FR2515001A1 - Small automated bakery installation for prodn. of french bread - allows single unskilled operator to produce fresh bread in one hour - Google Patents

Abstract

An automated process and installation for bakery prodn. of loaves of French bread. The installation is of the type which comprises a flour silo and a kneading machine into the bowl of which are automatically measured supplies of flour, salt, yeast, water and gas. Dough is passed to a dividing and forming machine from which dough pieces are converted to an oven. The kneading machine has a variable speed drive and the kneading cycle is programmed as follows 1. 45 R.P.M. for 5 minutes as flour, cold water and yeast are measured into the bowl. 2. High speed, e.g. 130 R.P.M. kneading for about 13 minutes as an oxygenated gas is blown in. Salt is dosed in towards the end of this stage. 3. Five minutes with machine stopped to allow dough to settle. 4. 15 R.P.M. operation to discharge dough through an outlet in the base of the bowl. The bowl outlet has a power cylinder actuated shutter which is only opened to discharge dough. The outlet leads into a screw conveyor discharging via an automatic guillotine which cuts off dough pieces. The installation is viable for small bakery units requiring an output of French bread corresp. to only one or two 50 kg. sacks of flour.

Description

Process and installation for automated production of French bread.

 The subject of the present invention is an automated manufacturing process and installation making it possible to debit batches of a determined number of fresh French breads.

 The technical sector of the invention is that of the production of French bread and automated bakery installations.

 It is recalled that the so-called French bread consists essentially of wheat flour, water, salt and yeast. Improvements such as ascorbic acid or vitamin C are tolerated in reduced amounts.

 It will be recalled that the traditional production of French bread comprises the successive operations of kneading the mixture, of initial mass fermentation or "pointing", of rest, of division of the dough into dough pieces of determined weight and shape, of final fermentation or " sprout ", counterbore or transverse incision of the dough pieces and baking. These successive operations require several hours.

 Various methods have been proposed to reduce the duration of these operations in mechanized installations.

 A first modification of the traditional process was made thanks to the mechanical kneading of the dough which made it possible to carry out a so-called rapid or intensified kneading at 80 revolutions / minute for 20 to 25 minutes.

 While the pointing time is three to four hours if you knead by hand or slow kneading, it is reduced to a time between half an hour and an hour and a half after rapid kneading.

 Another improvement has been made in terms of baking ovens by using rapid baking ovens in which the crumbs are cooked separately, for example in a microwave oven and the crust by infrared radiation.

 Such an oven is described for example in the FR patent. AT.

2,443,205 (78.34689) (Electricité de France).

 Semi-automated bread making facilities have been proposed.

 Thus the FR patent. A. 80.03215 (Perfluktiv-Consult AG) describes a process and an installation in which, starting from the dough after standing, it is divided into dough pieces which are placed in molds. The mussels are then placed in an oven for the first cooking. Then, after possible preservation in a freezing chamber, the dough pieces pass through a doser which fills the molds which pass in a final baking oven.

 Mechanical kneaders with different improvements have been proposed.

The FR patent. 1,194,565 (LOISELET Foundries and Workshops and
VERNOUILLET) and patent DE - B - 1,200,763 (GL EBERHARDT) describe mechanical kneaders with rotating bowl and oblique mixer arm which include means for introducing air into the dough during kneading.

 An objective of the present invention is to provide automated installations for manufacturing French bread having a reduced size and a production capacity which corresponds to the needs of a traditional point of sale, that is to say a corresponding daily sale. to one or more bales of flour weighing 50 kilograms, whereas the automatic installations known to date are real bread factories which require a large daily sale in order to be depreciated.

 Another object of the present invention which follows from the previous one is to provide automated bread-making installations which, thanks to their reduced size, can be installed in a retail bread shop or on a truck to constitute mobile installations which can be brought to a place of seasonal consumption, for example near a campsite, or which can be exported in the form of a complete manufacturing unit ready to be used abroad to make French bread without requiring any specialized staff.

 Another object of the invention is to provide breadmaking units which require the presence of a single person, at the cash desk, who distributes the fresh breads coming out of the installation ready in batches which correspond for example to a bale flour.

 Another objective of the present invention is to provide an automated bread-making installation capable of delivering fresh breads within a period of between half an hour and one hour after being started, which makes it possible to program the bread-making cycles for that they precede the distribution by about an hour and therefore constantly sell fresh bread. In addition, this very short period allows new production cycles to be launched according to the sales flow to avoid accumulating unsold products at the end of the day which must be annealed.

Another objective of the present invention is to provide an automated bread-making installation, which makes it possible to manufacture French bread without having to add to it reducers or oxidants prohibited in the composition of French bread, which differentiates the process and the installations according to the invention of certain industrial manufacturing techniques, practiced outside
France, which shorten the stage of biological maturation of the dough during mass fermentation by substituting a development of the dough based on chemical additives which result in breads whose organoleptic qualities are very altered.

