TECHNICAL FIELD

The invention refers to a percussion mill used for the transformation of the cereal grains into flour, especially for the obtaining of white wheat flour.

BACKGROUNDART.

There are known percussion mills for cereals, like the hammer mill, that have disadvantage that they can realize only wholeflour, the core and the glume of the grains being ground for the same granulation that can not be modified only by means of constructive changes of the mill. There are known milling plants, like that described in the French patent No. 2.138.074, that use ring roller mills (roller) and that require more grinding and screening steps in order to assure the desired granulation of the grinding, having the disadvantage of a complex construction, with a lot number of equipments disposed on more levels, difficult to be controlled and maintained, requiring the stopping of the installation and constructive changes in order to change the granulation of the final product.

The American patent No.4.461.428 is known, that presents a plant for material grinding and separation of the coarse and fine fractions, the mill having the disadvantage that it uses an air or gas flux in the reverse direction towards the transportation direction through the mill, fact that determines its loss of efficiency : it also has the disadvantage that, during running, the granulation of the resulted product and the efficiency of the installation can not be modified.

There are also known the American patents No. 4.522.342 and No. 4.813.61 that presents two variants of percussion disintegrators that consist of two rotors, provided with crushing pieces, that turn in counter direction, being located in a carcass and having the disadvantages that result from a complicated construction and from the fact that they do not peπnit during running the modification of the granulation of the resulted product, this being possible only be means of construc¬ tive changes of the rotors equipped with crushing tools.

DISCLOSURE OF INVENTION

The percussion mill for cereals, in accordance with the invention, removes the above mentioned disadvantages by the fact that in order to realize the grinding through one single passing with the adjustment possibility, during running, of the granulation of the products resulted from the grinding and of the efficiency, it uses a flap that is driven by means of modifying the output-pressure parameters of the transportation air current through the mill, the flap being located in a carcass, at the cereals flux entrance and cooperating with at least two outlets disposed equidistant on the carcass circumference; the mill consisting also of two rotors provided with some bolts that turn in counter direction with a variable speed or not, each rotor consisting of a constraining disk and a bolts fixing flange, one of the rotors being provided radial with some pairs of threaded equilibrating elements simetrically disposed according to the diameter and equidistant on the circumference and that are blocked in position by means of some blocking bodies in the constraining disks, and opposite to the bolts being practiced frontal channels that have a deflecting zone inclined in a conducting sense of the grinding in the impact zone between the bolts, these bolts having a α conicity. The bolts number (Z _h , Z., Z., Z _k , Z Z _m and Z _n ) from each concentric circle (h, i, j, k, 1, m and n) is divisible by the alignement number in the radial direction Z a connected by ^J the relation (Z, n ,' Z i.,' Z y., Z. k ,' Z„ I' Z m ,' Z iv )

= (4xZ , 5xZ , 6xZ , 7xZ , 8xZ , 9xZ , 1 OxZ ), Z being at the time and the number

SUBSTITUTE SHE

of directions accordind to which the echilibration is carried out. Angle decreasing towards the centre between two bordering bolts disposed on the same circle will be done with a certain value at once with the increase of the circles diameters as follows: for circles (h) and (i): 360°x(l/Z _h -l/Z.); for the circles (i) and (j): 360°x(l / Z-l/Z ); for the circles (k) and (1): 360°x(l/Z _k -l/Z ₁ ); for the circles (1) and (m); 360°x(l/Z _f l/Z _m ; for the circle (m) and (n): 360°x(l/Z _m -l/Z _n ).

The percussion mill for cereals has the advantage of a relative simple construc¬ tion with a low specific power demand, with increased efficiency and with the possibility of grinding nodification, during running, by means of an adjustment flap.

BRIEF DESCRIPTION OF DRAWINGS

Further on is given an example for carrying out the invention in connection with the figures 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11 ; 12; 13; that represent: -fig.l - general assembly -front view; - fig. 2 - general assembly - top view;

- fig. 3 - general assembly - side view;

- fig. 4 - functioning technological sheet of the installation;

- fig. 5 - constructive sheet of the grinding device;

- fig. 6 - structural sheet of the specific operations; - fig- 7 - section along line A^A, realized within fig. 5;

- fig. 8 - section along line A ₂ -A ₂ realized within fig. 5;

- fig. 9 - detail according to A ₃ realized within fig. 7;

- fig. 10 - detail according to A ₄ realized within fig. 8;

- fig. 11 - detail according to A realized within fig. 5, observing the interferance of the rotore provided with bolts;

- fig. 12 - bolt and bolt bore (in detail) before mounting;

- fig. 13 - mounted bolt (detail)

BEST MODE FOR CARRYING CUT

For simplicity, the description refers to the case of wheat milling in an installation (that includes the percussion mill for cerealsin accordance with the invention) composed of a feed system A, a selector B, a vacuum system for transportation and fast mixing of the light impurities C, a vertical decorticator D, a percussion milling device E, in a vacuum system for transportation and fast mixing G, and an electric cabinet H, all these being placed on a support frame I.

