JPS6112853B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for bending heat-softened glass sheets or similar materials by clamping them between two rigid shaped members of complementary curvature. This method, known as press bending, is useful for the relatively inexpensive mass production of curved sheet glass within close tolerances. More specifically, the present invention relates to a method of press bending glass sheets into a very small radius of curvature bend known as a "V" bend. Generally, press bending is done by S.L. Seymour (S.
L. Seymour, U.S. Pat. No. 3,367,764, is well known in the art. However, conventional press bending methods are limited in the sharpness of the bend that can be imparted to the glass, with a minimum radius of about 23 centimeters (9 inches) or even larger required for commercial press bending. This is typical of the device. Desirably is a "V" shape with a radius of less than 20 centimeters (8 inches), preferably on the order of 10 centimeters (4 inches), or even less.
It is about creating a bend. Creating sharp "V" bends has most commonly been accomplished by gravity sag bending methods, in which a sheet of glass is placed over an appropriately shaped contoured mold. The glass sheet is placed in a generally horizontal orientation and heated to the point of failure of the glass so that it sag and conform to the shape of the mold. Through a wire or ribbon held close to or in contact with the locally heated glass to concentrate such bending along a so-called "live wire" to form a "V-shaped" bend. or applied along the live wire by electrical resistance heating via a conductive material glued to the glass. The use of heated wire or ribbon is recommended by R.A.
Jansson) and TJ Riese (TJ
Reese) U.S. Patent No. 3795501, R.
U.S. Patent No. 3795570 to A. Jianson and D. L. Thomas; U.S. Patent No. 3847586 to T. G. Riese, G. R. Glaassen, and M. D. L. Tobin.
US Patent No. 2111392 to JHGallay, US Patent No. 2176999 to RAMiller, US Patent No. 2176999 to JHGallay, and US Patent No. 2176999 to JHGallay.
No. 2215228, G.S. Golightly (J.
U.S. Patent No. 3248195 by Messrs. S. Golightly and HE Mackelvey
No., and R. L. Richardson (RL.
Richardson, U.S. Pat. No. 2,999,338. The use of conductive stripes glued to a glass surface is disclosed in US Pat. No. 3,762,903 by HE Hamilton.
No., H.E. Hamilton, R.E.
U.S. Patent No. 3762904 by REBamford and P.Pastorek
No. 1, U.S. Patent No.
No. 3,879,184 and US Pat. No. 3,865,680 to T.G. Riese and H.S. Koontz. It has been proposed prior to the present invention to apply localized heat to the sheet glass during the press bending process in a manner compatible with forming a "V" bend. One such proposal was made by R. E. Richardson (RE
Richardson (Canadian Patent No. 799907), which states that in order to equalize the temperature of the sheet glass from the leading edge to the trailing edge,
The leading edge of each glass sheet is heated at the press bending operation. The heat is provided by a radiant heater directed near the leading edge of the glass sheet. CE Valcher
and S.J. Mlodziski (S.J.
Mrozinski) U.S. Patent No. 3,333,935,
A method is shown in which additional heat is provided to the lower part of each glass sheet by a pair of gas burners to enable the lower part to be bent into sharp curvatures. However, this does not create the narrow, precisely positioned heating wire necessary to create a "V" bend. Another method of using localized heat for press bending width is described by H. E. Hamilton (HE
No. 3,960,535 to Messrs. Hamilton and WWOelke, which describes the application of heat to a press bending width by means of a gas burner around a hole in a glass sheet. ing. Its purpose is to maintain isothermal conditions in the glass, and therefore “V
It has little in common with creating a "shape" bend.Canadian Patent No. 900720 shows a press bending mold together with a number of elongated electric heating elements penetrating the mold along a vertical line. However, the electric heating elements are located below the surface of the mold, since their purpose is not to provide localized heat to the glass, but to warm the entire surface of the mold. The glass is suspended from a metal carriage connected to a metal carriage with rails resting on grounded rollers.Flat glass is electrically conductive because it is formed by press bending. Therefore, applying electrical energy along the desired line to a sharp bend will result in electricity leaking through the torsion and the supporting carriage to the earth. Such leakage reduces the effect of the applied voltage along the line where sharp bends are desired and causes less sharp bends than desired and uncontrolled temperature distribution between the glued conductive wires of the sheet glass and the glass supports. This additional heating can cause a few problems, for example, because the additional heat softens this area of the glass. , cutting deeper into the glass than desired.
