US3235350A

US3235350A - Method and apparatus for bending glass sheets

Info

Publication number: US3235350A
Application number: US398835A
Authority: US
Inventors: Ronald E Richardson
Original assignee: Pittsburgh Plate Glass Co
Current assignee: PPG Industries Inc
Priority date: 1960-10-31
Filing date: 1964-09-18
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15
Also published as: DE1149864B; FR1304445A; ES271556A1; GB956021A

Description

Feb. 15, 1966 R. E. RICHARDSON 3,

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept. 18. 1964 5 Sheets-Sheet 1 Feb. 15 1966 R. E. RICHARDSON 3,235,350

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept 18 1964 5 Sheets-Sheet 2 Feb. 15, 1966 R. E. RICHARDSON 3,235,351}

METHOD AND APPARATUS FUR BENDING GLASS SHEETS Filed Sept. 18 1964 5 Sheets-Sheet 5 Feb. 15, 1966 R. E. RICHARDSON 3,235,350

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept 18 1964 5 Sheets-Sheet 4 Feb. 15, 1966 R. E. RICHARDSON 3,235,350

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept.'l8. 1964 5 Sheets-Sheet 5 ATTORNEYS United States Patent 3,235,350 METHOD AND APPARATUS FOR BENDING GLASS SHEETS Ronald E. Richardson, Oshawa, Ontario, Canada, assignor to Pittsburgh Plate Glass Company, Pittsburgh, Pa. Filed Sept. 18, 1964, Ser. No. 398,835

Qlaims priority, application (lanada, Oct. 31, 1960,

810,043 6 Claims. (Cl. 65-107) This application is a continuation-in-part of the pre viously filed application Serial No. 96,846, filed March 20, 1961, and now abandoned. This invention relates to improvements in the construction of concave, multipart, skeleton type molds of the type having a fixed center section and an end section pivotally secured to opposed ends thereof and particularly to providing in such molds intermediate or ancillary supports rigidly fixed to the center section and projecting therefrom into the zones of the mold end sections.

Skeletonized molds are well known in the art wherein the pivotal end sections are biased, usually by means of weights, so that they tend to move from an open position to a closed position. Initially, a flat, cold glass sheet is placed on a mold with the end sections pivoted to an open position where it is held by the weight of the glass sheet. In this position the glass sheet is supported at relatively few spaced points, two of which are constituted by the extreme end tips of the mold and/or by ancillary supporting devices located adjacent such tips.

Upon heating of the glass to bending temperature the glass softens with the result that the downward force exerted by the glass sheet on the end sections diminishes and the end sections move upwardly towards their closed positions. At the completion of the bending operation when tthe end sections are fully closed, they serve to define with the fixed main section a continuous concave shaping surface adapted to impart the desired curvature to the glass sheet.

Modern trends in automobile design call for the use of increasingly larger glass sheets in Windshields and rear windows and for curvatures of increasing complexity. The production of these large sheets of complex curvature on skeleton type molding surfaces involves some difficulty. For example, the glass shaping rails constituting the portion of the shaping surface presented by the center section of the mold frequently have an upward curvature at the parts thereof adjacent to the glass shaping rails of the end sections of the mold. The longitudinal extremities of the center section rails are therefore raised above the level of the remainder of these rails. As a result, when the glass sags longitudinally during the bending towards the shaping surface the first points of contact of the glass sheet with the shaping surface (other than the points of initial support mentioned above) are at these raised extremities of the center section rails commonly referred to as cut points. If the glass remains in contact with these out points for an appreciable length of time, kinking of the sheet is liable to occur. Similarly, kinking of the tips of the sheet can result from the force exerted thereon during the bending operation when the sheet is solely or primarily supported by the tips of the end sections or the mentioned ancillary supports at such tips during bending.

Another difiieulty arises from the fact that the design of automobile Windshields and rear windows now frequently involves the provision of curvature transversely of the length of the glass. This results in the necessity to use a skeleton type mold having some portions of its shaping surface much lower than others and hence farther removed from the glass sheet during the initial stages of the bending operation. Since the metal of which the mold is constructed exercises a chilling effect on glass located adjacent thereto, there is thus a tendency for unequal heating between the two sides of the glass sheet with the result that sagging tends to occur at the side where the shaping surface is farthest removed from the glass. This problem is particularly encountered when forming sheets having a curvature containing a compound bend with a pronounced transverse curvature.

