Agitators with elliptical blades for kneading minced meat consist of a rotary trough (Fig. 1, f), in which counter-rotating blades are mounted. The blade 2 has a larger size, the blade 3 rotates inside it. Their counter movement gives a sharp cut of the mass and ensures rapid mixing of the components. The blades are driven by gears. When overturning, the trough rotates around axis 6 with the help of a worm pair and a handle.
Meat mixers open intermittent action with trough overturning have a working capacity of 0.15 and 0.34 m3.
Meat mixers can be with open and sealed containers. The latter are equipped with vacuum pumps. In such meat mixers, the quality of the products obtained is higher than I; the raw materials processed in them have the required color and consistency, as well as a low level of microbiological contamination.
For uniform mixing of several components, three parallel screws are used, which dose the supply of different products to the fourth mixing screw. In screw mixers, the pitch of the helical surface can be constant and variable.
Horizontal mixing devices of meat mixers have two shafts rotating at different angular speeds towards each other. Various blades (helical, Z-shaped, spiral, etc.) are placed on the shafts. The position and design of the blades are selected in such a way that when the blade is raised up, the minced meat is fed from the edge to the center, and when lowered, vice versa. Of the two rotating blades, the leading one has an angular velocity 1.3 ... 2 times less than the driven one. The meat mixer is serviced from the side of the low-speed blade.
Paddle mixers resemble screw mixers, where the helical surface is replaced by oblique blades. These blades on the shaft form a discontinuous surface, which not only mixes the mass, but also shifts it along the axis of the shaft. Obliquely placed blades may be in the form of a rectangle or a trapezoid, expanding from the center of the shaft. In cross section, the blades are located at an angle of 120° relative to each other.
Spiral mixers are used for mixing different components of minced meat. A spiral is a helical strip rectangular section, which is cantilevered on the shaft or has support axles at the opposite end. Mounting to the shaft is rigid with a clamp connection. The spirals are placed in the gutters of the bowl, which can be from one to three.
Mixers with Z-shaped and helical blades are most often used in meat mixers. Practice has shown the feasibility of their use, they achieve the most complete mixing effect with a relative simplicity of design. The blade can be made in the form of a section of a curved Z-shaped strip or in the form of a sail. In some cases, it may have a plug-in shaft.
The required technological effect of the operation of mixing meat raw materials primarily depends on design features and type of mixers. Depending on the location of the working bodies, they are divided into vertical and horizontal.
Meat mixers of the first type have a mixing device! fixed on a vertical shaft lowered into the bowl; for meat mixers of the second type - one or two horizontal shafts, on which the mixing working bodies are fixed. The latter may be screws, blades or paddles.
With a two-shaft mixing system, the shafts rotate towards each other with the same or different speed. 2 Description of the meat preparation complexA complex of minced meat preparation A1-FLV (Fig. 2) consists of an FLV / 5 unit for mixing and fine grinding of minced meat, which includes mixers
and chopper 5 ;lift 2; mince pump 3; nitrite dispenser 4; power board bunker 7; cooler-dispenser 8; control and management board 9; relay-kinetic shield 10.
Ripened raw materials (beef, pork) from the salting and ripening shop are transported in floor carts to lifts, with the help of which they are unloaded from the carts into the receiving hoppers of the corresponding mince pumps. The stuffing pumps alternately transport raw materials to the weighing hopper, where the required portion is automatically weighed, as well as unloaded into the kneading trough of the mixer, where the required amount of cold water (t = 1 ... 2 C), blood serum (t \u003d 1), a solution of nitrite (t E16 ...! 8 C). The addition of flake ice, bulk components is carried out manually.
After mixing the raw materials with the components for 3 minutes, the finished product is fed by the mixer pump through the meat pipeline to the grinder "of continuous action for further grinding the minced meat. From it, the minced meat is sent along the meat pipeline to the floor cart (when developing structureless sausage products).
Contents of delivery
The delivery set of the A1-FLV/5 meat preparation equipment includes:
unit A1-FLV/5 for mixing and fine grinding of minced meat.
Composed of:
A1-FLV/2 mixer, pcs…………………..1
shredder A1-FKE/3, pcs…………..…..1
K6-FPZ-1, pcs. . ……………………………one
Pump stuffing A1-FLB/3, piece…………1
nitrate A1-FLV/4, pcs ………..1
Weight hopper A1-FLB/2, pcs……………1
Dispenser A1-FLV/3, pcs. . . . ... …………….one
Control board A1-FLB/4-02, pcs. . . ……one
Pipeline, piece………………………..… 3
Operational documentation, copy…….1
3 The principle of operation of the meat mixer type L5-FMU-150Depending on the method of unloading, meat mixers are divided into machines with a rotary, overturning and fixed container. They are loaded manually or mechanically. In the latter case, the meat mixers are equipped with special hoists-tippers of transport carts.
Meat mixers can be with open and sealed containers. The latter are equipped with vacuum pumps. In such meat mixers, the quality of the products obtained is higher - the raw materials processed in them have the required color and consistency, as well as a low level of microbiological contamination.
