OVERLOAD PREVENTION MECHANISM

Abstract

Provided is an overload prevention mechanism including a load receiving part provided with a flange having at least three ribs on the upper surface of the flange; a pedestal located below the load receiving part; an elastic body which has one end in contact with the load receiving part and the other end in contact with the pedestal, and which biases the load receiving part and the pedestal in such a direction that the load receiving part and the pedestal are separated from each other; and a connection member having on the lower surface thereof recessed grooves which engage with the ribs. The three or more ribs are disposed so as to restrict inclination and rattling of the load receiving part due to a load applied to the load receiving part.

Claims

1. An overload prevention mechanism comprising: a load receiving part comprising a support part supporting a weighing dish, a side wall continuously provided downward from the support part, and a flange continuously provided sideways from a vicinity of a lower end of the side wall, and having three or more ribs on an upper surface thereof; a pedestal located below the load receiving part and having a fastening hole at a peripheral edge thereof; an elastic body in contact with the load receiving part at one end and with the pedestal at the other end, and biasing the load receiving part and the pedestal in a direction to be apart from each other; and a connection member having grooves engaging with the ribs on a lower surface thereof, having a through hole in contact with a base of the side wall in the center thereof and having a fastening hole at a building portion, the three or more ribs being disposed so as to restrict inclination and rattling of the load receiving part due to a load applied to the load receiving part, and the connection member and the pedestal being fixed to each other by fastening between the fastening hole of the connection member and the fastening hole of the pedestal.

2. The overload prevention mechanism according to claim 1, wherein at least one of the ribs is disposed at each of both sides of an arbitrary virtual center line passing through a center of the load receiving part so as to restrict inclination of the load receiving part.

3. The overload prevention mechanism according to claim 1, wherein the number of the ribs is an odd number.

4. The overload prevention mechanism according to claim 2, wherein the number of the ribs is an odd number.

5. The overload prevention mechanism according to claim 3, wherein the number of the ribs is three, and the ribs are arranged at equal intervals in a circumferential direction.

6. The overload prevention mechanism according to claim 4, wherein the number of the ribs is three, and the ribs are arranged at equal intervals in a circumferential direction.

7. The overload prevention mechanism according to claim 1, wherein sections of upper ends of the ribs have semicircular shapes, the grooves are downward V-shaped grooves, and the ribs and the V-shaped grooves are brought into line contact.

8. The overload prevention mechanism according to claim 2, wherein sections of upper ends of the ribs have semicircular shapes, the grooves are downward V-shaped grooves, and the ribs and the V-shaped grooves are brought into line contact.

9. The overload prevention mechanism according to claim 3, wherein sections of upper ends of the ribs have semicircular shapes, the grooves are downward V-shaped grooves, and the ribs and the V-shaped grooves are brought into line contact.

10. The overload prevention mechanism according to claim 4, wherein sections of upper ends of the ribs have semicircular shapes, the grooves are downward V-shaped grooves, and the ribs and the V-shaped grooves are brought into line contact.

11. The overload prevention mechanism according to claim 5, wherein sections of upper ends of the ribs have semicircular shapes, the grooves are downward V-shaped grooves, and the ribs and the V-shaped grooves are brought into line contact.

12. The overload prevention mechanism according to claim 6, wherein sections of upper ends of the ribs have semicircular shapes, the grooves are downward V-shaped grooves, and the ribs and the V-shaped grooves are brought into line contact.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a perspective view of an overload prevention mechanism according to one example of the present invention;

[0024] FIG. 2 is a plan view of the overload prevention mechanism of FIG. 1;

[0025] FIG. 3 is a longitudinal sectional view of the overload prevention mechanism with a weighing dish, taken along line A-A of FIG. 2;

[0026] FIG. 4 is an enlarged longitudinal sectional view taken along line B-B of FIG. 3;

[0027] FIG. 5 is an exploded perspective view of the overload prevention mechanism of FIG. 1 viewed from above;

[0028] FIG. 6 is an exploded perspective view of the overload prevention mechanism of FIG. 1 viewed from below; and

[0029] FIGS. 7A to 7F are schematic diagrams illustrating arrangements of a plurality of ribs.