 The installations according to the invention include devices such as kneader, extruder dosing machine, pusher chamber, two-stage oven which are known but it combines these devices in a new way by improving some of them and it uses them according to a new process with particular regard to the kneading operation which is fundamental for the development of the fermentation and the duration of all the operations leading from kneading to baking the bread.

 The kneading operations take place in a mechanical kneading machine having a fixed bowl, the bottom of which has gas injection orifices, and a rotating arm which is rotated by a multi-speed motor, which bowl is equipped with automatic distributors alone, yeast and water and receives the spill from a transporter that connects it to a flour silo.

A batch kneading cycle has the following steps, which are controlled automatically
- said motor is started at low speed, of the order of 45 revolutions / minute, for approximately 5 minutes and, during this first step, said conveyor is automatically started and the cold water supply is supplied for the duration wanted to introduce into said tank a determined quantity of flour and the quantity of water necessary for kneading the latter;
- At the end of this first step, a dose of yeast is introduced into said tank;
- In a second kneading step, said motor is made to rotate at high speed, of the order of 130 revolutions / minute for approximately 13 minutes;
- a few minutes before the end of this second step, a dose of salt is introduced into the tank;
- During the second step, a gaseous mixture containing oxygen is injected into the bottom of the tank, through the orifices;
- In a third step, said motor is stopped for approximately 5 minutes to allow the dough to stand;
- In a fourth step, said motor is rotated at very slow speed, of the order of 15 revolutions / minute, in order to evacuate the paste by an orifice located in the bottom of the mixing tank.

 The installations for the automatic production of French bread according to the invention are of the type comprising a kneader having a fixed tank, the bottom of which has gas injection orifices and a rotating arm which is rotated by a motor at several speeds, which tank is equipped with automatic, yeast and water dispensers and receives the spill from a transporter which connects it to a flour silo.

 In an installation according to the invention, the kneader tank is fixed and has at its bottom an orifice which is closed during kneading by a shutter driven by a jack and comprises an extraction device comprising a cylinder with horizontal axis having, at the rear end, an opening which communicates with said orifice and an endless screw which is rotated inside said cylinder and the front end of said cylinder comprises a movable knife perpendicular to the axis of the cylinder and a movable stop which is equipped with a limit switch which automatically controls said knife.

 According to a preferred embodiment, the fixed bowl of the kneader comprises a rotating cover which carries a motor driving in rotation a mixing arm and which also carries a shaft, which shaft carries a pinion which meshes with a pinion driven by said motor and a roller which rolls on a fixed raceway, so that said mixing arm rotates both around its axis and around the tank.

 The invention results in the automated production of French bread in automatic installations with a small footprint.

 An installation according to the invention makes it possible to automatically manufacture batches of French bread, for example batches of baguettes of 200 grams, in a relatively short time and without any manual intervention. Between the time when a kneading cycle begins and the time when the cooked baguettes come out of the oven, there is an hour or so. In addition, we can keep in a fermentation chamber doughs already kneaded for a period of between half an hour and a few hours and as the baking lasts between 15 and 30 minutes we can get a new batch of fresh bread, about half hour after ordering it.

 Bread sales outlets equipped with an installation according to the invention may therefore only sell fresh bread by launching the new batches at the rate of sales.

 An important advantage of the automatic installations according to the invention is that they can be designed to process batches corresponding for example to 50 kg of flour, that is to say in the range of conventional artisan bakeries.

 The installations according to the invention can therefore cost-effectively equip retail outlets with a sales flow comparable to that of artisan bakeries.

 Another important advantage of the installations according to the invention is that they are compact and can therefore be accommodated in a small room adjoining a point of sale or even on towed trailers or on a truck to serve seasonal outlets or to be exported.

 A production cycle of a batch of French bread by an installation according to the invention takes place entirely automatically, without any manual intervention from the loading of the kneader to the exit from the oven. The succession of cycles can also be programmed.

 An installation according to the invention, equipped with a kneader capable of kneading 50 kg of flour, which is a relatively small kneader, can nevertheless allow a significant daily production if it is equipped with a fermentation chamber with two internal conveyors which serves buffer storage between the kneader and the oven.

In this case, the kneader can operate continuously, at the rate of 50 kg of flour every half hour.

 The advantages of the installations according to the invention derive from the overall design of the kneader. This is equipped with an extractor-doser located under the fixed bowl of the kneader which allows the operation of emptying the kneader without loss of time and obtaining at the exit of the kneader dough pieces in which the final fermentation or sprout can start right away.

 A kneader according to the invention provided with a rotating cover which carries the kneading arm makes it possible to obtain a homogeneous kneading of the dough while using a fixed kneading tank which facilitates the automatic introduction into the kneader of the flour, the water, single, yeast and gas.

 The design of the mixing tank bottom with perforations allows oxygen-laden gases to be injected into the dough, which accelerates the mass fermentation which begins in the kneader. The perforations also make it possible to inject gases to control the temperature of the dough during kneading.

 The hydrostatic motor at low speed which drives the mixing arm and the cover allows kneading to be carried out in several stages, one of which at high speed of the order of 130 revolutions / minute, which has the effect of reducing the time global kneading.

