GB2072479A - Automatic final baking oven for pre-baked dough-based products - Google Patents

Abstract

The baking of pre-baked dough-based products, especially elongate white French bread, is automatically completed in a baking oven in which a gondola conveyor (10) conveys the products through a baking area heated by a recirculatory hot air blower. The products are supplied via a gravity supply chute (9) to a separator (8) which is moved by a respective release member associated with each gondola (25)-(28) to allow the products to drop into successive passing empty gondolas. After baking, the products are ejected by means of a ejector (29) which engages successive passing gondolas to pivot each gondola so that the baked product falls therefrom. The falling product passes through a normally closed trap door (30) into a collecting chute (31). <IMAGE>

Description

SPECIFICATION Automatic final baking oven for pre-baked dough-based products The invention relates to an automatic final baking oven for pre-baked dough-based products, especially elongate white French bread, also called stick loaves, and baguettes.

It is desirable to be able to supply the customer with freshly baked white bread, whenever this is required. Such bread is produced centrally in large bakeries and is then brought to the individual sales outlets. Time elapses on the way from the central bakery to the customer and the bread loses its freshness. In addition, during the transportation and stacking of freshly baked loaves the sensitive crust is often damaged. It is therefore desirable to only pre-bake the bread at a central location and then, if necessary, finally bake the same at the sales outlet. In this way, most of the working processes are carried out in an economic manner at the central location and only the relatively simple final baking process is performed on a decentralized basis.

The aforementioned automatic final baking oven is used for the final baking process and it is an object of the invention to so develop such an oven that, whilst being constructed in an uncomplicated and reliable manner, it makes it possible to uniformly finally bake the loaves individually as required for retail sales.

According to the present invention, there is provided an automatic final baking oven for pre-baked dough-based products, said oven comprising a gondola conveyor arranged within a baking area, which conveyor has axially parallel gondolas which are open at the top for receiving respective dough product portions (as hereinafter defined) and are suspended at spaced locations on a circulating endless conveying means so as to pivot about a horizontal axis transverse to the direction of movement thereof; a gravity supply chute; a separator into which the gravity supply chute debouches and arranged on a wall bounding the baking area and movable by a respective release member associated with each gondola to allow dough product portions from the gravity supply chute to drop into successive passing empty gondolas; an ejector spaced from the separator by a distance of more than two thirds of the conveying path and adapted to engage successive passing gondolas to pivot each gondola so that the dough product potion therein falls therefrom; a trap door located in the path of the downwardly falling dough product portion and openable against a restoring force by the weight of said portion to allow the said portion to pass to a collecting chute; and a hot air blower whose suction side and delivery side are both connected to the baking area.

Usually, the gondolas will be equidistantly spaced apart on the conveying means; said means will be constituted by a pair of transversely spaced chains; and the separator will be located on the top wall bounding the baking area.

Suitably, the separator has a stationary stop bar located in the path of the supply chute and in front of which is provided a lifting platform movable between an inoperative position extending the supply chute and a discharge position from which a dough product portion will pass over the stop bar. Preferably, the lifting platform is raised and lowered by a pair of rocker arms arranged on either side thereof and actuated by the release member.

By means of this lifting platform, the furthest forward dough product portion is raised over the stop bar synchronously with the passing gondolas and can drop into the appropriate gondola. On lowering the lifting platform, the next dough product portion will pass from the supply chute onto the lifting platform.

It is preferred that the lifting platform is raised synchronously at both sides thereof but is lowered asynchronously at both sides. As a result of the asynchronous lowering operation, two vibrations occur which facilitate sliding of the dough product portion from the supply chute onto the lifting platform.

It is also preferred that behind the stop bar is provided an opening in the cover wall dimensioned for the dough product portion and closable by a trap door, the latter being opened by a lever pair arranged on either side thereof actuated by a release member of the gondola and closed again by a following lever pair also arranged on either side thereof and actuated by the same release member. This arrangement ensures that the charging opening is only opened for the minimum time necessary for insertion of the dough product portions into the oven, thereby avoiding unnecessary heat losses. The trap door is actively operated in order to avoid false insertions of the type which would be expected if it was only operated by the weight of dough product portions dropping thereon, because the pre-baked products are in part tacky and non-uniform.

In order to provide a long residence period in the baking area, it is preferred that the conveying means zig-zags downwards over guide pulleys from the separator to the ejector with elongate horizontal sections and the conveying means passes vertically upwards from the ejector back to the separator.

