Patent GB-735184-A (GB)
Title: Manufacture of dough and baked products
IPC: A21D8/00
Filed: 1951-08-03
Abstract: 735,184. Mixing appliances. WALLACE & TIERNAN PROCESS CO. Aug. 3, 1951 [Aug. 3, 1950], No. 18439/51. Class 86. [Also in Groups V and VI] In an apparatus for producing a fully developed dough, dry ingredients, namely flour from feeders 21, 22, Fig. 1A, and sugar, salt and powdered milk from feeders 23, 24, 25 respectively, are fed to a main inlet hopper 20, Fig. 1B, which delivers them to a pre-mixing and degassing unit 30, Fig. 2, where they are joined by broth, premelted shortening and one or more improving agents in solution from feeding devices 34, 35, 36 respectively. The premixed dough is discharged from unit 30 to a dough pump 32 which advances it into and through a closed developer 40, Fig. 1B, provided with power-driven mixing elements. All the driving elements of the apparatus may be subject to remote control, e.g. by means of regulators on a panel 50, Figs. 1B and 9, which would normally be set to obtain a substantially continuous flow of dough to the developer and, while the feeding devices can be operated in exact correspondence with the dough pump, additional means may be provided for controlling the feeders to correct overloading or underloading of the premixer. Ingredient feeders. The flour feeders, which may vary in number, each comprise a hopper such as 52, Fig. 1A, and a motor-driven endless conveyer having its centre forming part of or resting on a platform or balance mechanism whereby the weight of the flour can be counterbalanced by a scale beam and counterpoise 58, 59, which may be adapted to regulate a valve or gate between the hopper and the belt. The feeders 23, 24, 25, which are driven by electric motors 78, 84, 85 respectively, may be screw feeders as described in Specification 653,622, [Group XXX], or the feeder 23 may be like the flour feeders. The broth feeder 34 comprises a tank 97 having a thermostatically controlled water jacket 98 for controlling the temperature of the fermented liquor, which is fed to a spray inlet 108, Fig. 2, in the pre-mixing chamber 30 by a motor-driven pump 106 and pipe 107. Normally the broth is stirred by a motor-driven stirring device. Shortening material, e.g. lard or hydrogenated vegetable oil, and one or more improving agents are similarly fed to the premixing unit 30 through nozzles 122, 130 from containers 115, 126, the shortening material being kept molten in its container by thermostatically controlled heating means. Pre-mixing. The pre-mixing unit 30 comprises an open topped vessel 95 traversed by two parallel motor-driven shafts 143, 144 having angularly disposed interfitting blades 173 which mix and advance the dough mixture from the ingredient feeding end towards a baffle 176 and an outlet spout 142 leading to a pump 32, the early part of the pre-mixing causing a substantial amount of gas (chiefly air) to be released from the mixture and a substantially uniform high-density dough to be delivered to the spout 142. By displacing the ingredient inlet spouts and nozzles collectively towards the outlet end of the pre-mixer the dough may be left with a higher content of gas. Supplementary control of the feeding means and of the loading of the pre-mixing vessel 95 is obtained by supporting the whole of the pre-mixing unit, together with a platform 168 for the driving motor 160, on frame members 171, 172, Figs. 1B and 3B, which are pivoted on brackets 187, 188 on the main frame so that the vessel can rock with variations in loading and thereby influence a weightsensitive device extending between a fixed support and the underside of a platform 192 connecting members 171, 172. When the weight of the contents of vessel 95 decreases or increases the platform 192 rises or falls and moves a switch arm 198 to effect acceleration or deceleration of the ingredient feeding devices. A dash pot 204 may be provided to damp fluctuations. Developing. The dough from the unit 30 is advanced to the developer 40, by way of conduit 227 and preferably under pressure, by means of interfitting rotors 214, 215, Figs. 2 and 3, which are driven by a variable-speed motor 218, the conduit 227 having a thermometer 228 and a pressure gauge 229 with their sensitive elements exposed to the passing dough. The developer, Figs. 4 and 5, comprises a body 230 enclosing an upright oval chamber 232 closed top and bottom and having