RU2487088C1 - Device for bending sheet glass - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed device comprises shaped convex mould 1 accommodating glass workpiece 2 and bending mechanism. Said mould is placed in electric furnace 3 with sight holes. Light beam generator and photo receiver are arranged opposite said sight holes. Said photo receiver is electrically connected with mechanism displacing the stops through actuator relay. Bending mechanism comprises pressure frame composed of two profiled plates 8 boned by flexible tapes t. Bending mechanism drive is composed of driven shaft 9 arranged under mould and coupled with pressure frame edges by flexible members 11. Bending device additionally comprises two support elements composed of plates 13 in contact with glass workpiece bottom surface opposite profiled plates 8 and four stops 14 connected with plates edges to displace said plates to electric furnace bottom by stop drive.

EFFECT: ruled out glass workpiece rupture.

2 dwg

Description

The invention relates to the building materials industry, in particular to the manufacture of bent glass, and can be used in the glass industry to produce bent large-sized glass products with a cylindrical curvature of the surface with a deflection arrow equal to the radius of curvature (half cylinder), used, for example, as glazing elements for fireplaces .

A device for molding sheet glass, comprising a concave frame shape installed in an electric furnace with heaters and viewing windows, against which on the outer opposite sides of the electric furnace there is a beam shaper and a photodetector connected to the heaters through an electric heating regulator [1].

A disadvantage of the known device is that in order to obtain large-sized glassware with a cylindrical curvature of the surface with a deflection arrow equal to the radius of curvature (half cylinder), it is necessary to use a large-sized shape in order to place a flat glass blank (half-cylinder scan) on the forming surface of the mold in its boundary regions . This, in turn, requires the use of an electric furnace with a large working space and, therefore, with high power. In addition, when using a concave frame shape for bending large-sized glass workpieces to produce glass products with a cylindrical curvature of the surface with a deflection arrow equal to the radius of curvature (half cylinder), glass products with a given cylindrical curvature of the surface are not obtained. This is due to the fact that when molding large-sized glass workpieces under the influence of their own weight, they bend not only along the given cylindrical curvature of the forming surface of the frame shape, but also between its forming surfaces, which leads to double curvature on glass products (barrel-shaped surface).

A device for molding sheet glass containing a convex shape located on the base, and the bending mechanism, made in the form installed at an angle to the base of the racks with guide grooves and glass fixing elements in the form of two bodies of circular cross section [2].

A disadvantage of the known device is that it has a limitation in its application, so when using glass blanks, in their overall dimensions exceeding the critical value, they are destroyed. This is explained by the fact that at the initial moment on the flat glass billet a maximum bending moment is created between the glass billet edges and the central part of the convex shape, which is equal to the product of the glass billet weight and the weight of circular bodies by the value of the half-cylinder generatrix, i.e. the bending moment is equal to πR, where R is the radius of curvature of the convex shape of the forming surface. It is known that the strength of silicate glass is 100 kgf / cm ² . When using large-sized glass blanks, in connection with this, when creating a bending moment exceeding the specified value of strength, the glass blanks are destroyed. In addition, when bending glassworks to obtain glassware with a cylindrical curvature of the surface with a deflection arrow equal to the radius of curvature (half cylinder), the bending moment decreases as the glass workpiece adheres to the convex shape, since the weight of the glass workpiece and the shoulder of the effect of bending moment on the weight bodies of circular cross section. This circumstance requires an increase in the bending temperature as the glass blank adheres to the forming surface of the convex shape, which, in turn, will damage the glass work surface when it comes in contact with the forming surface of the mold.

Closest to the proposed invention is a device for bending sheet glass containing a profiled convex shape, a bending mechanism including a clamping frame made in the form of two profiled plates connected by flexible tapes, and its drive, made in the form of a shaft located under the form of a drive connected by flexible organs with the edges of the clamping frame [3].

A disadvantage of the known device is that it has a limitation in its use. So, in the case of the use of glass blanks, in their overall dimensions exceeding a certain critical value, they are destroyed. This is explained by the fact that at the initial moment on the glass billet the maximum bending moment is created between the glass billet edges and the central part of the convex shape, which is equal to the product of the glass billet weight and the weight of two profiled plates by the half-cylinder generatrix equal to πR, where R is the radius of curvature of the convex forming surface forms. When creating a bending moment on the glass work, exceeding the strength of silicate glass, which is 100 kgf / cm ² , the glass work is destroyed.

