Balance weighing pan

Abstract

Providing technology related to the weighing pan of a balance that achieves high-precision repeatability. [Solution] The weighing pan 2 of the balance 1, which is exposed to wind, is provided with a pan body 25 having a mesh portion 28 and an impact absorbing mechanism 34 for absorbing impact loads.

Description

[Technical Field]

[0001] The present invention relates to a technology relating to a weighing pan of a balance that achieves high-precision repeatability. [Background technology]

[0002] FIG. 3 of Patent Document 1 discloses a weighing pan for a load weighing instrument that has a single-axis boss portion on the lower center side, and such a weighing pan is sometimes used in small, high-resolution analytical balances. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2007-333605 Summary of the Invention [Problem to be solved by the invention]

[0004] Compact, high-resolution analytical balances equipped with a draft shield are required to have high repeatability (small variations in measurement values ​​when the same mass is repeatedly placed on and removed from the balance). Furthermore, the accuracy of this repeatability can be adversely affected by slight convection on the weighing pan or by a certain magnitude of impact load when the sample is placed on the pan.

[0005] Furthermore, when it comes to weighing large objects, it is desirable to enlarge the weighing pan used in small, high-resolution analytical balances equipped with a windshield to accommodate the objects. However, the problem arises that the larger the pan, the greater the adverse effect of convection on the weighing value.

[0006] In view of the above problems, the present invention provides a weighing pan for a balance that can reduce the adverse effects of convection and impact loads on the weighing pan even if the weighing pan is large in size. [Means for solving the problem]

[0007] In order to solve the above problem, the inventors considered achieving highly accurate repeatability in windy environments by making the weighing pan less susceptible to wind pressure even if the pan is large, and by reducing the impact load on the weighing pan.

[0008] The present invention was made based on the above findings, and provides a weighing pan for a balance that is exposed to wind, which includes a pan body with a mesh section and an impact absorption mechanism that absorbs impact loads. The mesh section reduces the total area of ​​the pan body of the weighing pan that is exposed to wind, thereby reducing the wind pressure itself, and as the wind passes through the mesh, the moment caused by wind pressure acting near the outer periphery of the weighing pan is also reduced, and the impact absorption mechanism absorbs impact loads of a predetermined magnitude that occur on the weighing pan. Even if the weighing pan is large, the reduction in wind pressure reduces the adverse effects on the weighing value.

[0009] Furthermore, it is more desirable that the weighing pan of the balance have a central portion on the pan body and a mesh portion around the central portion, with the shock absorbing mechanism being provided on the backside of the central portion. The shock absorbing mechanism provided on the backside of the central portion acts to absorb impact loads of a predetermined magnitude, and the mesh portion around the central portion acts to reduce the wind pressure itself and the moment caused by the mesh portion provided on the outer periphery of the pan body. Even if the outer diameter of the mesh portion is increased, the moment generated on the outer periphery by wind is reduced, thereby reducing the adverse effect on the weighing value.

[0010] Furthermore, it is more preferable that the mesh portion be formed by a plurality of base portions formed integrally in the radial direction from the central portion, a plurality of connecting portions that connect the plurality of base portions together, and a plurality of openings defined between the plurality of base portions and the connecting portions. By placing the object to be weighed on either the central portion and the base portions or the central portion and the connecting portions, flexibility in placement is improved, and the openings reduce wind pressure and moment.

[0011] It is also preferable that the mesh portion has a plurality of openings formed from the vicinity of the center of the dish body to the vicinity of the outermost connecting portion. With this configuration, wind can pass through both the vicinity of the center and the vicinity of the outermost connecting portion, thereby further reducing wind pressure and moment.

[0012] It is also preferable that the shock absorbing mechanism is fixed to the mesh-like pan main body. By moving the shock absorbing mechanism together with the weighing pan rather than on the weighing sensor side, the weight of the shock absorbing mechanism is not exerted when the weighing sensor is moved, reducing adverse effects on the weighing sensor and making it less likely to break.

[0013] It is also preferable that the main body of the pan has a step around the center of the center. When a thin plate-shaped weighing object is placed on a flat surface, it is difficult to grasp the edge, but when the thin plate is placed on the step, the edge is raised and placed, making it easier to grasp.