 The following description refers to the appended drawings which represent, without any limiting nature, an embodiment of an installation according to the invention.

 FIG. 1 is a diagram, in the form of a block diagram, which represents the combination of devices and operations occurring successively in an installation according to the invention.

 FIG. 2 is an overall diagram of an embodiment of an automatic bread-making installation according to the invention.

 Figure 3 is an elevational view of a fermentation chamber which can optionally be inserted between the kneader and the molding machine.

 Figures 4 and 5 are vertical sections of a kneader fitted to an installation according to the invention.

 Figures 6 and 7 are vertical sections of automatic yeast and salt dispensers.

 Figures 8 and 9 are a top view and an elevational view of a dough lamination apparatus.

 Figure 1 shows a silo 1 containing a stock of wheat flour. This silo 1 includes a hopper extractor which pours into a mechanical kneader 2. The kneader 2 is equipped with an automatic salt distributor 3, an automatic yeast distributor 6, a unefontaine 5 which delivers cooled water and an air diffuser 6 which diffuses air or a mixture of air and oxygen into the dough during kneading. The kneader 2 fulfills the functions of kneader, reactor, fermenter and air diffuser.

 The lower part of the kneader is equipped with a device for extracting the dough, which divides the dough into calibrated dough pieces and which distributes the dough pieces on a carpet which feeds the rest of the installation.

 In the case where the duration of the cooking is greater than the duration of kneading and where it is desired to use the kneader at a continuous rate, it is necessary to place an intermediate storage at the outlet of the kneader. This consists of a fermentation chamber 7, shown in dotted lines, in which the growth operations take place, that is to say the fermentation of the dough pieces which makes them swell.

 As a variant, it is possible to omit the fermentation chamber 7 and to pass the dough balls into a ball leaving the dough extractor cutter associated with the kneader directly in a shaping machine 8 where the dough pieces are shaped.

 The dough pieces come out of the shaping machine 8 on a conveyor on which they undergo the counterbore operation 9 which consists in printing oblique cuts on the dough piece. After which the dough pieces enter a baking oven 10. After a stay in the oven sufficient, fresh breads are stored in a storage store 11 for retail sale.

 The reference 12 represents the cash register, where the person in charge of the retail sale is located, which is located near the storage store 11. The person located at the cash register has a programmer which he can adjust at the start of a day of sale so that it triggers successive cycles during each of which a determined number of loaves, for example 250 loaves of 200 grams, are produced automatically, according to a program which corresponds to the flow of the sale.

 As a variant, the cashier may have a push button which allows her to trigger the start of a new manufacturing cycle for a determined number of loaves or else a baking cycle each time the stock located in the store 11 falls to a level which corresponds to the probable sales rhythm during the duration of a manufacturing cycle.

 During a batch production cycle, for example a batch of 250 baguettes weighing 200 grams, the programming unit automatically controls the kneading stages and the running of the conveyors connecting the devices together, the operation of the oven and the various appliances.

 FIG. 2 schematically represents a detailed view of an installation comprising the successive devices indicated on the block diagram of FIG. 1. We find on the left of FIG. 2 a flour silo which is a vertical hopper which is supplied for example by flour transport vehicles equipped with a pneumatic transfer which are connected to a stripping tube la. Silo 1 has a capacity which corresponds to the minimum weight of flour which can be delivered in bulk by truck with pneumatic unloading.

Silo 1 is equipped with a filter lb which allows the automatic filling of the silo from a truck. The silo 1 is equipped with a high level sensor îc and a low level sensor Id which are for example capacitive sensors or any other equivalent sensor. It may also include a low level alarm.

 The bottom of the silo 1 is equipped with an extractor 13, which consists for example of several endless screws or of several wires wound in a helix which are placed in a box with a flat bottom.

 The extractor 13 brings the flour to a conveyor 14 which is a metering conveyor which delivers, at a determined driving speed, a constant weight of flour per unit of time.

 The conveyor 14 pours into the fixed kneading tank of the kneader 2. By adjusting the operating time of the extractor 13 and of the conveyor 14, the weight of flour which is sent to the kneader at the start of a cycle is determined. For example, using a conveyor 14 having a flow rate of 1,000 kg / hour and operating it for 3 minutes during which it sends 2.50 kg of flour into the kneader. The extractor 13 and the conveyor 14 are advantageously constituted by flexible helicoids composed of wires wound in a helix and driven in rotation by one of their ends.

 The kneader 2 is advantageously composed of a fixed mixing tank, closed by a rotating cover 56 which carries a hydraulic motor 63 at slow and adjustable speed which drives both a mixer arm and the cover. This kneading machine is described in detail with reference to FIGS. 4 and 5.

 The fixed tank includes an automatic distributor of salt 3 and yeast 4. A fountain 5 delivers fresh water at a temperature of a few degrees centigrade. The fountain 5 feeds the kneading tank by a pipe 77 and it also feeds a cooling coil of the yeast tank 4.

 The bottom of the kneader has a gas inlet 6 which allows air or vitamin oxygen or gaseous reagents to be injected into the dough during kneading.