The objective of the invention is to prevent the destruction of glass blanks upon receipt of bulky glassware with a cylindrical curvature of the surface with an arrow of deflection equal to the radius of curvature (half cylinders).

To achieve the objective of the invention, there is provided a device for bending sheet glass containing a profiled convex shape, a bending mechanism including a clamping frame made in the form of two profiled plates connected by flexible tapes, and its drive made in the form of a shaft located under the form with a drive connected by flexible bodies with the edges of the clamping frame, characterized in that the device further comprises two support elements made in the form of plates in contact with the lower surface of the glass opposite the profiled plates and four stops, connected to the plates along their edges with the possibility of moving the plates to the level of the hearth electric furnace using the mechanism for moving the stops, and the form is installed in the electric furnace with viewing windows, against which on the opposite sides of the electric furnace there is a light beam former and a photodetector, which is electrically connected to the mechanism for moving the stops through the actuating relay.

The proposed device provides large-sized glassware with a cylindrical radius of curvature with an arrow of deflection equal to the radius of curvature, without destroying the glass blanks. This is because the edges of the glass work are supported by supporting elements in the form of plates, which eliminates the creation of a bending moment on the glass work, and therefore prevents its destruction. Glass work is supported until the glass softens when the glass is heated in an electric furnace, which is fixed using a light beam shaper and a photodetector. At the beginning of the bending of the glass blank under the influence of its own weight, the light beam is blocked by the glass blank and ceases to be fed to the photodetector, while the executive relay sends a signal to the mechanism for moving the stops, which moves the stops together with the plates to the level of the electric furnace. Subsequently, glass bending is carried out on a convex shape using the known bending mechanism.

Figure 1 presents the device, a top view.

Figure 2 is the same, longitudinal section, the dashed line shows the final position of the glass and stops with plates.

The device contains a profiled convex shape 1 with a glass blank 2 located on it and is installed in the electric furnace 3 with viewing windows 4, against which on the opposite sides of the electric furnace 3 there are a beam shaper 5 and a photodetector 6. The bending mechanism includes a clamping frame made in the form connected by flexible tapes 7 of two profiled plates 8 located at the edges of the glass 2. The drive of the bending mechanism is made in the form of a shaft 9 located under the form 1 and a drive 10 installed outside the electric furnace 3 with the possibility of connection with the shaft 9. The shaft 9 is connected by flexible bodies 11 with the edges of the profiled plates 8 through the rollers 12. The device contains two support elements made in the form of plates 13 located under the glass blank 2 opposite the profiled plates 8. The plates 13 are connected with stops 14, which are mounted to move to the hearth level of the electric furnace 3 using the movement mechanism 15 of the stops 14. The photodetector 6 is electrically connected to the actuating relay 16, which is electrically connected to the movement mechanism 15 of the stops 14 and with a source of electric current (figure 1, 2 is not shown).

The device operates as follows.

Glass billet 2 is mounted on a convex shape 1 and on a plate 13, then on a glass billet 2, profiled plates 8 are placed, connected by flexible tapes 7. Flexible bodies 11 made, for example, of heat-resistant steel in the form of cables, connect the profiled plates 8 to the shaft 9 through by means of rollers 12. The assembled device is placed in an electric furnace 3 and the shaft 9 is connected to the drive 10. After that, the electric furnace 3 is heated and the executive relay 16 is connected to an electric current source (not shown in FIGS. 1, 2). When heating the glass workpiece 2 to the softening temperature of the glass, it bends under its own weight in the gap between the upper part of the mold 1 and the plates 13. The glass workpiece 2 covers the light beam coming from the shaper of the light beam 5. At the moment when the light beam ceases to arrive at the photodetector 6, the actuating relay 16 is activated, which includes a movement mechanism 15 of the stops 14, after which the plates 13 are moved to the hearth level of the electric furnace 3 (the position of the plates 13 and the stops 14 is shown by a dashed line in FIG. Next, bending of the glass workpiece 2 to a given curvature of the surface of the convex shape 1 is carried out using a known device, for example [3]. After receiving the bent glass workpiece 2 (the position of the bent glass workpiece 2 is shown by the dashed line in Fig. 2), it is annealed in the electric furnace 3 and at a temperature of 40-50 ° C the device is removed from the electric furnace 3, and the bent glass workpiece is transferred to the machining section to obtain glassware.

