force is generated by the electromagnetic force generator 10 installed in the vicinity (right end in FIG. 1) and the balance bar 7 does not tilt. At that time, the load applied to the left end of the balance bar 7 and the mass of the sample placed on the sample placing plate 20 are measured from the current value flowing in the coil built in the electromagnetic force generating unit 10.
[0012]
The elastic fulcrum 8 described above uses a leaf spring having a thin portion that is partly thinned to facilitate bending. This is because the fulcrum needs to be able to bend left and right freely with a small force. Further, the connecting member 9 also has a thin portion, and absorbs the difference between the vertical movement of the movable column 3 and the movement of the end of the balance bar 7 so that an unreasonable force is not applied to the balance bar 7. Furthermore, as described above, the thin portions 6 are also formed on the upper and lower beams. These thin-walled portions are mechanically fragile portions, and are easily damaged when there is a large vibration or an excessive external force is applied to the sample mounting plate 20.
[0013]
The electronic balance according to the present invention protects a fragile mechanism inside the balance from vibration during transportation, etc., so that the sample mounting tray 20 is fixed to a case covering the internal mechanism of the balance (part A in FIG. 1). ). 2 and 3 are diagrams illustrating the A portion of FIG. 1 in an enlarged manner. FIG. 2 shows a state in which the sample mounting plate 20 is not fixed and is used for mass measurement as usual, and FIG. 3 is used to protect the internal mechanism of the balance from vibrations when the balance is transported. It is a figure which shows the state which fixed the sample mounting tray to the plate fixing stand. It should be noted that the number of plate fixing bases is not limited to two as shown in the figure, and at least one plate fixing base is sufficient, and three or more may be used.
[0014]
2 and 3, the tray fixing base 21 includes a cylindrical guide shaft 22 formed on the upper portion of the case 11, and a cylindrical slider 23 fitted around the guide shaft 22 so as to be movable up and down. Furthermore, it includes a spring 25 that pushes the slider 23 upward along the guide shaft, and a fixing screw 24 that is a slider fixing means for fixing the slider to the guide shaft at an appropriate position. A female screw 27 is cut at the center of the guide shaft, and a through hole 26 is formed at a position corresponding to the position directly above the guide shaft of the sample mounting plate 20.
[0015]
When measuring the mass, as shown in FIG. 2, the slider 23 is fixed by a fixing screw 24 at a position where it is pushed down along the guide shaft 22. A moderate gap 28 is formed between the shaft 22 and the upper end of the slider 23. In this state, the sample mounting tray 20 can freely move up and down independently of the tray fixing base 21, so that the mass of the sample placed on the tray can be measured as usual.
[0016]
When it is necessary to protect the internal balance mechanism as in the case of transporting the electronic balance, the sample mounting tray 20 is fixed to the tray fixing base 21 in the state shown in FIG. First, the fixing screw 24 is loosened by placing nothing on the sample tray 20 and placing it in an unloaded state. Then, the slider 23 is pushed upward by the action of the spring 25, and the upper end of the slider 23 is pressed against the lower surface of the sample mounting tray 20. In this state, the fixing screw 24 is tightened to fix the slider 23 to the guide shaft 22. Next, when the bolt 29 is inserted into the female screw 27 formed on the guide shaft 22 through the through hole 26 from above the sample mounting plate 20 and screwed, the sample mounting plate 20 is firmly fixed to the plate fixing base 21. .
[0017]
The above-described slider fixing means for fixing the slider 23 to the guide shaft 22 will be described in further detail. FIG. 4 is a view showing a preferred example of the slider fixing means, and is a cross-sectional view of the guide shaft 22 and the slider 23 fixing screw 24 cut along a horizontal plane. The slider 23 has a substantially rectangular cross section, a circular space in which the guide shaft 22 enters the center, and a shape in which a slit 32 is provided in part. A through hole for passing the fixing screw 24 is formed on one side of the portion sandwiching the slit 32, and a female screw 33 screwed with the fixing screw 24 is cut on the other side. When the fixing screw 24 is tightened in the combined state as shown in FIG. 4, the slider 23 is strongly pressed against the cylindrical guide shaft 22, and the slider 23 is fixed to the guide shaft 22. If the fixing screw 24 is loosened, the slider 23 can slide freely along the guide shaft 22 (in the direction perpendicular to the paper surface).
[0018]
FIG. 5 is a view showing another example of the slider fixing means, and is a cross-sectional view cut along a horizontal plane. The slider 23 has a cylindrical shape, and has a female screw into which a fixing screw 24 is screwed. The guide shaft 22 has a cylindrical shape, and a flat surface 34 is formed on a part thereof. When the fixing screw 24 is tightened in the combined state as shown in FIG. 5, the slider 23 is fixed to the guide shaft 22, and when loosened, the slider 23 can freely slide along the guide shaft.
[0019]
In the above-described embodiment, the guide shaft 22 and the slider 23 have a columnar shape and a cylindrical shape. However, as long as the shape can freely move in the vertical direction, the cross section need not be circular, and may be a quadrangle or other shapes. The above-described spring 25 is a coil-like pressing spring for pushing up the slider to improve workability. However, the spring 25 is not necessarily essential, and may be a spring having another shape. Further, the means for fixing the slider 23 to the guide shaft 22 is not limited to the fixing screw 24 as described above, but may be a simple pin. At this time, a hole or the like for engaging the pin may be formed in the guide shaft. If the bolt 29 is a butterfly bolt or the like so that an operator can tighten it by hand, the workability is good and convenient.
[0020]
【The invention's effect】
The electronic balance of the present invention can prevent the inside of the balance mechanism from being damaged by vibration generated during transportation or work by fixing the sample mounting tray to the pan fixing base. This plate fixing base consists of a guide shaft extending in the vertical direction and a slider that can slide up and down along the axis, and the slider can be fixed to the guide shaft at any position of the guide shaft, so that the sample mounting The work of fixing the pan is easy and the balance mechanism can be easily protected with little effort.
[Brief description of the drawings]
1 is a longitudinal sectional view of an electronic balance according to the present invention.
FIG. 2 is a diagram showing a state during mass measurement in the vicinity of a plate fixing base, which is a main part of the present invention.
FIG. 3 is a diagram showing a state at the time of protection in the vicinity of the plate fixing base which is a main part of the present invention.
FIG. 4 is a diagram showing an example of a slider fixing means.
FIG. 5 is a view showing another example of the slider fixing means.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electronic balance 2 ... Fixed column 3 ... Movable column 4 ... Upper beam 5 ... Lower beam 6 ... Thin part 7 ... Balance bar 8 ... Elastic fulcrum 9 ... Connecting member 10 ... Electromagnetic force generation part 11 ... Case 12 ... Take-out part 13 ... Base 20 ... Sample mounting plate 21 ... Dish fixing base 22 ... Guide shaft 23 ... Slider 24 ... Fixing screw 25 ... Spring 26 ... Through hole 27 ... Female screw 28 ... Gap 29 ... Bolt 31 ... Through hole 32 ... Slit 33 ... Female thread 34 ... Flat surface

Claims (1)

In an electronic balance having a case with a built-in load sensing portion and a sample mounting plate disposed above the case, a guide shaft extending upward from the case, and a slider movable up and down along the guide shaft When a plate fixing base comprising a slider fixing means for fixing the slider to the guide shaft is disposed in the case and the load sensitive part is to be protected, the slider is attached to the bottom surface of the sample mounting tray. The plate is moved upward until it hits, and at that position, the slider is fixed to the guide shaft by the slider fixing unit, and in this state, the sample mounting plate is fixed to the plate fixing base. An electronic balance characterized by comprising:

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