Abstract:
Dough intended for use in producing bakery products is homogenized and advanced to extrusion nozzles where it is cut into successive pieces that fall onto a moving conveyor. The pieces are of precisely uniform weight because a constant pressure is maintained on the dough as it is forwarded by a metering pump toward the nozzles. Apparatus for achieving such result includes an auger, a developer positioned downstream from the auger, and a transition chamber fed by the developer and located upstream from the metering pump. A pressure-measuring monitor serves to control the rotational speed of the auger, thereby maintaining the dough under constant pressure within the apparatus.

Description:
RELATED APPLICATIONS 
     This Application is a continuation-in-part of U.S. patent application Ser. No. 08/516,431, filed Aug. 17, 1995, now U.S. Pat. No. 5,516,272, which is a continuation-in-part of U.S. patent application Ser. No. 08/297,123, filed Aug. 29, 1994, now U.S. Pat. No. 5,443,854. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the handling of dough for baking, and more particularly concerns a method and apparatus for dispensing successive pieces of dough of constant weight. 
     2. Description of the Prior Art 
     Methods and apparatus for pumping, homogenizing and dividing dough into pieces of predetermined uniform weight for baking into bread loaves, buns, rolls and the like are disclosed in U.S. Pat. Nos. 4,960,601; 4,517,212; 4,449,908; 4,424,236; and 4,332,538. In general, such apparatus includes a hopper which receives dough, auger means for advancing the dough, metering means which control the advance of the dough, multiple nozzles which receive the metered dough, and cutting means which sever the continuously advancing dough into discrete pieces which fall onto an underlying moving belt. A homogenizing step is usually included, which may be accomplished by mixing means generally referred to as a &#34;developer&#34;. 
     It is very important that each dough piece be as equal in weight to each other as possible. The uniformity of weight not only produces products of uniform quality but facilitates the automated handling and packaging of the baked products. Also, the weight of the dough is one of the most expensive cost elements in manufacturing baked goods, and control of the weight tolerances can reduce the need for excess dough. The production of dough pieces of a given weight is known as scaling in the trade. In general, less than 2% deviation in weight is sought relative to a target weight. 
     Metering means such as cylinder-housed pistons have been employed to achieve improved scaling. However such devices require use of mineral oil which escapes as an undesirable atomized vapor of concern as a health hazard. Such devices also produce an undesirable high noise level. Although metering means, such as a positive displacement pump, has been employed to achieve uniform scaling, inaccuracies are experienced. This results from the fact that the metering pump dispenses a constant volume, but the dough has a non-uniform density because of gas formation produced by the yeast content of the dough. Prior efforts to achieve greater uniformity of dough density have included degassing techniques and pressurization of the dough upstream of the volumetric metering means. 
     It has been found however, that dough can degrade in the dough-handling apparatus, the degree of degradation being increased by factors such as high pressure, the time duration of said pressure, and shearing forces at the surfaces of passages through which the dough travels. The degradation becomes apparent in the finished product in the form of swirl patterns and non-uniformity of texture along with discoloration and circular stratiform. 
     Equipment for processing the dough has generally involved hydraulically driven motors. Such motors permit leakage of hydraulic fluid onto the surfaces that contact the dough, and further produce high noise levels. 
     It is accordingly an object of the present invention to provide apparatus for pumping, homogenizing and dividing dough into successive pieces of uniform weight. 
     It is another object of this invention to provide apparatus as in the foregoing object which produces minimal degradation of the dough. 
     It is another object of the present invention to provide apparatus of the aforesaid nature having few moving components. 
     It is a still further object of this invention to provide apparatus of the aforesaid nature which can be easily dismantled to facilitate cleaning and repair. 
     It is yet another object of this present invention to provide a method, achievable by the aforesaid apparatus, for dispensing successive pieces of dough of uniform weight. 
     These objects and other objects and advantages of the invention will be apparent from the following description. 
