HK1198021B - Heating system for an oven for performs - Google Patents

Description

Heating module and oven comprising same

Technical Field

The present invention relates to an oven for preforms, in particular to a heating system for use in said oven, said heating system comprising one or more infrared heating modules.

Background

Obtaining containers by blowing special preforms of suitably heated plastic material in moulds having the desired shape is a widely used technique in the field of packaging, in particular for making bottles for beverages.

Basically, there are two different techniques, namely simple blowing and stretch blowing, providing pneumatic blowing of the preform and simultaneous mechanical stretching in the mold. In both cases, the preforms must reach the blowing machine or stretch-blowing machine in a thermal condition corresponding to the softening point of the material, in order to be able to be plastically deformed inside the mould.

The softening of the preforms is carried out in a special oven comprising a series of heating modules arranged in succession along the path of the preforms.

In order to maximize both the thermal efficiency and the size of the oven, it is desirable to introduce the preforms at as close a spacing as possible and to slide them within the oven.

In fact, the problem of heat losses generated by the heating module is a particularly acute problem, since this represents an energy consumption which is always very high for such ovens.

Disclosure of Invention

The aim of the present invention is to provide a heating system for preforms in an oven dedicated to the preforms, in particular an infrared oven, which allows to maximize the thermal efficiency, thus obtaining considerable energy savings.

Another object of the present invention is to provide a heating system of preforms which allows to obtain an optimal energy distribution.

This and other objects are achieved by a heating system for preforms as set forth in the appended claims, the definition of which is an integral part of the present description.

Drawings

Further characteristics and advantages of the invention will become better apparent from the description of some embodiments, given by way of indicative and non-limiting example below, with reference to the accompanying drawings in which:

FIG. 1 shows a schematic plan view of an oven blower assembly;

fig. 2 shows a simplified cross-sectional schematic view of a heating module according to the invention;

fig. 3A shows a perspective view of a heating module according to the invention;

FIG. 3B shows a cross-sectional view of the heating module of FIG. 3A;

fig. 4A shows a perspective view of a detail of the heating module according to the invention in the direction a of fig. 3B;

FIG. 4B shows a perspective view of the detail of FIG. 4A according to direction B of FIG. 3B;

fig. 5A shows a perspective view of a different detail of the heating module according to the invention in the direction a of fig. 3B;

fig. 5B shows a perspective view of a detail of fig. 5A according to direction B of fig. 3B.

Detailed Description

With reference to the figures, the oven for preforms is indicated with the number 1, which is operatively connected with handling means 2, 3 for the preforms entering and leaving the oven 1.

Such handling means 2, 3 are generally constituted by a dispensing star comprising a series of gripping means 4, for example notches, grooves or pincers, suitable for engaging with the preform, for example at the neck.

The handling means 3 for the preforms leaving the oven 1 are in turn operatively connected with a blowing machine 5 (as used in this description, the term "blowing machine" means any type of blowing machine or stretch-blowing machine) comprising a plurality of modules 6, into which the heated preforms are inserted and from which the preforms leave in the shape of blow-moulded (or stretch-blow-moulded) bottles.

The blowing machine 5 is in turn operatively connected to a dispensing device 7, generally a dispensing star, adapted to extract the blow-moulded bottles leaving the blowing machine and to transfer them to the next operating unit by means of a suitable transfer system. For this purpose, the dispensing star 7 comprises a plurality of notches 4' adapted to engage with the neck of a blow-moulded bottle.

A path of the preforms is thus defined, which is indicated in fig. 1 by the direction of the arrows, from where they are fed into the oven 1 into the modules 6 entering the blowing machine 5.

Oven 1 includes: a conveyor 8 adapted to process preforms P along a path inside the same oven and to rotate them about their vertical axis; and a heating device 9.

The heating means 9 consist of a plurality of heating modules 10 arranged along the path of the preforms.

The transfer device 8 comprises a plurality of mandrels 12, each adapted to engage a preform. Typically, the preform path comprises two straight lengths and two curved lengths, following a circular arc shaped path, connecting the straight lengths at both ends. The respective drive wheel 15, 15' is arranged at said curved length.

Conventionally, the preform P comprises: a hollow body B to be blow molded to form a container; a neck C, on which typically a thread or engagement geometry is obtained; and a flange F separating the hollow body B from the neck C.

The heating system of the preforms according to the invention comprises at least one heating module 10, as shown in fig. 3A and 3B and in fig. 2 in a simplified schematic shape.

The heating module 10 comprises a base plate 19 on which is mounted a body 20 of fork-shaped construction (i.e. having a U-shaped cross-section). The fork-shaped body 20 comprises a first side panel 25 and a second side panel 26, said panels 25, 26 facing each other to create a gap 24 having a shape and dimensions allowing the preforms P to move along the conveyor 8 passing between them.

