GB1597320A

GB1597320A - Installations for manufacturing continuous blocks of polyurethane foam

Info

Publication number: GB1597320A
Application number: GB16068/78A
Authority: GB
Original assignee: TECFOAM SA
Current assignee: TECFOAM SA
Priority date: 1978-02-14
Filing date: 1978-04-24
Publication date: 1981-09-03
Also published as: SE7809597L; FR2416787B1; ES466951A1; DE2818546A1; JPS54111574A; DE2818546C2; BE874128A; SE420581B; FR2416787A1

Description

(54) INSTALLATIONS FOR MANUFACTURING CONTINUOUS BLOCKS OF POLYURETHANE FOAM (71) We, TECFOAM S.A., a Spanish company, of PUXEIROS, Vigo, Spain, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to installations for manufacturing continuous blocks of polyurethane foam and, more particularly, to arrangements for heating a conveyor belt of a foaming tunnel in an installation of this kind.

According to a first embodiment of this invention, an installation for obtaining continuous blocks of polyurethane foam, of the type without "crust" or more compact layer at their bottom part, comprises a foaming tunnel the lower part whereof is constituted by the upper or conveying run of an endless belt formed, in a known manner, by a plurality of plate-like cross members connected in hinged fashion and mounted between end driving and guiding wheels at the ends of the tunnel, and is characterised in that said conveyor belt is surrounded by a box-like housing, constituted by a bottom, vertical sides of a height such that their upper edges are flush with the surface of the conveying run of said belt over its entire length. and vertical end plates, the end plate located on the upstream side belt being of a height equal to that of said sides and the end plate located at the downstream end of said conveyor belt being of a height less than that of said sides, said bottom, said sides and said end plates being totally or partially made of heat insulating material and the arrangement being such that the conveyor belt is located inside said insulated box with the upper surface of its conveying run flush with the edges of said sides and said upstream end plate, there being means associated with the housing for supplying heat to the interior of the housing and to the belt.

Preferably the space inside the box defined between said conveying and return runs of the belt and between the sides of said box is divided into two chambers by a cross partition which runs from side to side of said box-like housing, between the lower and upper runs of said conveyor belt.

Preferably the cross partition divides the housing transversely into an upstream and a downstream chamber, the heating means comprises hot air blowing means outside said housing, the outlet whereof is connected with a main supply conduit which branches off into two secondary conduits at a point located halfway along the length of said conveyor belt, each of said secondary conduits running toward the respective end of said housing, each secondary conduit having a plurality of bypasses, uniformly distributed over their length and ending, through adjustable opening outlets, in their associated chamber on one of said sides thereof, the opposite side has a plurality of air outlets, likewise uniformly distributed over the length thereof, said outlets aslo having adjustable openings. and a conduit starts from each of said outlets, all the outlet conduits which start from the side of the upstream chamber meeting at a first air outlet collecting conduit which goes toward the midpoint of the length of said conveyor belt, and all the outlet conduits which start from the side of the downstream chamber likewise meeting at a second air outlet collecting conduit which also goes toward said midpoint of said belt, to meet there with said first collecting conduit in order to form a single main air outlet conduit which is connected in turn with the intake of said hot air blowing means, so that closed circuit circulation of the hot air is obtained.

Preferably, in this first embodiment, there is a directing valve at the branch-off of said main hot air supply conduit which allows distribution of the flow of hot air fed by said blowing means to the respective secondary feeding conduits, equally or differently, and at the point where said first outlet collecting conduit and said second outlet collecting conduit meet there is another directing valve, which performs a similar function on the outlet flow of air, the orientation whereof depends on that of said valve which directs the supply flow of hot air.

According to a second embodiment of this invention, said belt is heated with heating means constituted by a coil arranged in said space in two planes: an upper one located beneath and beside the conveying run of said belt and a lower one located above and beside the return run thereof, and steam under high pressure and at high temperature from a supply source outside the installation is circulated through said coil.

According to a third embodiment of this invention, the belt is heated with heating means consituted by a plurality of infrared radiation heating elements arranged in two planes, an upper one where said elements are directed to radiate heat toward the lower part of said upper run of the conveyor belt, and a lower one where said elements are directed downward, to radiate heat toward the back of said return run of said conveyor belt, all the mentioned heating elements being uniformly distributed over the entire length and breadth of said conveyor belt. In this alternative embodiment there is a cross partition which runs horizontally over the entire length and breadth of said belt, at mid height in said space, so that it divides the latter into an upper chamber and a lower chamber.