It is an object of the present invention to provide a mold construction by means of which kinking of the glass sheet at the mold tips or at the cut points can be minimized.

It is a further object of the invention to provide a mold construction by means of which undesirable sagging of the glass sheet at portions thereof which are to be received by a part of the shaping surface farther removed from the sheet prior to bending than other portions of the shaping surface can be minimized.

In one aspect of the invention, there is provided a concave glass bending mold of the multi-part, skeleton type movable between an open position for receiving a sheet of flat glass thereon and a closed position peripherally defining a curved shaping surface with which the glass sheet is to conform after bending, said mold includes a center mold section comprising a first pair of spaced, substantially parallel glass-shaping rails defining a first portion of said shaping surface and having the longitudinal extremities thereof disposed above the level of other portions of said rail, an end mold section pivotally connected to said center mold section at opposed ends thereof for pivotal movement between an open position and a closed position, said end mold sections each including a second glass-shaping rail defining a second portion of said shaping surface lying contiguous with the ends of the rails of said first portion when the mold is in the closed position, and a glass intermediate support member rigidly secured to said center mold section and projecting therefrom into the area of at least one of said end sections, said supporting member having an upper arcuately shaped surface disposed within the area of the end section defining a plurality of successive support points for the glass sheet during movement of the mold from the open to the closed position.

The invention will be described by way of illustration and without limitation with reference to the accompanying drawings wherein:

FIG. 1 is a plan view of half of a skeleton type concave glass bending mold, only half of the mold being illustrated since the mold is symmetrical.

FIG. 2 is a side View of the mold of FIG. 1,

FIG. 3 is an end view of the mold of FIG. 1,

FIG. 4 is a side view of the mold of FIG. 1 with the mold parts somewhat differently disposed than in FIG. 2,

FIG. 5 is a side view of the mold of FIG. 1 similar to that of FIG. 4 when bending of a glass sheet thereon has been about half completed,

FIG. 6 is a view similar to that of FIG. 5 after completion of the bending operation,

FIG. 7 illustrates a modification of the embodiment of FIG. 1,

FIG. 8 illustrates diagrammatically the modes of operation of the mold of FIGS. 1 and 7,

FIG. 9 shows a further modification of the mold of FIG. 1,

FIG. 10 is a plan view of a detail of FIG. 9,

FIGS. 11 and 12 illustrate further modifications of the embodiment of FIG. 1 and FIGS. '13 and 14 are vertical side elevational views of one end of one side rail on the fixed portion of the mold having an arm extending therefrom with a short portion' adjacent the end thereof forming an intermediate support. Shown in the drawings is a skeleton type, sectionalized mold including a main central fixed section 1 having a pair of movable end sections 2 pivotally secured thereto at opposed ends thereof, only one such end mold section being visible in the drawing.

The main mold section 1 includes a pair of spaced shaping side rails 3 interconnected by bracing members 4. The bracing provided by the bracing members'4 is reinforced by vertically disposed upstanding plates 5 extending transversely across the mold and secured at their ends to the main side rails 3 and by bars 6 extending diagonally across the mold and secured to the plates 5.

The end mold section 2 includes a curved end shaping rail 7, a main bracing member 8 and subsidiary bracing members 9. To each end of the end rail 7 there is secured by struts 10 a plate 11 provided with a key hole slot 12. At each side of the mold there is mounted a grooved pivot pin 14 supported on a rod 15 secured to and extending upwardly from a mold supporting frame 16 to which the side bars 3 are connected by members 17. The keyhole slots 12 are formed with upper portions having a diameter only slightly greater than the inner diameter of the grooves in the pivot pins 14 and less than the diameter of these pins, and with lower portions of a diameter greater than that of the pivot pins 14. By passage of the pivot pins 14 into the lower portions of the slots 12, the edges of the upper portions of the slots 12 may be lowered into engagement with the grooves of the pivot pins 14 thereby to mount the end section 2 for pivotal movement relative to the main mold portion 1. Arms 19 carrying counterweights 20 are secured to the plates 11 and tend to urge the outer end of the end mold sections 2 upwardly from a spread mold position wherein the longitudinal outer extremities of each end rail 7 bears against the under surface and thereby support a flat glass sheet towards a closed position where, as shown in FIG. 6, the ends of the curved end rail 7 forms a contiguous smooth continuation of the side rails 3.