The second panel 26 comprises a plurality of vertically arranged infrared lamps 23. A lamp of conventional type and having a tubular shape is used. Typically, 5 lamps are used to cover the entire height of the preform P.

The panels 25, 26 comprise reflective surfaces 21, 22, which are opposite and oriented to convey thermal radiation on the preform surface.

The first reflecting surface 21 is arranged on the panel 25 and faces the lamp 23 to reflect the thermal radiation inside the gap 24, so that the thermal radiation is directed towards the preforms P passing through.

In some embodiments, referring to fig. 5A and 5B, the first reflective surface 21 comprises a first mirror element 21a and a second mirror element 21B arranged on a plane incident along a vertical corner 27 to create an open V with a recess facing the gap 24. In this way, a converging effect of the thermal radiation towards the inside of the cavity 24 is obtained.

The second reflective surface 22 is disposed on the second panel 26 and includes a plurality of vertically disposed indentations 28, each indentation 28 receiving an infrared lamp 23.

As shown in fig. 2, 3B and 4B, the grooves 28 extend in parallel along the entire length of the lamp 23, and thus for the majority of the length of the cavity 24.

Each recess 28 receives a cavity 31 and includes an inner portion 22a, 22b, and an upper side panel 22c and a lower side panel 22d forming a plurality of parallel tabs 29. The inner portions 22a, 22b are arranged on a plane incident along the horizontal corner 30 to create a V-shape with a concavity facing the inside of the cavity 31. This configuration of the reflecting surface 22 allows each groove 28 to focus the thermal radiation towards a portion of the surface of the preforms P at a small angle of incidence, ensuring an optimal utilization of the emitted thermal energy. By the term "small angle of incidence", it is meant an angle of incidence of less than 20 °, as calculated with respect to the perpendicular of the generator of the hollow body B of the preform P.

In some embodiments, with reference to fig. 2, 3B and 5A, the first reflective surface 21 comprises a third mirror element 21c arranged in the upper part of the first side panel 25 above the first and second mirror elements 21a, 21B to form a longitudinal cavity 32 in which the infrared lamp is housed.

The mirror element 21c has a recess oriented towards the portion of the preform P arranged directly below the flange F. In fact, such a portion typically has the need of a different thermal profile with respect to the rest of the hollow body C, and therefore it is necessary to strive for and focus an energy unequal to the rest of the hollow body to achieve a suitable softening.

The lamp 23' arranged in such a longitudinal cavity 32 has a surface portion 33, i.e. a portion facing the gap 24, which is shielded. In this way, the preform P does not receive direct thermal radiation, but only the radiation reflected by the mirror element 21 c.

In some embodiments, with reference to fig. 2, 3A and 5A, a moving mirror element 34 projecting within the gap 24 and located below the space occupied by the preform P is associated with the first reflective surface 21.

The moving mirror element 34 includes: a mirror adjustment lever 35 inclined with respect to a longitudinal vertical plane intersecting the gap 24; and two side plates 36 disposed at ends of the mirror adjustment lever 35. The side plates 36 are flanked by the sides of the panel 25 and have vertical rings 37. Stop means 38, for example stop screws, are associated with said vertical ring 37 and with the side of the panel 25. In this way, the height of the moving mirror elements 34 can be adjusted according to the height of the preforms P undergoing heating and can be fixed at the desired point. Indeed, the function of the mobile mirror elements 34 is to reflect a portion of the thermal radiation emitted by the lamps 23 towards the bottom of the preform, which would otherwise remain partially shielded.

In some embodiments, the mirror adjustment lever 35 is tilted in a range between 20 ° and 30 ° with respect to the vertical plane.

In some embodiments, the reflective surfaces 21, 22 are gold plated to maximize their reflectivity.

Both the first and the second side panel 25, 26 comprise cooling means 39, 39' of the reflecting surface 21, 22.

In the embodiment shown in the figures, such cooling means 39, 39' consist of a cooling system with a cooling fluid, typically water, glycol or a mixture thereof, circulating in the panels 25, 26, behind the reflecting surfaces 21, 22, through an inlet connector 40a and an outlet connector 40 b. Indeed, excessive heating of the reflective surfaces 21, 22 will change over time the thermal profile that the preforms P have to undergo.

