US2033261A - Leer - Google Patents

Description

O m 000000000 000000000000 E 000000000 000000000000 W 000000000 000000000000 l I 000000000 00000000000? I 000000000 0000000000 0 000000000 000000000000 7000000000 000000000000 000000000 000000000000 March 10, 1936.

Patented Mar. 10, 1936 S ATENT OFFICE LEER Application January 30, 1935, Serial No. 4,061

7 Claims. (01. 49-47) My invention relates to leers such as are emshows a modification of a portion of the strucployed in the annealing of glassware and the ture of Fig. 1.

like, and more particularly to a means for heating the same.

It is common practice to heat leers by gas or oil In some instances, these burners discharge through the side walls of the leer at points above the plane of travel of the Ware being treated, while in other instances, the burners are positioned in a burner chamber beneath the line of travel of the ware, adjacent to the entrance burners.

end of the leer chamber.

through the roof, to exhaust stacks.

arrangement, the glassware has no direct contact with the burned gases, and thereby clouding or glooming of the glassware by the gas fumes is avoided, but such structures are somewhat inemcient in that there is considerable loss of heat. Also, in many instances, it has been found necessary to provide fans for effecting a forced circulation, through the various side wall passages, in order to effect proper distribution of the heat.

My invention has for its object the provision of a simplified and improved method and apparatus for heating leers and the like, in such manner that the various objectionable features abovereferred to are avoided.

One object of my invention is to provide an improved means for distributing heat from burners in such manner that a leer belt will not become so unevenly heated as to cause it to become distorted or certain portions thereof unduly elongated relative to other portions, and hence to maintain it in a flatter condition, and to avoid deflection thereof from its proper path of travel through the 1eer chamber.

Still another object of my invention is to provide improved guiding and driving means for a leer belt.

Some of the forms which my invention may take are shown in the accompanying drawing wherein Figure 1 is a longitudinal sectional view of a leer structure; Fig. 2 is an enlarged view, taken on the line 11-11 of Fig. 1; Fig. 3 is a sectional plan view thereof; Fig. 4 is an enlarged view, taken on the line IV-IV of Fig. 1, and Fig. 5

The leer chamber 5 may be of somewhat the usual form and provided with heat-insulating walls. A leer belt or conveyer 6 preferably of the wire fabric or mesh type, is also provided, for conveying glassware or other articles through the leer chamber, and this may be mounted and driven, and adjustably tensioned in any wellknown manner.

The leer chamber has communication with a main stack or flue 1, through branch flues 8, 9 and Ill. The flues 8, 9 and ID are provided with suitable dampers which may be individually adjusted to control flow of hot gasesfrom the leer chamber. If the 1eer chamber becomes too hot at points in advance of the flue III, the dampers 8 and 9 can be opened to the desired degree to permit exhaust of the heating gases, and the damper of flue H] can be opened or closed to any desired degree, determined by the temperature conditions in the leer chamber, and in accordance with well- -known practice. The damper in flue I can, of course, be operated to control flow from all of the flues 8, 9 and Ill.

Vertically-adjustable baffle plates II, l2 and [3 are provided to control the flow of heated gases along the roof or top wall of the leer chamber, so that the heat will not pass off too quickly, and so the bafiling effect on the air will cause it to be deflected downwardly toward the conveyer belt. These baffles may extend entirely across the leer chamber, and can be raised and lowered by suitable hand-operated screws l3a.

Toward the discharge end of the furnace, I provide shutters I4 and IS in the top and bottom walls of the 1eer chamber, to permit escape of heat from the chamber, and to admit cooler outside air thereto whenever it is found that the ware is too highly heated when passing the location of these shutters. The shutters may be simply metal plates hinged at one edge to the leer, and may be held open or closed in any suitable manner.

The leer is provided with a burner chamber I! that may be somewhat in the form of a depression in the bottom wall of the leer chamber. Baffle plates l8 of cast iron or of more refractory material, such as clay, extend transversely of the leer and across the burner chamber. A burner tube l9, provided with a series of gas discharge openings, is mounted beneath each burner plate it, a mixture of gas and air being supplied to each of the burner tubes through a gas and air mixer 20. The gas is supplied to each air mixer By this 20 from a gas conduit 2! past a control valve 22. Additional or enlarged openings 23 are provided at the mixers 20, to admit additional air to the burner chamber so as to insure more perfect combustion of the gas, and in order to provide suitable natural draft flow of the hot gas through the leer chamber. Flow of gas through the conduit 2| to the mixers 20 is controlled by a valve 24, and this valve may be automatically actuated in accordance with temperature conditions in the leer chamber in any wellknown manner, as by means of a thermostatic device 25.

The bafile plates l8 may be of sufficient thickness toabsorb a considerable amount of heat, so that when the burner flame is reduced or cut off entirely, they will radiate heat to the underside of the belt 6, thus assisting in maintaining uniformity of temperature and avoiding quick changes in temperature within the leer, through fluctuations in flame intensity. The plates may suitably be one inch or greater in thickness.

An important feature of my invention resides in the provision of perforations in the plates l8 and the spacing thereof throughout the plates. As shown in Fig. 3, the center-to-center spacing of the perforations in the plates 18 gradually decreases from the axial centers of the plates to the marginal edges thereof in longitudinal and transverse directions. Also, the perforations are of graduated diameters, those disposed adjacent to the edges of the plates being of greater diameter than the perforations located adjacent to the axial center of the plates. By this arrangement, heat from the burners I9 is uniformly distributed throughout the length and width of the conveyer belt and the ware carried thereby over the combustion chamber.

For example, the perforations may be of diameters graduated between one-fourth inch and one-half inch diameter. Likewise, the center-tocenter spacing between the perforations may be one and one-half (1 inches adjacent to the axial center line of the plates and gradually decrease to one inch centers along the marginal edges of the plates. These dimensions, of course, may vary in accordance with particular conditions encountered or desired.

