GB2145504A - Preheaters for glass containers - Google Patents

Abstract

A preheat oven for glass containers, comprising an elongated horizontal open mesh conveyor (14), means (13) supporting said conveyor at an elevated position, a pair (22, 23) of elongated gas burners extending along the sides of the conveyor for impinging flames on the side of containers on the conveyor and an elongated burner (15) extending beneath the conveyor for flame impinging the bottom of the containers. <IMAGE>

Description

SPECIFICATION Preheaters for glass containers The present invention relates to a preheating apparatus for preheating glass containers to condition them for having heat shrinkable plastic sleeves applied thereto.

BACKGROUND OF THE INVENTION In the production of glass containers having plastic heat-shrunk sleeves thereon, it is common practice to provide machinery which will make a succession of cylindrical sleeves on one part of the machine from lengths cut from a roll supply of shrinkable. predecorated plastic web material. On another part of the machine, bottles or containers are loaded at spaced centers on a carriage which comprises a plurality of neck-gripping chucks on an endless chain of the elongated carriage. The bottles carried by the carriage move through an arc of a circle, at which time sleeves are telescoped from lower, sleeve-forming mandrels onto the containers positioned thereabove.Once the sleeves are positioned on the containers, the containers and sleeves are moved through a linear shrink tunnel or oven, while being simultaneously rotated by mechanism engaging the chucks holding the bottles.

It has been found in this process that it is necessary to have heated containers which either contain the heat of formation from the glass-forming process or are preheated in some fashion by a preheating oven. These preheat ovens in the past have been of the radiant energy type, either gas or electric. In configuration, they have been in the form of an elongated tunnel through which the chucks that hold the containers will be moved in series through a gap between opposed heatradiating surfaces. Radiant heaters of the gas type typically provide burners which impinge on or heat ceramics that in turn actually radiate the infrared radiation outward toward the containers with applied sleeves that are being moved through the elongated oven.The length of the pre-oven is selected, depending upon the amount of heat to be supplied to the containers, to elevate them to a suitable sleeve accepting temperature and to the speed with which it is desired to operate the sleeving machine.

The preheated container is believed necessary because of the inherent heat shrinking characteristics of the plastic sleeve. The heat that would normally shrink the plastic sleeve about the container is transferred from the heated sleeve to the cooled container and results in an uneven shrinkage of the sleeve on the container. To avoid this uneven shrinkage and resultant wrinkling of the plastic sleeve material, it is found necessary to have the container at a somewhat elevated temperature in the neighborhood of 100 -150 F. so that it will not become a heat sink for the radiation being absorbed by the sleeve during the shrinking process. Thus, it can be seen that it is necessary to have a preheating arrangement for the glass containers prior to their being introduced into the sleeving machine.

One serious drawback with the preheating ovens used in the past has been the requirement that, in the event the sleeve-applying machine breaks down and there is a supply of bottles within the length of the preheat oven, it is necessary that the containers be moved out of the oven. The radiant energy type preheaters have a great deal of heated surfaces therein which radiate for a considerable period of time even after they are shut down so that unless the containers are moved quickly out of the oven they can become overheated. This great amount of excess heat, which would distort and overheat the containers if the bottle-handling equipment were stopped, is a serious and important consideratin.In the situation where a stoppage of the sleeving machine is necessary, and since the containers are held by their necks and are already carried by the chucks that will move them through the entire cycle of the machine operation, it is necessary to continue to run the machine through a long cycle to clear the bottles from the machine. Obviously, these bottles will have to be stored somewhere because they will not have had sleeves placed thereon. They may even have been subjected to heat in the shrinking oven.