The mold also includes curved

intermediate support rails

22 and 23 referred commonly to as roll bars each rigidly secured to the main mold section, and extending longitudinally outwardly therefrom into the zone of the end section and slightly laterally inboard of the pivotal path traversed by the inner ends of end rails 7. The support rails are secured to the side rails 3. However, they could also conveniently be secured to other portions of the fixed mold structure. The support rail 22 is braced by bracing members 24 extending between the rail 22 and the outermost plate 5 and the rail 23 is braced by a bracing member 25 extending between the rail 23 and the outermost plate 5. Each of the

support rails

22 and 23 has a convex upper surface, the most part of which is above the level of the longitudinal extremity or cut point 26 of the associated side rail 3. iImmediately adjacent the cut point 26 however the upper edges of the

intermediate support rails

22 and 23 are below the level of the cut points 26. The upper edges of such rails are fixed in position to the side rails 3 and occupy a position above the upper edges of the inner ends of end rails 7 when the end section 2 occupies its flat glass supporting position depicted in FIG. 4. This position is below the upper edges of the inner ends of the end rails 7 when the end rails are pivoted to the closed mold position depicted in FIG. 6.

In FIGS. 2 and 3 the mold is shown with the end section 2 held downwardly away from the position it assumes at the time that a flat glass sheet is loaded onto the mold. This is merely to indicate more clearly the disposition of the immediate support rails 22 and 23 and the manner in which a glass sheet 28 rests upon these rails when first loaded onto the open mold.

FIG. 4 illustrates the relationship between the glass sheet and the mold immediately after loading of the sheet 28 onto the mold with the end section 2 being urged upwardly against the sheet by the counterweighted arms 19.

In this position the glass sheet is supported partly by the: tip of the end section 2 and partly by some portion along. the upper edge of the intermediate support rails 22 and? 23. This constitutes a three-point support at each end? of the mold in contrast to the single-point support which would exist in the absence of the intermediate support rails 22 and 23.

FIG. 5 shows the nature of the support afforded the sheet part way through the bending operation. Upon introduction of the mold together with the glass sheet into a bending lehr where the glass is heated to bending temperature, the sheet 28 softens. Under the influence of the counterweighted arms 19 the end section 2 of the mold pivots upwardly towards its closed position and when such movement has been completed, the glass has been bent to the prescribed curvature defined by the concave shaping surface of the mold in the closed position. It will be noted that the glass sheet 28 is still supported at its tip by the tip of the end section 2. It is also still supported by the intermediate support rails 22 and 23 but the points of support provided by these rails are located nearer to the cut points 26 than are the initial points of support shown in FIG. 2. With progressive bending of the sheet 28 towards final contact with the shaping surface of the closed mold the points of support provided by the intermediate support rails 22 and 23 move progressively inwardly towards the cut points 26. Since the cut points 26 are above the level of the adjacent portions of the intermediate support rails 22 and 23 the glass eventually comes to rest upon these cut points and moves out of contact taltogether with the

rails

22 and 23. It is then supported by the cut points 26 and the tip of the end section 2. This does not occur however until the bending operation has been almost completed so that the glass is in contact with the cut point for only a short time before the end sections of the mold have reached their closed positions and have completed the continuous shaping surface defined by the side rails 3 and the curved end rail 7 when the mold is in the closed position.

In molds of the prior art not provided with intermediate support devices, according to this invention, as exemplified by

support rails

22 and 23, the glass comes into contact with the cut points of the center section of the mold a considerable time before the bending operation has fully completed. As indicated above, this frequently causes kinking of the glass in the regions bearing on the cut points. Also before the glass sheet has sagged to a sufiicient extent that it contacts the cut points and is supported thereby the full weight, or much of the weight, of the sheet is supported at its tips with the result that kinking may occur adjacent the tips of the sheet.

By contrast, in the mold described above with reference to FIGS. 1 to 6, each of the support rails 22 and 23 provides an intermediate supporting surface with which the surface of the glass sheet is in rolling contact from the beginning until almost to the end of the bending operation. In other words each of the

rails

22 and 23 furnishes a continuous line of intermediate support points successively in contact with the glass during bending. This reduces the load at the tips of the sheet, thereby minimizing tip kinking, while at the same time keeping the glass sheet off the cut points 26 until so near to the end of the bending operation that the cut points bear against the glass for an insufficient length of time to cause appreciable kinking.

