JPH04275931A - Method for reinforcing glassware and glassware - Google Patents

Abstract

PURPOSE:To obtain a glassware high in compression stress in the bottom part thereof by carrying the opening edge part of a semiprocessed glassware on a supporting base and inversely placing it thereon and heating the inner and outer surfaces of the semiprocessed glassware and thereafter blowing cooling air thereon and regulating the glassware to prescribed compression stress. CONSTITUTION:A semiprocessed glassware 3 of unreinforcing treatment is placed on a supporting base 1 in an inverted state and the opening edge part of the glassware 3 is carried thereon. Flame is blown toward the inner and outer surfaces of this glassware 3 from a burner 6 to heat it. Then after it is heated, cooling air is blown on the inner and outer surfaces of the glassware 3 to reinforce it. Compression stress of the inner and outer surfaces in the opening part is regulated to <700mmu/cm and compression stress of the bottom part is regulated to 1000-1700mmu/cm by this air cooling reinforcing treatment.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for strengthening glassware,
In particular, the present invention relates to a method for strengthening glassware and a glassware that can make the bottom side of the glassware stronger than the mouth side and improve heat resistance.

0002

[Prior Art] Conventionally, glassware such as cups and plates have been strengthened by chemical strengthening or rapid cooling strengthening on their inner and outer surfaces to form a compressive stress layer to increase their mechanical strength. I'm trying.

[0003] Microwave ovens have become popular in recent years, and glassware is often used for heating and cooking in the microwave. glass with a coefficient of expansion (
Glassware has been proposed that utilizes the thermal shock resistance of the compressive stress layers on the inner and outer surfaces obtained by a rapid cooling strengthening method using a glass material (90 to 110
0).

On the other hand, even if glassware is quench-strengthened for the purpose of thermal shock resistance, it is still necessary to have mechanical strength, and for this reason, quench-strengthening is applied to increase mechanical strength. ing.

[0005] In the rapid cooling strengthening method, which aims to increase mechanical strength, heating and cooling are performed while the bottom or body of the glassware is held with a holder, etc.
The holding part will have a different thermal history from other parts,
There was a tendency for variations in stress to occur. Furthermore, in glassware that has been subjected to rapid cooling strengthening treatment using such a method, stress becomes extremely high at the mouth edge where the cooling efficiency is highest.

[0006] When the purpose of the above-mentioned conditions is to improve mechanical strength, the former has no effect, while the latter works favorably to increase strength.

However, when thermal shock resistance is required, variations in stress at the bottom and body of the glassware reduce the heat resistance strength, and there is a risk of glass fragments scattering when broken. For example, if you take out a glassware after cooking in a microwave oven and place it on a table with water, the bottom of the glassware may come into contact with the water and break.

Furthermore, extremely large stress at the edge of the glassware may cause the edge to peel off and scatter as needle-shaped pieces of glass during rapid cooling due to thermal shock.

[0009]

Problem to be Solved by the Invention The problem to be solved by the present invention is the breakage of glassware caused by non-uniformity of compressive stress during quench strengthening and insufficient mechanical strength against tensile stress caused by thermal shock.

[0010] As a result of various studies and studies on the changes in the state of glassware when subjected to thermal shock, the present inventor found that the part where the largest tensile stress occurs is on the outer surface of the bottom of the glassware. It was discovered that the tensile stress generated at the rim of a glassware is relatively small, leading to the present invention, which includes a method for strengthening glassware and a glassware.

[0011]

[Means for Solving the Problems] A method for strengthening glassware to realize the method of the present invention is to hold an unstrengthened semi-finished glassware in an inverted state with its mouth edge supported on a support stand. After placing the semi-finished glassware and heating the entire inner and outer surfaces of the glassware, the glassware is strengthened by blowing cooling air onto the inner and outer surfaces of the glassware.

[0012] In other words, since only the rim of the glassware is in contact with the support, when the glassware is heated, the rim side cools faster than the bottom side, and the cooling rate is faster from the bottom side to the rim side. This is a heat treatment in which the temperature gradually decreases. Therefore, by blowing cooling air onto the inner and outer surfaces of the glassware, a strengthening process is realized in which the compressive stress gradually decreases from the bottom of the glassware toward the rim, that is, the compressive stress is highest at the bottom of the glassware.

[0013] The glassware is heated by heating the bottom of the glassware at a high temperature that gradually decreases toward the rim, and in the cooling process, the cooling rate is increased by increasing the amount of cooling air blown to the bottom of the glassware. By decreasing gradually from the bottom side toward the mouth edge side, it is possible to efficiently obtain a reinforced glassware with a large compressive stress at the bottom.