SUMMARY OF THE INVENTION The present invention is directed to providing a bottle preheat oven wherein the bottles that are to be preheated are conveyed through the oven on an open weave, articulated linktype conveying belt. A pair of parallel, elongated gas burners extend essentially the full length of the preheat oven and flames from these burners are directed toward the opposed sides of the bottles which are positioned on the conveyor. The flames issuing from the two burners on opposite sides of the moving containers will have their flames impinge on the sides of the container as they are moved on the moving belt conveyor. A third burner generally coextensive with other burners and beneath the conveyor will impinge its flames on the bottom of the bottles as well. In this manner, the bottles may be preheated by flame impingement.In the event of a breakdown, so that the requirement for heated bottles is obviated, the burners may be shut off and the conveyor stopped with the bottles remaining within the confines of the oven without damage thereto.

It is, therefore, an object of the present invention to provide a preheat oven which may be shut down without requiring that the containers within the oven be moved out of the oven.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of the apparatus of the invention; Figure 2 is an end view of the apparatus of Fig. 1 looking in the direction of arrow 2 on Fig. 1; and Figure 3 is a perspective view, on an enlarged scale, of the burners used.

DETAILED DESCRIPTION OF THE DRAW INGS With particular reference to Figs. 1 and 2, the preheat oven of the invention will be described.

A rectangular frame including a pair of elongated channel beams 10 extend beneath and along the length of the apparatus serves as the base. Serving as side frames and extending up from the base are a plurality of vertical beams 11. The beams 11, along with the horizontal upper frame beams 12 and the base 10, provide a generally rectangular elongated framework. A pair of opposed horizontally-extending conveyor supporting tracks 13 extend the full length of the frame and serve to support and guide a conveyor 14. The conveyor 14 is an open weave metal, chainlink-type conveyor which extends through the framework from end to end at an elevated position, approximately half the height of the vertical beams 11. Thus, it can be seen that the tracks 13 serve to guide the conveyor 14 through the length of the apparatus.

Extending substantially the full length of the preheat oven, and in alignment beneath the conveyor 14, is an elongated gas burner 15.

The burner 15 is in the form of an elongated pipe having a plurality of burner openings in the upper surface thereof directed toward the bottom of the conveyor 14. The burner 15 is supported at its opposite ends by brackets 16 and held in place on the brackets by U-bolts 17. The brackets 16 are supported at an elevated position by vertical posts 18 and 19.

In addition to supporting the brackets 16, the posts 18 and 19 serve to support inwardlyextending brackets 20 and 21. The brackets 20 and 21 serve to support a pair of horizontally-extending, elongated burners 22 and 23.

The burners 22 and 23 extend along opposite sides of the conveyor 14 at a somewhat elevated position relative thereto. These burners have openings at the lower edge facing generally toward each other and toward the center of the conveyor 14.

As best shown in Fig. 2, flames which will issue from the ignition of the gas coming from the burners 22 and 23 will impinge on the sides of containers which are being moved through the oven on the moving conveyor 14.

The frame 12 above the run of the containers is provided with a top 24. The sides of the frame are closed down to the height of the conveyor brackets or tracks 13. The side of the oven, as best seen in Fig. 1, is closed in by a series of doors 25. These doors are hinged at their upper edge by hinges 26 fixed to the side of the oven. These doors are provided adjacent the center thereof with transparent glass panes 27. The panes or windows 27 provide viewing ports to observe the proper combustion and operation of the burners and the impingement of the flames from the burners on the containers as they pass through the oven.

The doors 25 are also provided with handles 30 which serve as a convenient mechanism for opening and, if necessary, provide access to the interior of the oven.

Above the containers, the entire upper area of the oven below to top 24 serves as a plenum chamber which is connected to the inlet 28 of an exhoust fan 29 mounted on the top of the oven. Operation of the exhaust fan 29 serves to carry fumes away from the oven and at the same time will insure that the heat produced by flame impingement will be of a predetermined heat input to the glass containers. In order to control to some extent the exhaust and the degree of movement of air upwardly out of the oven through the exhaust fan 29, a series of adjustable louvers 31 are provided between the burner chambers and the upper plenum chamber.