Therefore, the vicinity of the location where the glass-engaging element grips the glass will be locally distorted and damaged more severely than if the glass plate gripped thereon were not energized. Marceou U.S. Patent No. 3340039
The issue describes a sheet of glass held by metal bars connected by a metal bar to a metal carriage equipped with metal wheels that moves along metal rails. This patent provides a resilient or shock absorbing strip that is placed on the rail on which the carriage wheels ride. The elastic strip is preferably rubber. Certain compositions of rubber do not conduct electricity, and the device described in Marceau's patent allows for a direct grounding circuit from the conductive sheet glass through the glass grips and handles, connecting bars and carriages and wheels to the rail. However, the device described in this patent does not prevent damage between the wheel and the rail on which the wheel rides if a sufficiently high voltage is used to cause the glass to be locally heated by the resistor. No measures are being taken to avoid arcing. U.S. Pat. No. 3,363,930 to Webb discloses that aluminum oxide has a greater coefficient of friction against glass than stainless steel over the entire temperature range at which the glass is heat treated to produce assembled glass products. A glass-engaging element having a fired ceramic composition containing a large amount of This patent describes glass made of other ceramic materials having the requisite properties of greater hardness and higher tensile strength than pressurized asbestos and substantially lower thermal conductivity and substantially lower heat capacity than that of stainless steel. A few other embodiments of contact elements have also been described. Some of these materials are electrically insulating materials in nature. However, the size of the glass contacting elements is such that if a high voltage were applied to the conductive glass plate carried by the provided portion of Webb's glass-engaging elements, However, the possibility that some of these materials inherently possess electrical insulating properties with characteristics not appreciated prior to the present invention is relatively small, such that arcing is unavoidable. The invention requires gluing a strip of electrically conductive material to the major surface of the glass sheet along a line corresponding to the intended location for the "V" bend. The glass sheet, with the stripes in place, is heated as a whole to a temperature suitable for bending in the conventional manner by passing it through a furnace. After leaving the furnace,
A glass sheet is parked between opposing complementary press members, but before said press members are operated, opposing edges of the glass sheet are arranged such that a pair of electrodes completes a circuit through said conductive stripes. is moved into contact with the conductive stripe. A high voltage current is passed along the line defined by the stripe to heat the glass sheet to a temperature higher than the temperature of the body of the glass along the line. The electrodes are then withdrawn and pressurization begins immediately in the usual manner. “V
Localized heating along the line of bend enables press bending to achieve bends with radii of curvature well below 20 centimeters (8 inches). A device is also provided to insulate the support carriage from the support carriage, thus avoiding currents that result in uncontrolled currents, and providing additional heating and conductivity in the vicinity of the plate glass gripped by the support carriage for press bending purposes. The isolating device is located at a sufficient distance from the conductive heating strip and the grounded supporting carriage to avoid creating a current that bypasses the current passing through the conductive heating strip by arcing. Embodiments include a standoff device of electrically insulating material spacing the support member from the support element and having a length sufficient to effectively isolate the metal support carriage from the grounded support carriage. The plate glass and grounded supports are spaced from the support carriage at a sufficient distance to minimize arcing. Figure 1 of the accompanying drawings shows the Teshimatte 1
It includes a front edge view of a glass sheet G in place being bent by a pair of opposing presses 10 and 11. When viewed from the side as in FIG. 2, it can be seen that the bending operation point is
and the quenching operation point 13. Furnace 12 is provided with a door 14 which slides open as each glass plate passes from the furnace. Each pane of glass is suspended by a lever 15 which hangs from a carriage 20 which is propelled along a conveyor 21 (from right to left in FIG. 2). (For clarity, the device for supporting and transporting the glass sheets is not shown in Figure 1.) The structure shown in Figure 2 was designed by William J. Hay. US Patent No.
