RU2289797C1 - Conveyor balance - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: conveyor balance comprises weight pickups and two chute roller bearings arranged from opposite sides of one of the stationary roller bearing. Each roller bearing bears on free ends of two cantilever weight pickups and mounted one contrary to the other with respect to the built-in ends of the weight pickups. The axes of the rollers of weight roller bearings underlie the axes of weight pickups with side rollers inclined at an angle of 20° and at a distance of 0.15S or at an angle of 30° and at a distance of 0.157S, where S is the height of the chute of the belt.

EFFECT: enhanced precision and reliability of measuring and reduced metal consumption.

2 dwg

Description

The invention relates to a weighing technique, and in particular to devices for weighing bulk materials on conveyor belts.

Known conveyor scales of the type of VNK CJSC "Tenzo-M Weighting Company" (Kraskovo, Moscow Region), in which weight roller bearings transfer the load to one or two weight sensors with end fastening of the type T70, T100, middle and side rollers are located above the sensors weight. The disadvantage is:

1. Low accuracy of weighing when the load deviates from the value at which the balance was calibrated due to the additional moment loads arising from this, created by the horizontal components of the total load on the roller support (resistance forces to the movement of the belt, dynamic loads, etc.).

Known single-belt conveyor scales according to the application No. 2086593, Great Britain, G 01 G 11/4 Weighing device (Publ. 12.05.82). In them, a weight roller support is mounted on a transverse movable beam, which is connected on one side with a fixed beam (support) by parallel elastic springs forming a spatial parallelogram and having weakened sections, and on the other hand, through an adjustable lever, rests on a weight sensor mounted on a fixed support. It is assumed that under the influence of the vertical component of the load, the weight roller support moves freely in the vertical plane due to weakened sections and all the force is transmitted to the weight sensor, and when the horizontal component of the load is exposed, the overturning moment will be suppressed by the reaction of the springs. A similar construction is, for example, conveyor scales type WB company RAUTE (Finland), type SEG Belt Weigher AKA (Sweden).

The disadvantages of the scales are:

1. The decrease in weighing accuracy, because only partial compensation of the horizontal component of the load takes place (resistance to the movement of the belt, material dynamics, belt descent, uneven loading across the width, etc.), which has been proved theoretically (Current state and development trends of conveyor weights, Central Scientific Research Institute of Instrument Engineering and Instrument Engineering. TS-7 "Machines and devices for measuring mechanical quantities (Issue 3, M. 1986) and tests with a change in linear load according to GOST 30124 within 20 ... 100%.

2. Reducing the sensitivity of weights at low loads due to the use of springs having a certain rigidity, which leads to the introduction of additional bonds in the kinematic scheme.

3. Decrease in reliability and accuracy since in real production conditions, when the belt comes off or is not uniformly loaded across the width, the weight roller support is skewed, having only one fulcrum along the conveyor center line.

Known conveyor scales according to the patent of the Russian Federation No. 2193759, G 01 G 11/02, containing two articulated suspended two-arm weight platforms with grooved weight rollers, located on opposite sides of the stationary roller bearings and installed opposite to the location of the weight rollers relative to the hinges, the outer shoulders of the platforms are supported by sensors weights and equipped with counterweights to balance the "containers", and the inner shoulders - prisms for suspension of exemplary loads. Such a kinematic scheme minimizes the influence on the accuracy of the horizontal components of the load (forces of resistance to the movement of the belt, the dynamics of the material, etc.), asymmetric deformation of the belt on inclined conveyors and provides the possibility of using an indirect method of verification by alternately loading the platforms with standard weights when the conveyor is working under load.

The disadvantages of the scales are:

1. A decrease in accuracy with an increase in the width of the conveyor during the transfer of the load perceived by each weight roller support to a weight sensor mounted on one side of the platform, which leads to a drawdown (skew) of its other side and an additional error, determined by the amount of drawdown and tension of the belt.

2. Large metal consumption, dimensions, cost.

3. The complexity of installation and adjustment of the spatial lever structure in real production conditions with inevitable technological tolerances and inaccuracies in installation.

The objective of the invention is to improve the accuracy and reliability, reducing metal consumption and cost, simplifying the design.