According to a fourth embodiment of the invention, the belt is heated with heating means constituted by individual electrical resistor elements incorporated in each of the plate-like members which form the conveyor belt, and said heating elements take electric current from an arrangement constituted by current collector trolleys which slide in contact with current supply tracks arranged following a path which matches the contour of said conveyor belt.

Preferably there are means for continuously sensing the temperature inside said space, and these sensing means are adapted to generate control signals, adapted in turn to control, through known means, the operation of the means heating said space.

A more complete description of the subject matter of this invention will be given below with reference to the preferred embodiments thereof shown in the accompanying drawings, in which: Figure IA is a schematic plan view of the conveyor belt arrangement heated according to a first embodiment of the invention; Figure 1B is an elevational side view of the installation of Figure 1; Figure 2A is a schematic plan view of a second embodiment of the invention; Figures 2B and 2C are cross-sectional views along line A-A of Figures 2A and along line B-B of Figure 2B, respectively; Figure 3A is a plan view of a third embodiment of the invention; Figures 3B and 3C are sectional views along line A-A of Figure 3A and along line B-B of Figure 3B, respectively; Figure 4A is a plan view of a fourth embodiment of the invention; and Figures 4B and 4C are sectional views along line A-A of Figure 4A and along line B-B of Figure 4B, respectively; and Figure 4D is a fragmentary view of a detail of the installation shown in section in Figure 4B.

Figures 1A and 1B show a conveyor belt designated in general as 1, constituted by a plurality of plate-like cross members 2, connected in hinged fashion, and mounted between end driving and guiding wheels, 3, 4, respectively, at the ends of a tunnel (not shown), which belt is surrounded by a box-like housing 5, formed by a bottom 6, placed very close to the lower or return run of said conveyor belt, vertical sides 7, 8, also located very close to the side edges 9, 10 of said belt 1 and of a height such that their upper edges are flush with the upper surface of the conveying run of said belt over its entire length, and vertical end plates 11, 12 located close to the end parts of said belt 1.

The plate 11 located at the upstream end of the belt is of a height equal to that of said sides 7, 8, and the plate 12 at the downstream end of said conveyor belt is of a height less than that of said sides 7. 8. Said bottom 6, said sides 7. 8 and said end plates 11, 12 are totally or partially made of heat insulating material M, and the arrangement is such that the conveyor belt 1 is located inside said insulated housing 5 with the upper surface of its conveying run flush with the edges of said sides 7. 8 and of said upstream end plate 11.

Inside said housing 5. the space defined between said conveying (upper) and return (lower) run of the belt 1 and between the sides 7, 8 of said box is divided into an upstream chamber 13 and a downstream chamber 14 by a cross partition 15 which runs from one to the other side of said box-like housing 5. between the lower and upper runs of said conveyor belt.

Outside said housing 5 there are hot air blowing means S, the outlet whereof is connected with a main hot air supply conduit CP which, passing beneath the mentioned housing 5. subsequently branches off into two secondary conduits CS1, CS2 at a point located halfway along said belt 1, each of said secondary conduits CS1, CS2, running toward the respective ends of said housing. Each of said secondary conduits CS1, CS2 has a plurality of bypasses D, uniformly distributed over their entire length and ending, through adjustable opening outlets 16, in their respective associated chamber 13, 14, on one of said sides, for example 7. The opposite side, in this case 8, in each chamber has a plurality of air outlets 17, likewise uniformly distributed over the entire length thereof, said outlets 17 also having adjustable openings.

A conduit 18 starts from each of said outlets 17, all the outlet conduits 18 which start from the side 8 of the upstream chamber 13 subsequently meeting at a first air outlet collecting conduit, CCS1, which goes toward the midpoint of the length of said conveyor belt 1. All the outlet conduits 18 which start from the side 8 of the downstream chamber 14 likewise meet at a second air outlet collecting conduit, CCS2, which also goes toward said midpoint of said belt 1, to meet at 20 with said first conduit CCS1 in order to form a single main air outlet conduit CPS which is connected in turn with the intake A of the mentioned hot air blowing means S, so that closed circuit circulation of the hot air is obtained into and out of the housing.

At the point where said main hot air supply conduit CP branches off to form the conduits CS1, CS2, there is a directing valve 21 which allows distribution of the flow of hot air fed by said blowing means S to the respective secondary feeding conduits CS1, CS2, equally or differently, and at point 20 where said first outlet collecting conduit CCS1 and said second outlet collecting conduit CCS2 meet there is another directing valve 22 which performs a similar mission on the return flow of air, the orientation thereof depending on the valve 21 which directs the supply flow of hot air.