 The bottom of the kneading tank is also connected to a pipe 15 which comes from a boiler located in the cooking oven and which makes it possible to inject steam into the tank to clean and sterilize it once a day. Line 41 is used for the evacuation of steam condensates, if necessary with a pump.

 The kneader tank includes a probe 98 for measuring the temperature of the dough and a probe 99 for measuring the humidity of the dough.

 The bottom of the kneading tank communicates with a screw extractor 46 which extracts the kneaded flour in the form of rolls which are cut into dough pieces of determined length and weight, for example into dough pieces of 300 g having the general shape of a ball .

 The dough pieces leaving the extractor 46 fall on an endless conveyor 16 which is composed of two belts inclined towards each other forming a rounder which brings them to the top of a shaping machine 8 of a known type, which shapes the dough pieces raised to give them their final shape, for example the shape of elongated cylindrical rods.

 The moulder is capable of shaping 250 dough pieces of 300 grams in 30 minutes.

 The doughs leaving the shaping machine 8 are taken up by an endless conveyor 17 which brings them to another endless conveyor 18 which enters a baking oven 10.

 Above the conveyor 17 is placed an apparatus 9 for automatic continuous countersinking which prints on each dough several oblique cuts.

 A preferred embodiment of the counterbore 9 is shown in FIGS. 8 and 9.

 Advantageously, the cooking oven 10 is a tunnel oven of a known type comprising a first compartment 10a which is a microwave oven, which cooks the crumb in depth, followed by a second compartment 10b which is an infrared oven who cooks the crust.

 The speed of the conveyor 18 is such that the dough pieces remain between 15 and 30 minutes in the baking oven and that the conveyor delivers 250 baguettes of 200 grams at the outlet of the oven, in 15 or 30 minutes. The storage 11 which receives the cooked baguettes is not shown in FIG. 2.

 FIG. 3 represents a fermentation chamber 7 also called the rest or growth chamber, which can be interposed between the outlet of the kneader 2 and the molding machine 8 and which is shown in dotted lines on the block diagram of FIG. 1.

 In this case, the divider 46 located at the outlet of the kneader pours onto an endless conveyor 19 which is capable of transporting 250 dough pieces of 300 g in 7 minutes which is the time for emptying the kneader.

 The fermentation chamber 7 comprises a vertical enclosure which is equipped with at least one endless conveyor 20a.

 The conveyor 20a carries suspended swings 21 in each of which is placed a dough piece of 300 g. The conveyor 20a carries 250 swings and can therefore receive all of the dough pieces leaving the kneader after a kneading cycle.

 If you want to be able to use the kneader 2 at full capacity and start a new kneading cycle as soon as the previous one is finished, that is to say a kneading cycle of 50 kg of flour every half hour, the fermentation chamber 7 comprises two identical swing conveyors 20a, 20b, situated in two parallel vertical planes and the front end of the conveyor 19 comprises a switch 22 which makes it possible to direct the dough pieces towards one or the other of the two conveyors 20a or 20b. The two conveyors are poured, by reversing the swings, onto a very wide conveyor 23 which brings the dough pieces towards the shaping machine 8.

 There are already known fermentation chambers equipped with a single swing conveyor.

 By equipping these chambers with two parallel conveyors 20a, 20b, the operating cycle of the kneader is dissociated from the operating cycle of the oven by an intermediate storage chamber 8 in which the dough pieces remain for half an hour and during this time the fermentation and lifting of the dough pieces.

 The fermentation chamber 7 equipped with two conveyors makes it possible to quickly empty the kneader 2 in 7 minutes, in one of the conveyors 20a which then remains at a standstill while the second conveyor 20b pours out in 30 minutes in the shaping machine which feeds the oven at the same rate. At the end of a new kneading cycle of 30 minutes, the second conveyor 20b is ready to receive the dough pieces leaving the kneader while the first conveyor 20a feeds the moulder and the oven.

 The presence of a fermentation chamber 7 equipped with two swing conveyors therefore makes it possible to obtain a maximum capacity of 500 baguettes of 200 grams per hour, which is the capacity of the oven.

 If the hourly flow of the point of sale is lower, one can use a fermentation chamber 7 comprising only one conveyor 20 with swings. In this case, after a kneading cycle, the kneader is emptied in 7 minutes in the conveyor belt, the dough pieces are left in the fermentation chamber for a determined time, then the swing conveyor 20 is started. slower speed which corresponds to a flow rate of 250 dough pieces in 15 or 30 minutes which is that of the oven. After which the swing conveyor 20 is ready to receive dough pieces again coming out of the kneader.

 FIG. 4 is a vertical section of a preferred embodiment of a kneader 2 fitted to an installation according to the invention.

 Figure 5 is a vertical section of the kneader according to Figure 4 shown in position of the raised cover.

 The kneader 2 according to FIGS. 4 and 5 is a mechanical kneader which comprises a fixed mixing tank 30 which is of revolution about a vertical axis z z1. As can be seen in FIGS. 1 and 2, the mixing tank has a known shape, which is that of a half-torus which is extended by a column or central sleeve 30a which surrounds the axis z zi and the tank 30 has at its upper part an annular opening.