The simplest device and principle of operation characteristic of this group technological equipment, has a meat mixer L5-FMU-150. In its own way technical specification it belongs to the group of equipment of medium power, which implies its use both at small processing enterprises and at urban meat processing plants.
Meat mixer L5-FMU-150 (Fig. 2) consists of a frame, a container for kneading minced meat, in which two screws rotate towards each other in the form of a spiral, a screw drive and a loading mechanism.The bed is a cast iron pedestal covered with quick-release facing sheets.
The container for kneading minced meat (dezha) made of stainless steel is closed on top with two lattice-type lids. The augers are driven by an electric motor through a specially designed worm gear.
The loading mechanism consists of a trolley designed to transport raw materials to the meat mixer, and a device for its overturning, mounted in the frame. The overturning device is a system of levers shifted by means of a special worm gear with a separate electric motor. The finished product is unloaded through hatches located at the bottom of the bed. They are opened manually by turning the flywheel clockwise. To speed up the mixing of minced meat, the rotation of the augers is reversed, which is carried out by two buttons on the control panel.
Technical specifications
Productivity, kg/h. . . , 1000
Trough capacity (geometric), m3 ............... 0.15
Load factor..., 0.5-0.8
Cycle duration, min. . . . . . 3-4
Height from the base of the meat mixer, mm:
trough edges........ 1215
unloading. . . ,....., 690
dimensions(with loading mechanism), mm ........... 2350X965X1245
Weight (with loading mechanism), kg. . 990
The meat mixer consists of a bed, a kneading trough, a screw drive, a loading mechanism, a lid, a sliding device and electrical equipment.
Minced meat is mixed with augers in a trough, which is closed with two protective lattice covers.
6.1 Rules for use and safety requirementsPersons admitted to work on the machine must be familiar with its device, know the rules Maintenance and operation and undergo a safety briefing.
Before starting agitators and mixers, make sure that there is no danger service personnel.
Drives executive bodies(blades, augers) and overturning of the trough must have a reliable fence. Meat mixers with a tilting trough must have a device that securely fixes it in any position. Meat mixers and meat mixers with end unloading on the hatches for unloading minced meat are provided with gratings interlocked with the starting device and excluding the possibility of the worker's hands getting into the rotation zone of the augers. Covers on hatches must have sealing rubber gaskets and be pressed against the wall with a special handle. Minced meat should be unloaded from the trough of the meat mixer only with rotating blades with the trough in a vertical position and the grate cover closed, leaving a set gap between the trough and the grate for the free passage of minced meat.
The features of the used meat mixers are associated with the design and distribution of the executive bodies (blades) of the mixer, the product unloading units and the materials from which they are made. Meat mixer L5-FMU-335 refers to horizontal type meat mixers, in which the executive (mixing) body is fixed on a horizontal shaft.
Rice. 11 Meat mixer L5 - FMU - 335
1 - trolley; 2 - loading device; 3 - trough; 4 - lattice; 5 - drive; 6 - bed; 7 - kneading blades
It consists of a bed, a kneading trough, auger drive, a loading mechanism, right and left covers, a sliding device and electrical equipment.
The bed is a welded metal structure made of a corner with a size of 63-63 mm. The cover is welded, lattice type, made of stainless steel. The kneading trough consists of a crankcase, a stainless steel trough, inside of which there are two kneading augers driven by a shaft. They rotate from the electric motor through V-belt and worm gears located inside the cast-iron pedestal. Minced meat is mixed with kneading augers in a trough closed with two lattice covers. The augers are selected so that when they rotate, the minced meat is fed from the edge to the center, and at the bottom the flow is reversed (hand kneading is simulated). The rotation frequency of the blade on the service side is less (1.3 - 2.0 times) than the rotation frequency of the blade. The drive mechanism of the meat mixer is electric, with a reverse, which ensures the rotation of the mixing blades, both in one direction and in the other, and without a reverse, i.e. The blades only rotate in one direction.
Minced meat is loaded into the trough by a loading device, unloaded by kneading augers through hatches that are opened manually by rotating the flywheel clockwise. The control panel is a push-button post and is located on the pedestal. Rectangular electrical cabinet, mounted on the wall separately from the machine in a convenient place for operation. The bed and cabinet of the meat mixer are covered with metal facing sheets.
When unloading into mobile carts or a bunker, the trough is overturned, and the unloading level should be located at a height of 0.8-0.9 m. The most rational for mechanized unloading is tipping around the axis, when the loading and unloading conditions are the same.
Specifications
Productivity, kg/hour 2500-3200
Geometric capacity of the trough, m 3 0.335
Load factor 0.6-0.8
Cycle duration, min 3.5-8
Kneading auger speed:
Left, from 0.76
Right, from 0.76
Installed power, kW 7.0
Overall dimensions, mm 2900-965-1385
(with loading mechanism)
Weight, kg 1035
(with loading mechanism)
2.5.1 Calculation of the screw of the meat mixer L5-FMU-335
Initial data:
Productivity of the screw device П=0,861 kg/sec;
Maximum pressure p max \u003d 0.15 MN / m 2;
Product internal friction coefficient f=0.3;
Product density r=900 kg/m 3 .
