JP4504854B2 - Glass bottle - Google Patents

Description

  The present invention relates to a glass bottle in which a large number of protrusions are formed on the bottom of the bottle, and more particularly to a lightweight glass bottle with a reduced wall thickness and reduced weight.

  Conventionally, on the bottom of glass bottles, a group of protrusions called “knurling” has been formed to reduce the contact area with the transport conveyor that transports the molded bottles and prevent the bottom from being damaged during transport. Has been. There are various types of knurling. In recent years, knurling called “turbine type” has been widely used.

  FIG. 3 shows the body 2 of the glass bottle 1, and a turbine-shaped knurling 4 is formed in a circle on the bottom 3. As shown in FIG. 4, the knurling 4 includes a plurality of longitudinal protrusions 6 having a major axis larger than a width d of the region 5 in a donut-shaped region 5 assumed along the outer peripheral edge of the bottle bottom 3. Both end portions 6a and 6b are formed so as to be inclined in the same direction so as to be in contact with the outer edge 5a and the inner edge 5b of the region 5.

  Disposing each protrusion 6 on the circle in an inclined state is longer than the protrusion 6 in the same donut-shaped region 5 as compared to disposing the protrusion 6 in the circular shape along the radial direction without being inclined. This is because the length can be set long, whereby the strength of the bottle bottom 3 of the glass bottle 1 can be increased. Therefore, this kind of knurling 4 is designed to form as many projections 6 as possible in the region 5 having a predetermined width d along the outer peripheral edge of the bottle bottom 3.

  Recently, in order to improve the strength of the bottle bottom 3 of the glass bottle 1, as shown in FIG. 5, the curvature radius of the top 6e of the protrusion 6 is increased to relatively increase the height h of the protrusion 6, By reducing the distance L (pitch) between adjacent protrusions 6 and 6 from that of the conventional one so that the bottle bottom surface 7 between the protrusions 6 and 6 does not contact the ring of the conveyor, the strength is reduced. It has been proposed to prevent the bottle bottom surface 7 from being damaged due to contact with the conveyor (for example, see Patent Document 1).

Japanese Utility Model Publication No. 64-9112

In the bottle bottom 3 of the glass bottle 1 described above, a circular curved surface 8 is formed between both side end surfaces 6 c and 6 d of the projection 6 and the bottle bottom surface 7, but the circular curved surface 8 with respect to the height h of each projection 6. Since the radius of curvature of the glass bottle is small, when the glass bottle is molded, the round bottom surface 8 on both sides of the projection 6 is cracked or chattered due to mechanical impact when the bottom of the glass bottle is released from the mold (bottom mold). Has occurred, causing a drop in the strength of the bottle bottom 3. As a result, the projection 6 of the knurling 4 that should be provided to increase the strength of the bottle bottom 3 causes an unreasonable result that the strength of the bottle bottom 3 is reduced.
In particular, under the recent situation where glass bottles are being made lighter, a decrease in strength at the bottom of the bottle due to the occurrence of cracks and chatters at the time of mold release can be a major defect of lightweight glass bottles. There is a problem.

  The present invention has been made paying attention to the above problems, and after increasing the strength of the bottom of the bottle by knurling, suppresses the cause of the decrease in strength caused by mold release during the molding of the glass bottle. An object of the present invention is to provide a glass bottle having a generally improved bottle bottom strength.

The glass bottle according to the present invention has a plurality of long protrusions in a donut-shaped region assumed along the outer peripheral edge of the bottle bottom, with respect to a diameter line connecting the center of the bottle bottom and the center of each protrusion. Each of the protrusions is formed in a circumferential direction along the bottom of the bottle in a tilted state in the same direction, and the projections are circularly curved between both side end surfaces and the bottom of the bottle, and It is formed so that the ratio of the radius of curvature of the circular curved surface to the height of the top portion is 1.5 to 2.0.
Here, the “doughnut-shaped region” is a region having a donut shape assumed along the outer peripheral edge of the bottle bottom when designing the bottle bottom, and the region is divided or partitioned from other regions. It is not something that is actually formed at the bottom of the balance.

In a preferred embodiment of the invention, each protrusion of the, as large both ends major diameter than the width of the region of that is in contact with the outer edge inner edge of the region, the centers of the projections of the bottle bottom They are arranged in the circumferential direction along the bottom of the bottle in a state of being inclined in the same direction with respect to the connecting diameter lines .