[0014] It is also preferable that the weighing pan has grooves formed from the center to the periphery. By placing a rod-shaped object to be weighed in the center and the grooves extending radially from there, the object is held on the weighing pan and is less likely to roll.

[0015] It is also preferable that the weighing pan has a notch formed by cutting out a portion of the outer periphery of the pan body. By placing a portion of the object to be weighed on the notch, it becomes easier to grasp the portion of the object to be weighed within the notch. [Effects of the Invention]

[0016] According to the present invention, a weighing pan can be obtained that can achieve high-precision repeatability even when used in a balance that is used in a windy environment, with little adverse effects from increased wind pressure, moment generation, or impact loads. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view showing the appearance of a balance equipped with a weighing pan according to an embodiment of the present invention. [Figure 2]FIG. 2 is a perspective view of the balance of FIG. 1 with the windshield removed. [Figure 3] FIG. 2 is a perspective view of the weighing pan and the shock absorbing mechanism according to the present embodiment, as viewed obliquely from above. [Figure 4] 4 is an exploded perspective view of the weighing pan and the shock absorbing mechanism of FIG. 3, seen obliquely from below. FIG. [Figure 5] 4 is a vertical end view of the impact absorbing mechanism obtained by cutting the weighing pan of FIG. 3 along line II. DETAILED DESCRIPTION OF THE INVENTION

[0018] Next, a preferred embodiment of the weighing pan of the balance of the present invention will be described below with reference to FIGS.

[0019] Figures 1 and 2 show an electronic balance 1 having a weighing pan of the present invention. Figure 2 shows the electronic balance 1 with the windshield 10 removed. As shown in Figure 1, the electronic balance 1 has a case 3 that houses a weighing mechanism (not shown) including a mass sensor such as an electromagnetic balance or load cell connected to the weighing pan 2 (see Figure 2), as well as a control unit (not shown) that controls various operations of the electronic balance. The front side of the case 3 also has a control panel 4. The top surface of this control panel 4 has a display 4a that displays weighing results and the like, and multiple touch panel switches 4b for various operations.

[0020] As shown in FIG. 1, a bottomless box-shaped windshield 10 consisting of a front panel 7, a pair of left and right side doors (only the right side door 8 is shown), a back panel (not shown), and a top door 9 is provided on the top panel 6 of the case 3, and the rectangular parallelepiped internal space forms the measuring chamber. The front panel 7, the pair of left and right side doors 8, the back panel, and the top door 9 that make up the windshield 10 are made of transparent materials, allowing the measuring chamber to be seen through; however, for convenience, the measuring chamber is not visible in FIG. 1. The windshield 10 keeps the measuring chamber closed during measurement, minimizing the effect of airflow during measurement, such as airflow from an air conditioner, a person's breathing during measurement, or airflow generated by a person walking, on the load-bearing portion centered on the measuring pan 2 as wind pressure and affecting the measurement.

[0021] As shown in FIG. 1, support boxes 11 and 12 are disposed at the left and right upper ends of windshield 10. Within support box 11, the upper end of right side door 8 is slidably suspended inside restricting member 13, and within support box 12, the upper end of left side door (not shown) is slidably suspended inside restricting member 14 (FIG. 2). Handles 15 and 16 for opening and closing are provided on right side door 8 and left side door, respectively. Furthermore, support boxes 11 and 12 slidably support the left and right side ends of top door 9. Top door 9 is manually slid and has a knob 17.

[0022] Handles 15, 16 of the right side door 8 and left side door (not shown) shown in FIG. 1 are detachably connected to engaging and disengaging members 18, 19, respectively, and the engaging and disengaging members 18, 19 are connected by a connecting plate 20 disposed below the case 3. The handles 15, 16 are connected and disconnected by switching the knobs 21a, 22a of the connecting member 21. When the knobs 21a, 22a are lowered to connect the handles 15, 16, both the right side door 8 and the left side door slide simultaneously, and when the knobs 21a, 22a are raised to disconnect the handles, they can slide independently.

[0023] Next, a preferred embodiment of a weighing pan of a balance equipped with a shock absorbing mechanism will be described with reference to Figures 3 to 5. The weighing pan 2 is composed of a pan main body 25 and a shock absorbing mechanism .