The feed supply A is made up of a feed hopper 1 , mounted on a rotative proportioning device 2 that has some vane valve 3 for adjusting the milling rate, being driven in rotation by a chain gearing 4 that takes over the movement from a spindle with conveyer screw 5 connected to a motoreducer 6; on the same spindle 5 is mounted a chain wheel (not represented) that is driving a transfer chain 7 in closed circuit on which are fixed transport blades 8, in a transport and elevation cavity 9; on the upper part of the cavity 9 is mounted another chain wheel (not represented) meant for the extension and turning of the chain 7. On the upper part of the cavity 9 is fixed a magnetic filter for raw material 10, a flexible connectionall that makes the connection to the selector B suspended on some elastic bars 12.

The selector B is fitted with more sieving screens 13, 14 with an inclined boottom 15, with an automatic cleaning system with rubber balls for the screens (not represented), with some accumulators 16 and 17 for impurities of the first category (smaller than the wheat berry) respectively of the second (bigger than the wheat berry) fixed on an own common frame 18. The selector B is fitted with an electric driving motor 19, with a belt gearing (not represented) between the motor 19 and an excentric flywheel (not represented) that generate together the sieving move- ment. The selector B has an enterance a for the raw material and outlet b for the selected wheat and more outlets for the impurities, namely: c for light impurities, where it takes place the connection by means of a flexible connection (not represented) with the vacuum system for transportation and fast mixing of the light

impurities C, and each one (not represented) for heavy impurities of the firs category and respectively of the second, collected in a sack 20, respectively 21

The decorticator D is made up of an upper part 22, a sight 23 and an inferior par

24 provided with air admission slits (not represented) that are fixed together. Th decorticator D has an inferior cavity 25, of a certain volumetric capacity, withi which a spindle 26 is turning of that are fixed some mixing blades 27 and a woπ 28. The spindle 26 is driven in rotation by the electric motor 29 assuring the fillin of the cavity 25 with wheat that was selected transported in the activ zone of th worm 28 from the zone of an entrance slit d in the decorticator D by a horizonta worm 30 driven by a motoreducer 31. The decorticator D has a slit e for absorbtio through the vacuum system C of the impurities resulted after decortication and a outlet slit for the decorticated wheat. On the inferior part of the cavity 25 i provided a vane valve not represented for the emptying of wheat of the cavity 2 through the slit g. The decorticator D is connected to the milling device E by faucet 32 fitted with a magnetic filter for protection 33 and a controll sight 34.

The milling device E is make up of a carcass 35 and cover 36 connected wit an articulation 37 and a boll 38. On the carcass 35 and on the cover 36 is fixed eac an electric motor 39 respectively 40, with or without variable speed, on wich shaf ends are mounted each a rotor 41 and respectively 42 in which are mounted som bolts 43 disposed on more concentric circles as for example: h, |; j; k; 1; m and n The rotors 41 and 42 turn in counter direction. In the carcass is practiced a entrance slit o for the decorticated wheat, fitted with an adjustment flap 44 of th surface of the slit o and one with more outlets p disposed equidistant on the carcas circumference 35. The rotor 41 has some access slits (not represented) of the whea from the central zone in the active zone between the bolts 43.

The transportation and fast mixing system of the grinding F consists of transport faucet 45 fitted with a control sight 46, of a cyclone 47 and of motoblower 48 having and outlet g towards a filtering system 49 fitted with som

fllters 50 that hold the upsetted flour powder together with the transport air of the grinding. The ciclone 47 has in the inferior part a slit r by means of which the fast mixed grinding arrives, through a control sight 51 , to a lock 52 fixed on the flour separator G. The flour separator G is made up of an exterior coat 53 in which the grinding entered through a slit s from the lock 52 is transported by a worm 54 fixed on a spindle 55, spindle on which are mounted and some mixing blades 56, disposed helical, that generate the sieving and feed motion on the surface of a tubularfix screen 57. The separator G is provided with three outlet slits; t for the bran that will be collected in a sack 58; u for flour of second quality that will be collected in a sack 59 and v for flour of first quality that will be collected in a sack 60. Also, the separator G is provided with a visiting cover 61 and handle 62, handle that peπnits the adjustment of the qualitative proportion between the two obtained flour qualities. The sack 58, 59 and 60 are fixed on the separator G by a clamping device (not represented). On the separator G is fixed an electric motor 63 on whose spindle is a pulley wheel 64 coupled by a belt 65 to a wheel 66 fixed on the spindle 55. On the same spindle 55 is fixed another pulley wheel 67 coupled by a belt 68 to a spindle with pulley wheel 69 belonging to the rotative lock 52.