Furthermore, the glassware according to the present invention has a compressive stress of 700 mμ/mm at the mouth due to the air-cooling strengthening treatment.
cm, and the bottom is 1000 to 1700 mμ/cm.

Since the mouth of the glassware is in contact with the holder, the heating condition is different from that of the other parts, and there is a difference in the compressive stress value obtained due to the strengthening treatment, which results in a difference in heat resistance. The strength decreased and the compressive stress value at the mouth was 700 mμ/
cm or more, this difference becomes large and the required heat resistance strength cannot be obtained. Furthermore, the ability to prevent glass fragments from scattering during breakage decreases when the compressive stress value at the mouth exceeds 700 mμ/cm.

The compressive stress value at the bottom of the glassware is 10
If it is less than 1,700 mμ/cm, the required heat resistance strength cannot be obtained, and if it exceeds 1,700 mμ/cm, fragments will scatter when broken.

[0017] If the wall thickness of the glassware is less than 1.5 mm, the required compressive stress and heat resistance cannot be obtained;
If this value is exceeded, if compressive stress is created to obtain the required heat resistance strength, the stress value will become large and fragments will scatter when broken.

If the height/diameter ratio of the glassware exceeds 1, uniform cooling air will not be distributed over the inner surface of the glassware during the cooling process, and if the diameter exceeds 250 mm, uniform cooling air will not be distributed between the inside and outside of the glassware. cannot reach the surface.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a sectional view of a glassware support in which the method of the invention can be carried out effectively.

[0020] This glassware support stand is for placing an unstrengthened semi-finished glassware 2 on a ring-shaped glassware placement stand 1, and the edge of the glassware 2 is supported on the stand 1. In order to prevent the glassware 2 from moving and falling when cooling air is blown onto the glassware 2, the glassware 2 is placed upside down. A circumferential fitting groove 1b into which the mouth edge of the glassware 2 fits is formed on the outer periphery of the glassware. The holes 1a of the mounting table 1 are used to heat the inner surface of the inverted glassware 2 with flame from a burner in the heating process, and to blow air from an air nozzle onto the inner surface of the inverted glassware 2 in the cooling process. The pillars 4 are mounted on the base 3 with an effective height for heating and cooling from below.
has been fixed through. Furthermore, the base 3 is connected to a rotating shaft 5 and rotates in the direction of the arrow, thereby making it possible to rotate the glassware 2 placed thereon.

FIG. 2 shows the direction of the burner 6 with respect to the glassware 2 placed upside down on the glassware support. The heating of the glassware immediately before the cooling process is performed on the inner and outer surfaces of the glassware 2, and the temperature is raised as uniformly as possible in the thickness direction of the glassware to an extent that does not cause deformation. At this time, it is necessary to heat the glassware so that it gradually decreases from the bottom of the glassware 2 toward the rim. In this example, the flame of the burner is applied directly to the bottom, and the rim is It is heated by the flame surrounding it.

FIG. 3 schematically shows the cooling device.

The cooling device includes a housing 7 surrounding the glassware 2.
An outer side cooler 9 is provided with a number of air outlets 8 for blowing cooling air toward the outer surface of the glassware 2.
and a nozzle 10 that blows cooling air to the inside of the glassware 2 through the hole 1a of the glassware mounting table 1. The outer cooler 9 has more air outlets 8 provided on the top plate 7a than air outlets 8 provided on the side wall surface 7b, and the amount of air from the air outlets 8 is distributed from the bottom of the glassware 2 to the mouth edge. The air from the nozzle 10 is applied directly to the inner bottom surface of the glassware 2,
The cooling is directed toward the mouth edge by the wraparound.

[0024] Therefore, the heat-treated glassware 2 is rapidly cooled on its inner and outer surfaces by the cooling device so that the cooling temperature is gradually decreased from the bottom to the mouth edge. Uniform cooling is possible if the heat treatment reduces the temperature from the bottom of the glassware 2 toward the mouth edge.

In the cooling process, in order to perform uniform cooling, the glassware mounting table 1 is rotated in the same way as to perform uniform heating. Further, the cooling air source may be either blower air or compressor air.

It is necessary to carry out the above-mentioned heating and cooling steps of the glassware 2 continuously, and as shown in FIG.
They are transferred to the conveyor 12 one after another, and are continuously heated in the heating zone 13 in which the heating device shown in FIG. 2 is arranged.
Next, the glassware 2 is rapidly cooled in the quenching zone 14 in which the cooling device shown in FIG.
2 to the unloader 15 and sent to the next process. By carrying out such continuous processing, it is also possible to process hot glassware immediately after molding.