[0024] 3 to 5, the dish main body 25 has a circular central portion 27, a mesh portion 28 integrally formed around the central portion 27, and a cylindrical portion 29 integrally formed directly below the central portion 27. The shock absorbing mechanism 34 has a rubber material 35, a compression coil spring 36, a dish support member 37, and a dish support holding member 38, and is fixed to the cylindrical portion 29 of the dish main body 25.

[0025] As shown in FIGS. 3 to 5, the mesh portion 28 has a concentric circular shape with respect to the central portion 27. The mesh portion 28 is composed of a plurality of base rib portions 28a, connecting portions 28b, and openings 28c. The plurality of base rib portions 28a are each formed integrally with the central portion 27 and extend radially from a center O1 of the central portion 27 at equal intervals. The plurality of base rib portions 28a are connected by a plurality of annular connecting portions 28b centered on the center O1. The connecting portions 28b are composed of inner connecting portions 28b1 formed integrally with the outer periphery of the central portion 27, outer connecting portions 28b3 connecting the tips of the base rib portions 28a (six locations), and middle connecting portions 28b2 provided between the inner connecting portions 28b1 and the outer connecting portions 28b3 and connecting the base rib portions 28a together. Furthermore, a plurality of inner openings 28c1 separated by a plurality of base rib portions 28a are formed in the circumferential direction between the inner connecting portion 28b1 and the intermediate connecting portion 28b2, and a plurality of outer openings 28c2 separated by a plurality of base rib portions 28a are formed in the circumferential direction between the intermediate connecting portion 28b2 and the outer connecting portion 28b3. The outer openings 28c2 are formed outside the inner openings 28c1. Note that the numbers of the base rib portions 28a, connecting portions 28b, and openings 28c are not limited to those disclosed in FIGS. 3 and 4.

[0026] As shown in Figure 5, the shock absorbing mechanism 34 is fixed to the back surface of the central portion 27 of the pan body 25 and absorbs the shock load when an object to be weighed is placed on the pan body 25. Meanwhile, the mesh portion 28 around the central portion 27 of the pan body 25 allows convection currents within the windshield 10, which occur when the right side door 8 is opened, to pass through the multiple openings 28c. The mesh portion 28 of the weighing pan 2 reduces the total area of ​​the pan body 25 that is subjected to convection currents. This makes the pan body less susceptible to wind pressure due to convection currents within the windshield 10 compared to a conventional solid weighing pan without the mesh portion 28, and the shock absorbing mechanism 34 also absorbs the shock load. As a result of this action, even if the size of the dish main body 25 of the weighing dish 2 of this embodiment is increased by expanding the mesh portion 28 so that large weighing objects such as filters can be placed on it, the total area exposed to convection is smaller than that of conventional weighing dishes, and the impact absorption mechanism reduces the adverse effects on the weighing values ​​of the electronic balance 1 to which the weighing dish 2 is attached, thereby achieving highly accurate repeatability.

[0027] Furthermore, mesh portion 28 has outer openings 28c2 radially outward from inner opening 28c1, which allows convection currents generated within windshield 10 to pass not only through inner opening 28c1 near center 27 of dish main body 25, but also through outer opening 28c2 near outer connecting portion 28b3 that forms the outer edge of dish main body 25, thereby reducing the wind pressure on the outer peripheral edge of dish main body 25. As a result, mesh portion 28 reduces the moment generated in dish main body 25 by wind pressure from convection currents within windshield 10, and further reduces adverse effects on weighing values, thereby achieving highly accurate repeatability.

[0028] 3 has a step portion 30 at the boundary between the central portion 27 and the inner connecting portion 28b1 of the mesh portion 28. The step portion 30 makes the central portion 27 one step lower than the upper surface of the mesh portion 28.

[0029] In the dish main body 25, if all thin plate-like weighing objects that are small enough to fit inside the central portion 27 are placed on the central portion 27, the objects will be placed so that they stick to the flat surface of the central portion 27, making it difficult to grasp both ends of the objects. However, if one end of such an object is placed against the step portion 30 so that the end is raised above the central portion 27, it becomes easier to grasp the end of the object after weighing.