The outer diameter of the screw D is taken equal to 0.34 m, the pitch is H=0.8 D=0.8×0.34=0.27 m.
The diameter d of the screw shaft must be greater than the maximum allowable diameter dpr determined from the condition (Fig. 12):
Rice. 12. To the choice of the diameter of the screw shaft
dpr = H/ptgj (1)
Let's take the diameter of the screw shaft equal to 0.16 m (a=2.12).
Helix angle on the outer side of the screw and at the shaft according to dependence (2):
Helix angles are equal to:
a D = arctgH/pD; a d = arctgH/pd
The average value of the angle of elevation of the helical lines of the screw turn by equality:
a cf = 0.5 (a D + a d).
a cf =0.5(14°19’+28°25’)=42°44’×0.5=21°22’
Auxiliary quantities:
cos 2 21°22’=0.9321 2 =0.8689; tg 21°22’=0.3882; sin2×21°22’=0.6748.
The lagging coefficient of material particles in the axial direction according to the equation without taking into account friction forces:
k 0 \u003d (H-h1) / H \u003d sin 2 a \u003d (pD-s1) / pD \u003d k in
taking into account friction forces:
k 0. T \u003d (H-h) / H \u003d sin 2 a + 0.5fsin2a \u003d (pD-s) / pD \u003d k in. T
If the molded or pressed material is plastic-viscous and has adhesion, then the coefficient of internal friction is taken as the coefficient of friction, which is determined from the condition of the connection of the particles to each other when the layers of the material are sheared.
Thus, the movement of product particles in the screw device can be taken into account by the displacement factor.
k \u003d 1 - k 0.T \u003d cos 2 a - 0.5 f sin 2a.
k 0 =1-(0.8689-0.5×0.3×0.6748)=0.2332
The bending moment in the flight of the screw along the inner contour, i.e. at the shaft according to expression (6):
Mi=PmaxD 2 /32 (1.9-0.7a -4 -1.2a -2 -5.2lna)/(1.3+0.7a -2);
where a \u003d\u003d D / d is the ratio of diameters, which practically lies in the range from 1.8 to 3. The highest stress (it is also equivalent):
s= ±6Mn/tb 2 ;
The screw turns will be made of steel 10, for which the allowable bending stress can be taken equal to the allowable tensile stress, i.e. 1300×10 5 N/m 2 .
Then the thickness of the screw coil from the formula:
s=±6Mn/tb 2 ;
.
Accept
The area of the inner cylindrical surface of the device housing at the length of one step according to the expression (8):
F B \u003d 3.14 × 0.34 (0.27-0.006) \u003d 0.2818 m. 2
Dependency sweeps of helix lines (9):
The surface area of the screw coil at the length of one step according to the condition:
Fw = 1/4p(pDL-pdl+H 2 ln(D+2L)/(d+2l));
where L and l are the development of helical lines corresponding to the diameters of the screw and shaft.
which satisfies the operating conditions of the screw.
Torque at three working turns of the screw according to the expression: Mcr =
0.131n p max (D 3 -d 3) tgas;
axial force
S \u003d 0 / 392n (D 2 -d 2) p max
where n is the number of working steps of the screw.
M cr \u003d 0.131 × 3.15 × 10 6 (0.34 3 -0.16 3) × 0.3882 \u003d 806 N × m,
S \u003d 0.392 × 3 × (0.34 2 -0.16 2) × 0.15 × 10 6 \u003d 6210 N.
Knowing the torque on the screw shaft and the axial force, we find the normal and shear stresses corresponding to them:
where F is the cross-sectional area of the screw shaft in m 2; W p - polar moment of resistance of the cross section of the screw shaft in m 3.
The equivalent stress according to the theory of the greatest shear stresses is determined by the formula:
and is within the allowable stress for the screw shaft material (St5 steel).
Taking the fill factor equal to one, we get:
Now we determine the dimensions of the workpiece of turns and their number.
Let the screw length be 3×0.27=0.81 m.
Width of coils according to dependence
b=0.5(0.34-0.16)=0.09 m.
The angle of the cut in the ring blank according to the expression:
a 0 \u003d 2p - (L - l) / b;
The length of the screw is determined by the formula:
L" = H"/sinaD; l" = H′ sinad ;(17)
From formula (18) we determine other parameters: D 0 = L "/p; d 0 =l"/p;
The technological calculations of the mixers include the determination of the capacity of the bowl and reservoir, as well as the engine power to the mixers.
The capacity of the bowl or mixer tank, if it is used as a reserve or storage tank, is determined by the formula
where M is the performance of the mixer or stirrer, m 3 / s; t is the duration of the kneading or mixing cycle, s; a - coefficient of filling the volume of the bowl with products.
V=0.00096×210×0.6 -1 =0.335 [m 3 ].
