Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
  • B29C51/26—Component parts, details or accessories; Auxiliary operations
  • B29C51/42—Heating or cooling
  • B29C51/421—Heating or cooling of preforms, specially adapted for thermoforming
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B13/00—Conditioning or physical treatment of the material to be shaped
  • B29B13/02—Conditioning or physical treatment of the material to be shaped by heating
  • B29B13/023—Half-products, e.g. films, plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
  • B29C51/26—Component parts, details or accessories; Auxiliary operations
  • B29C51/42—Heating or cooling
  • B29C51/421—Heating or cooling of preforms, specially adapted for thermoforming
  • B29C51/425—Heating or cooling of preforms, specially adapted for thermoforming using movable heating devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
  • B29C51/26—Component parts, details or accessories; Auxiliary operations
  • B29C51/46—Measuring, controlling or regulating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
  • B29C51/18—Thermoforming apparatus
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
  • B29K2023/12—PP, i.e. polypropylene

Definitions

• the invention relates to a forming apparatus for forming objects from a thermoformable sheet material, for example polypropylene .
• the invention further relates to heating stations that are insertible into a forming apparatus arranged for forming objects by forming a thermoformable sheet material, for example polypropylene.
• the invention relates to a method for heating set portions of a thermoformable sheet material following a machine downtime of a forming apparatus.
• Forming apparatuses for forming objects by forming a thermoformable sheet material comprise a system for advancing in an indexed manner the thermoformable sheet material .
• This material is unwound from a reel and is initially passed through a thermal conditioning station.
• the thermal conditioning station comprises a kiln arranged for heating the material to an operating temperature that is sufficient for preheating the material throughout the thickness thereof, i.e. as far as the innermost part thereof, or, as commonly said in the technical field, as far as the "heart" .
• this preheated material is passed through a heating station positioned at a certain distance from, and downstream of the thermal conditioning station.
• the heating station includes a plurality of heatable plates arranged in pairs along a horizontal advancing direction of the material through the heating station.
• the plates of each pair are positioned on opposite sides of the thermoformable sheet material, such as to heat opposite faces thereof.
• All the pairs of plates are simultaneously drivable between an operating position in which both plates of each pair contact the material to heat the material and a non-operating position in which the plates of each pair are at a certain distance from the material .
• the material that is thus softened is passed through a forming station in which it is deformed plastically to obtain the desired objects.
• One drawback of the aforesaid apparatuses relates to the significant quantity of material to be rejected at the restart of the forming apparatus after a more or less protracted machine downtime.
• a further drawback of such forming apparatuses is the significant energy waste thereof.
• the heat generated by the aforesaid plates in the non-operating position i.e. in the position in which they are following a machine downtime, is dispersed in the surrounding environment .
• One drawback of the aforesaid heating station relates to the significant quantity of material to be rejected at the restart of the forming apparatus after a more or less protracted machine downtime.
• the remaining portions of material positioned downstream of this portion along the advancing direction are gradually heated by a decreasing number of pairs of plates, this entailing inappropriate heating, inasmuch as the heating is for a shorter time than the set time, for subsequent forming .
• these portions are not heated by the pairs of plates positioned upstream of the portions, along the advancing direction.
• the plates are positioned in the non-operating position, i.e. they are distant from one another. This, together with the force of gravity, causes deformation of the material, which is arranged over a curved surface, i.e. it "bellies".
• the heat generated by the aforesaid plates in the non-operating position i.e. in the position in which they are following a machine downtime, is dispersed from the heating station in the surrounding environment.
• One object of the present invention is to improve forming apparatuses for forming objects from thermoformable sheet material .
• a further object is to provide forming apparatuses that compared with known apparatuses enables rejects of material to be reduced after restarts following machine downtimes.
• a still further object is to obtain forming apparatuses that enable energy consumption to be optimised.
• Another object of the present invention is to improve the heating stations that are includable in forming apparatuses arranged for forming objects from thermoformable sheet material .
• a further object is to provide heating stations that are includable in forming apparatuses arranged for forming objects from thermoformable sheet material that compared with known apparatuses enable rejects of material to be reduced after restarts following machine downtimes.
• a still further object is to obtain heating stations that are includable in forming apparatuses arranged for forming objects from thermoformable sheet material that enable energy- consumption to be optimised.
• Another further object is to provide a method for heating set portions of a thermoformable sheet material that compared with known methods enables rejects of material to be reduced after restarts following machine downtimes.