 The bottom of the tank 30 has a plurality of small holes 31 which are conical holes with walls which converge upwards.

 The bottom of the tank 30 further comprises an opening 32 which is intended for the discharge of the dough.

 During kneading, the opening 32 is closed by a shutter drawer 33 which is moved in a horizontal plane by a jack 34.

 Figure 3 shows the shutter in the open position while Figure 4 shows the shutter in the closed position.

 The holes 31 are arranged over the entire part of the bottom of the tank which is not occupied by the opening 32.

 The tank 30 is placed on a fixed frame 35 which carries a fixed plate 36 provided with vertical edges 37 which support the bottom of the tank and which delimit with it a chamber 38.

 The chamber 38 is connected to an inlet 40 for gas, for example compressed air or a mixture of air and vitamin oxygen.

 Advantageously, the gas arriving via the line 40 is a gas at regulated temperature and hygrometry.

 A pipe 41 is connected in the bottom of the chamber 38 to evacuate the liquid which condenses in the chamber.

 A movable plate 42 is located in the chamber 38. The plate 42 is supported by the piston 43 of an axial cylinder which makes it possible to move it vertically. The plate 42 carries, on its upper face, a plurality of vertical needles 44 whose upper end is a point. fine. The needles 44 are arranged opposite the holes 31 in the bottom of the tank, so that when the plate 42 is in the high position, the needles 44 close the holes 31 and seals provide sealing.

 When the plate 42 is in the low position, the holes 31 are opened and the gaseous mixture which arrives via the pipe 40 in the chamber 38 can diffuse under pressure into the mass of dough located in the mixing tank 2.

 The fact that the tank 2 is fixed allows it to be easily fitted with a movable plate 42 carrying needles 44 for closing and unblocking holes 31 used for injecting a gaseous mixture into the dough during kneading .

 The chamber 38 and the holes 31 make it possible to inject air or oxygen-enriched air into the dough during kneading, so that the yeasts are placed in aerobic fermentation conditions, which allows d accelerating the maturation of the dough and makes it possible to reduce the duration of stay of the dough in a rest or growth chamber and can make it possible to eliminate any growth chamber, the maturation operation then taking place in the kneader.

 The rapid kneading of the dough leads to a sharp increase in temperature which is likely to be detrimental to the good quality of the dough.

 The holes 31 and the chamber 38 allow a gaseous mixture to be injected into the dough, the flow rate of which can be varied as a function of the temperature and the humidity of the dough measured by temperature and humidity probes in order to maintain this temperature constant or below a threshold regardless of the quality of the flour and the climate of the country.

 Controlling the temperature during kneading is very important for the quality of the bread obtained. The height of the movable plate 42 can also be varied, which makes it possible to vary the flow rate of gas passing through the orifices 31 and this flow rate can be adjusted as a function of the temperature of the dough to keep the latter substantially constant or within specified limits.

 FIG. 3 represents the movable plate 42 in the high position while FIG. 4 represents it in the low position.

 A spring 45 exerts on the movable plate a force antagonistic to that of the jack 43 to bring the plate back to the lower position.

 The jack 43 carries a rod 43a which passes through a vertical slot in the jack body and which projects outside to indicate the position of the piston.

 A kneader according to the inventon is equipped with an extraction device 46 which communicates with the orifice 32 and which makes it possible to extract the dough, after kneading, in the bottom of the kneader and to divide it into calibrated pieces.

 The extraction and metering device 46 is composed of a cylinder 47 with a horizontal axis inside of which there is a coaxial worm 48 which is rotated by a geared motor group 49. The cylinder 47 has an opening which is located at the rear part of its upper generator and which is connected to the opening 32 located in the bottom of the tank, so that when the shutter 33 is open, the dough located in the tank can enter the cylinder where it is taken up by the worm, which pushes it forward.

 To facilitate the evacuation of the dough, the mixing arm rotates at slow speed (15 revolutions / minute) and rolls around the axis z z1 for. this operation.

 The worm 48 acts as a extruder and the dough comes out at the front end of the cylinder 47 in the form of a flange 52 having a diameter equal to that of the cylinder 47.

 A knife 50 movable in a plane perpendicular to the axis of the cylinder 47 is disposed at the front end of the cylinder. The end of the dough strand bears against a movable stop 51 which is arranged opposite the outlet of the cylinder 47, at a distance d in front of the knife 50. The movable stop 51 is equipped with a micro- switch which automatically controls the movement of the knife 50 which therefore cuts dough pieces 53 having a determined diameter and length, therefore a determined weight, for example a weight of 300 grams, from the flange 52. The dough pieces 53 fall onto a conveyor belt .54 of the muddy type, which is placed under the front end of the extractor. The rear end of the belt is surmounted by a flour distributor 55 which makes it possible to coat the carpet 54 and the dough pieces with a layer of flour to prevent the dough pieces from sticking to the carpet.

 FIGS. 3 and 4 schematically represent an automatic salt distributor 3 and an automatic yeast distributor 4 which open onto the side walls of the fixed tank 30.