Engine power to the mixer for mixing doughy and loose bodies (in particular minced meat)
;(20)
where z is the number of blades of this type; R is the resistance experienced by one blade, N; J is the speed of the corresponding blade, m/s.
For mixing dough-like and loose bodies, the resistance of one blade
P=Q×F, [H](21),
where Q is the corresponding resistivity, N/m2; F is the frontal surface of the blade.
According to Lapshin (for minced meat):
Q \u003d Q 0 + aJ N / m 2 (22),
where Q 0 - conditional initial resistance, N / m 2; a is a constant parameter depending on the type of minced meat.
For minced boiled sausages a \u003d 4000¸5000, Q 0 \u003d 4000¸8000 H / m 2
J=R×w=0.171×24=4.1 m/s
F= 
Q \u003d 15000 + 10000 × 4.1 \u003d 56000 H / m 2
P=56000×0.09=5040 N
N= 
Calculation of the working parameters of the meat mixer screw. Known productivity screw device P = 0.85 kg/s, the coefficient of internal friction of the product f = 0.3, the density of the product r = 1041 kg/m 3 .
The outer diameter of the screw D is taken equal to 140 mm, and the pitch
H \u003d 0.8 × 140 \u003d 112 mm.
Limit screw shaft diameter
d pr \u003d (N / p) tgj \u003d (0.112 / 3.14) × 0.3 \u003d 0.0107 m \u003d 10.7 mm.
Let's take the diameter of the screw shaft equal to 60 mm (a = 2.3).
Helix angle on the outer side of the screw and at the shaft according to dependencies
a D = arctg ; a d = arctg ;
a D = arctg = 14°;
a d = arctg = 31°.
The average value of the angle of elevation of the helical lines of the screw coil by equality
a cf \u003d 0.5 (a D + a d) \u003d 0.5 (14 ° + 31 °) \u003d 22.5 °.
Auxiliary quantities are
cos 2 22.5° = 0.854; tg 22.5 °= 0.414; sin 2×22.5° = 0.707.
The lag coefficient of material particles in the axial direction according to the equation
k 0 \u003d 1 - (cos 2 a cf - 0.5f sin 2a cf) \u003d 1 - (0.854 - 0.5 × 0.3 × 0.707) \u003d 0.252.
The bending moment in the flight of the screw along the inner contour, i.e. at the shaft by expression
The screw turns will be made of steel 10, for which the allowable bending stress can be taken equal to the allowable tensile stress, i.e. 125×10 6 Pa. Then the thickness of the screw coil from the formula
s and \u003d ± 6M / d 2
We accept d = 4 mm.
The area of the inner cylindrical surface of the device body at the length of one step
F in \u003d pD (H - d) \u003d 3.14 × 0.14 (0.112 - 0.004) \u003d 0.0475 m 2.
Lengths of development of helical lines
l = 
L= 
l = 
= 0.219 m;
L= 
= 0.454 m.
The surface area of the screw coil at the length of one step
F w = 
F w = = 0.0133
m 2 that satisfies the conditions of work, because. F w< F в.
Torque at two working turns of the screw
M cr \u003d 0.131 n p max (D 3 - d 3) tg a cf
M cr \u003d 0.131 × 2 × 0.2 × 10 6 (0.14 3 - 0.06 3) 0.414 \u003d 54.84 N × m.
Axial force
S \u003d 0.392 n (D 2 - d 2) p max
S \u003d 0.392 × 2 (0.14 2 - 0.06 2) 0.2 × 10 6 \u003d 2509 N.
Normal and shear stresses of the shaft
s s = S/F; t \u003d M cr / W p,
where F is the cross-sectional area of the screw shaft, m 2; W p - polar moment of resistance of the cross section of the screw shaft (W p » ,2 d 3).
s compress = 2509 × 353.857 = 887827 Pa = 0.9 MPa.
t \u003d 54.84 × 23148 \u003d 1 269 444 \u003d 1.3 MPa.
Equivalent voltage
and is within the allowable stress for the material of the screw shaft (steel St 5).
Taking the filling factor equal to unity, from the equation we obtain the angular velocity of the screw
P \u003d 0.125 (D 2 - d 2) (H - d) (1 - K 0) ryw,
where d is the thickness of the screw coil in the axial direction along the outer diameter, m; r is the density of the material, kg/m 3 ; y is the filling factor of the interturn space; w is the angular speed of rotation of the screw, rad/s.
0.85 \u003d 0.125 (0.14 2 - 0.06 2) (0.112 - 0.004) (1 - 0.252) 1041w;
w = 5.06 s -1 (48 rpm).
Now let's determine the dimensions of the blanks of turns and their number. Let the screw length be 6×112 = 672 mm.
Coil Width
b \u003d 0.5 (D - d) \u003d 0.04 m \u003d 40 mm.
Cutout angle in the ring - workpiece
a 0 \u003d 2p - (L - l) / b \u003d 2 × 3.14 - (0.454 - 0.219) / 0.04 \u003d 0.405 rad \u003d 23 °.
