The present invention relates to an apparatus for testing the water hammer strength of a glass bottle using a single glass bottle.
The water-hammer-strength test of glass bottles is defined by the “water-hammer test method” prescribed by Japan Glass Bottle Association. This defines the water-hammer test method for packaged glass bottles.
The sample stage is set at a predetermined drop height (the distance between the bottom surface of the upper dummy and the top surface of the sample), and the upper dummy is dropped onto the sample from a drop height of, for example, at first, 30 cm. The drop tests are repeated until a predetermined drop height is reached to see if any one of the glass bottles in the sample is damaged, while increasing the drop height by an increment of 5 cm (for a drop height of 60 cm or more, an increment of 10 cm is applied). The drop height at which any one of the sample bottles is damaged is regarded as the water hammer strength.
When the upper dummy 25 falls onto the sample 24, the case of the lower dummy 23 is deformed, and the glass bottles in the sample 24 are abruptly pushed downward. However, the content (liquid) of the glass bottles remains at the original position due to inertia, creating vacuum portions (vacuum bubbles) at the bottoms of the bottles. Immediately after that, the content abruptly falls onto the bottoms, which are in a vacuum state, causing a water hammer effect.
The “water-hammer test method” prescribed by Japan Glass Bottle Association is for measuring the water hammer strength of packaged glass bottles and is not for testing the water hammer strength of glass bottles themselves (the water hammer strength changes depending on the specifications of packages). Furthermore, because the test cannot be performed without preparing cartons, the test requires many products (about 10 cases). Thus, the water hammer strength evaluation cannot be performed in the test production in the design phase of bottle parisons. Moreover, the test requires considerable labor for tasks such as lifting the cartons, checking the bottles for damage, cleaning up of the damaged bottles, checking the cartons for damage, etc.
PTL 1 below proposes a technique that solves the above-described problems, enables measurement of the water hammer strength of glass bottles themselves with relative ease, and enables strength evaluation in the test production (in the design phase of bottle parisons).
This is a method for testing the water hammer strength of a glass bottle, in which holding means is provided on a fixing stage via a cushion member, the holding means holds the bottle filled with content and sealed with a cap at a position above the center of gravity thereof so as to suspend the bottle in the air, a weight is directly or indirectly dropped onto the cap to apply an impact to the bottle, and the weight is repeatedly dropped while gradually increasing the drop energy, thereby testing the water hammer strength of the bottle on the basis of the drop energy of the weight when the bottle is damaged.
When the weight is directly or indirectly dropped onto the cap, the cushion member is deformed, and the bottle is abruptly pushed downward, causing a water hammer effect. If the weight is dropped onto the bottle held at a position above the center of gravity thereof and suspended, the drop energy of the weight acts on the bottle efficiently. Thus, the drop energy of the weight is strongly associated with the impact applied to the bottle, making it possible to accurately know the water hammer strength of the bottle on the basis of the drop energy of the weight when the bottle is damaged.
PTL 1: Japanese Unexamined Patent Application Publication No. 2009-133708
In this test apparatus, a base stage 6, a post 7, and a fixing stage 2 are formed as a single component. Four cushion members 3 are disposed around a through-hole 2a in the fixing stage 2, and holding means 4 is placed thereon. The cushion members 3 are made of elastic members composed of rubber, soft resin, or the like. The holding means holds a bottle 1 that is filled with content and sealed with a cap 1b at a position above the center of gravity thereof (in this case, below a bead 1a) and suspends the bottle in the air. The weight 5 is provided above the cap 1b of the bottle 1.
When the weight 5 is dropped onto the cap 1b of the bottle, the cushion members 3 are compressed and deformed due to the impact, and the bottle 1 is abruptly pushed downward, causing a water hammer effect.
At this time, because the cushion members 3 are very soft, the compression and deformation thereof do not always occur in the vertical direction, and, as shown in
It cannot be said that the measured water hammer strength is correct if the bottle is significantly inclined or if the cushion members 3 jump out of the apparatus when the weight 5 is dropped. Thus, in such a case, the cushion members have to be returned to the original positions and the measurement has to be performed again.