It is similar to the conventional one as exemplified in No. 3089727. The carriage and conveyor are insulators made of electrically insulating material 1
6 and electrically insulated from the glass plate and the glass support and gripping member 15. The insulator shall be of sufficient length to effectively isolate the metal support carriage from the grounded support carriage, and shall be connected to the glass plate and ground at a sufficient distance to minimize arcing. It is placed at a distance from both the supported carriage and the supporting carriage. The length of the insulator may vary depending on the voltage applied along the conductive wire to induce the sharp bend line. A connection that prevents arcing and connects a strip of conductive material, through glass that becomes conductive when heated, through a metal support, and from that to a grounded support carriage. A device 86 (the upper part is connected to the carriage 20, the lower part is connected to the yatsuko 15,
A minimum length of 2.5 centimeters is preferred to avoid a continuous current path through the device (referring to the device including the insulator 16 between the top and bottom). Although there is no upper limit to the length of the insulator, as a practical matter the maximum dimension of the insulator should be selected with a view to minimizing the mass which determines the heat capacity of the insulator. The recommendation is to minimize the mass of the structural elements used to transport the glass sheets to be processed. For example, insulators that provide a six-pane spacing between the metal piece and the support member have been successfully used. A barrier plate 22 may be provided at the inlet end of the quenching operation area to prevent quenching air from being blown into the bending operation area. Jama board 2
2 may slide or oscillate to enable entry of each pane into the quenching operation point. Generally, sheet glass is rapidly cooled at a quenching point so that it can be tempered. Cooling is accomplished by blowing air onto both sides of the glass sheet from a number of orifices 23 in a pair of opposed blow heads 24, all of which devices take forms known in the art. I don't mind. The press bending operations shown in the accompanying drawings are of the preferred configuration as described in S. L. Seymour, US Pat. No. 3,367,764. Since the press itself is not part of the invention, only a brief overview of its construction and operation needs to be described to understand the invention. The forming members of both opposing presses 10 and 11 each have a back plate 3
1. A triple plate arrangement of the adjustment plate 32 and either a molded plate 33 on one side which is curved in a medium-high manner or a complementary molded plate 34 on the opposite side which is curved in a medium-low shape. has been done. These plates are adjustably mounted by a number of threaded rods 35 and nuts (of which only a representative number are shown in FIG. 1). By turning these nuts, the effective curvature of the molded part can be adjusted. Each curved profiled plate 33 is provided with a series of notches 36 along the upper edge of the plate. press 1
The notches on the forming plate for 0 are aligned with the corresponding notches on the forming plate for press 11.
The position of each press 15 is for both presses 10 and 11.
When the glass sheet G approaches both major surfaces of the glass sheet G for forming, the glass sheet G is adjusted so that it is received in one or the other of the matched pair of glass receiving notches 36. Formed plates 33 and 34 are shown as having sharp curved lines running vertically across their centers. When the glass is bent to relatively large angles, it is sometimes preferred to provide a hinged piece on the curved member to follow the glass as it bends. In the embodiment shown, it is advantageous to divide the curved part into left and right halves which are hinged to each other for bending along the axis of rotation which intersects the line of sharp bend in vertical plan. Something happens. The glass-facing surfaces of both molded members 33 and 34 are made of a material 37 that does not damage the glass at elevated temperatures;
For example, it is covered with a stretchable fiberglass cloth made of textured thread. The coating is held in place against the glass-facing surface by a number of clamps 38 attached to the edges of the control plate 32 or some other convenient structural member. In the illustrated embodiment, each molded member has a base 4
4 is fastened to a frame 40 carried by a housing 43 which reciprocates in a substantially horizontal direction relative to 4. A damping device 41 and a return spring device 42 limit the impact of the pressing action on the glass pane. Each housing 43 can be tilted by a fulcrum shaft 45 and a cylinder 46 so as to reciprocate at angles slightly offset from the horizontal; It has sometimes been found to be advantageous in reducing the It should be clear that the present invention is not limited to vertical press bending, but also applies to other press bending configurations known in the art where the glass sheets are held generally horizontally or diagonally. It is something that can be done. The plate glass G has both upper and lower electrodes 50 and 5.
In preparation for applying local wire heat between 1 and 2, the molded member and
and is shown parked in alignment with upper electrode 50 and lower electrode 51. Both electrodes are preferably made of tungsten carbide and have a "T"
The transverse members of the "T" can be shaped so that the transverse members of the "T" contact the adjacent edges of the glass sheet and extend laterally at right angles to both edges to make alignment non-critical and to provide good electrical contact. It is now being ensured. Electric wire 5
2 and 53 connect both electrodes to high voltage electric wires (not shown), respectively. It has been found that such an electrode arrangement also has a secondary advantage by helping to stabilize the glass sheet immediately before pressing. The upper electrode 50 is mounted to an electrode holder 54 which is a block of insulating material such as a high temperature resistant reinforced plastic material similar to that identified by Mycarta® or Bakelite. The electrode holder 54 is mounted on an arm 55 attached to the end of a supplementary rod 56. The filler rod 56 is made of steel of a sufficiently small diameter to impart some resiliency to the outer end of the upper electrode mounting assembly to avoid damage to the glass when the electrode is brought into contact with the glass. Preferably, it is a sex rod. A filler rod 56 is attached to the end of a piston rod 57 of a pneumatic cylinder 58. The cylinder 58 is supported by a pin 6 supported by a support beam 62 which can be rigidly mounted at any convenient point on an existing adjacent structure.