This is achieved by the fact that the conveyor scales contain two grooved weight roller bearings located on opposite sides of one stationary roller bearing and resting on the free ends of two cantilever weight sensors located on opposite sides of the conveyor, and the weight roller bearings being installed opposite each other relative to the clamped ends of the weight sensors, the axis the middle roller of the weight roller support is located below the axes of the weight sensors, with an angle of inclination of the side rollers α = 20 degrees at a distance h = 0.158, with an angle of inclination α = 30 degrees at a distance h = 0.157S, where S is the height of the gutter of the tape.

Figure 1 shows a diagram of a conveyor scale, figure 2 - view a in figure 1.

The balance contains two grooved weight rollers 1, 2 located on different sides of one stationary roller 3. Each weight roller rests on the free ends of two cantilever weight sensors 4, 5 located on different sides of the conveyor. Relative to the clamped ends of the weight sensors, the weight rollers are mounted opposite each other, the axes I-I of their middle rollers 6 are located below the axes of the cantilever weight sensors II-II, which coincide with the line of action of the resultant frictional force of the grooved belt 7 of the conveyor. The decrease in the level of the location of line I-I relative to line II-II by h is determined as follows. The decrease in the level of the location of the line of action of the resultant friction force of the grooved tape 7 on the roller bearings is determined by the load distribution on the rollers.

The middle roller is loaded with force

Normal pressure on the side rollers, taking into account the spread of the tape

When the angle of the side rollers

α = 20 deg - R _{B =} 0,153 (q _n -q _l ) l _cf

α = 30 deg - R _{B =} 0,165 (q _n + q _l ) l _cf

The position of the resultant from the lower edge of the gutter (the upper generatrix of the middle roller) is determined by the weighted average value of the friction forces on the rollers

at

Where

q _n - nominal linear load (linear density) of the material,

q _l - linear mass of the tape,

l _p is the length of the roller,

S ₀ - the depth of the gutter of the tape;

α is the angle of inclination of the side rollers.

If the rolling friction component of the bearings of the weight rollers is insignificant compared to the total friction force (resistance to movement) of the belt, which is mainly determined by the deformation of the belt and load when moving through the grooved roller support, the indentation of the rollers, etc. (Spivakovsky A.O., Dmitriev V . G. Theory of conveyor belts. Science, 1982), we can assume that the friction force is applied to the axis of the roller. Therefore, in order to increase the reliability of the weight sensors, the axes of the middle rollers II are positioned lower than the axes II-II of the weight sensors, thereby achieving a coincidence of the line of action of the resultant friction force with the axis of the weight sensors. In this case, the action of the horizontal components at the rated load q _n is fully compensated. The displacement of the line of action of the resultant frictional force when the load deviates from q _n leads to the appearance of additional moment loads from the horizontal components and the corresponding increments of the signals of the weight sensors having opposite signs when counter-mounted weight rollers. Summing up by the adder 8 of the output signals of the weight sensors 4, 5 after multiplying the speed converter 9 by amplification and integration by the adders 10 and 11 provides mutual compensation of these signal increments, as well as other non-informative disturbance signals (dynamic loads, asymmetric deformation of the belt on inclined conveyors and etc.), affecting accuracy, and integration over time of only measured performance

The impact on the reliability of additional torque loads due to their insignificance can be neglected.

The offered conveyor scales provide:

1. Improving accuracy due to

- compensation of the influence of the horizontal components of the load in the oncoming installation of weight rollers and the location of the line of action of the resultant force of resistance to movement of the tape at the level of the axis line of the console weight sensors;

- elimination of uneven subsidence of weight rollers across the width of the belt using two weight sensors located on both sides of the conveyor.

2. Improving reliability through

- minimizing additional moment loads on weight sensors.

In addition, it provides:

1. Reducing metal consumption and cost, simplifying installation and configuration by eliminating two-arm linkage platforms and counterweights.

2. The implementation of the indirect verification method by alternately loading the weight rollers with standard weights when the conveyor is under load due to the mechanical isolation of the two measurement channels by installing the weight rollers on opposite sides of the stationary rollers.

Claims (1)

The conveyor scales comprise weight sensors, two grooved roller bearings located on opposite sides of one stationary roller bearing, characterized in that each weight roller bearing is supported by the free ends of two cantilever weight sensors, the weight roller bearings being installed opposite each other relative to the clamped ends of the weight sensors, the axis of the middle rollers weight rollers are located below the axes of the weight sensors, with the angle of inclination of the side rollers α = 20 ° at a distance of h = 0.15S or with the angle of inclination of the side rollers α = 30 ° at a distance of h = 0.157 S, where S is the height of the gutter of the tape.

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