Furthermore, in said upstream chamber 13 of said box-like housing 5 there are ventilation means constituted by cooling air blowing means 19 in communication with said secondary conduit CS1 through a flow control valve 23, on one side of said chamber, and air outlet means 24, provided on the opposite side of said chamber 13 and also having a flow control valve 25. Said ventilating air flow control valves 23 and 25 can adopt any position, between a completely closed position and a completely open position, operating in mutually dependent form should an excessive temperature be detected in said upstream chamber 13, above a preset limit value, which might be detrimental for the foaming of the material on the conveyor belt 1, if this belt were to stop as a result of a breakdown, for example.

Each secondary conduit CS1, CS2 for supplying hot air to the inside of said housing 5 is extended, at its end part, into a conduit 26 designed to feed said hot air to the inside of said housing 5 through the end parts of the latter, said end conduits being provided with several hot air feed openings (not shown) distributed over the entire breadth of the associated end plate 11, 12 of said housing.

Inside each of said upstream and downstream chambers, 13, 14, respectively, there are temperature sensing means P designed to control, according to the temperature sensed in each of said chambers 13, 14, the position of the air supply and air outlet directing valves 21, 22 respectively, as well as the opening of said supply outlets 16, on the sides of said housing, and 26 at the end parts thereof, and of said air outlets 17 on the sides of said housing. These temperature sensing means are also capable of actuating the ventilation means 19, 24 provided in said upstream chamber of the installation when said preset limit temperature value is exceeded.

Figures 2A to 2C illustrate a second embodiment of this invention. They show the heat-insulated box-like housing 5 which surrounds the conveyor belt 1, on the upper run whereof the material is foamed. In this particular case, in the space defined between the upper and lower run of said belt 1 and the two sides 7, 8 of said housing 5 there is a coil-like conduit V inside which steam circulates under high pressure and at high temperature from a supply source outside the installation (not shown), the inlet of steam being controlled by a control valve VR, the position whereof is controlled by the temperature sensor P.

This steam conduit is arranged in two planes, an upper one and a lower one, the sections of the coil being placed in each plane, respectively. close to the back of the upper run of the belt 1 and close to the back of the lower run of the same belt, so that the output of heat from the steam conduit V is distributed over the entire breadth and length of the backs of said runs of the conveyor belt. in order to heat all said belt as uniformly as possible.

One one of the sides of the housing 5 there is a fan, marked 200, adapted to provide movement of the mass of air inside the space to be heated.

Figures 3A to 3C schematically show a third embodiment of the invention. where the upper and lower runs of the conveyor belt 1 are heated bv incorporating, inside said space, heating means constituted by a plurality of infrared radiation heating elements 300 arranged in two planes, an upper one, where said elements 300 are directed to radiate heat toward the lower part of the upper run of said conveyor belt 1, and a lower one, where said elements 300 are directed downward, to radiate heat toward the back of the return run of the mentioned belt 1. All these elements 3(X) are uniformly distributed over the cntire length and breadth of the conveyor belt 1, Rs can be scen in the Figures, there being 'i partition T which runs holic,ntallv over the entire length and hlca(lth ol sai(l bclt. at mid height in said Sp;lCC. to divide the latter into 'ill upper chamber 3() and a lower chamber 31, there being at least one temperature sensing device l' which actu;ltcs a device con(rolling the feed of electric power to said heisting elements (not shown) in response to the temperature sensed in said upper cham ber and in said lower ch'iml'er, to control the radiation strength of the elements 30() 'issociated to each of said cli'imbers.

In a contemplated altern;ltive of this third embodiment, in each of s'iid chambers 30 and 31 the temperature could be sensed separately and, therefore, the electric power feed to the heating elements 300, upper or lower, would be controlled independently, with at least two sensing devices and corres ponging control means, thtls providing the installation with greater flexibility.

Finally, Figures 4A to 41) show a fourth embodiment of this invention.

In this embodiment the conveyor belt is heated with heating means constituted by individual electrical resistor elements R incorporated in each of the platc-like memher 40 which form the conveyor belt 1, duly insulated therefrom to avoid faults through passing of electric power to said belt 1.

Electric current is fed to each of said electrical resistor heating elements R through an arrangement (see Figure 4D) which comprises two trolleys T. one at each end of a plate-like member 40 of said belt 1, each of which trolleys slides in contact with a power supply track 41 arranged following a path which matches the path of said belt 1 over its entire contour, close to its edges.

In an alternative of this fourth embodi ment. said two trolleys T would be arranged at the same end of each of said plate-like members 40 of said belt 1, said power supply tracks 41 being placed in mutually adjacent position. close to one or the other edge of said conveyor belt 1, over its entire contour.