Furthermore, it will be seen from FIG. 2 that the intermediate support rail 23 bears against a side of the sheet 28 which, at the beginning of the bending operation, is farther separated from the portion of the end rail 7 lying beneath it than is the other side of the sheet 28. This unequal separation between the sheet 28 and the opposite sides of the end rail 7 is dictated by the nature of the curvature being imparted to the sheet. As a result of it the end rail 7 exercises a greater chilling efieet on one side of the sheet than the other during the bending operation.

This can give rise to unequal heating of the two sides of the sheet with the consequence that the side of the sheet farthest separated from the end rail '7 sags downwardly more than is tolerable in order to obtain a satisfactorily bent sheet. Such undesirable sagging is however minimized in the mold described because the tendency for it to occur is counteracted by the presence of the support rail 23. The latter rail provides physical support for the portion of the sheet which would tend to sag and also exercise a chilling effect thereon.

FIG. 7 shows a modification of the mould of FIG. 1 wherein an intermediate support rail 230, corresponding to the intermediate support rail 23 of FIG. 1, is mounted on a pin 30 secured to the main side rail 3 so as to be pivotable relative to the side rail. An arm 31 provided with counterweights 32 issecur-ed to the inner end of the intermediate support rail 23a and serves to urge the rail 23a upwardly against the sheet 28. This has the effect of still further relieving the load on the tip of the glass sheet where it bears against the tip of the end of section 2. During the bending operation the intermediate support rail 23a is continuously in rolling contact with the sheet 28 and provides a line of successive support points during the bending operation until immediately before the end section 2 has attained its closed position and the desired curvature has been imparted to the sheet 28. The inter-. mediate support rail 23a: is prevented from contacting the glass sheet 28 when the mould is in the fully closed position in that the arm 31 contacts a fixed stop (not shown) shortly before attainment of the closed position of the mould thereby preventing further upward movement of the rail 23a.

FIG. 8 indicates diagrammatically the contour of the line of spaced support point provided by the intermediate support rail 23 of FIG. 1 and by the intermediate support rail 23a of FIG. 7 during the bending operation. The broken line A represents the fixed position of the intermediate support rail 23 or the initial position of the intermediate support rail 23:: or immediately after loading of the glass sheet 28 onto the mould. In the case of the intermediate support rail 23 the point of support of the glass sheet by the rail moves downwardly along the broken line A during the bending operation as indicated by a series of circles representing a few of the infinite number of successive support points. In the case of the intermediate support rail 23a of FIG. 7 the positions of the upper edge of this rail at three successive stages during the bending operation is indicated by the broken lines B, C and D. Four of the infinite number of successive support points provided by the intermediate support rail 23a for the sheet 28 during the bending operation is indicated by a series of crosses each of which lies on one of the dotted lines A, B, C and D. It will be observed that the use of the pivoted intermediate support rail 23a makes it possible to provide an intermediate supporting surface of a highly convex natur-eso convex that a fixed rail having the same contour would not provide satisfactory rolling contact throughout the bending operation because its highest point would be fairly close to the cut point 26 of the center section 3. The provision of a line of support points having such a pronounced convex curvature may be of considerable advantage when forming some of the highly complicated bends now required in the production of automobile glass.

FIG. 9 shows a further modification of the mold of FIG. 1 wherein an intermediate support rail 23b corresponding to the intermediate support rail 23 of the mold of FIG. 1, is secured to the side rail 3 in such manner that the upper convex surface of the intermediate support rail 23b is contiguous with the upper surface of the side rail 3. As a result, the sheet 28 remains in rolling contact with the intermediate support rail 23b throughout the whole of the bending operation and is still in contact therewith after bending has been completed. This is clearly desirable in that such a construction prevents the sheet 28 from ever coming into contact with the cut points 26 of the side rails 3. The reason that such a construction is not adopted in the mold of FIG. 1 is that it would result in an effective thickening of the shaping surface within the regions where the side rail 3, the end rail 7 and the intermediate support rail 23 are in close proximity to one another, i.e., in the region of overlap between the side rail 3 and the intermediate support rail 23 and in the region where the end rail 7 lies closely adjacent to the intermediate support rail 23. The shaping surface would therefore have an increased thermal capacity at these regions which would give rise to a shadowing effect. This difficulty is overcome in the construction of FIG. 9 in that, as shown in FIG. 10 (which is a plan view of FIG. 9), the outer end of the side rail 3b and the inner end of the end rail 7b are diminished in thickness in the region of overlap between the side rail 3b and the intermediate support rail 23b so that they together have a combined thickness equal to that of the general thickness of the side rail 3. Also, in the region where the end rail 7 lies closely adjacent the intermediate support rail 23b the thickness of the end rail 7 is reduced so that there is no appreciable effective thickening of the shaping surface in that region. The shadowing effect mentioned above is thereby substantially eliminated and the advantage of having the intermediate support rail in rolling contact with the glass sheet 28 throughout the whole of the bending operation can be obtained.