Using the proposed device, a batch of bent glass blanks was obtained to obtain large-sized glass products used as glazing elements for fireplaces. We used flat glass blanks made of industrial glass (GOST 111-2001) with a thickness of 6.7 mm and dimensions of 1450 × 1633 mm. Glass bending was carried out in a convex form with a radius of curvature of the forming surface of 520 mm. The total weight of the profiled plates 8 was 16 kgf. The form, as well as all elements of the device, were made of stainless heat-resistant steel. To prevent damage to the surface of the glass workpiece from contact with the mold and other metal elements during its bending, heat-resistant fiberglass KT-11 was laid between the glass workpiece and them. For bending glass blanks after moving the plates 13 to the level of the electric furnace 3, a known device was used [3]. Obtained on the proposed device, large-sized glassware (half-cylinders) are characterized by high surface quality and compliance with a given surface curvature.

It should be noted that when using the known device it is impossible to obtain large-sized glassware with the above geometric parameters, since the glass blanks would be destroyed already at the initial moment from the bending moment created on them.

Indeed, the calculation of the critical value of the bending moment (M _max ), upon reaching which there is a destruction of the glass, produced by the well-known formula:

$$M_{\max }=\frac{\text{[}\delta \text{]}\cdot b\cdot {\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="00000004.png"\; state="\{\{state\}\}">h</figure-callout>}}^2}{6},$$

where M _max is the maximum bending moment, kgf · cm;

[δ] is the minimum bending strength of silicate glass, kgf / cm ² ;

b is the width of the glass, cm

h is the thickness of the glass, see

gives a value of ≈108452 kgf · cm, based on the geometric parameters of the glass blanks given above, while the minimum strength of silicate glass at the specified sizes of glass blanks was taken - 100 kgf / cm ² .

The actual value of the bending moment (M _fact ) on the glass workpiece when it is located on a convex shape in accordance with the known device is calculated by the well-known formula:

$$M_{\text{fact}}=\frac{g\cdot {\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="00000004.png"\; state="\{\{state\}\}">l</figure-callout>}}^2}{2}+P\cdot l,$$

where M _fact - bending moment, kgf · cm;

g is the intensity of the load from the dead weight of the glass, kgf / cm;

l is the length of the glass, cm;

P is the load on the edges of the glass, kgf.

Substituting the values given in the example of using the proposed device into this formula, we obtain M _fact ≈531417 kgf · cm, while the intensity of the load from its own weight was calculated based on the density of silicate glass of 0.0025 gc / cm ³ . From the above calculations it can be seen that the value of the actual bending moment (M _fact ) created at the glass blank is about five times higher than the critical value of the bending moment (M _max ), which would certainly lead to the destruction of the flat glass blank using a known device.

Information sources

1. USSR Copyright Certificate No. 734150, IPC ⁷ C03B 23/02, publ. 05/15/1980

2. USSR author's certificate No. 1049440, IPC ⁷ C03B 23/023, publ. 10/23/1983

3. USSR Author's Certificate No. 743955, IPC ⁷ C03B 23/02, publ. 06/30/1980 - Prototype.

Claims (1)

A device for bending sheet glass containing a profiled convex shape, a bending mechanism comprising a clamping frame made in the form of two profiled plates connected by flexible tapes, and its drive, made in the form of a shaft located under the form of a drive connected by flexible bodies to the edges of the clamping frame, characterized in that the device further comprises two support elements made in the form of plates in contact with the lower surface of the glass blank opposite the profiled plates and four pores connected to the plates along their edges with the possibility of moving the plates to the level of the furnace hearth using the mechanism for moving the stops, and the form is installed in the furnace with viewing windows, against which on the outer opposite sides of the furnace there is a light beam former and a photodetector that is electrically connected to the mechanism movement of emphasis through the executive relay.

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