WHAT WE CLAIM IS: 1. An installation for manufacturing continuous blocks of polyurethane foam without "crust" or more compact layer at their bottom part, comprising a foaming tunnel the lower part whereof is constituted by the upper or conveying run of an endless belt formed by a plurality of plate-like cross members connected in hinged fashion and mounted between end driving and guiding wheels at the ends of the tunnel, characterised in that said conveyor belt is surrounded by a box-like housing, constituted by a bottom, vertical sides of a height such that their upper edges are flush with the surface of the conveying run of said belt over its entire length, and vertical end plates, the end plate l()c;iicl on the upstream side of said belt l)eillg of a height equal to that of said sides and the end plate located at the downstream end of said conveyor belt being of a height less than that of said sides, said bottom said sides and said end plates being totally or partially made of heat insulating material and the arrangement being such that the conveyor belt is located inside said insulated box with the upper surface of its conveying run flush with the edges of said sides and said upstream end plate, there being means associated with the housing for supplying heat to the interior of the housing and to the belt.

2. An installation according to claim 1, in which the space inside the box defined between said conveying and return runs of the belt and between the sides of said box is divided into two chambers by a cross partition which runs from side to side of said box-like housing, between the lower and upper runs of said conveyor belt.

3. An installation according to claim 2, in which the cross partition divides the housing transversely into an upstream and downstream chamber, the heating means comprises hot air blowing means outside said housing, the outlet whereof is connected with main supply conduit which braches off into two secondary conduits at a point located halfway along the length of said conveyor belt, each of said secondary conduits running toward the respective end of said housing, each secondary conduit having a plurality of bypasses, uniformly distributed over their length and ending, through adjustable opening outlets, in their associated chamber on one of said said sides thereof, the opposite side has a pluralitv of air outlets likewise uniformly distributed over the length thereof, said outlets also having adjustable openings, and a conduit starts from each of said outlets, all the outlet conduits which start from the side of the upstream chamber meeting at a first air outlet collecting conduit which goes toward the midpoint of the length of said conveyor belt. and all the outlet conduits hitch start from the side of the downstream chamber likewise meeting at a second air outlet collecting conduit which also goes toward said midpoint of said belt. to meet there with said first collecting conduit in order to form a single main air outlet conduit which is connected in turn with the intake of said hot air blowing means. so that closed circuit

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. one, where said elements 300 are directed to radiate heat toward the lower part of the upper run of said conveyor belt 1, and a lower one, where said elements 300 are directed downward, to radiate heat toward the back of the return run of the mentioned belt 1. All these elements 3(X) are uniformly distributed over the cntire length and breadth of the conveyor belt 1, Rs can be scen in the Figures, there being 'i partition T which runs holic,ntallv over the entire length and hlca(lth ol sai(l bclt. at mid height in said Sp;lCC. to divide the latter into 'ill upper chamber 3() and a lower chamber 31, there being at least one temperature sensing device l' which actu;ltcs a device con(rolling the feed of electric power to said heisting elements (not shown) in response to the temperature sensed in said upper cham ber and in said lower ch'iml'er, to control the radiation strength of the elements 30() 'issociated to each of said cli'imbers. In a contemplated altern;ltive of this third embodiment, in each of s'iid chambers 30 and 31 the temperature could be sensed separately and, therefore, the electric power feed to the heating elements 300, upper or lower, would be controlled independently, with at least two sensing devices and corres ponging control means, thtls providing the installation with greater flexibility. Finally, Figures 4A to 41) show a fourth embodiment of this invention. In this embodiment the conveyor belt is heated with heating means constituted by individual electrical resistor elements R incorporated in each of the platc-like memher 40 which form the conveyor belt 1, duly insulated therefrom to avoid faults through passing of electric power to said belt 1. Electric current is fed to each of said electrical resistor heating elements R through an arrangement (see Figure 4D) which comprises two trolleys T. one at each end of a plate-like member 40 of said belt 1, each of which trolleys slides in contact with a power supply track 41 arranged following a path which matches the path of said belt 1 over its entire contour, close to its edges. In an alternative of this fourth embodi ment. said two trolleys T would be arranged at the same end of each of said plate-like members 40 of said belt 1, said power supply tracks 41 being placed in mutually adjacent position. close to one or the other edge of said conveyor belt 1, over its entire contour. WHAT WE CLAIM IS:

1. An installation for manufacturing continuous blocks of polyurethane foam without "crust" or more compact layer at their bottom part, comprising a foaming tunnel the lower part whereof is constituted by the upper or conveying run of an endless belt formed by a plurality of plate-like cross members connected in hinged fashion and mounted between end driving and guiding wheels at the ends of the tunnel, characterised in that said conveyor belt is surrounded by a box-like housing, constituted by a bottom, vertical sides of a height such that their upper edges are flush with the surface of the conveying run of said belt over its entire length, and vertical end plates, the end plate l()c;iicl on the upstream side of said belt l)eillg of a height equal to that of said sides and the end plate located at the downstream end of said conveyor belt being of a height less than that of said sides, said bottom said sides and said end plates being totally or partially made of heat insulating material and the arrangement being such that the conveyor belt is located inside said insulated box with the upper surface of its conveying run flush with the edges of said sides and said upstream end plate, there being means associated with the housing for supplying heat to the interior of the housing and to the belt.

circulation of the hot air is obtained.

4. An installation according to claim 3, in which there is a directing valve at the branch-off of said main hot air supply conduit which allows distribution of the flow of hot air fed by said blowing means to the respective secondary feeding conduits, equally or differently, and at the point where said first outlet collecting conduit and said second outlet collecting conduit meet there is another directing valve, which performs a similar function on the outlet flow of air, the orientation whereof depends on that of said valve which direct the supply flow of hot air.

5. An installation according to claim 3 or claim 4, in which ventilation means are associated with said upstream chamber of said housing, the ventilation means being constituted by cooling air blowing means in communication with said space through a flow control valve, and there are air outlet means on the opposite side of said chamber and also having a flow control valve, and said cooling air intake flow control valve and said cooling air outlet flow control valve can adopt and position between a completely closed position and a completely open position, operating in a mutally dependent manner.

6. An installation according to any of claims 3 to 5, in which each secondary conduit for supplying hot air to the intake of said housing is extended, at its end part, into a conduit designed to feed air to the inside of said housing through the end part of the latter, said end conduits being provided with several hot air feeding openings distributed over the entire breadth of the associated end plate of said housing.

7. An installation according to claim 1, in which the belt is heated with heating means constituted by a coil arranged in said space in two planes; an upper one located beneath the beside the conveying run of said belt and a lower one located above and beside the return run thereof, and steam under high pressure and at high temperature from a supply source outside the installation is circulated through said coil.

8. An installation according to claim 7, in which the temperature in said space is controlled by a sensing device which generates a signal adapted to control the flow of steam to said coil by actuating a flow control valve provided in the conduit which feeds steam to the coil.

9. An installation according to claim 2, in which said belt is heated with heating means constituted by a plurality of infra-red radiation heating elements arranged in two planes an upper one where said elements are directed to radiate heat toward the lower part of said upper run of the conveyor belt, and a lower one where said elements are directed downward, to radiate heat toward the back return run of said conveyor belt, all the mentioned heating elements being uniformly distributed over the entire length and breadth of said conveyor belt, and the cross partition runs horizontally over the entire length and breadth of said belt, at mid height in said space, so that it divides the latter into an upper chamber and a lower chamber.

10. An installation according to Claim 9, in which a single temperature sensing device actuates a device controlling the feed of the electric power to said upper and lower heating elements in response to the temperature sensed in said upper chamber.

11. An installation according to claim 9, in which the sensing of temperature in each of said upper and lower chambers and, therefore, the control of the electric power feed to the upper or lower heating elements, is carried out independently, with at least two sensing devices and corresponding control means.

12. An installation according to claim 1, in which said belt is heated with heating means constituted by individual electrical resistor elements incorporated in each of the plate-like members which form the conveyor belt, and said heating elements take electric current from an arrangement constituted by current collector trolleys which slide in contact with current supply tracks arranged following a path which matches the contour of said conveyor belt.

13. An installation according to claim 12, in which said two trolleys are arranged at the same end of each of said plate-like members of said conveyor belt, and in that the mentioned power supply tracks are therefore placed in adjacent position, close to one or the other edge of said conveyor belt, over its entire contour.

14. An installation according to any one of the preceding claims, in which in the upstream part of said space there are ventilation means which operate when the temperature inside the space exceeds a preset maximum limit value.

15. An installation according to claim 3 and claim 14, in which inside each of said upstream and downstream chambers there are temperature sensing means, adapted to control, according to the temperature sensed in each of said chambers. the position of the air supply and air outlet directing valves as well as the opening of said air outlets and supply inlets of the sides of said housing, and also, when a preset limit temperature value is exceeded, to actuate the ventilation means provided in said upstream chamber of the installation.

16. An installation according to claim 1, substantially as described herein with reference to Figures 1A and 1B. Figures 2A, 2B and 2C, Figures 3A, 3B, and 3C, or Figures 4A, 4B and 4C of the accompanying drawings.