CH634655A5 - Precision balance with overload protection - Google Patents

Description

The invention relates to a precision balance, the balance of which is essentially a circular outline and which is arranged on a dish at the upper end of a spacer which is distributed evenly with a low-range transducer from a circle of art-interacting load sensors and is made of fabric. they are arranged on the bottom molded parts - at least one elastic component for protection against overloaded stops. Here there is a relative rotation of the two when yielding under impact or overload

A well-known scale of this type (Swiss> Pa-shaped parts. It is expedient to use at least 604 143), has a multi-part round weighing pan ^ plastic spacers through connecting webs to

and the lower part of the weighing pan is connected via a common common component. This measure requires

In addition to the fact that it acts on the load receiver in a punctiform manner, it simplifies assembly and saves more complicated

Elastic parallel guidance with the «> gene ^ arranged under a force attack. Tension is preferred.

Load receiver connected. This known arrangement is fine; whose direction of action lies at an acute angle to the outer point of attack, which is useful for round weighing pans and for rectangular tangents on the circumference of the circle. Weighing scales for scales with a smaller capacity (up to a few kilograms maximum load). In a further embodiment of the invention, the overload protection which is known between the rule of rectangular, relatively large-scale weighing pan is less suitable; Such larger tensioned tension coil springs are arranged at an incline in such a way, for reasons of even load distribution, that a spring force component acts in the direction of an approach via a plurality of, as a rule four connecting links with the manufacture of the two molded parts. This arrangement begins

3rd

634 655

in the event of an overload, the uniform and simultaneous yielding of all springs.

The invention is explained below with reference to the drawing. In the drawing is

FIG. 1 shows a section through a first embodiment,

FIG. 2 shows a view from below of FIG. 1,

3 shows a section through a second embodiment, and

Figure 4 is a bottom view of Figure 3.

The actual weighing mechanism is not shown in the explanation of the examples, since it does not contribute to an understanding of the present invention. It is only important that the scales are low-displacement (e.g. not an inclined scales).

Example I

(Figures 1 and 2)

A scale with a capacity (nominal load) of 8 kilograms is enclosed in a stable housing 10.

Four pins 12 protrude through four openings therein, which support a three-part weighing pan 14 and connect to the lever mechanism (not shown) in the interior of the housing 10. The uppermost element 16 of the weighing pan is used to hold the goods to be weighed; it rests loosely, in a form-fitting manner, on a composite system of two molded parts 1-8 and 20, which are referred to below as the upper part (18) and lower part (20).

The upper part 18 consists of a flat sheet metal plate, the ends 22 of which are bent at right angles on the narrow sides. Double turns are provided on the broad sides, the inward end strips 24 of which run parallel to the top surface. Two tabs 26, each provided with an eyelet, are folded inwards (below) from the top surface. Another four larger tabs 28 project downward parallel to the narrow sides.

The lower part 20 is somewhat narrower and in the other direction about one centimeter shorter than the upper part 18. It is bent upwards at right angles on all four sides. Four bores 30 serve to receive the pins 12. Two tabs 32, each provided with an eyelet, are folded upwards. Another four tabs 34 protrude upward parallel to the narrow sides, somewhat offset from the tabs 28. Furthermore, four smaller tabs 36 are also provided in the lower and upper part, also parallel to the narrow sides.

Between the tabs 28 and 34 (or 36) acting as stops, a sheet metal strip 38 is inserted near the ends of the weighing pan, which acts as a spacer. The stop lugs in the lower and upper part are arranged so that they are offset so that the two metal strips, parallel to each other, always remain inclined to the vertical. Two flaps 39, bent out of the upper and the lower part, pointing inwards, transversely to the metal strips 38, form notches in the latter to secure the position against displacement.

Two parallel helical tension springs 40 of the same dimension, accessible through two windows 41 in the lower part, are stretched between the tabs 26 and 32. They hold the two molded parts 18, 20 in the area of their preload in the limit position shown in FIG the lower part 20 is pressed onto the strips 24 of the upper part. In the event of impacts or overload, the springs give way, and the upper part 18 is deflected to the right while moving parallel to the lower part 20 until the strips 24 come into contact with the housing 10. The two spacer strips 38 act as pivot bearings.

The dimensioning is chosen so that the overload protection responds at about 12 kg and the weighing pan rests on the housing with the end strips 24 on the housing 10 s after a further several hundred grams and about four millimeters of travel (the possible path between the upper and lower part makes about 6 mm). To enable the weighing pan to return to the starting position (normal position), the load must be reduced to about 9 kg (the release force to overcome the spring preload is greater than the force required to hold the folded weighing pan in this position).

In the view from below according to Figure 2, both the housing 10 and the top element 16 of the weighing pan have been omitted.

15

Example II

(Figures 3 and 4)

The arrangement described here belongs to a scale with a nominal load of 3 kg. Figure 3 is a section along the line 20 III-III in Figure 4; the same reference numerals were used for components that correspond functionally to those of the first example, each supplemented by an apostrophe ('). In Figure 4, the housing and the uppermost part of the weighing pan were again omitted.

25 The upper, conically shaped end of a load receiver 12 'protrudes through a bore in the housing 10'. Symmetrical to it, a three-part weighing pan 14 'sits on the cone: an uppermost element 16', which is used to hold the goods to be weighed, rests positively on the upper part 18 '. The lower part 20 '30 has a rotationally fixed central pin 42 which projects through a bore in the upper part 18' and has a flat collar at the top. The collar rests in a recess in the upper part, with approximately 3 mm play to the element 16 ', and serves as a stop for the upper part 18'. A conical bore in the lower part of the pin 35 fins 42 centers the cone of the load receiver 12 '.