The side panels 25, 26 further comprise respective masking profiles 41, 42 for the flange F of the preform P. The masking profile comprises a hollow rod 43 having an elongated tongue 44 extending almost to contact the flange F of the preform. The hollow bar 43 comprises cooling means consisting of a cooling system with a cooling fluid, typically water, glycol or a mixture thereof, circulating in the hollow bar 43 through inlet connectors 45, 45 'and outlet connectors 46, 46'. The cooling means of the masking profiles 41, 42 have the function of keeping the optical masking structure of the flange F at a low temperature, thereby keeping the neck C of the preform P at a low temperature, at which it will break. In fact, this part does not have to undergo changes during the blowing of the container.

The masking profiles 41, 42 may be height and width adjustable to adapt the module 10 to different types of preforms P.

In some embodiments, with reference to the figures, the second side panel 26 housing the plurality of infrared lamps 23 is movable to allow to hold the same panel 26 and to approach the side panel 25 facing it. For this purpose, the panels 26 are mounted on slides 47 which can slide on rails 48 integral with the base plate 19. The clip means 49 is arranged to urge retraction of the panel 26.

In other embodiments, the first side panel 25 is movable and the other panel 26 may be fixed, or both may be movable.

The heating module 10 further comprises means for circulating air within the gap 24. Such air circulation means promote an even distribution of heat around the preforms P, avoiding undesired heat build-up in certain areas of the gap 24.

The air circulation means comprises ventilation means 50 and suction means 51.

The ventilation device 50 is arranged on the first side panel 25 and comprises a fan 52 housed in a casing 53. The housing 53 comprises baffles 54 terminating in laminar openings 55 arranged above the reflective surface 21 to convey the cooling fluid flow tangentially to the reflective surface 21.

The suction means 51 are arranged below the bottom plate 19 and communicate with the gap 24 through special openings in said bottom plate 19.

The suction device 51 comprises a downwardly open suction hood 56, below which suction hood 56 a suction 57 is arranged, typically a vane suction. Aspirator 57 is housed in a housing 58, and housing 58 may include a bottom flange 59 for securing module 10 to an oven floor or structure.

In some embodiments, the suction flow rate is higher than the output flow rate of the ventilation device 50.

The advantages of this solution are several.

As mentioned above, the arrangement of the reflecting surfaces 21, 22 according to the invention ensures that the heat radiation is effectively directed towards the preform P. In fact, after the thermal radiation has undergone various reflections, the thermal radiation reaches portions of the preform surface in a substantially parallel condition. Thus, the typical conical diffusion of thermal radiation is avoided, according to which a portion of the radiation strikes the preform surface at a small angle of incidence, reducing its efficiency. In fact, in conventional ovens, this problem is solved by arranging a number of lamps, for example to obtain a partial overlap of the radiation cones. This, of course, results in increased operating costs for the oven.

Furthermore, the fact that the heat radiation reaching the surface of the preform is substantially parallel avoids having to adjust the distance of the lamp from the preform according to its diameter. This fact is solved by the structural simplification of the module 10.

The arrangement of the mirror elements 21c and the respective lamps 23', and of the mobile mirror 34, allows focusing the portion of the thermal radiation to the main area of the preforms P, ensuring a complete control of their heating function.

For this purpose, the cooling air circulation system is also constructed to ensure an even distribution of heat.

By means of the heating module 10 according to the invention, the number of lamps can be reduced compared to conventional modules, to half the number of lamps to be used. Furthermore, the lamps will be able to be used together with less power than those typically used (e.g., 1500W instead of 2500W), thereby substantially reducing energy consumption.

It will be apparent to those skilled in the art that while only a few specific embodiments of the invention have been described, all those modifications which are necessary to adapt it to a particular use will be able to be made without departing from the scope of protection of the invention.

Claims (24)

1. A heating module (10) for heating preforms (P) for an oven (1), wherein the preforms (P) comprise a hollow body (B), a neck (C) and a flange (F) separating the hollow body (B) from the neck (C), the module (10) comprising a first side panel (25) and a second side panel (26), the first side panel (25) and the second side panel (26) being mounted on a bottom plate (19) and facing each other so as to create a gap (24) having a shape and dimensions allowing the preforms (P) to move therethrough, characterized in that the first side panel (25) comprises a first infrared lamp (23') and a first reflective surface (21), the second side panel (26) comprises a second infrared lamp (23) and a second reflective surface (22), the first reflective surface (21) and the second reflective surface (22) are opposite and oriented to convey thermal radiation on the surface of the preforms, wherein the second reflective surface (22) of the second side panel (26) is configured such that the thermal radiation hits the surface of the preforms at a small angle of incidence.

2. The heating module (10) according to claim 1, wherein said second reflective surface (22) arranged on said second side panel (26) comprises a plurality of vertically arranged indentations (28), each of said indentations accommodating a second infrared lamp (23).