     SUMMARY OF THE INVENTION 
     The above and other beneficial objects and advantages are accomplished in accordance with the present invention by a method of moving and treating dough comprising the steps of: 
     a) entering dough into an auger that pressurizes and imparts downstream impetus to the dough. 
     b) entering the pressurized dough into a confining region having an upstream zone which establishes a first operating dough pressure, and a downstream zone which establishes a second operating dough pressure, 
     c) advancing the pressurized dough from said upstream zone to said downstream zone by a positive displacement metering device, and 
     d) permitting controlled emergence of the dough from the downstream zone of said confining region. 
     In preferred embodiments, the hydraulic pressure of the dough in the confining region is continuously sensed, and the rotational speed of the auger is varied responsive to the sensed pressure, thereby controlling the pressure in said confining region. A developer may be interposed between the auger and metering device within the confining region, in which case the pressure is preferably sensed between the developer and metering device. The controlled emergence of the dough from the confining region is preferably accomplished by a device which resiliently resists movement of the dough through an outlet orifice, thereby dampening excursions of pressure from a sought pressure within said confining region. 
     The present invention further encompasses apparatus for treating and dispensing dough, said apparatus comprising: 
     a) an auger for pressurizing dough received at atmospheric pressure to a first operating pressure above atmospheric pressure, and for simultaneously imparting a downstream impetus to the pressurized dough, 
     b) confinement means for receiving the pressurized dough and directing downstream transport of the dough under the impetus of said auger, 
     c) means for metering said pressurized dough within said confinement means and advancing the dough in a downstream direction, and 
     d) outlet means for dispensing the dough from said confinement means. 
     In preferred embodiments of the apparatus, a developer is disposed within the confinement means between the auger and metering means. A sensor downstream of the auger senses pressure, and is interactive with means for varying the rotational speed of the auger responsive to the sensed pressure, thereby controlling the pressure within said confinement means. The outlet means preferably includes a nozzle for receiving dough from the metering means. Between the metering means and the nozzle, there is preferably interposed means for resiliently resisting the downstream passage of dough toward said nozzle, thereby dampening excursions of pressure within the confinement means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the figures of the drawing: 
     FIG. 1 is a front view of an embodiment of the apparatus of the present invention, with portions broken away to reveal internal details. 
     FIG. 2 is a side view of the embodiment of FIG. 1 with portions broken away. 
     FIG. 3 is an enlarged sectional view taken in the direction of the arrows upon the line 3--3 of FIG. 1. 
     FIGS. 3a and 3b are enlarged fragmentary views of FIG. 3. 
     FIG. 4 is an enlarged fragmentary front view of the embodiment as shown in FIG. 1. 
     FIG. 5 is an enlarged fragmentary bottom view taken in the direction of the arrows upon the line 5--5 of FIG. 4. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1-5, an embodiment of dough treating and dispensing apparatus of the present invention is shown comprised of hopper 10 disposed above advancing assembly 11 which is positioned above transition housing 12, metering pump 13 and extrusion conduits 56. An outer framework 42 provides support for said components. 
     Hopper 10 is of integral construction and tapered downwardly from upper extremity 15 to lowermost exit extremity 16. The hopper is contoured so as to have no corners where dough might accumulate as a stagnant zone. Exit extremity 16 is equipped with an outwardly directed flange 17 which permits sealed joinder to advancing assembly 11 using bolts 18. A resilient gasket or O-ring, or equivalent means may be employed to assure pressure-tight joinder of the hopper to the advancing assembly. 
     As shown in FIGS. 1, 2, and 3, advancing assembly 11 is comprised in part of receiver block 19 of generally rectangular configuration bounded by flat upper and lower surfaces 20 and 21, respectively, flat front and rear surfaces 22 and 23, respectively, and opposed side surfaces 24. First and second circular cylindrical bores 25 and 26, respectively, extend in parallel disposition between said front and rear surfaces. As shown in FIGS. 3a and 3b, sealing bushings 27 and 82, associated with bores 25 and 26, respectively, are associated with rear surface 23. 
     It is to be noted that bushing 27 contains an outwardly directed wiper lip 83 adapted to prevent fluid flow into bore 25 whereas bushing 82 contains an inwardly directed wiper lip 84 adapted to prevent fluid flow out of bore 26. 