Furthermore, the strengthening treatment by heating and cooling the glassware 2 is not a continuous treatment as shown in FIG. 4, but is performed using a burner, a cooling air nozzle, etc. so that heating is performed in one place and then cooling is performed. It is also possible to provide a heating device and to operate the heating device and the cooling device alternately to carry out the strengthening treatment repeatedly.

Example 1 A small glass bowl (diameter 80 mm, height 40 mm) made of lead crystal glass with a thermal expansion coefficient of 105×10 −7° C. after being molded and slowly cooled was heated and cooled by the above-described repeated treatment to reduce compressive stress at the bottom. A sample was obtained with stress distribution of (strain value) 1300 mμ/cm and mouth compressive stress (strain value) 600 mμ/cm. In the cooling process, cooling air was blown out from the air outlet 8 of the housing 7 for 20 seconds, and cooling air was blown out from the nozzle 10 for 2 minutes.

[0029] For these 30 small glass bowls, 140
After being held for 30 minutes in a hot air circulation thermostat set at 0.degree. C., the sample was placed in cold water at 20.degree. C. and examined for damage. Thereafter, the temperature setting of the thermostat was increased by 10° C. to gradually increase the temperature difference, and the above-mentioned damage investigation procedure was repeated to conduct a heat resistance test.

As a result, five pieces were broken at a temperature difference of 150°C, and the heat-resistant temperature could be guaranteed up to a 140°C difference. In the test at a difference of 180°C, the number of undamaged products was zero, and the average failure temperature was 159°C. A small glass bowl that was damaged by a 180°C difference remained in its original shape with only cracks appearing on the entire surface, and was completely safe.

Example 2 A glass bowl (diameter 100 mm, height 4
5mm) was heated and cooled by continuous processing from a molding machine, passed through a slow cooling furnace below the transition temperature (400°C), and the compressive stress at the bottom was 1200 mμ/cm, and the compressive stress at the mouth was 500 mμ/c.
A sample with a stress distribution of m was obtained.

FIG. 5 shows the stress state of this glass bowl. As a comparative example, FIG. 5 shows the stress distribution of a glass bowl of the same size that was rapidly cooled using a conventional method. In addition, the measured values of the glassware according to Example 2 and the conventional glassware shown in FIG.
Table 1 shows the compressive stress on the inside and outside of the glassware (measured at 14 locations up to 65 mm from the mouth end to the bottom with zero).

[0033]

[Table 1]

From the above table and the like, it can be seen that the stress of the glass bowl of Example 2 is large at the bottom and small at the rim. Note that this value was measured using a strain meter manufactured by Toshiba Glass (SVP-2 type).

[0035]

Effects of the Invention As explained above, according to the method of the present invention, by supporting the rim of the glassware in an inverted state, the bottom of the glassware is also held at its highest point. It is possible to heat and cool the glassware in such a way that it gradually decreases toward the bottom, and it is possible to provide a glassware with the highest compressive stress at the bottom.

[0036] Furthermore, the glassware formed by this method is
It has increased heat resistance and is extremely safe, with no glass fragments scattering when broken.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a glassware support on which the method of the present invention can be effectively carried out.

FIG. 2 is a diagram showing the arrangement of burners and a heating method.

FIG. 3 is a schematic cross-sectional view showing one embodiment of a cooling device.

FIG. 4 is a schematic plan view of the strengthening treatment device.

FIG. 5 is a diagram showing the relationship between the position in the height direction and the compressive stress value in Example 2.

[Explanation of symbols]

1...Glassware mounting stand
12...Belt conveyor 2...Semi-finished glassware
13... Heating zone 3... Base
14...Rapid cooling zone 4...Strut
15... Unloader 5... Rotating shaft 6... Burner 7... Housing 8... Air outlet 9... Outer side cooler 10... Nozzle 11... Loader

Claims (4)

[Claims] Claim 1: After placing an unstrengthened semi-finished glassware in an inverted state with its mouth edge supported on a support base and heating the entire inner and outer surfaces of the semi-finished glassware,
A method for strengthening glassware, which strengthens glassware by blowing cooling air onto the inner and outer surfaces of the glassware. [Claim 2] Through air-cooling strengthening treatment, the compressive stress on the inner and outer surfaces is less than 700 mμ/cm at the mouth and 1000 mμ/cm at the bottom.
A glassware characterized by having a diameter of 1700 mμ/cm. [Claim 3] In Claim 2, the wall thickness is 1.5 to 1.
A glassware characterized by having a diameter of 0.0 mm. 4. The glassware according to claim 2 or 3, wherein the height/aperture ratio is 1 or less and the aperture is 250 mm or less.