A more detailed description of these distributors is given below.

 The tank 30 is covered by a rotating cover 56 which includes a peripheral flange 56a which comes to bear against a flange 30a fixed to the external periphery of the tank 30.

 A seal 57 of self-lubricating material, for example polytetrafluoroethylene, is interposed between the flange 56a and the flange 30a and this seal gives the assembly of the cover and the tank, a seal which is sufficient if the interior of the tank is at atmospheric pressure or under slight overpressure due to the injection of a gaseous mixture through the holes 31.

 In the case where the interior of the tank is kept under vacuum, the flange 30a is equipped with a seal 58 placed in a groove, for example an O-ring or a hydraulic seal. The cover 56 comprises a chimney 59 equipped with a register 59a which serves as an air inlet and for evacuating the gases (C02) resulting from the fermentation.

 The cover 56 carries a mixer arm 60 which is composed of a shaft 61 mounted obliquely to the axis z z1 and of arms 62 which plunge into the bowl to knead the dough. The shaft 61 is rotated by a slow speed hydrostatic motor 63 whose speed depends on the flow of liquid which feeds it so that this speed can be varied from 0 to 130 revolutions / minute. The output shaft 63a of the motor 63 carries a bevel gear 64 which meshes with a pinion 65 with a vertical axis keyed onto a shaft 66 carrying a wheel or a roller 67.

 The wheel 67 preferably comprises a tire made of rubber or any other elastomeric material having a high coefficient of friction. It rolls on a fixed circular track 68 which is fixed to the top of a central column 69, which is supported by the cylinder 70 of an axial cylinder whose piston 71 is supported on a fixed horizontal partition 72. The shaft 66 is supported by a vertical bearing 73 fixed on the top of the cover 56.

 The cover 56 has a central pivot 74 which is supported by bearings 75 on the fixed column 69, so that the pivot 74 and the cover can rotate around the column 69.

The jack 70, 71 makes it possible to lift the cover and the assembly of the mixer arm and of the drive mechanism to access the interior of the tank 30, as can be seen in FIG. 5. Of course, as a variant the cylinder 70 of the jack could be fixed and the column 69 could be supported by the piston 71 which would move vertically in the cylinder. The adapted arrangement makes it possible to place the conduit 76 which supplies the jack with compressed fluid in the axis of the column 69.

 We see that the motor 63 drives the mixer arm 60 in rotation about its axis y y1 and, at the same time, it drives the cover in rotation around the axis z z1 by friction of the wheel 67 which rolls on the circular track 68. These two combined movements make it possible to obtain good kneading of the dough while having a fixed bowl, which greatly facilitates the construction of the kneader.

 There is shown on the side of the tank an inlet 77 dteau provided with a solenoid valve.

 An operating cycle of a kneader 2 equipping an installation according to the invention, for kneading a batch, comprises the following steps.

 At the start of the cycle, the motor 63 is started up at a twisting speed of 45 revolutions / minute for 5 minutes and during this phase, a determined quantity of flour and cold water is admitted into the tank 30, example 50 Kgs of flour and 30 liters of fresh water at a temperature between Oc and 20C.

 The flour is brought into the tank by a conveyor 14 which pours on one side of the fixed tank and which is a volumetric conveyor having a flow rate of 1000 kg / hour, so that it takes only 3 minutes of operation to feed the tank. The water is supplied via a pipe 77 which can deliver 600 liters / hour and it is therefore sufficient for the solenoid valve 77 to remain open for 3 minutes to supply 30 liters of water.

 At the end of this first phase, a dose of yeast of the order of 1 kg is injected into the tank through the distributor 4, which requires approximately 10 seconds.

 We then pass to a second phase of rapid kneading during which the motor 63 rotates at a speed of the order of 130 revolutions / minute, for approximately 13 minutes.

 About 3 minutes before the end of this second phase, the distributor 3 injects into the tank, in 10 seconds, about 1.2 kg of salt.

 During the second phase, a gaseous mixture of air and vitamin oxygen is injected into the tank, through the holes 31.

 During a third phase which lasts approximately 5 minutes, the motor 63 is stopped and the dough rests.

Finally, during a fourth phase which lasts from 7 to 30 minutes, the motor 63 is operated at a speed of 15 revolutions / minute> the shutter 33 is opened and the motor 49 is started, driving the screw 48 During this fourth phase, the 75 kg of fresh dough contained in the kneader, are evacuated by the mat 54 in the form of 250 dough pieces of 300 grams each. The conveyor belt 54 advances at a speed of the order of 0.3 m / second, which is enough to evacuate the 250 pieces in 7 minutes,
Finally, the minimum duration of a kneading and evacuation cycle is 30 minutes and, at the end of this cycle, the kneader 2 is ready to start a new cycle if necessary, so that the kneading capacity is order of 100 kg of flour per hour.