     A coupling block 28 is removably associated with front surface 22 by bolts 29, and has a passage 30 configured to establish continuity between the front extremities of both bores. A receiving port 31 penetrates upper surface 20 and establishes communication between exit extremity 16 of the hopper and first bore 25. An auger 32 is housed within said first bore, said auger being comprised of a continuous vane 33 that extends to a radial clearance of 0.020-0.040 inch with respect to said bore, and centered shaft 34 that extends rearwardly to socketed engagement with receiver shaft 35 secured by bushing 27. To achieve said socketed engagement, the rearward extremity of the centered shaft is of a square contour, matching the contour of pocket 85 of said receiver shaft. The forward extremity of shaft 34 is rotatively supported by bearing boss 81 held by coupling block 28. By virtue of such manner of construction, auger 32 can be easily pulled out of bore 25 to facilitate cleaning. A degassing port 40 extends through block 19 into said first bore at a site rearwardly of vane 33, and communicates with a vacuum source, not shown. Bushing 27 prevents air from being drawn into bore 25 in response to the vacuum applied to receiving port 31. 
     A developer unit 36 is disposed within said second bore, said developer comprised of a plurality of blades 37 equiangularly disposed about shaft 38 that extends rearwardly to socketed engagement with receiver shaft 39 secured by bushing 82. The blades are radially spaced about 1/16&#34; from the bore. The forward extremity of shaft 38 is rotatively supported by bearing boss 81 held by coupling block 28. The developer unit 36, like the auger, can accordingly be pulled out of its bore to facilitate cleaning. The developer may alternatively be of paddle or ribbon design. An exit port 41 extends between the rear extremity of the second bore and lower surface 21. Receiver block 19 and coupling block 28 are preferably fabricated of engineering grade plastic having a low coefficient of surface friction. Suitable plastics include ultra-high molecular weight polyolefin, polyacetal, polyester, polyamide, and other moldable plastics having equivalent properties. 
     The rear extremities of receiver shafts 35 and 39 extend to right angle drive units 43 and 44, respectively, which are driven by inverter-controlled variable speed electric motors 45 and 46, respectively. The auger and developer are preferably adapted to rotate in opposite directions. A separate inverter electrical speed controller 48 is associated with each motor 46 and 45. Inverter 48, of standard construction, is designed to receive a control signal which is utilized to control the voltage and frequency of current which powers the respective motor. A suitable inverter controller is the Movitrac model G-2 made by the Toshiba Company. Both motors may be identical, having a horsepower rating in the range of 3 to 7 HP. The auger is typically rotated at speeds in the range of 50-250 rpm. The developer is typically rotated at speeds in the range of 50-300 rpm. The entire advancing assembly may be constructed so that it may be pivoted upward about pivot rod 49 attached to frame 42 in parallel relationship to end surface 24 adjacent motor 45. Pivoted lifting of the advancing assembly facilitates cleaning and repair. Suitable means may be provided to secure the head assembly in its upper, cleaning position, and in its lowermost, functional position. 
     Transition housing 12 is disposed below lower surface 21 of said head assembly and configured to establish pressure-tight connection with exit port 41. The front surface 51 of housing 12 secures a pressure indicating device 52 which senses and indicates the hydraulic pressure within housing 12. An electronic pressure-sensing transducer 75 inserted through rear surface 76 of housing 12 produces an electrical control signal which is fed to inverter 48. By virtue of such arrangement, the speed of auger 32 is controlled. Because the route taken by the rotational speed of the auger produces increased pressure on the dough at transducer 75. In general, the configuration of the apparatus and its operating parameters are such that a constant pressure in the range of 15-28 psig is maintained at transducer 76. 
     A rotary positive displacement metering pump 13 is joined in a pressure-tight manner to the underside of housing 12, and receives dough therefrom. A suitable metering pump is Model 34 made by the Waukesha Company of Delavan, Wis. Said pump is driven by inverter controlled variable speed motor 69, acting through a right angle coupling 70, and is characterized in having two dual lobe intersecting rotors 54. A face plate 57 held by bolts 58 can be removed to facilitate removal of the rotors and cleaning of the interior of the pump. 