The diameters of the rings are determined by the formulas
mm
In the manufacture of a ring - a workpiece without an angular cut, it will be located on the length of the screw, determined by the condition
The number of rings - blanks without a corner cutout is necessary
0.672 / 0.12 = 5.6 pcs.
Practically it is necessary to make six rings - blanks
Literature
1. Karmas E. Sausage technology / E. Karmas. - M.: Light and food industry, 1981. - 256 p.
2. Rogov I.A. General technology of meat and meat products / I.A. Rogov, A.G. Zabashta, G.P. Kazyulin. – M.: Agropromizdat, 2000. – 563 p.
3. Handbook of the technologist of sausage production / I.A. Rogov, A.G. Zabashta, B.E. Gutnik and others - M .: Kolos, 1993. - 431 p.
4. Peleev A.I. Technological equipment of meat industry enterprises / A.I. Peleev. – M.: Agropromizdat, 1963. – 634 p.
5. Technology of meat and meat products / L.T. Alekhina, A.S. Bolshakov et al.; Ed. I.A. Rogova. – M.: Agropromizdat, 1988. – 576 p.
6. Technological equipment for meat processing plants / Ed. S.A. Bredikhina. - M.: Agropromizdat, 2000, - 557 p.
MINISTRY OF AGRICULTURE AND FOOD OF THE REPUBLIC OF BELARUS
BELARUSIAN STATE AGRARIAN TECHNICAL UNIVERSITY
Department of ONIP
COURSE PROJECT
in the discipline “Machines, apparatus and equipment for processing and storage processes with. X. products"
on the topic “Meat preparation complex with the calculation of a meat mixer type L5-FMU-150”
Completed by: student of the 4th year of the 4th group
Domasevich T. D.
Head: Branch A. A.
ESSAY
The course project consists of pages explanatory note, including: figures, tables.
KEYWORDS:
AT term paper the complex for preparing meat is considered.
The operating principle of a meat mixer of the L5-FMU-150 type is described.
A technological calculation of a meat mixer of the L5-FMU-150 type was made.
CONTENT
Introduction………………………………………………………………………………5
1 State of the art and literature review ………………………………….6
2 Description of the meat preparation complex…………………………..12
3 The principle of operation of the meat mixer type L5-FMU-150…………………..13
4 Operating rules and safety requirements…………….15
5 Settlement part
5.1 Technological calculation…………………………………………………..16
5.2 Energy calculation……………………………………………………….17
Conclusion……………………………………………………………………..19
List of sources used………………………………………….
Applications…………………………………………………………………………
INTRODUCTION
Mixing is the process of obtaining homogeneous systems. The need for mixing arises in production when it is required to intensify thermal processes. Mixing can be the main and accompanying process.
Methods of mixing, the choice of equipment for its implementation are determined by the purpose of mixing and the state of aggregation of the mixed media. The most common mixing methods are using agitators of various designs (mechanical), compressed air, steam or inert gas (pneumatic), using nozzles and pumps (circulation), continuous mixing due to close contact in a stream of two or more dissimilar liquids (flow) and etc.
In the meat industry, mechanical mixing is the most widely used. It is used as the main process in the production of sausages, minced canned food, semi-finished products; as a concomitant - in the production of salted and smoked meat products, edible and technical fats, processing of blood, glue, gelatin, organ preparations, etc.
For mixing, equipment of periodic and continuous action is used. The first group includes meat mixers, and the first and second groups - meat mixers. The mixing process in meat mixers and meat mixers takes place both in contact with ambient air (open) and under rarefaction (vacuum).
1 State of the art and literature review
 |
Mixing is the mechanical process of forming a homogeneous product from separate parts of heterogeneous products: bulk, liquid and gaseous.
Mixing is widely used in the meat industry as the main and auxiliary technological processes. The main ones include:
Mixing of two or more components to obtain a given mutual concentration in the total volume.
Mixing products in order to obtain a given consistency in volume.
I Combined process combining mixing and kneading.
As an auxiliary process, mixing is used to intensify thermal (heating, cooling, melting) and mass transfer (salting) processes.
In the sausage and meat-packing industries, after grinding the raw material, it is mixed with the ingredients of the recipes to obtain homogeneous systems. The need for this operation may arise when mixing various components; for kneading raw materials to the desired consistency; in the process of preparing emulsions and solutions; to ensure a homogeneous state of products for a certain time; in the case when it is necessary to intensify heat and mass transfer processes.
The choice of mixing method and equipment for performing the operation is determined by the purpose of mixing and the state of aggregation of the media being processed. There are the following types of mechanical mixing - using mixers of various designs; pneumatic compressed air, steam or inert gas; circulating - using pump H nozzles; flow In continuous mixing due to the intensive interaction in the flow of two or more dissimilar liquids, etc. In the meat industry, the most widespread? mechanical mixing used as the main (in the production of sausages, minced canned food and semi-finished products) or an accompanying (in the production of salted and smoked meat products, edible and technical fats, glue, gelatin, organ preparations, blood processing) operation.