It is also preferred that the ejector has a stationary member with two upright legs in the path of respective forward and rearward cross-bars carried by the gondolas so that the forward cross-bar first abuts the first leg causing the respective gondola to pivot to approximately half the required ejection angle, subsequently the rearward cross-bar abuts the sec ond leg to further pivot the gondola to the required ejection angle, and thereafter the gondola is allowed to swing back to its normal position under its own weight. This arrangement offers a simple and operationally reliable manner of ejecting the finished dough products at the correct time. The ejection angle will usually be between 100" and 140 , especially 130'.

Preferably, the hot air blower has a radial fan wheel blower arranged coaxially to the gondola axes approximately in the centre of a wall bounding the baking area, said wall having a suction opening aligned with the suction opening of the blower and having along its vertical edges elongate slots opening into the baking area, said radial fan wheel blower being located in an otherwise closed heating area containing heat registers in the vicinity of the pressure flow. This arrangement provides a particularly favourable flow guidance along the longitudinal extension of the dough products thereby ensuring that hot air flows uniformly around them over their entire length, so that they are uniformly baked.

An upwardly open liquid tank can be provided on the bottom of the heating area and supplied with water from an external liquid supply to provide the desired humidity in the heating area. This arrangement provides the possibility of obtaining a glazed coating on the finished product and of preventing drying out within the dough product.

Usually, the baking area will be defined by a casing which is closed except for a closable supply slot for the separator, a closable ejection slot for the ejector, air inlets and outlets, vapour discharge openings and an intervention opening provided on the casing front wall and closable by a manually operable flap containing a viewing window, and with thermal insulation for the outer walls. This arrangement offers the possibility of continuously observing the baking process and also of manual intervention whilst conserving heat.

In order to provide for fully automatic operations under optimum operating conditions, it is preferred that temperature or programmecontrolled regulators are provided to control the conveying speed, operating temperature and/or moisture content.

The following is a description, by way of example only and with reference to the accompanying drawings, of presently preferred embodiments of the invention. In the drawings: Figure 1 is a diagrammatic cross-section through an oven in accordance with one embodiment of the invention; Figures 2A and 2B together constitute a perspective view of an oven in accordance with a second embodiment; Figure 3 is a cross-section along the line 111- 111 of Fig. 2; Figure 4 is a cross-section along the line IV IV of Fig. 2; Figure 5 is a cross-section along the line V V of Fig. 2; and Figure 6 is a cross-section corresponding to Fig. 4 of an oven in accordance with a third embodiment.

It should be noted that the term "dough product portion" as used in this Specification (including the description with reference to the drawings and the Claims) means an individual dough product or a plurality of juxtapised dough products. In particulr the term includes elongate, especially white, bread.

Referring now to Fig. 1 of the drawings, a baking area 1 is enclosed by a substantially parallelipipedic easing 2. The casing cover wall 3, rear wall 4, botton 5 and side wall 6 are filled. with thermally insulating material.

The not shown casing side facing the viewer is terminated by a fixed box containing the hot air blower. The upper area of casing cover wall 3 contains the supply conveyor 7 to which belongs the separator 8, constructed as a cell wheel, which ensures that the loaves sliding down a chute 9 individually pass through a slot-like insertion opening into the baking area at the correct time to ensure that they always drop into an underlying empty gondola of the gondola conveyor 10. The casing front wall 32 is constructed as a flap, preferably with an inserted viewing window.

The gondola conveyor 10 has two conveying chains, whereof the conveyor chain 11 only is visible. The conveying chain facing the viewer is constructed in exactly the same way and is also guided over a total of seven guide pulleys arranged coaxially to the visible pulleys 1 8 to 24. Conveying chain 11, like the not visible conveying chain is guided with a total of six horizontal portions and one vertical portion. Elongated, upwardly open gondolas, e.g. gondolas 25 to 28 are equidistantly suspended on the two chains. These gondolas extend longitudinally of the loaves at right angles to the drawing plane of Fig. 1, so that they are axially parallel, pivotable and are freely suspended with the open side upwards.

Reference numeral 29 designates an ejector which swings over the passing gondolas, like gondola 27, so that the loaf contained therein drops out through an elongated ejection slot 30 and from there onto a collecting chute 31 During operation gondola conveyor 10 cir- culates in the direction of arrow 28, the empty gondolas pass beneath the separator 8, are filled there with a loaf, which then passes a time in the heated baking area 1 on the way to ejector 29, is finally baked and is then ejected at the ejector 29 in the finally baked state.

