RU2574523C1 - Oscillating structure meter - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: oscillating circuit comprises a base, a casing, a loading device, a measurement device, a reservoir and a control unit. At the same time the loading device includes a reduction gearbox connected to a shaft of a stepped electric motor with transmission ratio of at least 20:1, at the outlet shaft of which there is a cam bushing fixed, to which a cam disc is fixed with screws with a through window arranged at its centre, and at the side of the bushing and symmetrically to its central axis, perpendicularly to the axis of longitudinal holes for screws, in it there is a slot of rectangular shape, where an eccentric with a splint is placed as capable of rotation, the tail of which with a gap is inserted into the central hole of the cam bushing. At the same time the disc of the cam contacts with a pusher installed coaxially to it in the central bushing attached vertically above it to the bracket of the base, and on the upper end of which there is a table with a reservoir fixed horizontally. The metering device comprises a sensitive element placed with a gap into the reservoir, arranged in the form of corrugated plates, attached with equal pitch along the circumference to the vertically arranged metering rod, fixed in a lock of a precision strain dynamometer installed on the bracket on the base.

EFFECT: simplified design and increased accuracy of measurements.

6 dwg

Description

The invention relates to devices for continuous monitoring of the gelation process in the production of, for example, cheeses and sour-milk products, as well as for controlling the processes of structure formation in other industries producing or using structured liquids.

Known rheometer designed to study the kinetics of shear deformation of food materials under vibration [1]. The device has a base on which a cuvette with the studied food material is installed on a vertically and reciprocating platform, into which a sensitive element, a plate, is vertically inserted. The upper end of the plate is suspended from the rod of a mechanical gauge of movement of the watch type, designed to measure the frequency and amplitude of its vibrations. The case of a mechanical displacement meter is connected with a two-arm lever, on the second shoulder of which a load is suspended. Research is carried out by varying the static stresses (when the weight of the load changes) and vibration parameters. The reciprocating movement of the platform is provided by an eccentric exciter (cam) from the electric drive.

The disadvantages in the design of the device are as follows: a) the movement of the platform with the cuvette is provided by an eccentric exciter (cam) with a constant amplitude, which reduces the scope of the device, because in various gelling media, the strength of the structure differs by orders of magnitude. For this reason, for such media it is necessary to experimentally establish the optimal values of the amplitude. For example, for media with a “delicate” consistency (fermented milk products, creams, etc.), it is necessary to reduce the amplitude of shear deformations in order to avoid excessive destruction of the structure and decrease the accuracy of measurements, and for media of increased strength, on the contrary, increase; b) to measure a controlled parameter - linear displacements of the plate (sensitive element), a mechanical gauge of the watch type is used, the speed of which is limited by the inertia of its moving parts, and the measurement accuracy depends on the skill of the operator, i.e. from the human factor; c) the design of the device does not provide for an output signal for automatic recording of measurement results, which does not allow its use in automatic process control systems.

The closest technical solution, selected as a prototype, is an oscillatory shiftometer [2]. It contains a housing, a base, on which a loading device is mounted, consisting of a stepper motor, on the shaft of which a cam is made, made in the form of a sleeve, to which, with an adjustable eccentricity, the disk is attached with screws passing through two oblong holes made in it along the axial line. A ball bearing is pressed onto the disk, the outer ring of which is in contact with a hollow spring-loaded plunger mounted under the cam in the central sleeve attached perpendicular to the base with the possibility of translational movement.

The measuring device consists of a calibrated cylindrical coil spring fixed with the upper turn to the lower end of the hollow plunger, and the lower turn to the measuring rod mounted in bearings coaxially with the hollow rod, on the lower end of which is mounted a sensitive element in the form of a corrugated plate, which is immersed in a container with controlled environment.

The meter of the controlled parameter (resistance forces of the medium to the displacements of the sensing element) is fixed coaxially to the measuring rod on an arm mounted on the base and includes a permanent magnet made in the form of a cylinder of circular cross section with a flat disk glued on top of an annular shape, in the hole of which is coaxial with the permanent magnet the core is pressed in. In the annular gap between the permanent magnet and the core with a gap and coaxially inserted mounted on the upper end of the measuring rod coil with a winding, the conclusions of which are connected to the unit for recording and processing of measurement results.