• Figure 1 is a schematic frontal view of a forming apparatus according to the invention in a first embodiment
• Figure 2 is an enlarged detail of Figure 1 ;
• Figure 3 is a plan view of the enlarged detail in Figure 2 ;
• Figure 4 is a schematic frontal view of a forming apparatus according to the invention in a second embodiment;
• Figure 5 is a schematic frontal view of a forming apparatus according to the invention in a third embodiment;
• Figure 6 is an enlarged detail of Figure 5;
• Figure 7 is a plan view of the enlarged detail in Figure 5 ;
• Figure 8 is a schematic frontal view of a forming apparatus according to the invention in a fourth embodiment
• Figure 9 is a schematic frontal view of a forming apparatus according to the invention in a fifth embodiment.
• Figure 10 is a schematic frontal view of a forming apparatus according to the invention in a sixth embodiment
• Figure 11 is a schematic frontal view of a forming apparatus according to the invention in a seventh embodiment
• Figure 12 is a schematic frontal view of a forming apparatus according to the invention in an eighth embodiment.
• the material 2 is unwound from a reel 3 and moved, for example in an indexed manner, by advancing means along an advancing direction F through a plurality of operating stations .
• this advancing means includes a driven roller 4, a plurality of rollers 7, or gears, and a guide pulley 21.
• the aforesaid operating stations comprise a thermal conditioning station 5 through which the material 2 is advanced .
• the thermal conditioning station 5 comprises a kiln 6 arranged for heating the material 2 to an operating temperature that is sufficient for preheating the material 2 throughout the entire thickness thereof, i.e. as far as the innermost part thereof, or, as it is commonly called in the technical field, as far as the "heart" .
• the rollers 7, or gears are positioned in such a manner as to make the material 2 travel along a sufficiently long path in the kiln 6 as to be heated to the desired operating temperature, whilst the guide pulley 21 is positioned in such a manner as to maintain the material 2 taut both during advancing of the latter in an indexed manner and during a machine downtime.
• the aforesaid operating stations further comprise a heating station 8, positioned downstream of the thermal conditioning station 5, through which the material is advanced 2 that was previously heated by the kiln 6.
• the heating station 8 is provided with heating means 9 that are positioned in succession along the substantially horizontal advancing direction F, of the material 2 through the heating station 8, to heat set portions 23 ( Figures 2 and 3) of the material 2 to a temperature near a softening temperature of the material 2.
• the kiln 6 and the heating means 9 are positioned near one another in such a manner that a part 11 of the material 2 interposed between the thermal conditioning station 5 and the heating station 8 is heated by the heat generated by the kiln 6 and/or by the heating means 9.
• the apparatus 1 comprises a single heating chamber 12, bounded by a thermally insulated case 13 housing both the kiln 6 and the heating means 9.
• this part 11 is maintained by the aforesaid heat generated by the kiln 6 and/or by the heating means 9 at a temperature that is even and sufficient for ensuring, at the restart, suitable physical and mechanical properties for correct subsequent forming.
• the apparatus 1 enables significant energy to be saved, inasmuch as the heat dispersed by the heating means 9 is used to heat the heating chamber 12, inasmuch as, owing to the thermally insulated case 13, it is not dispersed in the environment as occurs in known apparatuses .
• the apparatus 1 comprises, instead of the single heating chamber 12, a first heating chamber 14 for housing the kiln 6 and a second heating chamber 15, communicating with the first heating chamber 14, for housing the heating means 9.
• first heating chamber 14 is bounded by a thermally insulated first case 16, whereas the second heating chamber 15 is bounded by a second case 17, which is also thermally insulated and contiguous with, more precisely in contact with, the first case 16, a passage 33 for the material 2 being provided between the first case 16 and the second case 17.
• a third embodiment C shown in Figure 5, is a version of the first embodiment A.
• the third embodiment C differs from the first embodiment A inasmuch as the advancing direction F of the material 2 through the heating station 8 is substantially vertical.
• the heating means 9 is positioned substantially vertically.
• this portion 20 during the machine downtime, remains arranged, owing to the force of gravity, along a substantially vertical and flat surface, this ensuring, at the restart, suitable physical and mechanical properties of this portion 20 for correct subsequent forming.
• the guide pulley 21 is positioned in the heating station 8 upstream of the heating means 9 along the advancing direction F so as to maintain the material 2 taut both during advancing of the latter in an indexed manner and during a machine downtime.
• the guide pulley 21, together with the force of gravity, contributes to maintaining the portion 20 arranged along the aforesaid surface substantially vertical and flat, in particular during the machine downtimes.
• a fourth embodiment D shown in Figure 8, is a version of the second embodiment B .
• This fourth embodiment D differs from the second embodiment B inasmuch as the advancing direction F of the material 2 through the heating station 8 is substantially vertical.
• the heating means 9 is positioned substantially vertically.
• the guide pulley 21 is positioned in the heating station 8 upstream of the heating means 9 along the advancing direction F, such as to keep the material 2 taut both during advancing of the latter in an indexed manner and during a machine downtime.
