JP2015134695A - Plate glass cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate glass cutting method for slicing a plate glass in a plane direction simply while reducing the material loss of the plate glass as much as possible.SOLUTION: To two sides of a core plate glass 2, there are jointed surface layer plate glasses 3 having a linear expansion coefficient different from that of the core plate glass 2, by an optical contact, and a jointed laminate 1 is subjected to a heat treatment accompanied by a temperature change. In this heat treatment, moreover, a tensile stress Ptz in the thickness direction is caused by the temperature change in the core plate glass 2 contained in the laminate 1, so that the core plate glass 2 is sliced in a plane direction.

Description

  The present invention relates to a technique for slicing and cutting a plate glass in a plane direction.

  As a method of cutting the glass, for example, as disclosed in Patent Document 1, the wire is reciprocated in the longitudinal direction while supplying the slurry while pressing the wire stretched linearly against the glass. There is a method of letting you slice.

Special table 2009-535224

  However, the cutting method disclosed in Patent Document 1 is a method of slicing glass while scraping a part of the glass with a wire. Therefore, no matter how thin a wire is used, glass powder is inevitably generated and material loss can occur.

  Furthermore, when the glass to be cut is plate-like, the wire cannot be brought into precise contact with the side surfaces constituting the periphery (each side) of the plate glass, so that the plate glass can be sliced in the plane direction. It becomes extremely difficult.

  In view of the above circumstances, an object of the present invention is to easily slice a plate glass in a plane direction while reducing the material loss of the plate glass as much as possible.

  The sheet glass cutting method according to the present invention, which was created to solve the above problems, is produced by a lamination process in which a surface layer glass having a linear expansion coefficient different from that of the core sheet glass is bonded to both surfaces of the core sheet glass by an optical contact, and a lamination process. And a heat treatment step for applying a temperature change to the laminated body, and a tensile stress in the thickness direction is generated in the core plate glass by the temperature change in the heat treatment step, and the core plate glass is sliced in the plane direction by the tensile stress. And

  According to such a configuration, when a temperature change is applied to the laminate in the heat treatment step, tensile stress in the thickness direction can be generated in the core plate glass due to the difference in the linear expansion coefficient between the core plate glass and the surface layer plate glass. When such a tensile stress is generated, the core plate glass is automatically sliced so as to be torn into two at the middle portion in the plate thickness direction, that is, the front side and the back side. As a result, when slicing the core plate glass, it is not necessary to scrape and remove a part of the core plate glass, so that the material loss accompanying the glass powder can be suppressed to almost zero. In addition, since the core plate glass can be sliced only by applying a temperature change to the laminate, it can be easily sliced even if the plate glass is relatively thin compared to a glass block or the like and the plate glass is to be cut.

  Such a slice of the core plate glass is considered to occur as follows. First, a stress concentration portion is formed in the vicinity of the end portion of the core plate glass due to a temperature change applied to the laminate, and a crack serving as a cutting starting point is formed in the stress concentration portion. And the tensile stress of the thickness direction which arose in the core plate glass by the temperature change acts with respect to this crack. Thereby, a crack progresses in a plane direction and a core plate glass is sliced in a plane direction.

In the above configuration, the thickness of the core plate glass is h _c [mm], the linear expansion coefficient of the core plate glass is α _c [/ ° C.], the thickness of the surface plate glass is h _s [mm], and the linear expansion coefficient of the surface plate glass is When α _s [/ ° C.] and the temperature difference generated in the laminated body due to the temperature change in the heat treatment process is ΔT [° C.] (however, it is assumed that the temperature is lowered and the temperature is raised and −).
h _c / h _s <[(α _s −α _c ) ΔT / 0.00005] −2
It is preferable to satisfy the following relationship.

  That is, the inventor of the present application has come up with the above relational expression as a result of intensive studies. And when such a relational expression was satisfy | filled, it became clear that a core plate glass is sliced reliably with the tensile stress which generate | occur | produces with a temperature change.

  In the above configuration, the linear expansion coefficient of the core plate glass may be made larger than the linear expansion coefficient of the surface layer plate glass, and the core plate glass may be cut by tensile stress at the time of temperature rise in the heat treatment step.

  Moreover, in said structure, the linear expansion coefficient of core plate glass may be made smaller than the linear expansion coefficient of surface layer plate glass, and core plate glass may be cut | disconnected by tensile stress at the time of the temperature fall in a heat treatment process.