In the embodiments of mold construction described above, the

rails

22, 23, 23a and 2312 are all located inboard of the mold. In fact, in intermediate support all such embodiments the intermediate support rails further are located effectively wholly within the zone of the end section. It is however possible to mount these rails outboard of the mold provided that the edge of the glass sheet extends for a sufiicient distance over the edge of the shaping surface presented by the mold for the sheet to remain in rolling contact with the support rail at least until near the completion of the bending operation.

Furthermore, although FIGS. 7 and 9 illustrate modifications of only the intermediate support rail 23 it will be evident that similar modifications can be made to the intermediate support rail 22. In some instances it may bedesirable to have a fixed intermediate support rail at one side of the mould and a pivoted, counterweighted intermediate support rail at the other side of the mold.

Another possibility within the scope of the invention is the provision of a single intermediate support rail. This may be disposed at one side only of the mold or, if the bracing of the end section permits, may extend all the,

tion of a glass sheet having a highly complex bend it ispossible that a glass supporting member with a concave upper surface could usefully be employed provided that the radius of curvature of the upper surface of the glass supporting member if substantially greater than that of the concave shaping surface of the mold so that the upper surface of the support rails 22, 23, 23a and 23b have a contour that follows the line of contact produced by sagging the glass sheet inwardly of the portion lifted upwardly on the mold extremity as the bending operation takes place. Generically the shape of the upper surface of the intermediate support rail may be referred to as being arcuate. Such shaping causes effectively rolling contact between the glass during bending and the upper surface of the intermediate support rail. Also it is sometimes desirable to use glass intermediate supporting members, the upper edges of which are provided with both concave and convex portions or include fiat portions. For example, FIG. 11 shows an intermediate support rail 230 the upper surface of which has a convex portion 231/, a concave portion 23v and a flat portion 23w while FIG. 12 shows an intermediate support rail 23d the upper surface of which has a first convex portion 23x, a concave portion 23y and a second convex portion 23z. Such composite curvatures are often of assistance when it is desired to provide a plurality of support points for a glass sheet to which a compound bend is being imparted.

The intermediate support rails 22, 23, 23a and 23b all serve to provide a continuous line of successive support points for the glass sheet during movement of the mold from the open to the closed condition since they each have a smoothly convex upper surface. This is not necessarily true of the support rails 23c and 23d. The line of successive support points provided by these latter support rails may be discontinuous, depending on the characteristics of the mould to which the rails are fitted. Such discontinuity does not prevent the advantages of the invention from being obtained. It is merely necessary that a plurality of successive support points be provided during the movement of the mould from the open to the closed position.

The intermediate supports described are effectively in rolling contact with the lower surface of the glass sheet during bending. Such described intermediate supports are also referred to as roll bars and since they extend over a considerable length they may be referred to as long roll bars. In FIGURES 13 and 14 there is shown short roll bars wherein the intermediate support is relatively short in length and is in spaced relation with respect to the cut oint.

p Referring to FIGS. 13 and 14 shown therein is a side rail 3 having a bar 40 rigidly secured thereto and projecting outwardly from the cut point 26. The bar 40 terminates in an enlarged outer end portion 41 having an upper arcuate edge portion 42 to be in rolling contact with the glass sheet during the bending thereof and provide an intermediate support therefor. In FIG. 13 the edge portion 42 is an integral part of the bar 40 while in FIG. 14 it consists of a separate portion added thereto and the latter is substantially relatively shorter than the former. In the particular embodiment illustrated in FIGS. 13 and 14, the length of the roll bar in contact with the glass is approximately one half inch. This may be termed a relatively short roll bar in that the length of contact in the other embodiments is approximately nine inches. This latter bar, accordingly, may be referred to as a relatively long roll bar. The upper surface for supporting glass in any event is convex and such shape minimizes the time of dwell of the soft glass on each point of the intermediate support as the glass sheet moves from the flat to the curved configuration. By minimizing the time of support at any one point, penetration of the intermediate support into the softened glass is reduced.