An object of the present invention is to prevent the bottle from being inclined when the weight 5 is dropped and to prevent the cushion members 3 from moving due to the impact, thereby enabling efficient and correct measurement of the water hammer strength.
The present invention is an apparatus for testing the water hammer strength, the apparatus including: a fixing stage; a cushion member placed on the fixing stage; holding means that is placed on the cushion member and holds a bottle filled with content and sealed with a cap at a position above the center of gravity thereof so as to suspend the bottle in the air; and a weight to be dropped onto the cap to apply an impact to the bottle,
wherein push-down means for forcibly pushing the holding means downward is provided, and wherein the cushion member is compressed and deformed by the push-down means. (Claim 1)
By compressing and deforming the cushion member in advance using push-down means, the cushion member becomes less susceptible to out-of-plane deformation when the weight 5 is dropped. As a result, the inclination of the bottle is considerably reduced. The movement of the cushion member is also reduced.
The push-down means may have any mechanism as long as it can forcibly push the holding means downward. Besides the mechanism disclosed in claim 2 below, push-down means utilizing a known mechanism, such as a clamp or a vice, may be employed.
More specifically, the push-down means may be a bolt screwed to the fixing stage from a top surface side of the holding means. (Claim 2)
By providing a bolt hole in the holding means, by providing a female screw hole in the fixing stage, and by screwing the bolt to the fixing stage from the top surface side of the holding means, it is possible to easily push down the holding means to compress and deform the cushion member. The extent by which the holding means is pushed downward may be easily adjusted by changing the tightness of the bolt.
The cushion member may be formed of a plurality of cushion bodies bonded together with a non-cushioning plate therebetween. (Claim 3)
By doing so, the cushion member becomes even less susceptible to out-of-plane deformation when the weight 5 is dropped, and, as a result, the inclination of the bottle is further reduced, and the movement of the cushion member is also further reduced.
Examples of the material of the non-cushioning plate include plastic, metal, and wood, which are less likely to be deformed than the cushion member.
A non-slip sheet may be disposed between the fixing stage and the cushion member and between the cushion member and the holding means. (Claim 4)
Because the cushion member experiences significant deformation during the tests, the cushion member is deteriorated (cause cracks) after being subjected to impact several hundreds of times. Thus, the cushion member is an expendable member that requires replacement every time it is deteriorated. Therefore, the cushion member cannot be securely bonded to the fixing stage and the holding means. To prevent the cushion member from falling off, a non-slip sheet having a high coefficient of friction may be disposed between the fixing stage and the cushion member and between the cushion member and the holding means.
By doing so, the cushion member becomes even less likely to move when the weight 5 is dropped.
A sheet having good non-slip effect, such as a natural rubber sheet or a silicone rubber sheet, may be used as the non-slip sheet. The appropriate thickness of the sheet is from about 0.3 mm to 1 mm.
Furthermore, the present invention is the apparatus for testing the water hammer strength according to claim 4, wherein the fixing stage and/or the holding means has a recess in a surface in contact with the cushion member, wherein the non-slip sheet is provided in the recess, and wherein the cushion member is embedded in the recess by 0.2 mm to 0.8 mm. (Claim 5)
By doing so, the non-slip sheet and the cushion member do not come off from the recess, and the movement thereof can be prevented. Although the recess may be provided in only one of the fixing stage and the holding means, it is desirable that the recess be provided in both of them.