  That is, the timing at which a tensile stress is generated in the core plate glass differs depending on the magnitude relationship between the linear expansion coefficients of the core plate glass and the surface layer plate glass. Therefore, there are cases where the core plate glass is sliced when the temperature is raised and cases where the core plate glass is sliced when the temperature is lowered.

  Said structure WHEREIN: It is preferable that the plate | board thickness of surface layer plate glass is 0.1 mm or more.

  That is, when the plate thickness of the surface layer plate glass satisfies the above range, it is possible to generate sufficient tensile stress for cutting the core plate glass.

  As described above, according to the present invention, since the plate glass is automatically sliced by the tensile stress generated inside the plate glass, the plate glass is easily cut in the plane direction while reducing the material loss of the plate glass as much as possible. can do.

(A) And (b) is a schematic diagram which shows each process contained in order in the cutting method of the plate glass which concerns on 1st Embodiment of this invention in order. It is a schematic diagram for demonstrating the principle of the cutting method of the plate glass which concerns on 1st Embodiment. It is sectional drawing which shows an example of the plate glass cut | disconnected by the cutting method of the plate glass which concerns on 1st Embodiment. It is sectional drawing which shows another example of the plate glass cut | disconnected by the cutting method of the plate glass which concerns on 1st Embodiment. (A)-(d) is a schematic diagram which shows in order each process contained in the cutting method of the plate glass which concerns on 2nd Embodiment of this invention.

<First Embodiment>
The cutting method of the plate glass which concerns on 1st Embodiment of this invention is demonstrated according to FIG. 1 (a), (b). In the drawing, the expansion and contraction of the plate glass are exaggerated. The same applies to FIG. 5 described later.

(1) Laminating Step First, as shown in FIG. 1A, an optical contact is made between a mating surface 2x of one core plate glass 2 and a mating surface 3x of two surface layer glass 3 at, for example, a room temperature of 20 ° C. To join. Thereby, the laminated body 1 which laminated | stacked the surface layer plate glass 3 on both surfaces of the core plate glass 2 is produced.

  Here, in this embodiment, the following are used as the core plate glass 2 and the surface layer plate glass 3.

The linear expansion coefficient of the core plate glass 2 is larger than the linear expansion coefficient of the surface layer plate glass 3. The difference in linear expansion coefficient at 30 to 380 ° C. is 1 × 10 ⁻⁷ / ° C. to 50 × 10 ⁻⁷ / ° C., preferably 3 × 10 ⁻⁷ / ° C. to 30 × 10 ⁻⁷ / ° C. .

  The plate | board thickness of the core plate glass 2 is 0.1 mm-5.0 mm, for example, Preferably it is 0.3-2.0 mm. The plate | board thickness of the surface layer plate glass 3 is 0.1 mm-2.0 mm, for example, Preferably it is 0.3-1.0 mm. The plate thickness of the core plate glass 2 is preferably larger than the plate thickness of the surface layer plate glass 3.

And the plate thickness of the core plate glass 2 is h _c [mm], the linear expansion coefficient of the core plate glass 2 is α _c [/ ° C.], the plate thickness of the surface layer glass 3 is h _s [mm], and the linear expansion coefficient of the surface layer plate glass 3 Is α _s [/ ° C.], and the temperature difference generated in the laminate 1 by the temperature change in the heat treatment step is ΔT [° C.] (however, it is assumed that the temperature difference is + and the temperature increase is −).
h _c / h _s <[(α _s −α _c ) ΔT / 0.00005] -2 (1)
This relationship is established. However, ΔT is based on the temperature when the glasses are first bonded together.

Both the surface roughness Ra of the mating surface 2x of the core plate glass 2 and the surface roughness Ra of the mating surface 3x of the surface layer plate glass 3 are 2.0 nm or less, more preferably 1. It is 0 nm or less, more preferably 0.5 nm or less, most preferably 0.2 nm or less, and in this embodiment 0.2 nm or less. Further, the GI values of the mating surfaces 2x and 3x of the core plate glass 2 and the surface layer plate glass 3 are 1000 pcs / m ² or less. The surface roughness Ra is a value measured using AFM (Nanoscope III a) manufactured by Veeco, and the GI value is a value measured using G17000 manufactured by Hitachi High-Tech Electronic Engineering Co., Ltd.

  The core plate glass 2 and the surface layer plate glass 3 are formed by an overflow down draw method or a float method. In the former case, the molding surfaces are used as they are as the mating surfaces 2x and 3x without being polished, and in the latter case, they are used as the mating surfaces 2x and 3x after the molding surfaces are polished.