• a fifth embodiment E shown in Figure 9, is a version of the fourth embodiment D.
• This fifth embodiment E differs from the fourth embodiment D inasmuch as the apparatus 1 does not comprise the second heating chamber 15, communicating with the first heating chamber 14, for housing the heating means 9.
• the heating means 9 is positioned substantially vertically.
• this portion 20 during the machine downtime, is arranged, owing to the force of gravity, along a substantially vertical and flat surface, this ensuring, at the restart, suitable physical and mechanical properties of this portion 20 for correct subsequent forming.
• the heating station 8 comprises a guide pulley 21 for maintaining the material 2 taut both during advancing of the latter in an indexed manner, and during a machine downtime.
• the guide pulley 21, together with the force of gravity, contributes to maintaining the portion 20 arranged along the aforesaid substantially vertical and flat surface, in particular during the machine downtimes.
• a sixth embodiment F shown in Figure 10, is a version of the second embodiment B .
• This sixth embodiment F differs from the second embodiment B inasmuch as the apparatus 1 does not comprise the second heating chamber 15, communicating with the first heating chamber 14, for housing the heating means 9.
• the sixth embodiment F there is provided only the thermally insulated first case 16, bounding the first heating chamber 14 in which the kiln 6 is housed.
• the heating station 8 comprises the guide pulley 21 for maintaining the material 2 taut both during advancing of the latter in an indexed manner, and during a machine downtime.
• a seventh embodiment G is shown in Figure 11.
• the apparatus 1 is devoid of the kiln 6.
• the material 2 is unwound from a reel 3 and moved, for example in an indexed manner, by advancing means along an advancing direction F through a plurality of operating stations.
• this advancing means includes a driven roller 4, a plurality of rollers 7, or gears, and a guide pulley 21.
• the guide pulley 21 is positioned in such a manner as to maintain the material 2 taut both during advancing of the latter in an indexed manner, and during a machine downtime.
• the heating station 8 is provided with heating means 9 which is positioned in succession along the substantially horizontal advancing direction F of the material 2 through the heating station 8, to heat set portions 23 ( Figures 2 and 3) of the material 2 to a temperature near a softening temperature of the material 2.
• the heating station 8 further comprises a thermally insulated case 13 that houses the heating means 9.
• the case 13 has a substantially parallelpipedon shape and comprises an inlet 33 and an outlet 66 for the material 2.
• this portion 20 is maintained by the heat generated by the heating means 9 at a temperature that is even and sufficient to ensure, at the restart, suitable physical and mechanical properties for correct subsequent forming.
• the heating station 8 provided with the thermally insulated case 13, permits a significant energy saving, inasmuch as the heat dispersed by the heating means 9 is used to maintain the aforesaid portion 20 heated and is not dispersed in the environment as occurs in known heating stations .
• the apparatus 1 is devoid of the kiln 6.
• the advancing direction F of the material 2 through the heating station 8 is substantially vertical.
• the heating means 9 is positioned substantially vertically.
• this portion 20, during the machine downtime is arranged, owing to the force of gravity, along a substantially vertical and flat surface, this ensuring, at the restart, suitable physical and mechanical properties of this portion 20 for correct subsequent forming.
• the guide pulley 21 is positioned in the heating station 8 upstream of the heating means 9 along the advancing direction F so as to maintain the material 2 taut both during advancing of the latter in an indexed manner, and during a machine downtime.
• the guide pulley 21, together with the force of gravity, contributes to maintaining the portion 20 arranged along the aforesaid substantially vertical and flat surface, in particular during the machine downtimes.
• the aforesaid heating means 9 comprises a plurality of pairs of plates 24, 25, 26, 27, 28 and 29 ( Figure 2, 3, 6 and 7) .
• the heating means 9 includes a first pair of plates 24, a second pair of plates 25, a third pair of plates 26, a fourth pair of plates 27, a fifth pair of plates 28 and a sixth pair of plates 29 arranged in succession along the advancing direction F.
• pairs of plates 24, 25, 26, 27, 28 and 29 are positioned such that the first pair of plates 24 is positioned further upstream of the advancing direction F with respect to the remaining pairs of plates 25, 26, 27, 28 and 29.
• Each pair of plates 24, 25, 26, 27, 28 and 29 comprises two heatable plates 22 that face one another and are positioned on opposite sides of the material 2, such as to heat opposite faces thereof .
• the plates 22 of each pair of plates 24, 25, 26, 27, 28 and 29 are movable along a movement direction M that is substantially perpendicular to the advancing direction F, this movement direction M being substantially vertical in the first embodiment A, in the second embodiment B, in the sixth embodiment F and in the seventh embodiment G, and being substantially horizontal in the third embodiment C, in the fourth embodiment D, in the fifth embodiment and in the eighth embodiment H.