Fig. 2 shows inter alia baking area 41, casing 42, casing cover wall 43, casing rear wall 44, casing bottom 45, the right-hand casing side wall 46, casing front wall 72, supply conveyor 47, separator 48, insertion opening 49, gondola conveyor 50, the lefthand conveying chain 51, the right-hand conveying chain 52, guide pulleys 56 to 64, the ejector 70 with the collecting chute 71 and a heating box 80 connected at the left-hand side to the baking area and which contains a hot air blower. Cover wall 43, rear wall 44, bottom 45 and side wall 46 of the casing are filled with thermal insulation 1 80. Vent slots 90 for venting the insulation are provided in a casing side wall 46.

A radial fan wheel blower 81 is placed in the heating box 80 and its suction opening 82 is aligned with an opening 108 in the partition 84 separating heating box 80 from baking area 41. Electrical heat registers 85 are positioned within the heating box 80 in the pressure area of the radial fan wheel blower 81. Elongated slots 86, 87 are provided in partition 84 along the casing rear wall 84 and the casing front wall 72. The electric motor 88 drives the radial fan wheel blower 81.

In accordance with the arrows shown in Fig. 3 during operation a circulating airflow is produced which, on the pressure side, initially passes through the heat registers 85, is heated and then passes through the elongated slot 86, 87 into the baking area 41 and from there back to the radial fan wheel blower 81.

A gear area 91 incorporated into casing 42 contains a water supply 92 which, by means of a water pipe 93, controlled by a solenoid valve 100 supplies water in a metered manner to a water pan 89 positioned below the radial fan wheel blower 81. The water is entrained as steam by the passing hot air. The solenoid valve is controlled by a microswitch 179, which is in turn actuated by trip cams mounted on disk 1 85. Disk 1 85 is fitted in non-rotatable manner on shaft 97. The water supply can be metered by means of a corresponding number of trip cams.

The gondola conveyor 50 arranged within the baking area 41 is driven by a drive motor 182 arranged in gear area 91. By means of a chain 94 drive motor 1 82 drives the chain wheels 95, 96, mounted coaxially and nonrotatably on shaft 97, 98 for guide pulleys 56, 61 or 57, 62. As there is only a total of two pairs of five guide pulleys, besides the vertical portion conveying chains 51, 52 are only guided along four horizontal portions, unlike in Fig. 1.

With the exception of the single gondola 99 the gondolas are not drawn in in Figs. 2 and 3. However, all the other equidistantly arranged gondolas and which are suspended with their longitudinal axis corresponding to longitudinal axis 101 in a horizontal and axially parallel manner with respect to the conveying chains 51, 52, are constructed in precisely the same way as gondola 99. Gondola 99 is open at the top and has on its upper edge an elongated, rectangular wire frame 102, between which and distributed in lengthwise manner there are five curved members 103, along which are fixed two crossbars 104, 105.

On either side of the wire frame 102 coaxial journals 106, 107 are provided by means of which gondola 99 is suspended in the two conveying chains 51, 52 so as to pivot about its axis 101.

As can be seen from Fig. 4 supply conveyor 47 is equipped with a lifting platform 114 instead of a cell wheel. In the extension of the sloping chute 110 a lifting platform 114 is guided in a recess 111 in a vertical manner following the double arrow 11 2 in a two-sided bar guide 11 3. The platform extends over the entire width of loaves 11 5, 116, 11 7 and in its lower inoperative position its portion 11 8 extends chute 11 0. 1 20 is a stop bar against which strikes the furthest forward loaf 11 6 and then stops.Lifting platform 114 is controlled by means of a lever gear arranged on either side and which comprises a rod 121 and bent lever 1 24 mounted in pivot 1 22 so as to be pivotable in the direction of double arrow 1 23. The free end 1 25 of bent lever 1 24 is located in the path of journals 126, 1 27, 1 28 of other gondolas corresponding to journal 106 and is actuated by the same, so that during each passage of such a journal, i.e. a gondola, the lifting platform 11 4 is briefly raised once and the loaf 11 6 located upon it is raised into the position of loaf 117, so that due to gravity it can subsequently drop over the stop bar in accordance with arrow 1 29. In the inoperative position lifting platform 114 engages on stop member 1 90 bearing against chute 110 via the bar guide and a fixing bush 1 91. An identical lever gear is provided on the other side, but its stop nuts corresponding to stop nuts 1 30 are positioned somewhat higher, so that the lifting platform drops somewhat later on the other side compared with the side shown in Fig. 4, so that the dropping of the platform causes not a single vibration, but two successive vibrations which aid the sliding of the loaves on chute 110. The loaf dropping in the direction of arrow 1 29 passes through the feed slot 140 into an open gondola, which is then in the receiving position. The feed slot 140 is normally closed by a trap door 141, because the latter is supported on a spring-loaded bent lever 143 pivotably mounted in pivot bearing 1 42 and which just beforehand was swung to the side by the passing journal, so that trap door 141 is pivoted downwards about its swivel bearing 145 by gravity. It is subsequently swung back into the indicated closed position by a third bent lever 146, pivotably mounted in pivot bearing 147 and also actuated by the journals. It then engages behind the bent lever 143 which has in the meantime also been swung back into the indicated position. Guides, stop members and the like are provided for bent levers 124, 143 and 146, but in part they are not shown in the drawings.