(2) Heat treatment step Next, the laminated body 1 produced as described above is subjected to a heat treatment in a furnace, whereby surface contact portions of the mating surfaces 2x and 3x of the plate glasses 2 and 3 are obtained. When the temperature reaches about 300 ° C., the mating surfaces 2x and 3x of these plate glasses 2 and 3 are directly bonded to each other and are more firmly bonded. Thereby, although it is a low temperature state of about 300 ° C., these plate glasses 2 and 3 are temporarily fixed. From this state, by further raising the temperature in the furnace, due to the difference in the linear expansion coefficient of these plate glasses 2 and 3, as shown in FIG. While Pc is formed, a tensile stress Pt in the planar direction is formed on the surface layer glass sheet 3. In addition, tensile stress in the thickness direction acts locally on the vicinity of the front surface and the vicinity of the back surface at both end portions of the core plate glass 2 to form stress concentration portions S1, S2, S3, and S4. The said heating is performed within the range below the lower softening point in these plate glass 2,3. Here, the direct bonding means that the bonding surfaces are directly bonded without interposing another layer such as an adhesive or glass frit between the bonding surfaces 2x and 3x of the core plate glass 2 and the surface layer glass 3. Means that

  And the core plate glass 2 in which stress concentration part S1-S4 was formed in the four corners by sectional view in this way is sliced in the plane direction as follows. That is, as shown in FIG. 2, an initial crack serving as a starting point for cutting is formed in any of the stress concentration portions S1 to S4. In the illustrated example, a case is shown in which an initial crack is formed in one of the upper and lower stress concentration portions S1, S2 located on the left side (one end side) of the core plate glass 2 in the drawing. At this time, a tensile stress Ptz in the thickness direction is formed on the core plate glass 2 along with the compressive stress Pc in the planar direction shown in FIG. Therefore, the initial crack formed in the stress concentration portion S1 (or stress concentration portion S2) propagates along the arrow A (or arrow B) by the tensile stress Ptz in the thickness direction, and the thickness direction of the core plate glass 2 In the substantially central part of the head, it progresses in the plane direction along the arrow C. Thus, the crack which progressed toward the other end side from the one end side of the core plate glass 2 intersects with the stress concentration portions S3 and S4 on either the upper or lower side on the right side (the other end side) of the core plate glass 2 in the drawing. Further progress along arrow D (or arrow E). The initial crack is formed in a part of the stress concentration portion, but is often formed in a corner portion when the glass is viewed in plan.

  Then, when an initial crack is formed in the upper stress concentration portion S1 on one end side of the core plate glass 2, and the initial crack propagates to the upper stress concentration portion S3 on the other end side, as shown in FIG. The core plate glass 2 is sliced into two in the upper and lower directions in the middle part in the plate thickness direction. In detail, the upper core plate glass piece 4 has rounded chamfered portions 4a at both ends, and the lower core plate glass piece 5 has protruding portions 5a at both ends, and the protrusions 5a are mutually connected. There is a recess 5b in between. In addition, the protrusion part 5a of the lower core plate glass piece 5 may be formed in all four sides, and the recessed part 5b may be formed in the space enclosed by the protrusion part 5a. In this case, the upper core plate glass piece 4 is formed with chamfered portions 4a on all four sides. When the chamfered portion is formed on the core plate glass piece at the same time as the cutting as described above, it is unnecessary to separately perform chamfering afterwards, which can contribute to reduction in manufacturing man-hours and reduction in manufacturing cost.

  Also, in FIG. 2, when an initial crack is formed in the upper stress concentration portion S1 on one end side of the core plate glass 2, and the initial crack propagates to the lower stress concentration portion S4 on the other end side, FIG. As shown, the core plate glass 2 is sliced into two upper and lower portions in the middle portion in the plate thickness direction. Specifically, the upper core glass sheet piece 6 has a rounded chamfered portion 6a at one end portion and a protruding portion 6b at the other end portion. The lower core plate glass piece 7 has a rounded chamfered portion 7a at the other end and a protruding portion 7b at one end.

  The breaking stress of the cut surfaces (slice surfaces) of the core plate glass pieces 4, 5, 6, and 7 is, for example, 300 to 5000 MPa.

  Here, the shape of the core plate glass pieces 4, 5, 6, and 7 formed by slicing the core plate glass 2 may be a shape obtained by inverting the top and bottom in FIGS. That is, taking the case of FIG. 3 as an example, the lower core plate glass piece has rounded chamfered portions at both ends, and the upper core plate glass piece has protruding portions at both ends, There may be a recess between the protrusions.