The disadvantages of the oscillatory shiftometer are: a) the adjustable cam does not structurally provide for the ability to accurately set the set value of the eccentricity e ; b) the complexity of the design (the presence of a measuring rod, coil with a winding and a composite permanent magnet); c) during measurements, the sensitive element moves, the measuring rod with a bracket attached to it with a calibrated spring, which have a certain inertia of rest, which reduces the accuracy of the measurements; d) due to the step (discrete) rotation of the motor shaft, especially at low angular rotational speeds of the cam, additional dynamic pulses will be transmitted to the material under study, which can cause partial destruction of the resulting medium structure and thereby reduce the reliability of the measurement results.

Rheometers that are designed to monitor the gelation process in continuous media, i.e. to study the formation and hardening of their structure, they are called structureometers. As a controlled parameter, take stress or resistance forces to movements of the sensitive element in the medium under study. In particular, the rheograms obtained by monitoring the gelation process of milk protein clots - cheese clot and sour cream with various mass fraction of fat are given below as an example.

The essence of the invention lies in the fact that in an oscillating structuremeter containing a base, a housing, a loading device, a measuring device, a capacitance and a control unit, the loading device includes a reduction gear connected to the shaft of the stepper motor, with a gear ratio of at least 20: 1, on the output shaft which the cam sleeve is fixed to which the cam disc is screwed with a through window made in its center. On the side of the sleeve and symmetrically to the central axis of the cam disk, perpendicular to the axis of the oblong holes for the screws, it has a rectangular groove in which an eccentric with a slot is inserted with rotation, the shank of which is inserted with a gap into the central hole of the sleeve. In this case, the cam disk is in contact with a pusher mounted coaxially to it in the central sleeve, mounted vertically above it to the base bracket, at the upper end of which a table with a container is horizontally fixed. The measuring device consists of a sensitive element placed with a gap in the tank, made in the form of corrugated plates attached with an equal step around the circumference to a vertically located measuring rod fixed in the lock of a precision tensometric force meter mounted on the base bracket.

The objective of the invention is to simplify the design and improve the accuracy of measurements.

In FIG. 1 shows a diagram of an oscillatory structuremeter, FIG. 2 is a view along arrow A; in FIG. 3 is a view of an eccentric for fine cam adjustment; in FIG. 4 - view along arrow B; in FIG. 5 - rheograms of cheese clots, depending on the variation of the amplitude (eccentricity e ) of the movements of the container with the medium under study, obtained on the proposed invention; in FIG. 6 - comparative rheograms of the formation of clots of sour cream with a mass fraction of fat,%: 15 and 20, obtained on the present invention (Fig. 5a, rheograms 1 and 2) and on a certified laboratory rotational viscometer "Rheotest-2 RV" (Germany) ( Fig. 5, b, rheograms 1 'and 2 ′), respectively.

The oscillating structuremeter has a base 1, on which a stepper motor 3 is mounted on the bracket 2, which is connected to a reduction gear 4 with a gear ratio of at least 20: 1, on the shaft of which a cam is fixed, consisting of a sleeve 5, to which the e disk is attached with a given eccentricity 6 using screws passing through two oblong holes 7, made along the axis of symmetry of the disk 6 (Fig. 2). In the disk 6 from the side of the sleeve 5 there is a rectangular groove 8 located along its axis of symmetry perpendicular to the axis of the elongated holes 7. In the groove 8 is mounted for rotation an eccentric 9 with a slot 10 made therein, the shank 11 of which enters the central hole of the sleeve 5 cam (Fig. 3). To access the slot 10 of the eccentric 9 in the disk 6, a Central hole 12 is provided (Fig. 2). To reduce friction, a bearing (a ring of antifriction material, such as caprolon, or a ball bearing) 13 is pressed onto the disk 6, which is in contact with the plunger 14 (Fig. 2).