 The supply of pressurized oil to the motor 63 is carried out by a pipe 77 pierced in the fixed column 69 which communicates by radial holes with three grooves 78 of the rotary pivot. These grooves 78 are connected to the motor 63 by pipes. Seals 79 seal between the rotary pivot 74 and the fixed column 69. A pump, not shown, makes it possible to vary the oil flow rate and therefore the speed of the motor 63. This pump also supplies the jacks 70 and 43..

 Figure 6 is an axial section of the device 4 for feeding the yeast tank. This device comprises a horizontal cylindrical reservoir 80 which is surrounded by a cooling coil 81 in which circulates cold water intended to conserve the yeast.

 The reservoir 80 is equipped with a first cylinder 82. horizontal axis whose piston 83 is kept pressed against the yeast located in the tank and pushes it towards the tank. The outlet of the reservoir 80 is closed by a plane shutter 84 which is fixed to the rod of a second cylinder 85.

 The front end of the dispenser 4 which opens into the tank, is equipped with a grid 86 intended to divide the yeast and distribute it in the dough, preventing the yeast from falling into the tank in the form of a block.

 Behind the grid 86 moves a plane shutter 87 which is moved transversely by a third cylinder 87a.

 The chamber 91 located between the shutter 84 and the shutter 87 has a determined volume which corresponds to the dose of yeast necessary for a kneading cycle of a batch, for example 1 kg of yeast for 50 kg of flour.

 The upstream shutter 84 comprises a flap 88 which is articulated around an axis 89 and which is pushed by a spring 90 which bears against the shutter 86.

 At the start of each kneading cycle, the shutters 84 and 87 are closed.

 The actuator 85 controls the opening of the shutter 84 and the chamber 91 is filled with a dose. The shutter 84 is then closed again, then the shutter 87 is opened with the jack 87a. The plate 88, pushed by the spring 90, then pivots around the joint 89 and pushes the dose of yeast into the tank .

We see in Figure 5 that the piston 83 can be placed outside the reservoir 80 when the cylinder rod is fully retracted, which allows to replenish the reservoir 80 in yeast. The rear end of the reservoir is flared to facilitate the introduction of the yeast;
The horizontal position of the yeast tank prevents it from settling.

 The hinged plate 88 moved by a spring, allows to push into the tank a dose of yeast despite the texture of this which slows the flow.

 FIG. 7 shows the automatic dispenser 3 for doses of salt. This distributor has a vertical reservoir 92, the lower end of which is connected by a chute 93 to an opening 94 in the side wall of the tank. The lower end of the tank has two superimposed flat shutters 95 and 96 which delimit between them a metering chamber 97 whose volume corresponds to the dose of salt necessary for the quantity of flour admitted into the kneader, for example at 1.2 kg. salt for 50 kg of flour.

 The shutters 95 and 96 are moved laterally by jacks 95a and 96a.

 To distribute a dose of salt in the kneading tank, the upper obturator is opened or closed successively, it is closed then the lower obturator, so that the dose flows by gravity first into the metering chamber 97, then in the tank. The upper end of the reservoir 92 is closed by a cover intended to protect the salt from humidity.

 FIGS. 8 and 9 represent a top view and an elevation view of a preferred embodiment of a continuous counterbore apparatus designated as a whole by the reference 9.

 We see in these figures the endless conveyor 17 which connects the molding machine to the baking oven and which carries the dough pieces 24 leaving the molding machine. This conveyor moves from left to right.

 The counterbore device 9 is placed above the conveyor 17. It comprises an electric motor 25 which rotates a shaft 26 carried by two bearings 27. The shaft 26 is arranged obliquely relative to the axis of the conveyor . It carries a plurality of parallel thin disks 28.

 The height between the top of the dough pieces 24 and the shaft 26 is less than the diameter of the discs 28, so that the latter obliquely cut the top of the dough pieces when they pass under the discs and make incisions or slits on them. 29 oblique to the longitudinal axis of the dough pieces.

 The dough pieces 24a, each carrying five oblique incisions 29, are shown on the right-hand side of FIG. 8.

It will be noted that the cover 56 in the closed position, avoids
any risk of accident due to the introduction of the hands inside
of the tank during kneading. A limit switch placed
for example at the bottom of column 30a automatically stops the
motor 63 as soon as the cover 56 begins to lift. The form
hollow cover increases the useful volume of the kneader.

Claims (12)