  In addition, the shape of a core plate glass piece can be controlled in a certain range by providing a temperature difference in the upper and lower sides of the laminated body 1 in a heat treatment process. For example, if the upper surface plate glass 3 side is set to a high temperature and the lower surface layer plate glass 3 side is set to a low temperature, the core plate glass 2 is easily sliced into the shape shown in FIG. The temperature difference between the top and bottom of the laminate 1 is preferably 10 ° C to 150 ° C. In addition to the above, for example, the shape of the core plate glass piece can be controlled even if the linear expansion coefficients and plate thicknesses of the two surface layer plate glasses are different from each other.

  According to the cutting method as described above, when the laminate 1 is heated in the heat treatment step, the thickness direction in the core plate glass 2 is caused by the difference in thermal expansion due to the difference in the linear expansion coefficient between the core plate glass 2 and the surface plate glass 3. The tensile stress Ptz can be generated. With such tensile stress Ptz, the core plate glass 2 is automatically sliced so as to be torn into two on the front side and the back side at the middle portion in the plate thickness direction at the time of temperature rise in the heat treatment step. That is, when slicing the core plate glass 2, it is not necessary to scrape and remove a part of the core plate glass 2, so that the material loss accompanying the glass powder can be suppressed to almost zero. Therefore, the situation where the core plate glass pieces 4, 5, 6, and 7 are soiled by the glass powder can also be prevented. Moreover, since the core plate glass 2 can be sliced in the plane direction only by applying a temperature change to the laminate 1, even a plate glass that is difficult to slice using a wire or the like can be easily cut.

  In addition, in order to advance the initial crack of the core plate glass 2 slowly and neatly, it is preferable that the temperature increase rate of the laminated body 1 in the heat treatment step is 0.1 to 10 [° C./min].

Second Embodiment
The cutting method of the plate glass which concerns on 2nd Embodiment of this invention is demonstrated according to Fig.5 (a)-(d). In addition, detailed description is abbreviate | omitted about the point which is common in the cutting method of the plate glass which concerns on 1st Embodiment.

(1) Pre-heat treatment process First, as shown to Fig.5 (a), it heats within the furnace in the state which made one core plate glass 2 and two surface layer plate glass 3 each separate. However, in the present embodiment, the linear expansion coefficient of the surface layer glass sheet 3 is made larger than the linear expansion coefficient of the core sheet glass 2. The difference in linear expansion coefficient between the two glass plates 2 and 3 is the same as in the first embodiment.

  That is, in this heating step, as shown in FIG. 5B, a difference in thermal expansion occurs between these glass sheets 2 and 3, but since these glass sheets 2 and 3 are separated from each other, The effects of do not interact with each other.

  In this heating step, the core plate glass 2 and the surface layer plate glass 3 are heated to less than the lower strain point. That is, the core plate glass 2 and the surface layer plate glass 3 are not heated up to the lower softening point, and the core plate glass 2 and the surface layer plate glass 3 are prevented from undergoing large shape deformation. The heating temperature varies depending on the glass composition of the core plate glass 2 and the surface layer plate glass 3, but is about 200 ° C. to 400 ° C. (in this embodiment, about 400 ° C.), for example.

(2) Laminating Step Next, in the state where the heating temperature (400 ° C.) is maintained, as shown in FIG. 5 (c), the surface layer plate glass 3 is optically applied to each of both surfaces of the core plate glass 2 in the furnace. Join by contact. Then, due to the heat in the furnace, the mating surfaces 2x and 3x of the plate glasses 2 and 3 are directly bonded to each other and more firmly joined.

(3) Heat treatment process Then, as shown in FIG.5 (c), the laminated body 1 is cooled to normal temperature within a furnace. As a result, the influence of the difference in thermal expansion directly acts between the core plate glass 2 and the surface layer glass 3 to generate a plane direction compressive stress Pc on the core plate glass 2 and to the surface layer plate glass 3 in the plane direction tensile stress Pt. Occurs. At this time, stress concentration portions S <b> 1 to S <b> 4 are formed in the vicinity of the front surface and the back surface at both ends of the core plate glass 2. An initial crack that becomes a starting point of cutting is formed in any one of these stress concentrated portions S1 to S4, and this initial crack develops due to a tensile stress in the thickness direction caused by the compressive stress Pc in the plane direction, and the first embodiment As explained with reference to FIG. 2 in the form, the core plate glass 2 is sliced in the plane direction. That is, in this embodiment, the core plate glass 2 is sliced in the plane direction by the tensile stress in the thickness direction when the temperature is lowered (cooling) in the heat treatment step.