• each pair of plates 24, 25, 26, 27, 28 and 29 are movable along the movement direction M, moving towards and away from one another between an operating position, which is not shown, in which they contact and heat the material 2 substantially to the softening temperature, and a non-operating position N , shown in Figures 1 to 12, in which they are at a certain distance from the material 2.
• each pair of plates 24, 25, 26, 27, 28 and 29 is movable along a further movement direction N that is substantially horizontal and perpendicular to the advancing direction F and to the movement direction M ( Figures 3 and 7) .
• each pair of plates 24, 25, 26, 27, 28 and 29 is movable along the further movement direction N between a first position, which is not shown, in which the plates 22 of each pair of plates 24, 25, 26, 27, 28 and 29 face, and are at a certain distance along the movement direction M from the respective portions 23 of the material 2, and a second position NX, shown in Figures 3 and 7, in which they are mutually facing and positioned laterally with respect to the material 2.
• pairs of plates 24, 25, 26, 27, 28 and 29 are positioned in the second position NX during the machine downtimes, in such a manner as not to overheat, during the machine downtimes, the respective portions 23 of the material 2 contained, at the moment of the machine downtime, in the heating station 8.
• the heating station 8 further comprises controlling means, which is not shown, for driving each pair of plates 24, 25, 26, 27, 28 and 29 between the operating position and the non- operating position NW.
• the controlling means simultaneously drives the pairs of plates 24, 25, 26, 27, 28, 29, maintaining each in the respective operating position for a time set by the following formula:
• - heating total heating time required for softening the set portions 23 of the portion 20 that are positioned at each pair of plates 24, 25, 26, 27, 28, 29 and are intended for being subsequently deformed plastically;
• the controlling means drives the pairs of plates 24, 25, 26, 27, 28, 29 independently of one another, maintaining the pairs of plates 24, 25, 26, 27, 28, 29 in the respective operating positions respectively for a time set by the following formula:
• the sixth pair of plates 29 will be driven first and subsequently the pairs of plates 24, 25, 26, 27, 28 positioned further upstream than the sixth pair of plates 29 with a delay set by the following formula :
• the controlling means again simultaneously drives the pairs of plates 24, 25, 26, 27, 28, 29 by maintaining each in the respective operating position for the t runn ing time.
• the portion 20 of the material 2 contained, at the moment of the machine downtime, in the heating station 8 is still reusable, inasmuch as each set portion 23 is heated, before leaving the heating station 8, to a temperature that is such as to enable the set portion 23 to be softened and subsequently deformed plastically.
• the controlling means maintains the respective pairs of plates 24, 25, 26, 27, 28 and 29 in the respective operating positions in such a manner that the pairs of plates 25, 26, 27, 28 and 29 positioned gradually downstream of the first pair of plates 24 with respect to the advancing direction F remain in the respective operating position for intervals of time that increase as the distance increases that separates the pairs of plates 25, 26, 27, 28 and 29 from the first pair of plates 24.
• the pairs of plates are greater or lesser in number than six. Still subsequently, the material 2 that has been thus softened by the pair of plates 24, 25, 26, 27, 28 and 29 is passed through a forming station 30 in which the material 2 is deformed plastically to obtain the desired objects 32 by forming means 31.
• a shearing station downstream of the forming station 30 a shearing station can be provided that is not shown, where suitable cutting means separates the objects 32 formed from the sheet of material 2 from which they have been obtained.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

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Citations (9)

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• 2011
  • 2011-07-25 CN CN201180045323.7A patent/CN103180121B/zh not_active Expired - Fee Related
  • 2011-07-25 WO PCT/IB2011/053298 patent/WO2012017352A1/en not_active Ceased
  • 2011-07-25 EP EP11746665.6A patent/EP2601038B1/en active Active
  • 2011-07-25 CN CN201510544511.4A patent/CN105082519B/zh not_active Expired - Fee Related
  • 2011-07-25 US US13/813,823 patent/US9403313B2/en not_active Expired - Fee Related
  • 2011-07-25 CA CA2807100A patent/CA2807100C/en not_active Expired - Fee Related
  • 2011-07-25 EP EP15160619.1A patent/EP2915654B1/en active Active
  • 2011-07-25 ES ES11746665.6T patent/ES2540860T3/es active Active
  • 2011-07-25 JP JP2013522324A patent/JP5727608B2/ja active Active
  • 2011-07-25 ES ES15160619.1T patent/ES2668372T3/es active Active
• 2015
  • 2015-04-01 JP JP2015075058A patent/JP6140754B2/ja not_active Expired - Fee Related
• 2016
  • 2016-06-15 US US15/183,121 patent/US9884446B2/en not_active Expired - Fee Related

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