Fig. 4.1. The structural scheme of the automated quality control test

Rheological properties of semi-can be successfully used for the evaluation of the individual processes. Technological machines in various structures that are intended for the same process, differ in the degree of impact on the processed mass, which leads to production of end products with unequal structural-mechanical properties, and the production of finished goods of different quality. Research of influence of individual machines on the properties of semi-allows you to choose the most appropriate design for the production of this type of bread and choose optimal regimes of processing.

One of the most actual problems of increase of efficiency baking production is automation of the dough kneading. A continuous process of kneading of the dough is carried out by mixing units, including dough mixing machine of continuous action, dosage of flour and liquid components, measuring devices.

In the process of work on the mixing machine effect of different disturbances, under which the adjustable pressure takes the value that you have specified, so the task of automatic regulation is to return the value of the controlled parameter on a stabilized value. For this, the encoder produces on the regulatory control of certain size up until the pressure is equal. Regulatory option may be the dosage value of one of the components coming from the dispensers. For the correct choice of regulatory component must be considered his dosing and altered rheological properties of a test depends on different percentage of this component is at a constant batching other components required by the recipe.

Studies show that consistency test largely influenced by the ratio dosage of flour and yeast solution. It is advisable to choose a yeast solution as regulatory component, as it can be dosed automatic dosing stations.

For the implementation of the regulatory process consistency substituted test, you need to know the function:

∆р = ∆р (∆η),

where: DP - R-deviation of output pressure from its stabilized value corresponding to the set value output pressure, %;

∆ETA - deviation of viscosity on the value corresponding to the set value output pressure, %.

In turn ∆ETA can be associated with the desired control - change in dosage yeast solution ∆GДР, i.e. to find dependency:

∆η = ∆η(∆G_ДР).

To identify the latter dependence is necessary to spend corresponding experiments. For a number of bakeries and results are relevant literature.

Using the methodology of calculation of the flow in channels of complicated form, you can, asking different content of yeast solution, to determine the corresponding values of the working pressure sensor, automatic control systems.

The calculation results on the plot. ∆η = ∆η(∆G_ДР) The linear dependence in relation to dough mixing machine as an object of regulation is static characteristic of the regulatory system. The tangent of the angle from straight defines a factor of transmission of the object COB. For the case in question COB = 2.6. The pressure at normal dosage of all components differed from the average value obtained through experimentation, on 12%.

The process of automatic regulation over time, i.e. to the dynamics of regulation imposed certain requirements. When selecting the controller and its configuration, you must consider the properties of the object of regulation, characterized by the ratio t/T, where t is time transportation lag, s; T - time constant of the object).

The value of t is determined by the curve of dispersal by measuring the time interval from the moment of application of perturbation to the moment of the sensor reaction consistency on this outrage. The time of transportation lag caused average speed test kneading capacity. Time constant, characterizing the changes in texture, also defined on curves of acceleration.

For the object of regulation, consisting of dough mixing machines and dosing station, applicable izotopnyi law regulation. Sograny, or proportional-integral (PI)controller has two settings: transmission coefficient of the regulator of the KR and the time of ipodrom THIES.

The transmission coefficient of the regulator is:

К_Р = К_С / К_ОБ,

where: CS - transfer coefficient of the regulation system;

COB - transfer ratio of the object.

The structural scheme of automatic control is shown in Fig. 4.3. The signal from the sensor D proportional to the value of working pressure in the outlet port of the machine enters the electronic controller. In measuring the controller unit IB, which depends on the type of sensor, electronic signal is multiplied by a constant factor, and it is compared with the set. Set value of the controlled parameter is a unit (usually a wire potentiometer). The measuring unit is a bridge alternating current, the output of which is connected to out phase-sensitive amplifiers.

In case of deviation from the setpoint signal offset enters the electronic block EB, which amplifies the signal of detuning of a corresponding law regulation and is affected by the output element VE on the starting device PU (usually the magnetic starter) actuator THEM. In addition, the electronic unit is receiving signals from non-contact position sensor that provides feedback (OS) on the status of the regulatory body.

The main elements of the electric actuator mounted on a dosing station VNIIKP are motor, gearbox, output device for the mechanical connection with the regulator RO and additional devices providing braking at disconnection of the electric motor, the stopping mechanism in the end positions, etc. Regulatory body - the piston, which takes some level in the glass yeast dosing depending on the values of the working pressure in the outlet port of the machine. In the scheme also provides for the index position of the regulatory body pack.

Checklist

1. Assessment of the quality of food products

2. Optimization of technological processes on the basis of engineering rheology

Date: 2015-12-24; view: 798