  In addition, this invention is not limited to said embodiment, It can implement with a various form.

  In the above-described embodiment, the core plate glass and the surface layer plate glass have been described mainly using a single plate glass. However, as the core plate glass, a laminate of a plurality of plate glasses may be used. At the same time, a laminate of a plurality of plate glasses may be used as the surface layer plate glass.

  Moreover, after slicing the core plate glass in the plane direction, the sliced core plate glass piece and the surface layer plate glass may be used as they are, or both may be separated from each other. At this time, for example, by applying a surfactant or the like to the bonding surface between the surface layer plate glass and the core plate glass, the adhesive force may be controlled to facilitate separation.

    Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention will be described. For Comparative Example 1 and Examples 1 and 2, laminates were produced by joining surface plate glass with optical contacts to both surfaces of the core plate glass at room temperature (20 ° C.). These laminates were heated to 500 ° C. by directly observing the behavior of the slices with a tubular heating furnace (MID-6s) manufactured by Irie Shokai. Moreover, about the comparative example 2 and Example 3, it laminated | stacked in the state heated to 500 degreeC, and cooled to normal temperature. At this time, the rate of temperature increase and the rate of temperature decrease were both set to 3 ° C./min. And it was experimented whether a core plate glass was sliced in a plane direction by adding such heat processing to a laminated body. The results are shown in Table 1 below.

  However, in Table 1, ΔT is a temperature difference based on the temperature (20 ° C.) when the glasses are first bonded together. That is, the temperature difference when the temperature is raised from room temperature to 500 ° C. is −480 ° C., and the temperature difference when the temperature is lowered from 500 ° C. to room temperature is + 480 ° C.

  According to Table 1, in Examples 1-3 which satisfy the relational expression of Formula (1), it can confirm that the core plate glass contained in a laminated body is sliced reliably in a plane direction. Further, as in Examples 1 and 2, when the linear expansion coefficient of the core plate glass is larger than the linear expansion coefficient of the surface plate glass, it can be confirmed that the core plate glass is sliced when the temperature is increased. On the other hand, when the linear expansion coefficient of the core plate glass is smaller than the linear expansion coefficient of the surface layer plate glass as in Example 3, it can be confirmed that the core plate glass is sliced when the temperature is lowered.

DESCRIPTION OF SYMBOLS 1 Laminate body 2 Core plate glass 3 Surface layer plate glass 4,5,6,7 Core plate glass piece Pc Plane direction compressive stress Pt Plane direction tensile stress Ptz Thickness direction tensile stress S1, S2, S3, S4 Stress concentration part

Claims (5)

On both surfaces of the core plate glass, a lamination step of joining the surface plate glass having a different linear expansion coefficient from the core plate glass by optical contact, and a heat treatment step of applying a temperature change to the laminate produced in the lamination step,
A method for cutting a plate glass, wherein a tensile stress in a thickness direction is generated in the core plate glass by a temperature change in the heat treatment step, and the core plate glass is sliced in a plane direction by the tensile stress. The thickness of the core plate glass is h _c [mm], the linear expansion coefficient of the core plate glass is α _c [/ ° C.], the thickness of the surface plate glass is h _s [mm], and the linear expansion coefficient of the surface layer plate glass is α _s [/ ° C.] When the temperature difference generated in the laminate by the temperature change in the heat treatment step is ΔT [° C.] (however, it is assumed that the temperature difference is + and the temperature increase is −).

The plate glass cutting method according to claim 1, wherein the following relationship is satisfied.   The linear expansion coefficient of the core plate glass is made larger than the linear expansion coefficient of the surface layer plate glass, and the core plate glass is cut by the tensile stress at the time of temperature rise in the heat treatment step. The cutting method of the plate glass of description.   The linear expansion coefficient of the said core plate glass is made smaller than the linear expansion coefficient of the said surface layer plate glass, and the said core plate glass is cut | disconnected by the said tensile stress at the time of the temperature fall in the said heat processing process. Cutting method of sheet glass.   The plate | board thickness of the said surface layer plate glass is 0.1 mm or more, The cutting method of the plate glass of any one of Claims 1-4 characterized by the above-mentioned.

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