For mixing, mechanical mixers, meat mixers, meat mixers, etc. are used. The first two groups of machines are classified as batch equipment. Mixers can be either continuous or intermittent.
The features of the used meat mixers are associated with the design and location of the actuators (blades) of the mixer, the product unloading units and the materials from which they are made. They are horizontal (trough) and vertical (cup) types. In horizontal meat mixers, the actuating (mixing) body is fixed on a horizontal shaft, and in vertical ones - on a vertical one. In the latter, the mixing body is lowered into the bowl, and in the horizontal meat mixers there are one or two horizontal shafts on which the mixing bodies are located. These organs may be screws, blades or paddles mounted on a rotating shaft. The preferred form of the mixing body of meat mixers, as practice has shown, are Z-shaped blades.
Meat mixers can be with stationary and detachable troughs (bowls). From meat mixers with stationary troughs, minced meat is unloaded through hatches located in the lower end part of the trough, or by tipping it over, and with a detachable thicket - only by tipping it over.
The parts of all meat mixers that come into contact with the product are made of stainless steel. Agitator blades can be solid (stainless steel) and composite, i.e., stainless steel and polymeric materials (fluoroplast, etc.) interconnected. The blades can also be made of steel and coated with food grade tin.
The drive mechanism of the meat mixers is electric, with a reverse, which ensures the rotation of the mixing blades both in one direction and in the other, and without a reverse, i.e., the blades rotate only in one direction.
Figure 1 shows a diagram of agitators and actuators mounted for mixing.
Figure 1 - Scheme of meat mixers of periodic action and executive bodies (blades): a - a mixer with helical blades: 1 - trough; 2, 3 - blades; 4- shaft; b - helical blade: 1.2 - trunnions; 3, 4-blades; 5,6,7 - levers; c - cast blade: / - blade; 2 - bushing; 3- shaft; g - z-shaped blade: 1 - blade; 2 - shaft; e - trough overturning scheme: 7 - trough; 2, 3, 4 - axes; e - mixers with elliptical blades: 1 - trough; 2, 3 - blades: 4, 5 - gears; 6 axis; 7.8 - worm pair; 9 handle
Each meat mixer consists of a trough (Fig. 1, a) in which two counter-rotating helical blades are installed, driven by a shaft.
Screw or other blades are selected so that when they rotate, the minced meat is fed from the edge to the center, and at the bottom the flow is reversed (hand kneading is simulated). The frequency of rotation of the blade 3 on the service side is less (1.3-^ 2.0 times) than the frequency of rotation of the blade 2. Screw blades (Fig. 1, b) are made of all-steel cast with trunnions 7 and 2, which are connected by leading levers 5 and b with blades 3 and 4 curved along a helix. Lever 7 (diametrical) secures the free ends of the helical blades. This design of the blades is quite difficult to cast and process. For simplification, composite oblique cast blades (Fig. 1, c) are proposed, equipped with a split sleeve mounted on the shaft, or composite Z-shaped blades (Fig. 1, d) with an insert shaft.
In batch mixers, the trough receives and dispenses the mixed products. When loading, trough 1 (Fig. 1, e) occupies the lowest position, it is loaded by gravity from the overlying floor, manually or mechanically from the floor of the same floor. When unloading into mobile carts or a hopper, the trough is tilted, and the level of unloading should be located at a height of 0.8-0.9 m. ); around axis 3 with hydraulic and pneumatic tippers, when the drive mechanism is located on one side of the trough, axis 3 is the longitudinal axis of the drive shaft; around axis 4 at mechanical methods overturning (screw and chain devices, worm pair, etc.). The design of the tipping mechanisms is chosen in such a way that when the trough is turned, the clutch in the gears is not disturbed. The most rational for mechanized unloading is tipping around axis 4, when the levels of loading and unloading are the same.
Agitators with elliptical blades for kneading minced meat consist of a rotary trough (Fig. 1, f), in which counter-rotating blades are mounted. The blade 2 has a larger size, the blade 3 rotates inside it. Their counter movement gives a sharp cut of the mass and ensures rapid mixing of the components. The blades are driven by gears. When overturning, the trough rotates around axis 6 with the help of a worm pair and a handle.
Meat mixers open intermittent action with trough overturning have a working capacity of 0.15 and 0.34 m3.
Meat mixers can be with open and sealed containers. The latter are equipped with vacuum pumps. In such meat mixers, the quality of the products obtained is higher than I; the raw materials processed in them have the required color and consistency, as well as a low level of microbiological contamination.
For uniform mixing of several components, three parallel screws are used, which dose the supply of different products to the fourth mixing screw. In screw mixers, the pitch of the helical surface can be constant and variable.
Horizontal mixing devices of meat mixers have two shafts rotating at different angular speeds towards each other. Various blades (helical, Z-shaped, spiral, etc.) are placed on the shafts. The position and design of the blades are selected in such a way that when the blade is raised up, the minced meat is fed from the edge to the center, and when lowered, vice versa. Of the two rotating blades, the leading one has an angular velocity 1.3 ... 2 times less than the driven one. The meat mixer is serviced from the side of the low-speed blade.