3. The heating module (10) according to claim 2, wherein each recess (28) accommodates a cavity (31) and comprises an inner portion (22a, 22b) and upper and lower side plates (22c, 22d) forming a plurality of parallel fins (29).

4. Heating module (10) according to claim 3, wherein said inner portions (22a, 22b) are arranged on a plane incident along a horizontal corner (30) to produce a V-shaped portion with a concavity facing the inside of said cavity (31).

5. The heating module (10) according to any one of claims 1 to 4, wherein said first reflecting surface (21) arranged on said first side panel (25) comprises a first mirror element (21a) and a second mirror element (21b) arranged on planes incident along a vertical corner (27) to create an open V with a concavity facing said gap (24).

6. Heating module (10) according to any one of claims 1 to 4, wherein said first reflecting surface (21) comprises a third mirror element (21c) arranged in an upper portion of said first side panel (25) to form a longitudinal cavity (32) in which said first infrared lamp (23') is housed.

7. The heating module (10) according to claim 6, wherein said third mirror element (21c) has a recess oriented towards the portion of the preform (P) arranged directly below the flange (F).

8. The heating module (10) according to claim 6, wherein the first infrared lamp (23') arranged within the longitudinal cavity (32) has a shielded surface portion (33), the surface portion (33) facing the gap (24).

9. The heating module (10) according to any one of claims 1 to 4, wherein a moving mirror element (34) projecting into said gap (24) and located below the space occupied by the preform (P) is associated with said first reflective surface (21) of said first side panel (25).

10. Heating module (10) according to claim 9, wherein the moving mirror element (34) is vertically slidable and comprises a mirror adjustment lever (35) inclined with respect to a longitudinal vertical plane intersecting the gap (24).

11. Heating module (10) according to claim 10, wherein the mobile mirror element (34) comprises two side plates (36) arranged at the ends of the mirror adjustment lever (35) to laterally meet the sides of the first side panel (25) and having a vertical ring (37), stop means (38) being associated with the vertical ring (37) and with the sides of the first side panel (25) to adjust the height of the mobile mirror element (34) according to the height of the preform (P) and to fix it at the desired point.

12. The heating module (10) according to any one of claims 1 to 4, wherein said first side panel (25) comprises first cooling means (39) of said first reflecting surface (21) and said second side panel (26) comprises second cooling means (39') of said second reflecting surface (22).

13. Heating module (10) according to claim 12, wherein said first (39) and second (39') cooling means consist of a cooling system with a cooling fluid circulating in said first (25) and second (26) side panels, behind the respective first (21) and second (22) reflecting surfaces, through an inlet connector and an outlet connector.

14. Heating module (10) according to any one of claims 1 to 4, wherein the first (25) and second (26) side panels comprise respective shielding profiles (41, 42) for the flanges (F) of the preforms (P), the shielding profiles (41, 42) comprising a hollow bar (43) having an elongated tongue (44) extending almost to contact with the flanges (F) of the preforms, wherein the hollow bar (43) comprises a cooling device consisting of a cooling system with a cooling fluid circulating in the hollow bar (43) through an inlet connector and an outlet connector.

15. The heating module (10) according to claim 14, wherein the shielding profiles (41, 42) are height and width adjustable.

16. The heating module (10) according to any one of claims 1 to 4, wherein said second side panel (26) is movable.

17. The heating module (10) according to claim 16, wherein said second side panel (26) is mounted on sliding means (47) slidable on rails (48), clamping means (49) being arranged to cause retraction of said first side panel (25).

18. The heating module (10) according to any one of claims 1 to 4, the heating module (10) comprising air circulation means for circulating air within the gap (24).

19. Heating module (10) according to claim 18, wherein said air circulation means comprise ventilation means (50) and suction means (51).

20. Heating module (10) according to claim 19, wherein said ventilation means (50) are arranged on said first side panel (25) and comprise a fan (52) housed in a housing (53), said housing (53) comprising baffles (54) ending in laminar openings (55) arranged above said first reflecting surface (21) to convey the cooling fluid flow tangentially to said first reflecting surface (21).

21. Heating module (10) according to claim 19, wherein the suction device (51) is arranged below the base plate (19) and communicates with the gap (24) through an opening in the base plate (19).

22. Heating module (10) according to claim 21, wherein the suction means (51) comprise a downwardly open suction hood (56), below which a suction (57) is arranged, said suction (57) being accommodated in a housing (58) comprising a bottom flange (59) for fixing the heating module (10) to the floor or structure of the oven.

23. Heating module (10) according to claim 21 or 22, wherein the suction flow rate of the suction means (51) is higher than the output flow rate of the ventilation means (50).

24. An oven (1) for preforms (P), comprising a plurality of heating modules (10) according to any one of claims 1 to 23.