The various embodiments of the invention have been described in terms of a mould having a fixed center section. It is inherent in the present invention that the intermediate support rails 22, 23, 23a, 23b, 23c, and 42, which serve as intermediate support members for contacting the bottom surface of the glass sheet longitudinally outwardly of the center mould section and longitudinally inwardly of the mould longitudinal extremities; i.e., in the zone of the end sections, may be attached to center section rails of a mould whose center section is not fixed to a support frame, but whose center section is permitted to move vertically with respect to the mould support frame as the pivoted end section oscillate between their open position and their closed position.

The important feature of all the embodiments illustrated and of the present invention in general is that the upper surface of the glass intermediate supporting

members

22, 23 etc., be located above the shaping surface of the adjacent pivoted end sections 7 when the latter occupy their open position and that each glass intermediate support member has its upper surface below the shaping surface of its adjacent end mould section 7 when the latter is pivoted into the closed mould position with each successive point along said upper surface that contacts the bottom surface of the glass sheet during its bending located longitudinally inwardly of the preceding glass contacting point.

The above description of various embodiments according to the present invention has been made for the purpose of illustration rather than limitation. Reference to the latter may be obtained by studying the claimed subject matter Which follows.

I claim:

1. A concave glass bending mold of the multi-part skeleton type movable between an open position for receiving a sheet of fiat glass thereon and a closed position peripherally defining a curved shaping surface with which the glass sheet is to conform after bending, said mold including a main mold section having a first glassshaping rail defining a first portion of said shaping surface and having a longitudinal extremity disposed above the level of other portions of said rail, an end mold section pivotally connected to said main mold section for movement betwen an open position and a closed position, said end mold section including a second glassshaping rail defining a second portion of said shaping surface lying contiguous with said first portion when the mold is in the closed position, and an intermediate glass supporting member rigidly secured to said main mold section, said glass intermediate supporting member having an elongated, arcuate, upper surface disposed within the zone defined by the end mold section and including a plurality of support points located longitudinally inwardly of one another at positions occupied and sequentially alternately engaged and disengaged by the bottom surface of the glass sheet during bending thereof in movement of the mold from the open to the closed position.

2. A concave mold as defined in claim 1 wherein the upper surface of the intermediate supporting member is relatively short and disposed within the zone of the end mold section and spaced a predetermined distance from the center section.

3. A concave glass bending mold according to claim 1 wherein the upper surface of said glass-supporting member is constructed to defined a continuous line of successive support points for the glass sheet during movement of the mold from the open to the closed position.

4. A concave glass bending mold of the multi-part skeleton type movable between an open end position for receiving a sheet of flat glass thereon and a closed position peripherally defining a curved shaping surface with which the glass sheet is to conform after bending, said mold including a main mold section comprising first and second laterally spaced, generally parallel, glassshaping rails each having two longitudinal extremities disposed above the level of other portions of the rail, an end mold section situated outwardly of said main mold section at opposite ends thereof, said end mold sections including respectively a third and fourth glass shaping rail, said end mold sections co-operating with said main mold section in the closed position of the mold to form a substantially continuous glass-shaping surface extending between an end of said third glassshaping rail and an end of one of said first and second glass-shaping rails and between an end of said fourth glass-shaping rail and the other of said first and second glass-shaping rails, a first glass intermediate supporting member extending longitudinally outwardly and upwardly from a longitudinal extremity of said first glass-shaping rail at one end of said main mold section, a second glass intermediate supporting member extending longitudinally outwardly and upwardly from one of said glass-shaping rails at the other end of said main mold section, each of said glass intermediate supporting members having an elongated upper arcuate surface including a plurality of support points located longitudinally inwardly of one another at positions occupied by the bottom surface of said glass sheet during bending thereto in movement of the mold from the open to the closed position.

5. In the method of bending a glass sheet into conformity with a shaping surface of concave elevation by a combination of heat sagging and upward lifting of a longitudinal extremity ofthe sheet wherein the glass sheet before bending is initially supported adjacent and intermediate its longitudinal extremities in an initial plane of support, the improvement comprising engaging the glass sheet intermediate its longitudinal extremities at an initial support point disposed along the initial plane of support for the glass and lifting said longitudinal extremities of the glass sheet above said initial plane of support while alternately engaging and disengaging the glass sheet intermediate its longitudinal extremities on points of support successively disposed longitudinally inwardly of one another before the entire length of the glass sheet is deposited on said shaping surface of concave elevation.