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Paddle mixers resemble screw mixers, where the helical surface is replaced by oblique blades. These blades on the shaft form a discontinuous surface, which not only mixes the mass, but also shifts it along the axis of the shaft. Obliquely placed blades may be in the form of a rectangle or a trapezoid, expanding from the center of the shaft. In cross section, the blades are located at an angle of 120° relative to each other.
Spiral mixers are used for mixing different components of minced meat. A spiral is a helical strip of rectangular section, which is cantilevered on a shaft or has support axles at the opposite end. Mounting to the shaft is rigid with a clamp connection. The spirals are placed in the gutters of the bowl, which can be from one to three.
Mixers with Z-shaped and helical blades are most often used in meat mixers. Practice has shown the feasibility of their use, they achieve the most complete mixing effect with a relative simplicity of design. The blade can be made in the form of a section of a curved Z-shaped strip or in the form of a sail. In some cases, it may have a plug-in shaft.
The required technological effect of the operation of mixing meat raw materials primarily depends on the design features and type of meat mixers. Depending on the location of the working bodies, they are divided into vertical and horizontal.
Meat mixers of the first type have a mixing device! fixed on a vertical shaft lowered into the bowl; for meat mixers of the second type - one or two horizontal shafts, on which the mixing working bodies are fixed. The latter may be screws, blades or paddles.
With a two-shaft mixing system, the shafts rotate towards each other at the same or different speeds.
2 Description of the meat preparation complex
A complex of minced meat preparation A1-FLV (Fig. 2) consists of an FLV / 5 unit for mixing and fine grinding of minced meat, which includes mixers
and chopper 5 ;lift 2; mince pump 3; nitrite dispenser 4; power board bunker 7; cooler-dispenser 8; control and management board 9; relay-kinetic shield 10.
Ripened raw materials (beef, pork) from the salting and ripening shop are transported in floor carts to lifts, with the help of which they are unloaded from the carts into the receiving hoppers of the corresponding mince pumps. The stuffing pumps alternately transport raw materials to the weighing hopper, where the required portion is automatically weighed, as well as unloaded into the kneading trough of the mixer, where the required amount of cold water (t = 1 ... 2 C), blood serum (t \u003d 1), a solution of nitrite (t E16 ...! 8 C). The addition of flake ice, bulk components is carried out manually.
After mixing the raw materials with the components for 3 minutes, the finished product is fed by the mixer pump through the meat pipeline to the grinder "of continuous action for further grinding the minced meat. From it, the minced meat is sent along the meat pipeline to the floor cart (when developing structureless sausage products).
Contents of delivery
The delivery set of the A1-FLV/5 meat preparation equipment includes:
unit A1-FLV/5 for mixing and fine grinding of minced meat.
Composed of:
A1-FLV/2 mixer, pcs…………………..1
shredder A1-FKE/3, pcs…………..…..1
K6-FPZ-1, pcs. . ……………………………one
Pump stuffing A1-FLB/3, piece…………1
nitrate A1-FLV/4, pcs ………..1
Weight hopper A1-FLB/2, pcs……………1
Dispenser A1-FLV/3, pcs. . . . ... …………….one
Control board A1-FLB/4-02, pcs. . . ……one
Pipeline, piece………………………..… 3
Operational documentation, copy…….1
3 The principle of operation of the meat mixer type L5-FMU-150
Depending on the method of unloading, meat mixers are divided into machines with a rotary, overturning and fixed container. They are loaded manually or mechanically. In the latter case, the meat mixers are equipped with special hoists-tippers of transport carts.
Meat mixers can be with open and sealed containers. The latter are equipped with vacuum pumps. In such meat mixers, the quality of the products obtained is higher - the raw materials processed in them have the required color and consistency, as well as a low level of microbiological contamination.
Meat mixer L5-FMU-150 has the simplest device and principle of operation, typical for this group of technological equipment. According to its technical characteristics, it belongs to the group of medium-power equipment, which implies its use both at small processing enterprises and at urban meat processing plants.
Meat mixer L5-FMU-150 (Fig. 2) consists of a frame, a container for kneading minced meat, in which two screws rotate towards each other in the form of a spiral, a screw drive and a loading mechanism.
The bed is a cast iron pedestal covered with quick-release facing sheets.
The container for kneading minced meat (dezha) made of stainless steel is closed on top with two lattice-type lids. The augers are driven by an electric motor through a specially designed worm gear.
The loading mechanism consists of a trolley designed to transport raw materials to the meat mixer, and a device for its overturning, mounted in the frame. The overturning device is a system of levers shifted by means of a special worm gear with a separate electric motor. The finished product is unloaded through hatches located at the bottom of the bed. They are opened manually by turning the flywheel clockwise. To speed up the mixing of minced meat, the rotation of the augers is reversed, which is carried out by two buttons on the control panel.