The appropriate amount by which the upper end or the lower end of the cushion member is embedded in the recess (y in
Note that the appropriate value for the distance between the cushion member and the outer periphery of the recess in the horizontal direction (x in
Furthermore, the present invention is the apparatus for testing the water hammer strength according to claim 1 or 2, wherein the cushion member is formed of a plurality of cushion bodies bonded together with a non-cushioning plate therebetween and non-cushioning plates bonded to the upper and lower ends thereof, wherein the fixing stage and/or the holding means has a recess in a surface in contact with the cushion member, and wherein the plate at the upper end and/or the plate at the lower end is disposed in the recess. (Claim 6)
By bonding the non-cushioning plates to the upper and lower ends of the cushion member, the soft cushion body does not collide with the outer periphery of the recess when the cushion member moves, whereby the endurance of the cushion member is maintained. Furthermore, because the upper and lower ends of the cushion member are the non-cushioning plates, the cushion member will not move beyond the recess, whereby the movement of the cushion member is reliably limited.
Furthermore, the present invention is the apparatus for testing the water hammer strength according to claim 1 or 2, wherein the cushion member is formed of a plurality of cushion bodies bonded together with a non-cushioning plate therebetween and non-cushioning plates bonded to the upper and lower ends thereof, wherein the plate at the upper end and/or the plate at the lower end has a hole in the top or bottom surface thereof, and wherein the fixing stage and/or the holding means has a projection that fits into the hole in the surface in contact with the cushion member. (Claim 7)
Because the hole in the cushion member and the projection on the fixing stage or the holding means fit together, the movement of the cushion member is prevented.
The fixing stage and the holding means do not need to have a recess and, thus, can be reduced in thickness.
With the apparatus for testing the water hammer strength of the present invention, the cushion member is less susceptible to out-of-plane deformation and is less likely to move when the weight is dropped. Thus, it is possible to efficiently and correctly measure the water hammer strength.
Cushion members 3 are placed at four corners around the through-hole 2a in the fixing stage 2, and holding means 4 is placed thereon.
As shown in
Non-slip sheets 9 are disposed between the fixing stage 2 and the cushion members 3, and between the cushion members 3 and the holding means 4. The non-slip sheets 9 are silicone rubber sheets having a thickness of 0.5 mm. The non-slip sheets 9 are bonded to the fixing stage 2 and the holding means 4.
The holding means 4 holds the bottle 1 filled with content and sealed with a cap at a position above the center of gravity thereof so as to suspend the bottle in the air. The material and shape of the holding means 4 are not specifically limited as long as it can securely hold the bottle 1 and it can be placed on the cushion members 3. For example, although the holding means 4 having various mechanisms, as disclosed in PTL 1, may be used, these mechanisms are omitted in the drawings of the present invention, and the glass bottle 1 is supported at a part immediately below the bead 1a by a through-hole 4a provided in the central part.
Although it is only necessary that the bottle 1 filled with content and sealed with a cap is held at a position above the center of gravity thereof, it is most desirable that the bottle 1 be held at a neck (immediately below a mouth or the bead).
The holding means 4 has two bolt holes, and the fixing stage 2 has corresponding two female screw holes. By screwing bolts 10 with the female screw holes in the fixing stage 2 from the top surface side of the holding means 4, the cushion members 3 are compressed and deformed (
The weight 5 is provided above the cap 1b of the bottle 1. The weight 5, which is formed of a shaft 5b and a weight body 5a provided at the lower end thereof, is formed so as to protrude from the post 7 and is capable of moving vertically upward and downward along a guide (not shown) having an insertion hole through which the shaft 5a extends. The weight 5, held at a desired height by a stopper (not shown), falls right onto the cap 1b by removing the stopper.
The post 7 is marked with a scale 8 so that the height of the weight can be easily known.
When the weight 5 falls right onto the cap 1b, the cushion members 3 are deformed due to the drop energy thereof, and the holding means 4 and the bottle 1 are abruptly pushed downward (
Because the bolts 10 slide in the bolt holes in the holding means 4 at this time, the downward movement of the holding means 4 is not blocked. Furthermore, because the bolts 10 guide the downward movement of the holding means 4, the holding means 4 moves downward always vertically, and thus, is less likely to be inclined.
Because the cushion members 3 are compressed and deformed in advance and the plate 3b is provided in the middle thereof, the out-of-plane deformation caused when subjected to the impact of the weight 5 is very small. Moreover, because the bolts 10 guide the downward movement of the holding means 4, the inclinations of the holding means 4 and the bottle 1 are very small.