The pusher 14 is mounted vertically and coaxially above the cam in the central sleeve 15 fixed on the bracket 2 with the possibility of reciprocating movement provided by any standard method, for example, with a finger 16 pressed in perpendicular to its longitudinal axis, which moves with a minimum clearance in the longitudinal groove 17 made in the Central sleeve 15 (Fig. 1, Fig 4). Moreover, in FIG. 2 and FIG. 3 shows the position of the eccentric, in which the cam eccentricity is e _max = 6 · 10 ^-3 m

At the upper end of the pusher 14, a stage 18 is horizontally mounted with a fixed thermostatic tank 19, equipped with an inlet 20 and an outlet 21 nozzles for connecting to a liquid thermostat (the details of attaching the tank 19 to the table 18 are not shown conventionally). A sensing element is immersed in the container 19 with the medium under study, for example, consisting of aluminum corrugated plates 22, which are attached with an equal pitch along the circumference to a vertically arranged measuring rod 23, which is fastened with a lock 24 to a precision tensometric force meter 25, which is fixed with a plate 26 on the tubular stand 27 mounted on the base 1.

In this case, as a tensometric force meter 25, a standard precision tensometric unit of electronic analytical laboratory balance, commercially available, is used. For example, Libra Sartogosm MB 210-A. http://www.sartogosm.ru/sartogosm_mv_210_a.html.

To ensure the tightness of the electric drive during sanitization, a housing 28 is provided. For access to the cam eccentric 9, a window is provided in the housing 28 that is closed by a cover 29.

To install the required oscillations amplitude value table 18 with the container 19 (i.e. the eccentricity e of the cam) is provided an indicator 30 for linear displacements ICH-10 with a scale division 0.01 · 10 ^-3 m, the measuring rod of which abuts the upper end of the container 19 ( Fig. 1). The indicator is fixed on the bracket 31, fixed by a screw 32 on the stand 27. Then, open the cover 29 of the housing 28, loosen the cam screws 7 through the window 12 and insert the screwdriver into the slot 10, turn the cam 9 (Fig. 2). According to the indications of indicator 30, the value of the oscillation amplitude (eccentricity e ) of the table 18 is set as required for the medium 18. Then the screws 7 are screwed and the cover 29 is put in place. After that, loosening the screw 32, the bracket 31 with the indicator 30 is moved up the stand 27 and fixed with a screw 32.

Oscillating structuremeter works as follows. Connect the connectors of the strain gauge 25 and the network cable of the stepper motor 3 with a grounding bus to the control unit (not shown conditionally), which is then connected to the network. On the table 18, a container 19 is fixed, filled with the test liquid, and its pipes 20, 21 are connected using hoses to a liquid thermostat (not shown conditionally). Then, the holder 23 of the sensing element 22 is fixed in the lock 24. The speed of rotation of the shaft of the stepper motor 3 is set on the control unit, the readings of the strain gauge force gauge 25 are reset. In this case, the control circuit of the stepper motor 3 is set so that the cam 5, 6, 13 always occupies the initial state the position at which the pusher 14 is in the upper position, as shown in FIG. 1 and FIG. 2.

Gel control is carried out according to the following procedure. From the control unit panel, by pressing the “Start” button, voltage is supplied to the stepper motor 3, the shaft of which will drive the cam disk 6 to rotate at a given angular speed, the bearing 13 of which will transmit the specified vertical reciprocating movements equal to the given eccentricity e through the plunger 14, the table 18, tanks 19 with the investigated environment. In this case, due to internal friction of the medium, resistance forces will appear on the sensitive element 22, which will increase as the bulk structure of the gel is formed and hardens, which will be measured by a strain gauge 25 and transferred to the control unit for processing and presenting the measurement results.

At the beginning of the measurements, the gelling medium is in a liquid state and practically does not resist the movements of the sensitive element 22. As the bulk structure is formed in the medium, the resistance on the surface of the sensitive element 22 will increase with each measurement cycle. As a result of this, on its working planes, the values of the ultimate shear stresses θ _o , which are calculated by the formula

where F is the current value of the force recorded by the strain gauge force meter 25, N; 8 A is the area of the corrugated planes of 4 plates 22, m ² (Fig. 1).