A swinging arm 6 supported swingably on the center of the swing arm 1
It is mounted on one end of 0. The opposite end of the swinging arm 60 is engaged by a small cylinder 63 via a U-link 64, so that the cylinder 63 can impart an oscillating motion in the vertical plane to the entire upper electrode assembly, thus By applying the upper electrode, the upper electrode is moved vertically into contact with and away from the radius of curvature. At the same time, the larger cylinder 5
8 can be actuated to horizontally reciprocate the upper electrode. Therefore, after the live wire has been created in the glass, the upper electrode is raised above the height of the press member and the same electrode is moved to both sides, as indicated by the dashed line position in FIG. It can be pulled back by pulling it out from between the two. Once the electrodes have been cleared, both presses can then be brought together to bend the glass, and after the presses have been pulled apart, the glass can be delivered from the press operating station. When the next sheet of glass is fed into the press operation and stopped, a reverse movement is imparted to the electrode, so that it is extended between the two and lowered to meet the top edge of the glass. Contact. The lower electrode 51 is likewise provided with a device for carrying it in and out of contact with the glass. The lower electrode is carried by an electrode holder 70, which, like the upper electrode holder 54, is formed entirely from a block of insulating material. The electrode holder 70 is
It is attached to the upper end of an "L"-shaped arm 71 which is swingably mounted to the end of the piston rod of a vertical pneumatic cylinder 73 by a U-link 72. The electrode end of arm 71 is pushed upward by a spring 74 connected to the opposite end of the arm, thus ensuring a firm but resilient contact between the electrode and the glass. The pneumatic cylinder 73 is a swingable boom 80 that swings in a horizontal plane using a vertical column 82 as a fulcrum.
It is carried on one end of the . The boom 80 is swung between an activated position and a retracted position by another pneumatic cylinder 83 connected by a fulcrum joint 84 to the opposite end of the boom from the cylinder 73. The cylinder 83 is supported by a fulcrum shaft 85 at one end. Therefore, the lower electrode assembly is subjected to two types of motion. The cylinder 73 raises and lowers the electrode 51 vertically between the raised position shown in Figure 1 and the position shown in broken lines in Figure 1, so that the lower electrode conducts current through the glass plate. can be brought into contact with the lower edge of the glass, and then:
It is pulled out so as not to interfere with the closing of the press. Given a horizontal movement by the cylinder 83, the lower electrode avoids any damage that may occur to the electrode as a result of falling glass due to occasional broken lines at the press-bending operation. can be swung laterally from below the glass pane. The entire lower electrode assembly is then rotated to move the electrode to a retracted position as shown in phantom in FIG. 1 and more clearly shown in plan view in FIG. The extension and retraction of both the lower and lower electrodes is preferably carried out in unison by an automatic control device responsive to the position of the glazing. If the electrodes 50 and 51 simultaneously engage the upper and lower edges of the glass sheet G, respectively, the position of the glass sheet is stabilized and oscillation is minimized. Therefore, the electrodes 50 and 51 are pulled back and out of contact with the radius of curvature, and the presses 10 and 11 are pressed against the glass plate G.
When engaged, each pair of mating notches 36 will be brought into alignment with the corresponding chamfer 15, thus avoiding damage to the chamfer and preventing breakage of the glass in the vicinity of the point where it is gripped. minimize. As shown in FIG. 2, the glass sheet has a stripe 90 of conductive material applied to one side of the glass along the line of the intended sharp bend. The stripe may extend over both the top and bottom edge surfaces of the glass sheet as shown in Figure 4, thus ensuring good electrical contact between the stripe and the "T" electrode. ing. Other possible shapes of electrodes may not require this stripe to extend on both edges of the glass sheet. Suitable conductive materials for the stripes include U.S. Pat.