 1. A method of manufacturing French bread in an automatic bread-making installation of the type which comprises a kneader (2) having a fixed tank (30), the bottom of which comprises gas injection orifices (31) and a rotating arm (60 ) which is rotated by a multi-speed motor (63), which tank is equipped with automatic distributors of salt (3), yeast (4) and water (5) and receives the spill from a transporter ( 14) which connects it to a flour silo (1), characterized in that each kneading cycle of a batch comprises the following stages, which are controlled automatically:  - Starting said motor (63) at slow speed, of the order of 45 revolutions / minute, for about 5 minutes and during this first stage, said conveyor (14) is automatically started and the arrival of cold water (5) for the time required to introduce into said tank (30) a determined quantity of flour and the quantity of water necessary for kneading it;  - At the end of this first step, a dose of yeast is introduced into said tank;  - In a second kneading step, said motor (63) is rotated at high speed, of the order of 130 revolutions / minute for approximately 13 minutes;  - a few minutes before the end of this second stage, a dose of salt is introduced into the tank;  - during the second stage, a gaseous mixture containing oxygen is injected into the bottom of the cwe, through the orifices (3);  - In a third step, said motor is stopped for approximately 5 minutes to allow the dough to stand;  - In a fourth step, said motor is rotated at a very slow speed, of the order of 15 revolutions / minute to discharge the dough through an orifice (32) located in the bottom of the kneading tank.  2. Automatic production facility for French bread of the type comprising a flour silo (1); a mechanical kneading machine (2) equipped with automatic distributors of flour (14) of salt (3), yeast (4), water (5) and gas mixtures (6); a dough shaping machine (8) and a baking oven (10), characterized in that the bowl (30) of said kneader is fixed and has> in its bottom, an orifice (32) which is closed during kneading by a shutter (33) moved by a jack (34) and comprises an extraction device (46) comprising a cylinder with horizontal axis (47) having, at the rear end, an opening which communicates with said orifice (32) and a screw endless (48) which is rotated inside said cylinder and the front end of said cylinder comprises a knife (50) movable perpendicular to the axis of the cylinder and a movable stop (51) which is equipped with a limit switch which automatically controls said knife (50).  3. Installation according to claim 2, characterized in that the fixed tank (30) of said kneader comprises a rotating cover (56) which carries a motor (63) driving in rotation a mixer arm (60) and which also carries a shaft ( 66), which shaft carries a pinion (65) which meshes with a pinion (64) driven by said motor (63 and a roller (67) which rolls on a fixed raceway (68), so that said mixer arm rotates both around its axis and around the tank.  4. Installation according to claim 3, characterized in that said motor (63) is a hydrostatic motor at slow speed which can be varied between 0 and 130 revolutions / minute by modifying the flow of oil under pressure which feeds.  5. Installation according to any one of claims 2 to 4, characterized in that said rotating cover (56) comprises a central pivot (74) carried by bearings (75) which rotate on a fixed column (69) supported by a axial cylinder (70, 71) which makes it possible to lift said cover (56) to access the interior of the tank.  6. Installation according to any one of claims 2 to 5, characterized in that said kneader comprises a chamber (38) delimited by the bottom of the mixing tank and by a fixed plate (36) and comprises, in addition, a movable plate (42) which is located inside said chamber and which is carried by the piston (43) of an axial cylinder which makes it possible to move it vertically, which plate carries, on its upper face, a plurality of vertical needles (44) which each engage in a hole (31) located in the bottom of said tank.  7. Installation according to claim 6, characterized in that said chamber (38) is connected to one or more gas inlets (40) provided with a solenoid valve and to a steam inlet (15) coming from a boiler heated by the baking oven.  8. Installation according to claim 7, characterized in that said mechanical kneader (2) comprises a probe (98) for measuring temperature and a probe (99) for measuring the humidity of the dough which automatically regulate the gas flow injected into said chamber to maintain the temperature and humidity of the dough within determined limits during rapid kneading.  9. Installation according to any one of claims 2 to 8, characterized in that the device (3) for supplying the kneader with salt comprises a vertical salt reservoir (3) whose lower end opens into the tank (30 ) of the kneading machine and which comprises two flat shutters (95, 96) each moved by a jack (95a, 95b) which delimit between them a chamber (97) whose volume corresponds to the quantity of salt necessary for a batch.  10. Installation according to any one of claims 2 to 8, characterized in that the device (4) for feeding yeast to the kneader comprises a cylindrical tank (80) containing yeast, which is surrounded by a coil (81 ) in which circulates fresh water supplied by a refrigerated fountain, which tank comprises> at the rear end, a first cylinder (82) whose piston (83) is supported on the yeast and comprises at the front end a grid (86) and two shutters (84, 87) each driven by a jack (85, 87a), which shutters delimit between them a chamber (91) whose volume corresponds to the dose of yeast necessary for a batch and the upstream shutter ( 84) carries an articulated flap (88) which is pushed by a spring (90) in order to push towards the tank the dose of yeast contained in said chamber.  11. Installation according to any one of claims 2 to 10, characterized in that it comprises a fermentation chamber (7) which is interposed between an inlet conveyor (19) coming from said extraction device (46) and an outlet conveyor (23) going to a shaping machine (8), which chamber comprises one or two internal conveyors (20a, 20b), each carrying a number of suspended swings (21) sufficient to contain the dough pieces of a batch, which internal conveyors are driven at high speed for a few minutes to receive the dough pieces brought by said inlet conveyor (19) and at slow speed for 15 to 30 minutes to feed said outlet conveyor (23).  12. Installation according to any one of claims 2 to 11, characterized in that it comprises a continuous counterbore device (9) which is located above a conveyor (17) connecting the outlet of said shaping machine (8 ) at the inlet of the oven (10) and which comprises several thin disks (28) mounted on a shaft (26) which is arranged obliquely to the axis of said conveyor (17) and which is rotated by a motor (25) -.