DESCRIPTION OF THE EMBODIMENTS

[0030] Embodiments of the present invention will now be described in detail. In an example of the present invention shown in FIGS. 1 to 6 (displaying a weighing dish only in FIGS. 3 and 4), an overload prevention mechanism 11 includes a load receiving part 21. The load receiving part 21 includes a relatively thick support part 13 supporting a weighing dish 12, a side wall 15 continuously provided downward from a periphery of the support part 13, and a flange 19 which is provided sideways from a vicinity of a lower end of the side wall 15 and having a plurality of ribs 17, in the illustrated example three ribs, on an upper surface thereof. As shown in FIGS. 1 to 3, three fixing holes 23 are formed and aligned on the support part 13. As shown in FIG. 3, the weighing dish 12 can be fixed by screws 24 to the fixing holes 23.

[0031] A circular recess 27 is formed at the center of the lower portion of the load receiving part 21. A pedestal 31 is formed at the center of the upper surface of the recess 27 and the pedestal 31 has an upward projection 29. Three fastening holes 35 in total are formed at a peripheral edge 33 of the pedestal 31 at angle intervals of 120°.

[0032] A connection member 37 includes a thorough hole 39 in the center thereof, three bulging portions 41 bulging in three directions from a circular main body and fastening holes 43 each formed in each of the bulging portions 41. Formed on the lower surface of the connection member 37 are a plurality of V-shaped grooves (grooves) 45, in the illustrated example three V-shaped grooves in total, at angle intervals of 120° (see FIG. 6).

[0033] The through hole 39 in the center of the connection member 37 is brought into contact with a base of the side wall 15 in the load receiving part 21, so that each of the three ribs 17 whose sections of upper end have semicircular shapes in the flange 19 of the load receiving part 21 is fitted with each of the three

[0034] V-shaped grooves 45 of the connection member 37.

[0035] Disposed between the lower surface of the support part 13 of the load receiving part 21 and the upward protrusion 29 of the pedestal 31 is a spring 47 which is an elastic body. Thus, the spring 47 energizes the load receiving portion 21 and the pedestal 31 in a direction to be apart from each other. The connection member 37 and the pedestal 31 are fixed to each other by fastening a bolt (not shown) between each fastening hole 43 of the connection member and the corresponding fastening hole 35 of the pedestal 31.

[0036] FIGS. 7A to 7F are schematic diagrams illustrating arrangements of the plurality of ribs. In the diagrams, the fixing holes of the load receiving part are omitted.

[0037] FIG. 7A illustrates an arrangement of the ribs 17 of the load receiving part 21 in the example illustrated in FIGS. 1 to 6. The three ribs 17 are arranged along a circumferential direction of the flange 19 at equal intervals, that is, at angle intervals of 120°, so that vertices of the ribs 17 form a regular triangle. In this arrangement, even when a load transmitted to the load receiving part 21 through the weighing dish is not uniformly dispersed and is unevenly concentrated on one point of the load receiving part 21 (for example, force F.sub.1 in FIG. 7A), at least one rib 17 exists on the same side of the point to which the force F.sub.1 is applied with respect to the center O in the flange 19 and engages with the V-shaped groove (not shown in FIGS. 7A-7F). Therefore, the force applied to the weighing dish is blocked by an engaging portion of the ribs 17 and the V-shaped grooves, so that the load receiving part 21 (weighing dish) does not rattle in the rotational direction.

[0038] FIG. 7B illustrates an example in which five ribs 17a are arranged along a circumferential direction of the flange 19 at equal intervals, that is, at angle intervals of 72°, so that vertices of ribs 17a form a regular pentagon. Also in this arrangement, even when a load transmitted to the load receiving part 21 through the weighing dish is not uniformly dispersed and is unevenly concentrated on one point of the load receiving part 21 (for example, a force F.sub.2 in FIG. 7B), at least one rib 17a exists on the same side of the point to which the force F.sub.2 is applied with respect to the center O in the flange 19 and engages with the V-shaped groove. Therefore, the force applied to the weighing dish is blocked by an engaging portion of the rib 17a and the V-shaped groove, so that the load receiving part 21 (weighing dish) does not rattle in the rotational direction.

[0039] FIG. 7C illustrates an example in which four ribs 17b are arranged in a circumferential direction of the flange 19 at equal intervals, that is, at angle intervals of 90°, so that vertices of the ribs 17b form a regular square. Also in this arrangement, at least one rib 17b exists on each of both side of an arbitrary virtual line passing through the center O of the load receiving part 21. Therefore, the load receiving part 21 (weighing dish) does not rattle in a rotational direction.