There are silver frits and graphites of the type described in Nos. 3,879,184 and 3,865,680. Either can be applied to the B radius of curvature in liquid or paste form by brushing, rolling or extrusion. Colloidal graphite dispersed in water has been found to be particularly suitable for use as a striping material and is marketed by Acheson Colloids Company under the name DAG 137. ing. When an electric current is passed through this stripe, its high resistance causes it to generate heat, which is transferred to the glass below the stripe. As the temperature of the glass increases, the electrical conductivity of the glass increases to such an extent that the glass itself becomes a leading conductor of current, thus heat is generated within the glass itself. This heat treatment fuses the silver frit to the glass, thus making it a permanent part of the glass sheet. On the contrary, at higher power intensities the graphite is sometimes completely removed, although it becomes oxidized during heating to become an easily removed deposit on the surface of the glass. By way of example, graphite from about 3 millimeters (1/8 inch) to 5 millimeters (3/16 inch) wide, although the width of the stripes will vary depending on the resistance requirements of the stripes and the sharpness of the bends performed. Stripes have been successfully used to create 20° to 30° V-bends within 3/8 inch wide sections of glass. The resistance of the stripe, the voltage and amperage applied to the stripe, and the length of time available to heat the stripe are all interdependent variables, each of which has a rather wide range of possibilities. It is also possible to have. The basic requirement is that, during the available time, sufficient thermal energy must be imparted to said live wire to reduce the viscosity along the hot wire of the glass sheet appreciably below the viscosity of the body of the glass sheet. be. For example, during one press bending process of the type shown in the accompanying drawings, glass typically
Leaves the furnace at a temperature of 125 °C. When bending into a “V” shape, the surface temperature along the live wire typically reaches an expected minimum of 816°C (1500°) and preferably a maximum of 1204°C (2200°) and at least 139°C.
(250〓) was observed to increase. It is usually the length of time available for providing a live line that primarily makes the process difficult. Since the glass begins to lose heat as soon as it leaves the furnace, it must be bent and tempered without delay before the temperature of the glass drops below the critical height. Therefore, no additional steps can be taken to provide a live wire that normally only takes a few seconds.
Moreover, part of that time must be spent moving the electrodes into place. The available time is highly dependent on the speed of the glass conveyor and the thickness of the glass and will vary from machine to machine. (The thinner the sheet glass, the more rapidly it must be processed.) To give an example, in the apparatus described above, the pressing process can be performed for 5 seconds (as the electrodes are brought into engagement with the glass). A delay of 2 seconds for heating and 3 seconds for heating was sufficient to create a live wire without compromising the quality of the subsequent temper applied to the 5.6 millimeter (7/32 inch) thick sheet glass. Excessive power intensity is usually required to achieve live heating in much less than 2 seconds, and if the glass is to be tempered, it is rarely necessary. A period of time greater than 10 seconds must be available. The resistance of the stripes and the voltage and amperage of the current applied to the stripes must be selected to provide sufficient power to achieve the desired temperature rise during the available time. Although a high resistance is preferred for the stripes, the resistance must of course be lower than that of the glass itself, and the resistance should not be so high that dangerously high voltages are required. For typical stripe lengths on the order of 50 centimeters (20 inches), the resistance may most conveniently be in the range of about 5000 ohms to 30000 ohms (measured at room temperature). In such a case the voltage is approximately
Although 2000 to 13000 volts (AC) may be used, higher voltages may be used if the electrodes are spaced far enough from adjacent conductive structures to prevent arcing. this
When it is within the range of 2000 to 13000 volts,
An air gap of about 18 centimeters (7 inches) surrounding the electrode should be a suitable safety limit.
The corresponding amperage may be, for example, about 0.5 to 2.5 amps. The following two examples illustrate typical situations in which "V" bends having a radius of about 10 centimeters (4 inches) can be made by vertical press bending.

【table】

[Front] Stripes may be attached to either side of the glass. When the bend is on the mid-low side, a peak is formed in the bent glass along the line of the bend, and when it is on the mid-high side, a slight indentation is created along the line of the bend. In either case, the glass becomes significantly hotter near the surface in direct contact with the stripe than near the opposite surface along the same stripe. As a result, one side of the live wire remains more viscous than the other side, which is advantageous in preventing a pinge-like effect, ie, stretching and tearing of the glass sheet along the live wire. It is to be understood that various other alterations and modifications, as already known to those skilled in the art, depart from the spirit and scope of the invention as defined by the following claims. It is possible without.