The vacuum transportation and fast mixing system of the impurities C is made up of a transport faucet 70, that will be conected by a choke 71 respectively 72 to the slit c of the selector B and respectively to the slit e of the decorticator D. The faucet for transport 70 is connected to a cyclone 73, and this one to a motoblower 74 that has a outlet slit in the atmosphere w. The cyclone 73 has an entrance slit x, a connecting slit to the motoblower 74 and a slit z through which the fast mixed impurities are collected in a sack 75 fixed on the inferior part to the cyclone 73 by means of a clamping device (not represented).

The electric cabinet H assures the control functions of the component units of the installation, protection functions of these for overload and warning functions, by means of a siren, 76 in case of damages.

INDUSTRIAL APPLICABILITY

There are mentioned further on the functioning of the installation in accordance with fig. 4, the constructiv-functioning paticularities of the above described components being underlined. The wheat is introduced in the feed system A, in the hopper 1 from where it is taken over by the rotative proportioning device 2, being driven in rotation by the gearing 4, that takes over the movement from the spindle with coveyer 5 connected to the motoreducer 6. The wheat output will be adjusted by opening a certain number of vane valves 3. The wheat is taken over by the spindle with conveyer 5 till the transfer chain 7, being driven by a chain wheel (not represented) from the same spindle 5, chain that by means of the blades 8 will transport it on the route marked by a dashed line in fig.4 to the selector B, passing it through the magnetic filter for raw material 10 and through the flexible connection 11.

Within the selector B the wheat that was introduced will be separated into selected wheat and impurities after the dimensional criterion, by sieving on the screens 13 and 14 and after the criterion of specific weight. The sieving movement is a quasioscillatoring one (pseudo-oscillating) of the selector B suspended by the bars 12 on frame I, generated by the rotation of an excentric flywheel (not represented) driven by the electric motor 19 by means of a belt gearing (not represented). The particles that do not correspond dimensionally are evacuated on the routes marked by solid line in fig. 4 in the sacks 20 and 21. The wheat falls by an ascendent air current, adjusted by the choke 71 , that takes over the light impurities by means of the slit c in the system C on the route marked in fig. 4 by full line. The selected wheat falls through the slit b of the selector B. The wheat enters into the decorticator D through the slit d of the decorticator, being transported by the worm 30 driven in rotation by the motoreducer 31 , in the active zone of the woπn 28 which at the rotation of the spindle 26 fills the interior cavity 25 in that are turning the mixing blades 27 by th same spindle 26 connected suBsrrruTs SHEET

to the electric motor 29. When the volumetric capacity of a certain value of the cavity 25 was exceeded, the wheat falls by overflowing between this and the elements 22, 23 and 24, that enclose it, in an ascendent air current started from the inferior base 24 through some access openings (not represented). This air current has the effect of taking over the impurities detached by the friction of the wheat berries and of exhausting them by the slit e, on the route marked by full line in fig.4, in the system C. The wheat, being separated from impurities, passes on the route marked by dashed line, through the faucet 32 over the magnetic protection filter 33 and enters in the milling device E. During running the rotor 41 and 42 turn in counter directions. The vacuum system for transportation and fast mixing of the grinding F, connected at the outlets of the milling device E realizes an air current of certain output and pressure parameters between the slit o for entrance and the output slits p of the milling device E. By means of correlation the speed of the transport air current between the slits o and p with the speed of rotation of the rotors 41 and 42 and by means of bolts agglomeration variation together with the variation of the location diameters (h, i, ϊ, k, 1, m, n) the gradual breaking of the wheat berries will be carried out by the impact with the bolts 43. The modification of the transport air current speed will be done by modifying the ouput and pressure parameters of this current together with modifiying the section of slit o by manual rotation of flap 44. By this correlation will be realized the uniformization of the breaking effect within the entire mass of the resulted grinding. Because of the structure of the wheat berry, characterized by resilient and density differences between the component parts of it, by the same impact practised on the wheat berry, diferences of granulation among the grinding parts will be obtained. The changing of the position of flap 44 during running of the mill determines the modification of the grinding granulation at the desired fineness. SUBSTITUTE SHEET

An additional facility for modifying the percussion value during running that determines the granulation variation is undrlined. The percussion can have modifiable values, if the electric motors 39 an 40 are provided with a system that assures the speed variation. The speed variation possibility can or can be not connected to an automatization system in connection with flap 44. The resulted grinding is taken over at the outlets p by the system F that transports it on the route marked by a thick dotted line and that mixes it fast. The air, as a transport fluid, and the flour powder are separated by the outlet g from the cyclone 47, being conducted towards the filtering system 49 in the route marked by a fine dotted rule. The fast mixed grinding passes through the inferior part r of the cyclone 47, through the sight for control 51, through the rotative lock 52, passing through the slit s in the separator G.