[0040] FIG. 7D illustrates an example in which four ribs 17c are arranged in a circumferential direction of the flange 19 at angle intervals of 120°, 60°, 60°, and 120°, in sequence, so that the ribs 17c form an isosceles quadrilateral having the same two adjacent sides. Like this, the present example includes an aspect in which the plurality of the ribs does not form vertices of a regular polygon. In such arrangement, the load receiving part 21 (weighing dish) does not rattle in a rotational direction.

[0041] FIG. 7E illustrates an example in which two ribs 17d are arranged at symmetrical points, that is, at angle intervals of 180° in the flange 19. Since the number of the ribs is two, this example is not included in the present invention. In this arrangement, as illustrated in the Figure, when force (for example, a force F.sub.3 in FIG. 7E) is unevenly applied in a direction perpendicular to an arbitrary virtual center line passing through the center O, there is no engagement between the ribs 17d and the V-shaped grooves at the side to which the force is applied, so that the load receiving part 21 (the weighing dish) inclines in the direction to which the force is applied.

[0042] FIG. 7F illustrates an example in which three ribs 17e are arranged in a circumferential direction of the flange 19 at angle intervals of 90°, 90°, and 180°, in sequence, so that the ribs 17e forms vertices of a right-angled isosceles triangle. In this example, when a load transmitted to the load receiving part 21 through the weighing dish is not uniformly dispersed and is concentrated on the rib 17e which is disposed at an angle of 90° from each of two adjacent ribs 17e (for example, a force F.sub.4 in FIG. 7F), the rib 17e to which the force is applied engages with the corresponding V-shaped groove, so that the load receiving part 21 (weighing dish) does not rattle in the rotational direction.

[0043] However, when a force F.sub.5 is applied to a symmetrical point of the point to which the force F.sub.4 is applied with respect to the center O, engagement of the rib 17e and the V-shaped groove does not exist on the side to which the force F.sub.5 is applied, so that the load receiving part 21 (weighing dish) inclines in a force F.sub.5 applying direction. On the other hand, on the side in which the rib 17e exists and to which the force F.sub.5 is not applied, an upward moment is generated. The rib 17e is merely engaged with the V-shaped groove by insertion. Thus, the rib 17e cannot resist the upward moment, so that the load receiving part 21 moves to float up. Consequently, it is impossible to avoid the inclination of the weighing dish. Therefore, this aspect is not included in the present example.

[0044] The operation of the overload prevention mechanism 11 of the present example having the above-described configuration will be described. The overload prevention mechanism 11 is disposed between a load transmission mechanism including a load detection unit such as an electromagnetic-force-balancing sensor and a weighing dish in a weighing apparatus, and the weighing apparatus is installed in a manufacturing line or the like. On the weighing dish 12, various kinds of weighing objects are sequentially placed, and in some cases, a large impact may be applied. If such impact cannot be absorbed, rattling or inclination occurs on the weighing dish 12, which makes it impossible to perform measurement with high precision.

[0045] In the present embodiment illustrated in FIGS. 1 to 6 is configured such that the load receiving part 21 including the flange 19 with three ribs 17 and the connection member 37 with V-shaped grooves 45 engaging with the rib s17 on the lower surface are coupled by tightening each other. The ribs 17 are arranged so as to restrict rattling of the load receiving part 21 (weighing dish) in the rotational direction due to the load applied to the load receiving part. Therefore, even when a load is applied to any point of the load receiving part, the load receiving part 21 (weighing dish) is prevented from rattling in the rotational direction of the load receiving part thanks to the plurality of ribs 17 and the V-shaped grooves 45 engaging with the ribs 17. Thereby, measurement can be carried out with high precision and smoothness.

REFERENCE NUMBER LIST

[0046] 11 Overload prevention mechanism [0047] 12 Weighing dish [0048] 17, 17a-17e Ribs [0049] 19 Flange [0050] 21 Load receiving part [0051] 31 Pedestal [0052] 37 Connection member [0053] 45 Groove (V-shaped groove) [0054] O Center [0055] F.sub.1-F.sub.5 Force