[Brief explanation of the drawing]

FIG. 1 is a downstream end view of a typical vertical press operation location incorporating the live wire heating device of the present invention during press bending process, and FIG. 2 is a longitudinal direction view of the press operation location in FIG. 1. FIG. 3 is a plan view of the lower electrode arrangement in FIGS. 1 and 2;
FIG. 4 is an enlarged partial cross-sectional view of the glass sheet showing how, in a preferred embodiment of the invention, the stripes are applied to the major surface and opposing peripheral surfaces of the glass sheet. G... "Plate glass", 10, 11... "Device for moving the molded member", 12... "Heated enclosure",
15... "Metal guy", 16... "Electrical insulating device" or "insulating material body", 20... "Grounded guy and support carriage", 21... "Device for feeding plate glass", 31, 32, 33, 31, 32,
34... "a pair of molded members", 50, 51...
"Pair of electrodes", 52, 53... "device for supplying current", 58, 73... "device for moving electrodes", 90... "stripe".

Claims (1)

[Claims] 1. A method of bending a sheet of glass into a shape having a sharp bend line with a radius of curvature less than about 20 centimeters (8 inches), the method comprising: forming a surface of the glass sheet along a predetermined sharp bend line; a forming position having both forming members that are extendable and retractable from said heated enclosure, said glass sheet being placed in a heated enclosure and heated to an overall temperature suitable for bending; and immediately after moving the glass sheet to the molding position while both molding members are separated, a pair is placed at each end of the stripe to ensure positioning of the glass sheet and to conduct a current through the stripe. and applying an electric current through the stripes and engaging the forming members to both surfaces of the heated glass sheet to form the glass sheet, the forming members being connected to both surfaces of the heated glass sheet. A method of bending a glass sheet comprising removing the electrode from engagement with the stripe while forming the glass sheet in engagement with the stripe. 2. In the method described in claim 1,
While the glass sheet is heated and pressurized, the glass sheet is suspended in a substantially vertical orientation from a gripping member gripping the edge of the glass sheet, and the glass sheet is suspended between forming members having forming surfaces of complementary curvature. 1. A method of bending a glass sheet, comprising bending the glass sheet to a desired curvature with a sharp bend less than about 20 centimeters in radius by pinching and applying pressure. 3. In the method described in claim 1,
A method of bending a glass sheet comprising pressurizing the glass sheet and then rapidly cooling the glass sheet in order to temper or harden the glass sheet. 4. In the method described in claim 1,
A method for bending sheet glass, characterized in that the temperature along the sharp bend line is raised to a temperature at least about 139°C (250°C) higher than the overall temperature by passing an electric current through the stripe. 5. In the method described in claim 4,
A method of bending sheet glass, characterized in that an electric current is passed along a predetermined line of bending for about 2 seconds to 10 seconds. 6. In the method described in claim 4,
The current is approx. A method for bending sheet glass, characterized in that the current is about 2000 volts to 13000 volts alternating current at 05 amperes to 2.5 amperes, and the stripes have a cold resistance of about 5000 ohms to 20000 ohms. 7. In the method described in claim 1,
A method for bending sheet glass, characterized in that the stripes are graphite and are oxidized by electric current. 8. A method of bending a sheet glass into a shape having a sharp bend line with a radius of curvature smaller than about 20 centimeters, the method comprising: pasting a conductive stripe on the surface of the glass sheet along a predetermined sharp bend line; is placed in a heated enclosure and heated to a suitable overall temperature for bending, the glass sheet is moved from the heated enclosure to a forming position having both extensible forming members, and the forming members are separated. Immediately after the glass sheet is moved to the forming position while the glass sheet is being moved to the forming position, a pair of electrodes are attached to each end of the stripe to ensure that the glass sheet is positioned securely and to conduct an electric current through the stripe. sinking, and engaging both forming members with both surfaces of the heated plate glass in order to form the glass plate, and forming the plate glass by engaging both forming members with both surfaces of the heated plate glass. the method of removing said electrode from engagement with said stripe while the glass engages a metallic gripping member of electrically conductive material connected to and supported by a grounded gripping member support carriage of electrically conductive material; a strip of electrically conductive material that heats the glass sheet while supported by an element to a temperature at which the glass sheet becomes conductive and is applied to the glass sheet along the sharp bend line; press-bending said glass sheet by passing an electric current along said glass sheet, insulating said grounded carriage and glass engaging elements of said gripping member, thereby making the glass sheet electrically conductive; An electrical isolation device provided between the gripping member and the grounded carriage is of sufficient length to prevent uncontrolled current flow from the stripe to ground through the member and the carriage. to effectively insulate the metallic gripping member from the grounded carriage, and the electrical isolation device is disposed a sufficient distance from the glass sheet and the grounded carriage to avoid arcing. from the stripe to the grounded carriage through the conductive glass, the gripping member, and the carriage so as to minimize generation and significantly reduce the current flowing along the stripe. A method of bending sheet glass, characterized in that the glass is adapted to prevent the flow of electric current. 