On the other side the arrangement is homologous, apart from dimensional differences with regard to the asynchronous lowering of the lifting platform 114.

The control system is so adjusted by the construction of the bent levers that the trap door 141 only keeps supply slot 140 open for the minimum time, so that as little heat as possible escapes from the baking area.

As can be gathered particularly clearly from Fig. 5 a stationary U-shaped member 1 60 is provided for the ejector and its two legs 1 61, 1 62 are positioned in the path of parts of gondolas 163, 168, as will be described hereinafter relative to Fig. 5.

Gondola 1 63 which, according to the direction of arrow 183 engages with member 1 60 strikes with its cross-bar 1 64 corresponding to cross-bar 105 in Fig. 3 against leg 1 61 and as a result is swung round by about 85 until cross-bar 1 64 overcomes leg 1 61. Cross-bar 167, corresponding to cross-bar 1 66 in Fig. 3 then strikes leg 1 62 and the gondola 1 63 is further pivoted to an angle of approximately 130 , corresponding to the position shown for gondola 1 68, where the loaf 169 contained therein drops out, passes through the ejection slot 170, forces downwards the trap door 1 72, closed by counterweight 1 71 and pivotable about axis 184, so that the loaf can pass on to the collecting chute 1 75 and from there into a storage box 1 73, where the finally baked loaves are manually accessible after opening a lid 174.

The temperature within the heating area is monitored and controlled by means of a not shown thermostat. A separate control switch in the theromstat ensures that the gondola conveyor only starts operating when a predetermined minimum temperature has been reached in the heating area. Drive motor 93 is a digitally speed-controlled geared motor with a tacho-alternator, which precisely monitors and controls the speed of movement of the gondola conveyor. Regulator 1 81 which is temperature and/or programme-controlled is used to control the conveying speed, operating temperature and/or moisture content. The casing front wall contains a manually operable flap 176, which normally closes an intervention opening 1 77. If it is opened the baking area becomes accessible.A viewing window 1 78 is incorporated in the flap. Heat-insensitive, not shown lights for illuminating the inside of the baking area are provided on the sides Another embodiment differs only with regard to certain details of the separator from the embodiment of Figs. 2 to 5 and will now be explained relative to Fig. 6. Components which are the same and have the same function as in the previous embodiments are given the same reference numerals in Fig. 6 as in Fig. 4, but the apostrophe is added, so that to this extent the description of Fig. 4 also applies to Fig. 6. Fig. 6 has no parts corresponding to stop bar 120, lifting platform 114 and bar guide 11 3. Instead an angular bar 202 is articulated to bar 201 corresponding to bar 121 and articulated to bent lever 124'.The rear end of bar 202 is pivotably mounted in a pivot bearing 203 about an axis perpendicular to the drawing plane an accordance with arrow 204. Bar 202 extends along one side of a separating member, whilst on the other side a correspondingly mounted and operated bar is provided. Two cross-bars 205 and 206 are placed between the said two bars. The cross-bars extend at right angles over the path of the ready loaves 206, 207, whilst bar 202 and the not shown bar on the other side are positioned laterally alongside the path of said loaves. In the represented inoperative state cross-bar 206 holds the furthest forward loaf 207 and consequently all loaves positioned behind it. If rocking lever 124' is actuated bar 202 and the bar on the other side are swung upwards in accordance with arrow 204, cross-bar 206 releases the furthest forward loaf 207 and cross-bar 205 temporarily holds the loaf 206 located behind it and all the following loaves. Loaf 207 can now roll into the position of loaf 208 above the supply slot 140' and then drops, as described hereinbefore relative to Fig. 4, with trap door 141 actuated into the gondola passing below it. Rocking lever 124' and with it bars 201 and 202 and the parts located on the other side return to the indicated position in which loaf 209 can advance into the position of loaf 207 and will be followed by the following loaves. Cross-bar 205 is unnecessary if the pre-baked loaves are round and uniformly shaped and as a result will advance individually controlled only by cross-bars 206.