[0030] 3, the dish main body 25 has cutouts 31 on its outer periphery, which are formed by cutting out a portion of the mesh portion 28. The cutouts 31 have a shape obtained by removing the middle connecting portion 28b2 and the outer connecting portion 28b3 from a pair of adjacent rib portions 28a. By placing part of the object to be weighed on the cutouts on the weighing dish 2, it becomes easier to grasp the part of the object to be weighed that protrudes into the cutouts 31.

[0031] As shown in FIG. 3 , the plate body 25 has grooves 32 on the connecting portion 28b of the mesh portion 28. The grooves 32 are formed at positions indicated by symbols 32a, 32b, 32c, and 32d on a line L1 that passes through the center O1 of the central portion 27 and the notch 31. Specifically, the grooves 32 are provided at two positions in the inner connecting portion 28b1: position 32a facing the notch 31; and position 32b opposite position 32a across the center O1. Additionally, the grooves 32 are provided at positions 32c and 32d extending radially outward from position 32b in the middle connecting portion 28b2 and the outer connecting portion 28b3, respectively. Each of the four grooves 32 is formed as an arc-shaped recess, and the lowest point of each groove 32 is formed flush with the top surface of the central portion 27.

[0032] As shown in Figure 3, a thin, rod-shaped object is positioned and held from the center O1 of the dish main body 25 by placing it inside four grooves 32, designated by the symbols 32a, 32b, 32c, and 32d, on the connecting portion 28b. Furthermore, since the lowest point of the recess is flush with the upper surface of the central portion 27, the rod-shaped object in the groove 32 is stably held in contact with both the connecting portion 28b and the central portion 27. Although six grooves 32 may be formed on the connecting portion 28b on a straight line that does not pass through the notch 31, in this embodiment, the grooves 32 are formed on the straight line L1 that passes through the notch 31. This is preferable because it not only prevents the thin, rod-shaped object from rolling but also makes it easier to grasp the end of the rod-shaped object placed on the notch 31.

[0033] 4 and 5, the shock absorbing mechanism 34 includes the cylindrical portion 29 of the dish main body 25, a rubber material 35, a compression coil spring 36, a dish receiving member 37, and a dish receiving holding member 38.

[0034] 4 and 5, a cylindrical portion 29 is integrally formed directly below the central portion 27 and concentric with the central portion 27, and a male thread portion 29a is provided on the outer periphery of the cylindrical portion 29. The inside of the cylindrical portion 29 is formed as a storage portion 29b for a rubber material 35. The rubber material 35 is a cylindrical buffer member, and has an outer diameter that is slightly smaller than the inner diameter of the storage portion 29b and a height that is equal to or smaller than the height of the inside of the storage portion 29b. The compression coil spring 36 has an outer diameter that is smaller than the outer diameter of the rubber material 35.

[0035] 4 and 5, the dish support member 37 is composed of a ceiling portion 37a, a first shaft portion 37b, and a second shaft portion 37c, which are integrally and coaxially formed from top to bottom. The ceiling portion 37a has a cylindrical shape with a bottom and a cylindrical portion 37a2 that protrudes upward from the outer periphery of a bottom portion 37a1. The inner diameter of the cylindrical portion 37a2 is slightly larger than the outer diameter of the compression coil spring 36, and the lower end of the compression coil spring 36 is held on the bottom portion 37a1 and inside the cylindrical portion 37a2. The first shaft portion 37b has a cylindrical shape with a constant outer diameter, and the second shaft portion 37c is smoothly formed integrally with the lower end of the first shaft portion 37b and has a truncated cone shape that tapers downward.

[0036] 4 and 5 has a three-stage cylindrical shape in which a first cylindrical portion 38a, a second cylindrical portion 38b, and a third cylindrical portion 38c, each having different outer and inner diameters, are integrally formed with a flange portion 38d and a crank portion 38e. The first cylindrical portion 38a is integrally formed with the lower end of the second cylindrical portion 38b by the flange portion 38d, which protrudes horizontally outward from the upper end of the first cylindrical portion 38a. The second cylindrical portion 38b is integrally formed with the lower end of the third cylindrical portion 38c via the crank portion 38e at a position offset horizontally outward from the upper end of the second cylindrical portion 38b by the thickness of the second cylindrical portion 38b.

