US2247289A - Process for suspending glass plates - Google Patents

Description

Hum 24, 194%. G, P. DESPRET 2,247,289

PROCESS FOR SUSPENDING GLASS PLATES Original Filed March 23, 1.936 2 Sheets-Sheet l attorney June 24, 1941. e. P. DESPRET PROCESS FOR SUSPENDING GLASS PLATES Original Filed March 23, 1936 2 Sheets-Sheet 2 Patented June 24, 1941 PROCESS FOR SUSPENDING GLASS PLATES Georges Paul Despret, Paris, France, assignor to The American Securit Company, Washington, D. 0., a corporation of Delaware Original application March 23, 1936, Serial No. 70,479, now Patent No. 2,156,011, dated April 25, 1939. Divided and this application October 13, 1928, Serial No. 234,832. In France March 2d,

2 Claims.

During the tempering step of glass plates, sheets or other similar products the sheets are generally suspended at their upper part by grippers of the so-called "frog leg" type, the advantage of this method of suspension consisting in that a very small zone or surface of the sheet is engaged.

The grippers themselves are attached to a support which is generally movable, for example a horizontal bar.

The sheets thus suspended are carried into a heating furnace of any suitable construction in which they are carried to a temperature near the softening point. When this temperature has been attained the sheets are withdrawn from the furnace and carried into a cooling apparatus where they are suddenly cooled. In this manner the sheets pass into the so-called tempered state, through which they are given new properties, such as resistance to fracture, to heat, etc.

During the operation the glass sheets suspended as before described may become deformed through the action of the heat, particularly if the sheets are of great dimensions.

The present invention relates to a suspension" apparatus for glass plates or sheets, panes or similar products, applicable particularly in the tempering operation, for the purpose of preventthe gripper support above, in raising the suspended sheet after the heating, the grippers are prevented from closing suddenly, "through the action of inertia, due to the massof the sheet, and sharply impressing their points into the glass, or sheets of other material and thus create deformation in the vicinity of these points. The resilient suspension thus precludes such local defamation.

The suspension device is completed preferably by a frame or chassis having rigid sides, intended to encompass temporarily one or more sides of the suspended plate, this frame comprising stop members mounted oppositely in pairs, between which the corresponding edge of the suspended plate engages.

These stops prevent deformation of the sheet during their heating. As known, the heat being concentrated at the centre of the furnace, the glass plates, sheets, etc. have a tendency to deform by bulging or torsion. The frame stops,

thus hold the sheet perfectly flat.

This application is a division of my prior filed application Serial No. 70,479, filed March 23, 1936, Patent No. 2,156,011, issued April 25, 1939.

Other features will be apparent from the following description.

On the accompanying drawings, given by way of example:

Figure 1 is a front elevation of the assembled improved suspension device.

Figure 2 is a profile.

Figure 3 is a partial, enlarged section on line 30 of Figure l.

Figures 4 and 5 are partial views, in elevation and plan, of the frame locking device in operative position.

Figure 6 is a partial section on line 0-6 of Fig. 5.

Figure 7 is a diagrammatic front elevation of a modification.

Figure 8 represents two positions of the frame very diagrammatically.

According to the construction illustrated on Figs. 1 to 6, the sheet II, of glass or other material, is suspended by grippers of the frog leg" type, in which the two jaws are provided with sheet engaging points 3 and are pivoted at 4 to each other, and at 5 and 6 to the arms of a com pass I, so that the whole forms a deformable quadrilateral.

The grippers are suspended by the top of their compass from a support or bar 8 through a resilient device.

In the exemplary embodiment shown each of the precedingly described grippers is connected by a rod 9 to a rod 80, terminating at its lower end in a hook i i and at its upper end in a shoulder formed, for example, of a Washer I? (Fig. l). The rod i 0 bears through this washer, from above, downwardly on a spring it or other resilient or cushioning member. This spring it, or similar member, is seated in a tube or casing it and rests on the base I5 in the lower end of said casing. At the upper end the tube or casing it carries a plug it which is connected by means of a hook ll to an attaching member it of the support.

As previously stated, by means of the resilient suspension described or modifications thereof, when the sheet is raised after being heated, the action of inertia, due to the mass of the plate, is overcome, and thus the grippers are prevented from suddenly closing and forcing their points 3 into the plate to such depth as to cause local deformation.

The mounting described provides resiliency not only vertically, but also torsionally in a horizontal plane, that is, the plate I may turn within certain limits about a vertical axis without resultant deformation, as would be the case if the distances ab-a b were invariable and equal. In fact, due to the resilient suspension, the attachments connecting the points a, b and a and b may vary in length and follow the geometric length variations of the distances ab and a b, due to said oscillations of sheet I, thus preventing the application of the entire force of the grippers on the sheet.