Claims (20)

1. An automatic final baking oven for prebaked dough-based products, said oven comprising a gondola conveyor arranged within a baking area, which conveyor has axially parallel gondolas which are open at the top for receiving respective dough product portions (as hereinbefore defined) and are suspended at spaced locations on a circulating endless conveying means so as to pivot about a horizontal axis transverse to the direction of movement thereof; a gravity supply chute; a separator into which the gravity supply chute debouches and arranged on a wall bounding the baking area and movable by a respective release member associated with each gondola to allow dough product portions from the gravity supply chute to drop into successive passing empty gondolas; an ejector spaced from the separator by a distance of more than two thirds of the conveying path and adapted to engage successive passing gondolas to pivot each gondola so that the dough product portion therein falls therefrom; a trap door located in the path of the downwardly falling dough product portions and openable against a restoring force by the weight of said portion to allow the said portion to pass to a collecting chute; and a hot air blower whose suction s'ide and delivery side are both connected to the baking area.

2. An oven as claimed in Claim 1 wherein the gondolas are equidistantly spaced apart on the conveying means.

3. An oven as claimed in Claim 1 or Claim 2 wherein the conveying means is a pair of transversely spaced chains.

4. An oven as claimed in any one of the preceding Claims wherein the separator is located on the top wall bounding the baking area.

5. An oven as claimed in any one of the preceding Claims wherein the separator has a stationary stop bar located in the path of the supply chute and in front of which is provided a lifting platform movable between an inoperative position extending the supply chute and a discharge position from which a dough product portion will pass over the stop bar.

6. An oven as claimed in Claim 5 wherein the lifting platform is raised and lowered by a pair of rocker arms arranged on either side thereof and actuated by the release member.

7. An oven as claimed in Claim 5 or Claim 6 wherein the raising of the lifting platform takes place synchronously at both sides thereof but its lowering takes place asynchronously at both sides.

8. An oven as claimed in any one of Claims 5 to 7 wherein behind the stop bar is provided an opening in the cover wall dimensioned for the dough product portion and closable by a trap door, the latter being opened by a lever pair arranged on either side thereof actuated by a release member of the gondola and closed again by a following lever pair also arranged on either side thereof and actuated by the same release member.

9. An oven as claimed in any one of the preceding Claims wherein the conveying means zig-zags downwards over guide pulleys from the separator to the ejector with elongate horizontal sections and the conveying means passes vertically upwards from the ejector back to the separator.

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10. An oven as claimed in any one of the preceding Claims wherein the ejector has a stationary member with two upright legs in th,e path of respect forward and rearward cross-bars carried by the gondolas so that the forward cross-bar first abuts the first leg causing the respective gondola to pivot to approximately half the required ejection angle, subsequently the rearward cross-bar abuts the second leg to further pivot the gondola to the required ejection angle, and thereafter the gondola is allowed to swing back to its normal position under its own weight.

11. An oven as claimed in Claim 10 wherein the said ejection angle is 100" to 140 .

12. An oven as claimed in Claim 11 wherein the said ejection angle is 130 .

1 3. An oven as claimed in any one of the preceding Claims wherein the hot air blower has a radial fan wheel blower arranged coaxially to the gondola axes approximately in the centre of a wall bounding the baking area, said wall having a suction opening aligned with the suction opening of the blower and having along its vertical edges elongate slots opening into the baking area, said radial fan wheel blower being located in an otherwise closed heating area containing heat registers in the vicinity of the pressure flow.

1 4. An oven as claimed in Claim 1 3 wherein there is an upwardly open liquid tank on the bottom of the heating area which tank can be supplied with water from an external liquid supply.

1 5. An oven as claimed in any one of the preceding Claims wherein there is provided a casing for the baking area, which casing is closed apart from a closable supply slot for the separator, a closable ejection slot for the ejector, air inlets and outlets, vapour discharge openings and an intervention opening provided on the casing front wall and closable by a manually operable flap containing a viewing window, and with thermal insulation for the outer walls.

16. An oven as claimed in any one of the preceding Claims wherein there are provided temperature- or programme-controlled regulators for controlling the conveying speed, operating temperature and/or moisture content.

1 7. An oven as claimed in Claim 1 and substantially as hereinbefore described with reference to and as illustrated in Fig. 1 of the accompanying drawings.

1 8. An oven as claimed in Claim 1 and substantially as hereinbefore described with reference to and as illustrated in Figs. 2A, 2B, 3, 4 and 5 of the accompanying drawings.

1 9. An oven as claimed in Claim 1 and substantially as hereinbefore described with reference to and as illustrated in Figs. 2A, 2B, 3, 4 and 6 of the accompanying drawings.

20. A method of completing the baking of pre-baked dough-based products which comprises conveying the products through an oven as claimed in any one of the preceding Claims.