The holes are of such small diameter that the plates will exert sufficient baffling effect on the flames to prevent the flames from direct engagement with the ware that is carried on the conveyer belt. Also, they cause a better distribution of the burner heat against the belt and the ware. It will be seen that if the plates were solid, the heat would mainly pass around the edges of the plates and against the lower side of the belt at somewhat localized areas. Not only would the ware thereby be subject to uneven temperatures in passing across the heating chamber I1, but the metallic belt 6 would be so unevenly heated as to increase danger of warping and shifting thereof.

If some longitudinal portions of the belt are heated to a materially smaller extent than other longitudinal portions thereof, there will, of course, be tendency for the belt to shift diagonally or transversely of its normal path of travel.

Ordinarily, the burner flames will be of such length that they do not quite touch the burner plates I8, thereby reducing danger of incomplete combustion and consequent smokiness of the burnt gases. The plates ill will become heated to red-hot temperature or higher, and thereby facilitate the complete combustion of the gases, after the manner of clay radiants employed in gasheating stoves.

The burner plates also shield the ware traveling on the conveyer belt 5 from the direct radiation of or contact with the burner flames, so that the Ware is protected from excessive heating, and there is less danger of it becoming clouded by the flames.

The perforated baiile plate arrangement will, of course, be useful also in connection with the annealing of sheet glass, which may be pushed through the leer simply on rollers, and without the use of a conveyer belt. The distribution and evenness of the heat on the sheets of glass will be better by reason of the perforations, as above explained.

The plates 13 may be of considerable thickness, so that they will absorb and retain a large amount of heat which will be given off. While there is gas flame at the burners, the upper sides of the plates will radiate heat against the bottom of the ware as the ware passes over the plates, with the result that there is better uniformity in the application of heat to the Ware.

Furthermore, in case the valves of the burners' are closed or nearly closed, the burner plates will radiate heat to the ware, and prevent too sudden cooling thereof.

Guide rollers 26 and 2'! are mounted adjacent to the front and rear ends of the leer, at points away from the more highly heated zones. These rollers have idling movement on vertical axes, and may be composed of or faced with some nonmetallic material such as rubber, or a substance that will not readily damage the edges of the metallic belt. The rollers are of such suitable length axially that they will properly guide the belt, even though there is some vertical displacement of the belt during operation of the leer.

The belt passes around the usual guide rollers at the entrance end of the leer, and at the discharge end thereof, passes around guide rollers 28, 29 and 30. A driven roller 3| is provided for driving the belt, the roller being driven in any suitable manner. It Will be noted that the driving engagement between the roller 3| and the belt is at the inner face of the belt, instead of with the ware-carrying surface thereof. This arrangement reduces danger of the ware-carrying surface of the belt being distorted through frictional driving engagement with the roller 3|, and hence there is less likelihood of the Ware tilting on the belt because of unevennesss in the ware-supporting surface of the belt.

In Fig. 5; I show a modified form of belt drive and guide, wherein while the driving roller 33 engages the inner surface of the belt, two guide rollers 34 and 35 are suficient as compared to the three rollers 28, 29 and 30. Also, in the form shown in Fig. 5, there is a greater area of driving engagement between the roller 33 and the leer belt.

I claim as my invention:-

1. The combination with a leer chamber and means for supporting ware during movement thereof through the chamber, of a burner disposed beneath the path of travel of the ware, and. a burner plate interposed between the burner and said path, the burner plate having perforations which are of less total area in the zone immediately above the burner than in the remaining portions of the plate.

2. The combination with a leer chamber and.- means for supporting ware during movement thereof through the chamber, of burners disposed beneath the path of travel of the ware, and a burner plate interposed between each burner and said path, the burner plates having perforations which are of less total area in the zones immediately above the burner than in the remaining portions of the plates, and the plates being spaced apart in directions longitudinally of the leer.

3. The combination with a leer chamber and means for supporting ware during movement thereof through the chamber, of burners disposed beneath the path of travel of the ware, and a burner plate interposed between each burner and said path, the burner plates having perforations which are of less total area in the zones immediately above the burner than in the remaining portions of the plates, certain of the edges of the plates being unobstructed, to permit upward flow of heated gases past said edges.

4. The combination with a leer chamber and a ware conveyer therefor, of burner plates disposed beneath the conveyer and extending transversely thereof, and burners disposed beneath the said plates and approximately oo-extensive in length therewith, the plates being laterally spaced relative to one another, the burner plates having perforations which are of less total area in the zones immediately above the burner than in the remaining portions of the plates.

5. The combination with a leer chamber and a ware conveyer therefor, of a burner chamber beneath the said conveyer, burner plates disposed in relatively spaced relation beneath the conveyer, and burners disposed beneath the said plates, the plates being positioned above the burners at such height that they are normally out of contact with the burner flames, the burner plates having perforations which are of less total area in the zones immediately above the burner than in the remaining portions of the plates.

6. The combination with a leer chamber and a ware conveyer therefor, of a burner disposed beneath the conveyer, a heat-absorbing and radiating member interposed between the burner and the conveyer, edge portions of the said member being unobstructed, and the member being provided with vertically-extending perforations which are of less total area in the zones immediately above the burner than in the remaining portions of the plates.

'7. The combination with a leer chamber and means for supporting ware during movement thereof through the chamber, of a burner disposed beneath the path of travel of the ware, and a burner plate interposed between the burner and said path, the burner plate having perforations distributed throughout the major portion thereof, the perforations in the zone above the burner being of smaller diameter than the perforations in the other portions of the plate.

EDWARD C. STEWART.

Images