9. In the method recited in claim 8,
An electrical isolation device provided between the gripping member and the grounded gripping member support carriage interrupts continuous circuit connection for a length of at least about 2.5 centimeters (1 inch). A method of bending plate glass characterized by: 10. A method according to claim 9, characterized in that the electrical insulation device interrupts the connection of a continuous circuit for a length of at least 6 cm. . 11. A heated enclosure having a device for heating the glass sheet to a softened state suitable for bending the glass sheet, including lines of sharp bends, having a radius of curvature of less than about 20 centimeters as desired. a pair of opposing molded members disposed on the exterior of the enclosure having complementary shaped surfaces that follow the shape; and a pair of opposing molded members disposed on the exterior of the enclosure; a device for moving the molding members into pressure contact; and a conveyor device for transporting the sheet glass into and out of the heated enclosure and into and out of the pressing position between the pair of molding members, the conveyor device comprising: a plurality of conveyor devices; The conveyor device has a gripping member that allows the sheet glass to be suspended in a substantially acute direction, and a pair of electrodes disposed on opposite sides of the pressurizing position, contacting both opposing edges of the glass plate when the glass plate is placed between the pair of molded members;
the pair of electrodes each having a device for moving the electrodes in a removable manner;
and a device for supplying current to both electrodes such that the current is passed along the sharp bend line of the glass sheet while the glass sheet is positioned between a pair of molded members. A device for bending plate glass. 12. In the device according to claim 11, when the glass plate is in the pressurized position and the pair of molded members are spaced apart from each other, the pair of electrodes is connected to both sides of the top and bottom of the glass plate. A device for bending sheet glass, characterized in that the glass sheets are vertically spaced apart so as to touch the edges. 13. Apparatus according to claim 12, characterized in that the means for moving the electrodes includes means for imparting both vertical and horizontal movements to each electrode. 14. A heated enclosure having a device for heating the glass sheet to a softened state suitable for bending the glass sheet, including lines of sharp bends, having a radius of curvature of less than about 20 centimeters as desired. a pair of opposing molded members disposed on the exterior of the enclosure having complementary shaped surfaces that follow the shape; and a pair of opposing molded members disposed on the exterior of the enclosure; a device for moving the molding members into pressure contact; and a conveyor device for transporting the sheet glass into and out of the heated enclosure and into and out of the pressing position between the pair of molding members, the conveyor device comprising: a plurality of conveyor devices; The conveyor device has a gripping member that allows the plate glass to be suspended in a substantially vertical direction, and a pair of electrodes disposed on opposite sides of the pressurizing position; contacting both opposing edges of the glass plate when the glass plate is placed between a pair of molded members;
the pair of electrodes each having a device for moving the electrodes in a removable manner;
and a device for supplying current to the electrodes so that the current is passed along the sharp bend line of the glass sheet while the glass sheet is positioned between a pair of forming members. , comprising a metallic gripping member, a grounded metallic carriage, and a connecting device having a lower part connected to the gripping member and an upper part connected to the carriage, the upper part of the connecting device an insulating material body disposed in distanced relation to the gripping member and the carriage, the insulating material body effectively insulating the carriage and the gripping member; the sheet glass, the sheet glass having a length sufficient to cause the glass sheet to move, and being spaced apart from both the glass sheet and the carriage by a distance sufficient to minimize the generation of arcs. Bending device. 15. Apparatus according to claim 14, characterized in that the insulating material has a minimum length of about 2.5 centimeters. 16. Apparatus according to claim 14, characterized in that the body of insulating material has a minimum length of about 6 centimeters.