Whereas the inclination of the bottle 1 when the weight is dropped is 4° at the maximum and 2° on average with the conventional test apparatus 7, the inclination of the bottle 1 was reduced to a visually unrecognizable level in this embodiment.
In the measurement of the water hammer strength according to this embodiment, the weight is dropped several times while gradually increasing the drop energy, and the water hammer strength of the bottle is represented by the drop energy of the weight when the bottle is broken. The drop energy is adjusted by changing the weight and the drop height (the distance between the bottom surface of the weight and the top surface of the cap). The drop energy is mgh, where m is the mass of the weight, h is the drop height, and g is the acceleration of gravity.
Similarly to the above-described embodiment, each cushion member 3 is formed of two cushion bodies 3a and a plate 3b disposed therebetween, which are securely bonded together (
The non-slip sheets 9 are silicone rubber sheets having a thickness of 0.5 mm and a size of 20.6 mm×20.6 mm.
The fixing stage 2 and the holding means 4 have recesses 12 having a depth of 0.8 mm and a size of 20.6 mm×20.6 mm, in surfaces in contact with the cushion members. Semicircular portions of the recesses denoted by the reference numeral 12a in
The non-slip sheets 9 are placed in the recesses 12 and 13 in the fixing stage 2 and the holding means 4, and the cushion members 3 are disposed therebetween (
As shown in
As shown in
The fixing stage 2 and the holding means 4 have the recesses 12 having a depth of 1.5 mm and a size of 22.8 mm×22.8 mm in the surface in contact with the cushion members. Semicircular portions of the recesses denoted by the reference numeral 12a in
The appropriate value for the distance between the plates 3b of the cushion members and the outer peripheries of the recesses 12 and 13 in the horizontal direction (except for the milling cutter relief portions) is from 0.1 mm to 0.5 mm, and in this embodiment, the distance is 0.4 mm.
The plates 3b at the ends of the cushion members are positioned in the recesses 12 and 13 in the fixing stage 2 and the holding means 4, and the cushion members 3 are disposed between the fixing stage 2 and the holding means 4 (
Although the cushion members 3 are basically the same as those shown in
The fixing stage 2 and the holding means 4 have cylindrical projections 15 (having a diameter of 2.5 mm and a height of 1.5 mm) in the surface in contact with the cushion members, at positions corresponding to the holes 14. The appropriate value for the difference in diameter between the holes 14 and the projections 15 is from about 0.1 mm to 1 mm.
The cushion members 3 are disposed between the fixing stage 2 and the holding means 4. At this time, the projections 15 loosely fit into the holes 14 (
In
The fixing stage 2 has the recesses 12 having a depth of 1.5 mm and a size of 22.8 mm×22.8 mm in the surface in contact with the cushion members (top surface). This configuration is the same as that of the fixing stage shown in
The holding means 4 has the cylindrical projections 15 (having a diameter of 2.5 mm and a height of 1.5 mm) in the surface in contact with the cushion members (bottom surface), at positions corresponding to the holes 14. This configuration is the same as that of the holding means shown in
The cushion members 3 are disposed between the fixing stage 2 and the holding means 4. The plates 3b at the lower ends of the cushion members 3 are positioned in the recesses 12 in the fixing stage 2, and the projections 15 loosely fit into the holes 14 at the upper ends of the cushion members. The cushion members 3, which originally have a total thickness of 26 mm, are compressed to a thickness of 24.5 mm by forcibly pushing the holding means 4 downward with the bolts 10.
This embodiment employs the structure of the embodiment in
Although each cushion member 3 is formed of two cushion bodies 3a securely bonded together with a non-cushioning plate 3b therebetween in the above-described embodiment, the number of the cushion bodies 3a may be three or more.
Number | Date | Country | Kind |
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2010-028566 | Feb 2010 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2010/053555 | 3/4/2010 | WO | 00 | 8/2/2012 |