inlet and outlet ports 240, 239 respectively. Within the developer are two mixer elements 242, 243, Fig. 5, each provided with solid blades arranged to swing past those of the other on counter rotation of their supporting shafts 224, 245 which have intermeshing gears 246, 247 and are driven through bevel gearing by an electric motor 42, Fig. 1B. The developer has a pressure gauge 259 and a thermometer near its outlet 237 to record the condition of the dough about to be delivered; it also has a valve-controlled opening 262 at the top for venting the chamber during filling. In a modified developer, Figs. 6 and 7, the mixing chamber 280 is a single cylinder traversed by a unitary impeller 282 and surrounded by a cylindrical wall 299 jacketed for temperature control. The impeller has four perforated blades which have very close clearance with a different number of vertical ribs on the inner face of the chamber. The developer also has a supply line 312, 315, 317 embodying a meter 314 and a back pressure valve 316, through which air or other gas under pressure may be introduced into the mixing chamber. An alternative form of developer, Fig. 8 (not shown), has four impellers carried by parallel shafts and located in a housing shaped as if constituted by four intersecting cylinders, the projections between cylinders being structurally embodied in the internal wall. In all the developers shown, the direction of flow of the dough, the impeller shafts, the blades and their edges and the chamber walls are all parallel and it is stated that this applies such a strain to the dough as to obtain its efficient development. Delivery arrangements. The outlet 237 leads to a conduit 265, Fig. 1B, embodying a manually operative valve 267, which can be adjusted to vary the dough pressure during mixing in the developer, and an orifice structure including a gate 269 for adjusting the size of the opening by displacement of a lead screw 270. The dough is extruded from orifice 268. At the outset of a given run, some dough may be extruded in an underdeveloped state and this dough may be fed back into the pre-mixer at a controlled rate through a feeding device 330, Fig. 1B, driven by an electric motor 336 and supplying the vessel 95 by means of a conduit 337. When dough is being prepared by the sponge process, the apparatus is provided with a sponge feeder 340, Fig. 1B, comprising a hopper 342, a mixing, advancing and degassing vessel 344, e.g. equipped like vessel 95, and a sponge pump 346 driven by a variable speed motor 350. The sponge is delivered to the vessel 95 through' a conduit 354 at a controlled rate determined by adjustment of the motor 350, e.g. by means of the pivoted pre-mixer vessel 95. Driving and control arrangements. As shown in Fig. 9, the control circuits of the several motors 56, 70, 78, 84, 85, 336, 112, 124 and 132 individually extend, through a corresponding pair of contacts 56a, 70a ..., and include speed control devices 78b, 84b . . ., for the ingredient feeder motors 78, 84, 85, 112, 124 and 132- The motor 218 for the dough pump 32 is con. trolled by a circuit which includes a speedadjusting device 382. The developer motor 42 is connected to a circuit which includes a speedadjusting device 392. The sponge feeder motor 340 may have its motor 350 controlled in similar fashion to the motors of other feeding devices. The pairs of contacts 56a, 70a . . . are made and broken by movement of an armature 365 of relay winding 360 which is connected through switch contacts 197, 198 which are closed and opened according to the weighting of the pivoted vessel 95. The feed of the ingredients is thus more or less intermittent, i.e. it stops and starts with the opening and closing of the contacts 197, 198, the main consideration being that a continuous feed of dough is supplied to the pump 32. In an alternative driving arrangement, Fig. 10 (not shown), the ingredient feeders are operated by a single master motor through a master speed control unit which is adjustable by an electric position sensitive device, including a motor and tap resistors, influenced by movement of the vessel 95. The feeders are all geared to a single line shaft and, apart from those supplying flour, the feeders may be adjusted individually through a variable speed gear box. The position sensitive device may also be used with the relay 362, Figs. 1B and 9B. Specification 735,218, [Group VI], also is referred to.