[0037] As shown in Figure 5, the inner diameter of the circular hole 38f of the first cylindrical portion 38a is formed to be slightly larger than the outer diameter of the first shaft portion 37b of the dish holder member 37. The second cylindrical portion 38b is formed to have the same inner and outer diameters as the cylindrical portion 29 of the dish main body portion 25. Furthermore, the inner diameter of the second cylindrical portion 38b is formed to be slightly larger than the outer diameter of the cylindrical portion 37a2 of the ceiling portion 37a of the dish holder member 37. Furthermore, a female threaded portion 38g is provided on the inside of the third cylindrical portion 38c, which can be screwed into the male threaded portion 29a formed on the outer periphery of the cylindrical portion 29 of the dish main body portion 25.

[0038] The shock absorbing mechanism 34 is assembled and fixed to the dish main body 25 as follows. First, the dish support member 37 is positioned and held inside the second cylindrical portion 38b and above the flange portion 38d with the first shaft portion 37b and second shaft portion 37c inserted into the circular hole 38f of the dish support holding member 38. Next, the compression coil spring 36 is held inside the cylindrical portion 37a2 of the ceiling portion 37a and above the bottom portion 37a1, and the upper end of the compression coil spring 36 is in contact with the rubber material 35 placed in the storage portion 29b of the cylindrical portion 29 of the dish main body 25. Then, the third cylindrical portion 38c of the dish support holding member 38 is screwed and fixed up to the upper end of the cylindrical portion 29 of the dish main body 25. The compression coil spring 36 is compressed and can expand and contract vertically, biasing the dish support member 37 against the dish support holding member 38. The pan main body 25 is fixed to the balance via the second shaft 37c of the pan support member 37. When the fixed weighing pan 2 receives an impact load when an object to be measured is placed on the pan main body 25, the pan main body 25 and the pan support holding member 38 move downward relative to the pan support member 37 against the biasing force of the compression coil spring 36, and the compression coil spring 36 further compresses within the second cylindrical portion 38b, thereby absorbing the impact. In addition, the rubber material 35 absorbs minute pressures acting on the pan main body 25 due to convection generated within the windshield, etc.

[0039] Furthermore, the shock absorbing mechanism 34 used during movement is fixed to the pan main body 25 rather than to the weighing sensor (not shown) of the electronic balance 1 to form the weighing pan 2, and is moved together with the weighing pan. As a result, the weight of the shock absorbing mechanism 34 does not act when the weighing sensor inside the electronic balance 1 moves, reducing the adverse effects on the weighing sensor and making it less likely to break. [Explanation of symbols]

[0040] 1. Electronic balance 2 Weighing pan 25 Plate body 27 Central part 28 Mesh section 28a Base bone 28b Connection part 28c opening 30 Step 31 Notch 32 Groove 34 Shock absorption mechanism 35 Rubber material 36 Compression coil spring 37 Pan support member 38 Dish holder holding member

Claims

1. On the weighing pan of a balance exposed to wind, a dish body having a central portion and a mesh portion around the central portion; an impact absorbing mechanism that absorbs impact loads; and The mesh portion is formed by a plurality of base portions formed integrally in a radial direction from the central portion, a plurality of connecting portions that connect the plurality of base portions together, and a plurality of openings defined between the plurality of base portions and the connecting portions.

2. 2. The weighing pan of a balance according to claim 1, wherein the shock absorbing mechanism is provided on the back surface of the central portion.

3. A weighing pan for a balance as described in claim 1 or 2, characterized in that the openings in the mesh portion are formed in multiple positions from near the central portion to near the outermost connecting portion of the connecting portion.

4. A weighing pan of a balance as described in claim 1 or 2, characterized in that the shock absorbing mechanism is fixed to the pan main body portion.

5. A weighing pan for a balance as described in claim 1 or 2, characterized in that the pan main body has a stepped portion formed around the center of the central portion.

6. A weighing pan for a balance as described in claim 1 or 2, characterized in that it has a groove portion formed from the center of the pan main body portion in the outer circumferential direction.

7. A weighing pan for a balance as described in claim 1 or 2, characterized in that it has a notch formed by cutting out a portion of the outer periphery of the pan main body.

Images