The worm 54 transports the fast mixed grinding in the sieving zone of the tubular screen 57, where the blades 56, disposed helical, generate the sieving motion. The grinding is separated into flour and bran. The flour according to the dimension of the meshes of the screen, passes in two categories into the sacks 59 and 60 through the slits u and y, on the routes marked by thick wav} ule. The bran passes in the sack 58 through the slit t on the route marked by fine wavy rule.

Adjusting correspondingly, by the chokes 71 and 72, the air output through the slits c and respectively e, the system C assures the separation of the light impurities according to the principle of floating speed different of that of the wheat berries. The light impurities (with low floating speed) are transported, on the route mareked by full line, through the faucet 70 in the cyclone 73 and are evacuated in the collector sack 75 through the slit z. The transportation air is evacuated in the atmosphere through the slit w of the motoblower 74.

Summarizing, the installation assures the following operations (see fig. 6):

I - proportioning, carried out by the rotative proportioning device 2;

II - elevation, carried out by the transfer chain 7;

- lo ¬ rn - magnetic filtration, carried out by the filter 10;

IV - impurities separation according to the dimension and specific weight, carried out by the selector B;

V - partial decorticator, carried out by the decorticator D; VI - grinding by a single passing, carried out by the milling device E;

VII - vacuum transport and fast mixing of the grinding, carried out by the system

F; Vπi - vacuum transport and fast mixing of the impurities, carried out by the system C; IX - separation through sieving of the constructive parts of the grinding, carried out by the separator C. Further on we underline the constructive particularities of the milling device E in connection with fig. 5 and figures, 7, 8, 9, 10, 11, 12 and 13.

A modality to remove the casual disequilibriation that can appear in running as a result of the replacement of the woπn out bolts during running in the radial displacement of some threaded parts 77.

After the equilibration of the parts 77 in position with some parts 78, also threaded, and the threaded seats are fille with some covers 79 flushed in the blades 80 practiced in the rotors 41 and 42. In order to allow the parts 77 to carry out some radial travel sufficient to carry out the equilibration, it is necessary of a certain number Z _a of alignment in the radial direction of the bolts mounted on the circles diameter h, i, j, k, 1, m and n in number of Z _h , Z., Z., Z _k , Z., Z _m and Z _n . These will be carried out by selecting the values Z _h , Z ι.,' Z j.,' Z, k ,' Z„ I' Z m ,' Z n ,' in order to be divisible by •> the value Z a . In order to obtain an uniform breaking effect of the wheat when passing from one row of bolts to the next one it will be established a decreasing increment of the angle toward the rotor centre, between two bordered bolts disposed on the same circle, corresponding to the desired granulation.

By means of the angular increment value and of the bolts number Z _h , Z., Z., Z _k , Z,, Z _m and Z _n it will be determined the diameters value corresponding to the circles h _> h X, , 1, m and n. The rotor 41 and 42 consists each of a constraining disk 81 respectively 82 and of a flange 83 respectively 84 for the frontal fixing of the bolts, being strenghtened by some screws 85 and secured by pulleys 86.

Opposite to the bolts, in the disks 81 and 82 are practiced frontal channels that have a deflecting zone inclined in the conducting sense of the grinding in the impact zone between the bolts.

In order to assure a secure running there are not permitted clearances between the bolt 43 and the constraining disk 81 (82). Because of the fact that a classical assembly with clamping will lead to the accumulation of remanent voltages in the disks and bolts, there is used an assembly solution through broaching the bolts in the disks. The constraining assembly bolt-disk will be done at the nominal quota d,. The bolt 43 is realized with a reverse conicity α, having the big cone diameter executed at the value d,. The constraining disks 81, respectively 82 have bores executed at the value d^, smaller than d,, but bigger than the value (^ of the active part of the bolt. When the bolt is introduced into the bore a material layer splinter- shaped 88 will be removed, the bolt remaining constrained without clearance and local low remanent voltages. In order to align the bolt into the bore (the layer being uniform on the bore circumference) it is executed a chamfering 89. The taking over of the x layer splinter-shaped is possible through the adequate hardness value of the bolt 43 and the constraining disks 81 (82).

The bolts 43 are heat treated and/or thermochemical in order to have a surface of increased hardness associated to a core of tenacity.

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