     The role of metering pump 13 is to accurately advance pressurized dough in a downstream direction while maintaining the upstream pressure of the dough. In fact, the portion of the apparatus between the auger and metering pump 13 is considered an upstream zone 87 of a large confining region 88 which encompasses dough-contacting portions of the apparatus including the upstream zone and downstream portions. The hydraulic pressure of the dough in said upstream zone may be considered a first operating pressure, which, as already mentioned, will be in the range of 15-28 psig. The hydraulic pressure of the dough in the portion of the apparatus downstream from the metering pump will be lower, as will be discussed hereinafter. 
     A horizontally disposed distribution manifold 55 is positioned below said pump and coupled thereto in pressure-tight but removable joinder by means of threaded fitting 73. 
     A plurality of parallel extrusion conduits 56 are downwardly directed from said manifold. Said distribution manifold and extrusion conduits 56 are exemplified as being fashioned from a single block 79 of engineering grade plastic. Each conduit contains a pressure drop regulator assembly 59, as best shown in FIG. 4, comprising a control stem 64 which extends upwardly through manifold 55 to the top of block 79 where it is threadably secured at a desired elevation by means of threaded control knob 71. 
     A conically tapered plug 61 is disposed upon the lowermost extremity of each control stem, and adapted to abut upwardly with a conically tapered shoulder 62 within conduit 56. Resilient resistive means such as coil spring 63 is interposed between the lowermost extremity of stem 64 and plug 61. By virtue of such arrangement, upward movement of stem 64 constricts conduit 56, thereby increasing the upstream pressure of the dough and thereby dampening excursions of pressure from the sought operating pressure upstream of plug 61. 
     Plug 61 defines the downstream extremity of confining region 88 whose upstream extremity is defined by the auger. Within said confining region, upstream zone 87 is defined by dough-contacting portions between the auger and the inlet of the metering pump; and a downstream zone 89 is defined by dough-contacting portions between the outlet of the metering pump and plug 61. The pressure of the dough within said upstream zone is considered a first operational pressure. The pressure of the dough within said downstream zone is considered a second operational pressure. Said second operational pressure, controlled in part by resistive means 63, is preferably 20% to 50% lower than said first operational pressure. 
     The lowermost extremity of each conduit has a tapered extrusion nozzle 65, as best shown in FIGS. 4 and 5, having an orifice 66 that is elongated in the same direction as manifold 55. A cutting wire 67 mounted upon opposed support posts 78 is disposed below said nozzles, and is adapted to pass back and forth over said orifices in sliding contact therewith to produce pieces of dough 72. The motion of the wire is transverse to the direction of elongation of the orifice. Such combination of elongated orifice and transverse cutting direction has been found to provide a faster cutting action. The wire is further caused to ride along the tapered sides of the nozzle before crossing the orifice. The sequentially severed pieces of dough fall onto a moving belt 68 of conventional design, which carries the pieces of dough to further downstream processing prior to baking. The aforementioned specialized configuration of nozzle and associated cutting wire reduces dwell time during cutting, thereby enhancing weight uniformity and producing more accurate positioning of the pieces of dough upon the belt. Positioning of the pieces is very important in order to assure that the pieces are timed accurately for handling by downstream processing equipment. Otherwise, the pieces would jam the equipment and stop the process. 
     The upper portion of the apparatus of this invention, comprising the hopper and advancing assembly may, as a unit, be installed upon existing dough dispensing apparatus. Said upper portion in fact includes novel features, as described above, which cause said upper portion to be a separately patentable aspect of the present invention. 
     By virtue of the aforesaid specialized features of the apparatus of this invention, the first operating pressure of the dough entering the metering pump is held constant while minimizing shear degradation. In particular, the first and second operating pressures of the dough within the apparatus of this invention are controlled throughout a confinement region defined at its upstream extremity by the auger, and defined at its downstream extremity by tapered plug 61. The attendant constant density of the dough at the metering pump and at the nozzle produces remarkably accurate scaling of below 1% deviation from a target weight. A further consequence of the method and apparatus of this invention is the production of bakery products of improved textural uniformity. In particular, the pore or cell diameter exhibits less than 4% variation from the average diameter. 
     While particular examples of the present invention have been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.