This second advantage of the resilient suspension is also of importance, the device being completed preferably by a frame intended to prevent or minimize all warping of the plate and at the same time any oscillation of the latter, which would cause inconvenience, as described hereinafter, at least during the critical period at the beginning of the heating before the tempering.

This rigid frame or chassis I9 is formed, for example, by four tubes I 9 braced together pairwise at 20 and connected below by a bar 2| (Figs. 1 to 3).

Ailixed to this bar connection 2| are a certain number of guides, which may consist, for example, of simple screws 22 oppositely disposed in supports 23, (Figs. 1 to 3).

Without exceeding the scope of the invention, the guides may also be formed of any other similar arrangement, for example, rods carried by screws, etc. i

The distance between two opposite screws is regulable according to the thickness of the sheets I to be tempered.

Each tube ll! of the frame or chassis l8 may slide in grooves ll (Fig. 5) provided in the horizontal frame members of the support 8.

The position of tubes l9 relative to support 8 may be fixed by any kind of retaining device.

For example according to the embodiment represented in Figures 1, 4, 5, 6, 7 and 8, the retaining device is formed by grippers 25 provided with handles 25 and with a retractile spring 26 serving to draw the operating ends of the grippers toward one another. Each member of the grippers 25 is mounted for oscillation about a pivot 21 on the bar 8. It is apparent that through the action of the spring 26 the grippers 25 hold the tubes l9 in the shallow recesses 8 formed in the bar 8. Notches 28 (Fig. 6) are also provided in the tubes at suitable intervals, so that the frame may remain suspended at different heights relative to the bar 8.

The descent of frame l9 after release from the grippers 25 is limited by stops 40 (Fig. 1), which are regulable in position.

The following is the improved method of heating, in accordance with the invention.

The sheet I of glass, plate, or similar material is first hooked to the grippers 2, the frame I9 is then carried into a position such that the bottom of the sheet is engaged between the screws 22.

The sheet I thus held by the rigid frame is then lowered into the furnace to be carried therein to the suitable tempering temperature. The heating of a glass sheet may be divided into two stages, namely, the initial heating at lower temperatures, and a subsequent or final heating I released by manipulating the retaining grippers at higher temperatures to bring the glass sheet to approximately its softening point. In the initial heating, distortion of the sheet is apt to occur. In the subsequent or final heating, whereby the glass sheet is brought approximately to its softening point, the tendency to distort or deform no longer exists.

When the temperature of the sheet has reached a certain value, the order of 450 C. for example, I have found that the tendency of the sheet to deform no longer exists. Thus, when this temperature is attained, the frame is 25, so as to lower it for a degree regulated by the stops 0, and so that the bottom of the sheet is no longer engaged between stops 22. This release of the chassis is necessary, because if left in its initial position badly tempered zones or nodes would be produced in the sudden cooling by an air jet, these zones being at the point of screws 22. It will thus be observed that the subsequent or final heating takes place without the glass sheet being supported by the chassis frame at its bottom, as shown in Figure 1, or at its bottom and sides, as shown in Figure 7.

On the other hand, notwithstanding that the pressure of the cooling air is exerted on both surfaces in an approximately equal manner, the glass plate oscillates slightly during the cooling, which would bring it in contact with the screws 22 in the form of repeated shocks, which might make impressions or imprints in the glass.

It is evident that other means for preventing deformation of the glass sheet in accordance with the invention may be realized, without departing from the scope thereof; for example, the guides may be distributed not only over the lower strip of the plate, but over the entire periphery. In such case the sheet is released before the tempering by any suitable mechanism.

Figure 7 shows by way of example a mecha- 7 part of the bar 8 by a locking device 25, of any.

kind, for example, of the type described. To open the chassis l9 so as to free the glass sheet the handles 25 of the gripping device 25 are moved toward one another, against the action of the retractile spring 26 thus removing the grippers from the tubes l9 permitting those tubes to be moved about the pivot 29 and out of the shallow recesses 8 in the bar 8.

When the chassis i9 is thus released it opens under the action of a spring 36, for example, which raises the arms 3| and 32 at 3i and 32' (Fig. 8) and removes the guides from the three edges of the sheet. The glass sheet is suspended I ing furnace will surround the supporting chassis I and the glass sheet for the necessary heating operation. The furnace will be of suflicient dimensions to permit the movement of the chassis frame according to the structures of Figures 1 claim is:

and '7. The top of the furnace or closure is preferably below the casing I4 of the spring suspension means;

It is, of course, to be understood that the in vention is not limited to the embodiments illustrated and described, which are given by way of example only.

Having thus described my invention, what I l. The method of supporting a sheet of glass for heating preliminary to tempering which consists in supporting thesheet from above and restraining the sheet against lateral movement during the initial heating and through the temperature range at which the sheet has a tendency ment from the sheet upon the increase in temperature thereof above the range of distortion.

I GEORGES PAUL DESPRET.

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