6. In a method of bending a glass sheet wherein the sheet is exposed to bending temperature while supported adjacent the longitudinal extremities of the sheet, the improvement comprising providing additional support for the sheet during bending thereof at a plurality of support points which are successively brought alternately into and out of contact with the sheet during the bending thereof, each of said support points being disposed longitudinally inwardly (if any of said plurality of support points previously in contact with said sheet.

References Cited by the Examiner UNITED STATES PATENTS DONALL H. SYLVESTER, Primary Examiner.

Claims

1. A CONCAVE GLASS BENDING MOLD OF THE MULTI-PART SKELETON TYPE MOVABLE BETWEEN AN OPEN POSITION FOR RECEIVING A SHEET OF FLAT GLASS THEREON AND A CLOSED POSITION PERIPHERALLY DEFINING A CURVED HAPING SURFACE WITH WHICH THE GLASS SHEET IS TO CONFORM AFTER BENDING, SAID MOLD INCLUDING A MAIN MOLD SECTION HAVING A FIRST GLASSSHAPING RAIL DEFINING A FIRST PORTION OF SAID SHAPING SURFACE AND HAVING A LONGITUDINAL EXTREMITY DISPOSED ABOVE THE LEVEL OF OTHER PORTIONS OF SAID RAIL, AN END MOLD SECTION PIVOTALLY CONNECTED TO SAID MAIN MOLD SECTION FOR MOVEMENT BETWEEN AN OPEN POSITION AND A CLOSED POSITION, SAID END MOLD SECTION INCLUDING A SECOND GLASSSHAPING RAIL DEFINING A SECOND PORTION OF SAID SHAPING SURFACE LYING CONTIGUOUS WITH SAID FIRST PORTION WHEN THE MOLD IS IN THE CLOSED POSITION, AND AN INTERMEDIATE GLASS SUPPORTING MEMBER RIGIDLY SECURED TO SAID MAIN MOLD SECTION, SAID GLASS INTERMEDIATE SUPPORTING MEMBER HAVING AN ELONGATED ARCUATE UPPER SURFACE DISPOSED WITHIN THE ZONE DEFINED B THE END MOLD SECTION ARE INCLUDNG A PLURALITY OF SUPPORT POINTS LOCATED LONGITUDINALLY INWARDLY OF ONE ANOTHER AT POSITIONS OCCUPIED AND SEQUENTIALLY ALTERNATELY ENGAGED AND DISENGAGED BY THE BOTTOM SURFACE OF THE GLASS SHEET DURING BENDING THEREOF IN MOVEMENT OF THE MOLD FROM THE OPEN TO THE CLOSED POSITION.

5. IN THE METHOD OF BENDING GLASS SHEET INTO CONFORMITY WITH A SHAPING SURFACE OF CONCAVE ELEVATION BY A COMBINATION OF HEAT SAGGING AND UPWARD LIFTING OF A LONGITUDINAL EXTREMITY OF THE SHEET WHEREIN THE GLASS SHEET BEFORE BENDING IS INITIALLY SUPPORTED ADJACENT AND INTERMEDIATE ITS LONGITUDINAL EXTREMITIES IN AN INITIAL PLANE OF SUPPORT, THE IMPROVEMENT COMPRISING ENGAGING THE GLASS SHEET INTERMEDIATE ITS LONGITUDINAL EXTREMITIES AT AN INITIAL SUPPORT POINT DISPOSED ALONG THE INITIAL PLANE OF SUPPORT FOR THE GLASS AND LIFTING SAID LONGITUDINAL EXTREMITIES OF THE GLASS SHEET ABOVE SAID INITIAL PLANE OF SUPPORT WHILE ALTERNATELY ENGAGING AND DISENGAGING THE GLASS SHEET INTERMEDIATE ITS LONGITUDINAL EXTREMITIES ON POINTS OF SUPPORT SUCCESSIVELY DISPOSED LONGITUDINALLY INWARDLY OF ONE ANOTHER BEFORE THE ENTIRE LENGTH OF THE GLASS SHEET IS DEPOSITED ON SAID SHAPING SURFCE OF CONCAVE ELEVATION.