Upon reaching the maximum gel strength in the control unit, an audible signal will be generated indicating its readiness, and a control signal will be sent to the automated control system for the transition to the next technological operation of its processing. The measurement cycle is over.

In FIG. 5 shows the influence of the amplitude of vibrations (when fixing all other factors of the gelation process) on the shape of the rheograms and on the strength of the structure of the finished cheese clot obtained by the claimed invention. In this case, the amplitude of oscillations of the capacitance 19 was varied within (1.0 ÷ 6.0) · 10 ^-3 m. From the analysis of the rheograms it can be seen that the rheogram obtained at е = 2 · 10 ^-3 m describes the gel process most reliably which clearly shows the main stages of the gelation process: AB is the induction stage, BC is the coagulation stage, and CD is the metastable hardening stage.

. В результате была получены реограммы зависимости «эффективная вязкость η_э - продолжительность процесса t» (реограммы 1′ и 2′, фиг. 6, б). Опыты выполнены при температуре 32±2°С.To control the reliability of the rheogram of the process of formation of clots of sour cream with a mass fraction of fat of 15 and 20%, obtained on the inventive oscillatory structuremeter in the coordinates "ultimate shear stress θ _o - process duration t" (rheograms 1 and 2, Fig. 6, a), were parallel comparative studies of the process of clot formation were carried out on a laboratory rotational viscometer "Rheotest-2 RV" (Germany). Studies were performed using a S / S ₃ measuring cell at a constant shear rate $$\dot{\gamma }=2.25{\text{from}}^{\text{-one}}$$

. As a result, rheograms of the dependence “effective viscosity η _e - process duration t” were obtained (rheograms 1 ′ and 2 ′, FIG. 6, b). The experiments were performed at a temperature of 32 ± 2 ° C.

An analysis of rheograms shows that they have a similar character. On both rheograms, three areas characteristic of the given process are clearly distinguished: AB (A ₁ B ₁ ) - induction stage (liquid milk mixture); BC (B ₁ C ₁ ) - flocculation stage (the beginning of the formation of a volumetric structure and hardening of clots); CD (C ₁ D ₁ ) - the stage of metastable equilibrium (reaching points C (C ₁ ) the maximum strength of the clots, rheograms suffer a kink and go to the horizontal section) - the strength of the clots does not change. In this case, deviations in the duration of the corresponding stages of the formation of sour cream clots are in the range Δ <± 4%, i.e. lie within the maximum relative measurement error of the Rheotest-2 RV rotational viscometer.

Information sources

1. Rheometry of food raw materials and products: Handbook / Ed. Yu.A. Machikhina. - M .: Agropromizdat. - 1990. - 271 p.

2. Pat. 2454655 Russian Federation, IPC ⁷ G01N 11/14. Oscillating structuremeter / A.N. Pirogov, I.A. Litvinova; Applicant and patent holder GOU VPO Kemerovo Technological Institute of Food Industry - No. 20111100982/28; announced 12.01.11; publ. 06/27/12, Bull. Number 18.

Claims (1)

An oscillating structuralometer comprising a base, a housing, a loading device, a measuring device, a capacitance and a control unit, characterized in that the loading device includes a reduction gear connected to the shaft of the stepper motor with a gear ratio of at least 20: 1, on the output shaft of which the cam sleeve is fixed, to which the cam disk is screwed with a through window made in its center, and from the side of the sleeve and symmetrically to its central axis perpendicular to the axis of the elongated holes for screws, it has a rectangular-shaped groove in which an eccentric with a slot is rotatably placed, the shank of which is inserted with a gap into the central hole of the cam sleeve, while the cam disk contacts the center sleeve mounted coaxially with it and attached vertically above it to the bracket base, a pusher, on the upper end of which a table with a capacity is horizontally fixed, and the measuring device consists of a sensitive element placed with a gap in the capacity, made in the form of a reef flax plates attached with equal pitch around the circle to a vertically arranged measuring rod fixed in the lock of a precision tensometric force meter mounted on the base bracket.

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