  In the above-described configuration of the present invention, the “projection” refers to a thick portion that is partially raised from the surface of the bottle bottom. Each protrusion may adopt various shapes such as an ellipse and an oval as long as the planar shape is a longitudinal shape. The top surface of each protrusion may be a circular curved surface or a flat surface.

  In the glass bottle having the above-described configuration, each protrusion has a circular curved surface between both side end surfaces and the bottle bottom surface, and the ratio of the radius of curvature of the circular curved surface to the height of the top of each protrusion is 1.5-2. As the height of the top of the protrusion increases, the radius of curvature of the circular curved surface increases correspondingly, and the circular curved surface between the side surfaces of the protrusion and the bottom of the bottle increases the height of the protrusion. A smooth curved surface according to the height. As a result, there is no occurrence of cracking or chattering on the circular curved surface due to mechanical impact at the time of mold release.

  Here, the ratio of the radius of curvature of the circular curved surface to the height of the top of each protrusion is set to 1.5 to 2.0. If the ratio is less than 1.5, the ratio is smooth according to the height of the protrusion. This is because a rounded curved surface cannot be obtained, and mechanical impacts at the time of mold release cause cracks and chattering on the curved surface, leading to a decrease in strength at the bottom of the bottle. For example, the distance between the protrusions is increased, and the decrease in the number of protrusions causes a decrease in the strength of the bottle bottom.

  The radius of curvature of the circular curved surface is preferably 0.5 mm or more in order to prevent the circular curved surface from being cracked or chattered by mechanical impact during mold release. In order not to cause a decrease in the strength of the bottle bottom due to the decrease, it is desirable that the thickness be 1.0 mm or less.

  According to the present invention, it is possible to increase the strength of the bottle bottom by knurling, and to suppress the cause of the strength decrease due to the mold release at the time of molding the glass bottle, the strength of the bottle bottom Can be improved comprehensively.

  FIG. 1 is an enlarged view of a turbine-type knurling 4 formed on the bottom of a glass bottle according to an embodiment of the present invention. As shown in FIGS. 3 and 4, the knurling 4 is arranged in a circle with a number of long protrusions 6 inclined in the same direction along the outer peripheral edge of the bottle bottom 3 of the glass bottle 1. Is formed.

  The knurling 4 of the illustrated example is formed by aligning the protrusions 6 in the circumferential direction in a donut-shaped region 5 assumed along the outer peripheral edge of the bottle bottom 3. Each protrusion 6 is partially raised from the surface of the bottle bottom 3, and the shape seen in plan is set to an elliptical shape having a major axis D1 and a minor axis D2 (D2 <D1). The major axis D1 of each projection 6 is larger than the width d of the region 5, and each projection 6 is inclined in the same direction so that both end portions 6a and 6b are in contact with the outer edge 5a and the inner edge 5b of the region 5. It is arranged in a circle.

In the figure, 9 is a diameter line connecting the center Q of the bottle bottom 3 and the center P of the protrusion 6, and the protrusion 6 is inclined with respect to the diameter line 9 by an inclination angle θ. The greater the inclination angle θ, the longer the length of the protrusion 6 (major axis D1).
Reference numeral 10 denotes a center line along the major axis direction of the projection 6, and 11 denotes a center line along the minor axis direction of the projection 6, and the projection when the projection 6 is cut along the center line 11 in the minor axis direction. The cross-sectional shape of 6 is shown in FIG.

  The top portion 6e of each projection 6 is curved in a convex shape along the minor axis direction, and the space between the side surface 6c, 6d of each projection 6 and the bottle bottom surface 7 is curved in a concave shape along the minor axis direction. It is a circular curved surface 8. Each protrusion 6 is formed such that the ratio (R / h) of the radius of curvature R of the circular curved surface 8 to the height h of the top 6e is 1.5 to 2.0.

  The lower limit of the ratio (R / h) of the radius of curvature R of the circular curved surface 8 to the height h of the top portion 6e of each protrusion 6 is set to 1.5 if the ratio (R / h) is 1. If it is less than .5, the curved surface 8 having a smooth curved surface corresponding to the height of the protrusion 6 cannot be obtained, and cracks and chattering are generated on the circular curved surface 8 due to mechanical impact at the time of mold release. This is because the strength of the bottle bottom 3 is reduced. The upper limit of the ratio (R / h) of the radius of curvature R of the circular curved surface 8 to the height h of the top 6e of each protrusion 6 is set to 2.0 if the ratio (R / h) If the value exceeds 2.0, the distance between the protrusions 6 and 6 increases, and the decrease in the number of protrusions causes the strength of the bottle bottom 3 to decrease.