Technical specifications
Productivity, kg/h. . . , 1000
Trough capacity (geometric), m3 ............... 0.15
Load factor..., 0.5-0.8
Cycle duration, min. . . . . . 3-4
Height from the base of the meat mixer, mm:
trough edges........ 1215
unloading. . . ,....., 690
Overall dimensions (with loading mechanism), mm ........... 2350X965X1245
Weight (with loading mechanism), kg. . 990
The meat mixer consists of a bed, a kneading trough, a screw drive, a loading mechanism, a lid, a sliding device and electrical equipment.
Minced meat is mixed with augers in a trough, which is closed with two protective lattice covers.
6.1 Rules for use and safety requirements
Persons authorized to work on the machine must be familiar with its device, know the rules of maintenance and operation and undergo safety training.
Before starting the agitators and mixers, make sure that there is no danger to the operating personnel.
Drives of executive bodies (blades, augers) and overturning of the trough must have a reliable fence. Meat mixers with a tilting trough must have a device that securely fixes it in any position. Meat mixers and meat mixers with end unloading on the hatches for unloading minced meat are provided with gratings interlocked with the starting device and excluding the possibility of the worker's hands getting into the rotation zone of the augers. Covers on hatches must have sealing rubber gaskets and be pressed against the wall with a special handle. Minced meat should be unloaded from the trough of the meat mixer only with rotating blades with the trough in a vertical position and the grate cover closed, leaving a set gap between the trough and the grate for the free passage of minced meat.
It is forbidden to open the safety grate by sticking your hands through it, unload minced meat manually until the blades of the meat mixer come to a complete stop. It is also forbidden to load and add raw materials to the meat mixer when the blades rotate. You can change the direction of the blades only after they have completely stopped. The meat compiler has no right to leave the switched on machine unattended.
It is necessary to keep the workplaces clean, to prevent the accumulation of waste around them.
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5 Technological calculation
Substantiation of design and kinematic parameters of meat mixers
The mechanical process of mixing products is quite energy-intensive and time-consuming, so any rational reduction unit costs energy and duration of the process should be used both in the operating conditions and at the stage of design and construction.
The possibility of intensifying the process of mechanical mixing by increasing the frequency of rotation of the working bodies, changing the configuration of the blades, reducing the capacity of the mixer reservoir, introducing breakwaters, reflectors, etc., has been established.
It is known that for bladed meat mixers, the duration of mixing is inversely proportional to the volume of the working chamber, and the quality of mixing depends on the nature of the installation of the blades on the working shaft.
So, if the blade is installed perpendicular to the direction of its movement, the mass almost does not mix, since the particles of the product encountered in the path of the blade will be repelled in different directions when hitting it: under the action of centrifugal force - mainly horizontally, under the influence of gravity - vertically down.
When the blade is set at a certain angle to the direction of its movement, vertical flows of the product also arise, the direction of which depends on the angle p of the blade. At an angle of inclination greater than 90°, particles hitting the I blade are reflected upwards, at an angle of inclination less than 90° I downwards.
By providing the agitator with several pairs of blades having an inclination and different sides, cross flows can be created and thus intensive mixing can be carried out. The rotational speed of the blades is chosen based on the condition that the centrifugal force of the product should not exceed their weight:
where n is the rotational speed of the blades, s""; R - radius of rotation of the blades, m;
Kpr - coefficient of slippage of product particles relative to the blades, 0.4-0.5.
Determining the performance of Meat Mixers
The productivity of batch-type meat mixers is determined by the formula 
:
where V is the volume of the working chamber, m3; - bulk mass of minced meat, kg/m3; - respectively, the time of loading, processing and unloading, s.
The processing time for a portion of minced meat in 8-10 kg is 80-100 s.
where c is the distance between the inner surface of the working chamber and the blade, c 12-3 mm; / - length of the working chamber, m.
Determining the power of the electric motor of meat mixers
The power of the electric motor of the meat mixers can be determined by the formula:
where P is the force necessary to overcome the resistance created by minced meat, N; o - the speed of the translational movement of the product along the r axis. When mixing minced meat, with a speed of movement of the blade I in the range from 0.3 to 1.5 m / s, the force P can be determined by the formula where a is the resistance to the outweighing of one blade, Pa; Ш - us|®vga[initial resistance of one blade, Pa; a - constant steam< а - 4800-4600 при <т0 = 4-6 Па; F - площадь лопасти, м2; z - количество лопаете:" установленных в одном ряду. The rate of axial displacement of the product by one blade rotating at a constant angular velocity is determined taking into account the friction of the product against the working bodies and the absence of guides according to the formula where a is the angle of inclination of the blade to the axis of the drive shaft; r - radius of rotation of the blade, m; / - coefficient of friction. The coefficient y/ is determined by the ratio where b is the width of the blade. It can be seen from formula (9) that it depends on the width of the blade. If the blade is constant, then it increases with increasing radius. For m where the blade width is equal to the radius
Average translational speed of the product along the mesh axis< определяется по формуле