The detail of the burners, separate from the oven, is shown in Fig. 3. Each of the burners 15, 22 and 23 have a gas supply line 35 connected to a cone-shaped inlet and air mixing connection 36. Atop each of the burners is mounted a temperature sensor 37 and pilot burner 38. The sensor 37 is in the flame produced by the pilot burner 38 and thus is a part of a safety system for shutting off the gas to an individual burner in the event the pilot flame is not functioning. It should be noted that the burner openings 39 in the burner 22 begin in a line directly beneath the pilot burner and, in fact, the pilot burner flame is configured to sweep over several of these openings 39. The openings then continue in a row over the corner of the square burner to a long line that extends along the lower inner corner of the burner. This row of openings is slightly above the level of the conveyor surface so that flames from the burner will be directed outward to impinge on the bottles.

The exhaust fan 29 will create an upward draft that causes the flames to bend upward along the sides of the bottles.

The center burner 15 has a pair of rows of burner openings in its top surface so that the flames therefrom will impinge on the bottom of the containers through the openings in the conveyor structure.

The temperature sensors may be connected to solenoid valves in the gas supply lines for shutting off the gas in the event the pilot burners are out.

With the apparatus as described, it can be seen that glass containers which are to be preheated are moved in the direction of the arrow shown in Fig. 1 by the conveyor through the oven where they are heated by flame impingement directly onto the container. This flame impingement, while serving to heat the containers, also has in some instances a salutory effect of cleaning any residue from the containers which might have been placed thereon during the forming cycle through inadvertence.

In the event it is necessary to stop the movement of heated containers to the previously described sleeve-applying machine, it is only necessary to signal back to the burners and the burners may automatically shut off.

At the same time, the conveyor 14 will be stopped and the containers may remain in the position in the oven that they have assumed.

At this time, the fan may or may not be shut down, depending upon whether it is desired to cool the containers or whether it is desired to let the containers retain the heat that they have already absorbed. However, when the burners are shut off, it is not necessary in the present preheat oven that the containers be removed therefrom as is the case in those infrared-type heaters used in the prior art.

Infrared heaters produce a great deal of radiation even after the source of fuel is shut off.

In the instance of the infrared-type gas heaters, it is necessary to move the containers out of the preheater or stand a chance of damaging the containers. It is particularly significant in the event the system for conveying the containers through the preheat oven fails and some containers are left positioned within the oven. In the prior art, it was necessary to provide for some means of moving the conveyor to get the containers out of the preheat oven. In the present case, regardless of whether the conveyor is running or not, the cutting off or shutting down of the burners is all that is necessary to interupt the flow of heated containers through the oven, and the containers may remain within the-oven once the gas is turned off without any problem relative to overheating.

Claims (9)

1. A preheat oven for glass containers, comprising an elongated, horizontal open mesh conveyor, means supporting said conveyor at an elevated position, a pair of elongated gas burners extending along the sides of said conveyor for impinging flames on the side of containers on said conveyor and an elongated burner extending beneath said conveyor for flame impinging the bottom of the containers.

2. The oven of Claim 1, further including a plenum chamber above the conveyor and means for exhausting said plenum.

3. The oven of Claim 1, wherein said conveyor is formed of metal links.

4. The oven of Claim 1, further including chamber-defining side walls along the side of the area above said conveyor and access doors in the side walls.

5. The oven of Claim 4, wherein said access doors are provided with viewing windows.

6. The oven of Claim 2, further comprising adjustable openings formed in the wall of said plenum immediately above said conveyor.

7. The oven of Claim 1, wherein said pair of burners are generally square in cross-section and the burner openings are in the lower side facing the conveyor.

8. The oven of Claim 1, further including a temperature sensor and pilot light mounted on each burner at the gas entrance end thereof in overlying relationship with a few of the burners openings in each burner.

9. A preheat oven for glass containers, substantially as described with reference to the drawings.