  In the glass bottle 1 of this embodiment, the width (minor axis D2) along the minor axis direction center line 11 of each projection 6 at the bottle bottom 3 is 1.8 mm, the height h of the top part 6e is 0.36 mm, The curvature radius R of the curved surface 8 is set to 0.65 mm. Therefore, the ratio (R / h) of the curvature radius R of the circular curved surface 8 to the height h of the top portion 6e is 1.81.

A plurality of glass bottles 1 of this example are prepared, while the width (minor axis D2) along the minor axis direction center line 11 of each projection 6 is 1.2 mm, and the height h of the top 6e is 0.28 mm. For the strength test, a plurality of comparative examples in which the radius of curvature R of the circular curved surface 8 is 0.35 mm and the ratio (R / h) of the radius of curvature R of the circular curved surface 8 to the height h of the top 6e is 1.25. The pressure resistance strength was measured for 10 examples and 10 comparative examples. The pressure strength was measured by the “stage pressurization method” of JIS standard S2302-1994 “Internal pressure test method for glass bottles for carbonated beverages”. Water was introduced into the sample bottle and the pressure was gradually increased. The pressure when the sample bottle is broken is read by the display.
As a result, the average value of the ten pressure-resistant strengths is 3.82 MPa in the example and 3.44 MPa in the comparative example, and the example is superior in strength to the comparative example.

Next, using the bottle specification data of the same example and comparative example as described above, a stress analysis was performed by a computer, and the maximum stress of the bottle bottom surface 7 between the protrusions 6 and 6 was measured. For the maximum stress, the maximum value of the stress acting on the bottom of the bottle when an internal pressure load of 0.098 MPa is applied to the sample bottle by a known method, for example, analysis software (NAVISTRUCT (registered trademark), manufactured by Sekisui Chemical Co., Ltd.). ) And the like.
As a result, the maximum stress of the example was 16.0 MPa, and the maximum stress of the comparative example was 17.8 MPa.

  In the glass bottle 1 having the above-described configuration, each projection 6 is formed as a circular curved surface 8 that is concavely curved along the minor axis direction between the side end surfaces 6c and 6d and the bottle bottom surface 7, and the top portion 6e of each projection 6 is formed. Since the ratio (R / h) of the radius of curvature R of the circular curved surface 8 to the height h is 1.5 to 2.0, the height h of the top 6e of the protrusion 6 is increased. Accordingly, the radius of curvature R of the circular curved surface 8 also increases correspondingly, and the circular curved surface 8 between the side end surfaces 6c, 6d of the protrusion 6 and the bottle bottom surface 7 becomes a smooth curved surface corresponding to the height h of the protrusion 6. As a result, the strength of the bottle bottom 3 is increased by the knurling 4, and the circular curved surface 8 is not cracked or chattered by a mechanical impact at the time of mold release. The strength of 3 will be improved comprehensively.

It is a top view which expands and shows the knurling formed in the bottle bottom of the glass bottle which is one Example of this invention. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which carried out the cross section of the trunk | drum of the glass bottle to the vertical direction. It is a top view which shows the bottle bottom of a glass bottle. It is an expanded sectional view of the knurling formed in the bottle bottom of a glass bottle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass bottle 3 Bottle bottom 4 Knurling 5 Donut-shaped area | region 6 Protrusion 6a, 6b End part 6c, 6d Side end surface 6e Top part 7 Bottle bottom surface 8 Circular surface

Claims (3)

In the donut-shaped region assumed along the outer periphery of the bottle bottom , a number of long protrusions are inclined in the same direction with respect to the diameter line connecting the center of the bottle bottom and the center of each protrusion. In the glass bottle formed by being arranged in the circumferential direction along the bottom of the bottle, each of the protrusions has a circular curved surface between both side end faces and the bottom of the bottle, and the height relative to the height of the top. A glass bottle formed so that the ratio of the curvature radii of the circular curved surface is 1.5 to 2.0. Each protrusion of the, as large both ends major diameter than the width of the region of that is in contact with the outer edge inner edge of the region, respectively the same direction with respect to the diameter line connecting the centers of the projections of the bottle bottom The glass bottle according to claim 1, wherein the glass bottle is arranged in a circumferential direction along the bottom of the bottle in a tilted state.   The glass bottle according to claim 1 or 2, wherein a radius of curvature of the circular curved surface is 0.5 to 1.0 mm.

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