Between the top part 18 'and the bottom part 20', four tension coil springs 40 'are stretched symmetrically, held on the one hand in tabs 26' bent out of the top part 18 'and on the other hand in holding eyes 32' placed on the bottom part 20 '. Four 40 wedges 38 'are formed by webs 44 and a ring 46 into a one-piece component made of polyamide. The wedges 38 'are movably caught between eyes 28' and 34 ', respectively, on the upper part 18' or. Lower part 20 'are attached. The springs 40 'are arranged in pairs parallel to one another and each form an angle of approximately 30 degrees with the webs 44; they are accessible through recesses 41 'in the lower part 20'.

The arrangement works - comparable to that according to Example I - as follows: at a load of about 5 kg, the springs 40 'give way, and the upper and lower part of the weighing pan twist 50 relative to one another until the upper part 18' opens after a vertical travel of about 2 mm the housing 10 'rests. If the load is reduced again, the weighing pan snaps back into its normal position (around 4 kg). -

Depending on the structural boundary conditions and the load conditions, a single spring can also suffice for rectangular weighing pans; because of the more uniform effect, however, the use of at least two springs is preferred. In the case of larger weighing pans, it may be expedient to arrange four or six springs in pairs, for example. Also, two springs of lower spring hardness can be used directly next to each other instead of a stronger spring to simplify assembly.

C.

1 sheet of drawings

Claims (8)

634 655 2 PATENT CLAIMS connected to the load receiver and four parallel guides of the 1. Precision balance, the weighing pan of which is of the type known at the upper end would require a very high outlay; In addition, the desired behavior of the weighing pan would be arranged in the load receiver and interact with a low-displacement measuring transducer and at least one elastic overload, namely parallel deflection even with an eccentric component to protect against overload, thus not being subject to stress, would be guaranteed. that the weighing pan (14) had two molded parts (18, 18 '; 20, 20') movable relative to each other. The object of the invention was to provide an overload protection device which includes both high-precision high-precision scales, wherein at least one spring (40; 40 ') acts on the rectangular weighing pan as well as on the low shaped parts for round weighing pans, and this can be used with the assistance of rigid scales. It should allow a flat constructional plurality of iose movably caught between the molded parts, to hold spacers (38; 38 ') practically independent of the point of application of the load in one of the limit positions and (in contrast to the known parallel guidance, and that the leaf springs on the side of the goods to be weighed) are arranged over a small load area between the molded part in such a way that, in the event of an overload, they reach the other limit position on the balance housing before the normal position and the position at the stop under overload put. (10; 10 ') rests. According to the invention, this object is achieved in that 2. Precision balance according to claim 1, characterized in that the weighing pan two relative to each other between two Grenzla-net that the two molded parts made of sheet metal over the gene comprises movable molded parts, at least one spring adapted to each other molded part, serving as stops on both Attacks molded parts and these have Mitwir zones (22,24) that define the limit positions. kung by a plurality of between the molded parts 3. Precision balance according to claim 1 or 2, characterized by drawing caught spacers in one of the limit positions, that the two molded parts (18, 20) are generally striving for, and that the rectangular on the side of the goods to be weighed Are shape and that the spacer-shaped part is arranged so that it consists of sheet metal strips (38) in the event of overload, held between projections (28, 34) provided in the two before reaching the other limit position on the scale-shaped parts lies on. will. 25 This solution means that in the event of overload, i.e. if the pre 4. Precision balance according to claim 3, characterized marked voltage of the arrangement is overcome, the weighing pan net that an even number of pairs arranged train practically immediately goes to the stop position. That is provided with this coil springs (40). Snapping effect regularly associated noise has a side effect 5. Precision balance according to claim 1, characterized in the case of an acoustic alarm signal: in the event of an overload, the Waagnet folds that the two molded parts essentially have a circular shape audibly together, with a subsequent sufficient deflating outline and that they are even on a circle The device suddenly returns to the normal position (spacer-spacers (38 ') made of plastic and intermediate). see stops arranged on the two molded parts (28 ', preferably the two are made of sheet metal 34 ') are held. Molded parts adapted over the other molded part as 6. Precision balance according to claim 5, characterized gekennzeich- 35 stops serving zones that define the limit positions. Serves that in each case at least two plastic spacers (38 ') this design enables a particularly efficient production by connecting webs (44) to form a common component made of stamped / bent parts or (in the case of larger series) deep-drawn parts. len, with optimal strength of the molded parts. 7. Precision balance according to claim 5 or 6, characterized- In a particularly suitable for higher-load scales, that helical tension springs (40 ') are provided. 40 preferred embodiment, the two molded parts are made in the direction of action at an acute angle to the tan. essentially rectangular shape and the distance gents are on the circumference in the outer point of attack (26 '). Pieces of sheet metal strips between the two molded parts 8. Precision balance according to claim 1, thereby marked projections are held. The net result is that between the two sudden yields, which are aligned parallel to one another and under overload, a parallel displacement of the molded parts, tension coil springs of this type 45 of the two molded parts relative to one another. It is arranged inclined that a spring force component acts with a view to the uniform effect of the overload protection in the direction of an approximation of the two molded parts. useful if an even number of tension coil springs arranged in pairs is provided. 5o In a preferred embodiment intended especially for low-load scales, the two molded parts in