Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Having discontinuous gas or vapor phase – e.g. – foam:
Reexamination Certificate
1999-11-04
2003-03-25
Lovering, Richard D. (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Having discontinuous gas or vapor phase, e.g., foam:
C261SDIG002, C425S00400R
Reexamination Certificate
active
06538040
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and an apparatus for mixing a high-viscosity material into a gas and a piston pump used therefor. For example, the present invention is applied to a process prior to foaming for producing a foamed-in-place gasket or a fill foam in a void.
The present invention also relates to a method and an apparatus for foaming a high-viscosity material and is applied to, for example, a foamed-in-place gasket, filling of a void, etc.
TECHNICAL BACKGROUND
FIG. 5
is a fluid circuit diagram of a foaming apparatus
90
using a conventional mixing device.
In
FIG. 5
, a high-viscosity material contained. in a container
91
is pressurized by a pump
92
and is transferred to a power mixer
94
. A compressed gas in a gas cylinder
93
is adjusted to have a high pressure and is transferred to the power mixer
94
.
The power mixer
94
is operated by rotating a motor M. The power mixer
94
mixes, under high pressure, a combination of the high-viscosity material and the gas supplied thereto to make the mixture thereof. The mixture of the high-viscosity material and the gas mixed by the power mixer
94
is discharged from a nozzle
96
through a pipe
95
. As the gas, a nitrogen gas, a carbonic acid gas or air can be used. The foaming apparatus
90
arranged as mentioned above is used for, for example, applying a high-viscosity polymeric material such as a hotmelt adhesive (see Unexamined Japanese Patent Application Public Disclosure No. 63-264327).
A hotmelt adhesive comprises a thermoplastic polymer which is in a solid form at room temperature. The hotmelt adhesive is melted and fluidized by heating. When the hotmelt adhesive in a molten state is cooled to room temperature, the adhesive solidifies and exerts not only adhesive strength, but also exerts physical strength as a solid mass. In conventional foaming apparatuses for a hotmelt adhesive, a mixture of a gas and a molten hotmelt adhesive is cooled before occurrence of an escape of the gas and then, the mixture is foamed, with the gas being incorporated into the hotmelt adhesive by utilizing the strength of the adhesive which is exerted immediately after cooling.
In the above-mentioned conventional foaming apparatus
90
, in order to mix the high-viscosity material and the gas, the high-viscosity material and the gas after heating must be transferred under high pressure to the power mixer
94
. When the viscosity of the high-viscosity material is as high as, for example, 100,000 cps, it is considered that the internal pressure of the power mixer
94
is 100 kg/cm
2
or more. Therefore, in order to supply the gas and the high-viscosity material to the power mixer
94
at the same time, the pressure of the gas needs to be higher than that of the high-viscosity material.
In the conventional foaming apparatus
90
, the amount of gas is measured by controlling the flow rate of the gas. However, when the pressure of the gas is high, it is difficult to control the gas flow rate. Further, a minor error in the gas flow rate under high pressure becomes a major error under atmospheric pressure. For example, an error in the flow rate of 50 kg/cm
2
becomes 50 times greater under atmospheric pressure. Therefore, in the conventional foaming apparatus
90
, there are great variations in the mixing ratio of the high-viscosity material and the gas, so that foaming ratio cannot be stably conducted, thus making it difficult to achieve uniform foaming ratio.
Further, the high-pressure gas cylinder
93
for supplying the gas must be replaced when the compressed gas in the high-pressure gas cylinder
93
has been exhausted, so that maintenance becomes cumbersome. Further, for replacement of the high-pressure gas cylinder
93
, another high-pressure gas cylinder
93
must be installed as a spare, so that a large space is required for installment of these gas cylinders. In addition, various measures must be taken from the viewpoint of safety, according to regulations for high-pressure gases. For these reasons, the conventional foaming apparatus is disadvantageous in terms of costs. SUMMARY OF THE INVENTION
In view of the above, the present invention has been made. It is an object of the present invention to provide a method and an apparatus for mixing a high-viscosity material into a gas and a piston pump used therefor, which enable the gas to be mixed or introduced into the high-viscosity material under low pressure and which achieves an accurate mixing ratio of the gas and the high-viscosity material.
It is another object of the present invention to provide a method and an apparatus four foaming a high-viscosity material, which enable the gas to be introduced into the high-viscosity material under low pressure and which are free from the problems accompanying the conventional technique due to the use of a high-pressure gas cylinder anal ensure easy maintenance, high safety and low costs.
In the method of the present invention, by using a piston pump comprising a piston and a cylinder, the piston being adapted to reciprocally move within the cylinder to effect a suction stroke and a discharge stroke, a gas and a high-viscosity material are supplied separately from each other into the cylinder in a batchwise manner so as to supply the gas during and/or after the suction stroke of the piston pump and to supply the high-viscosity material in the cylinder after the suction stroke. The discharge stroke of the piston pump is effected after completion of the supply of the high-viscosity material in the cylinder, to thereby discharge the gas and the high-viscosity material into a pipe.
In the method of the present invention, a dead space within the cylinder may become substantially zero at the condition of completion of the discharge stroke of the piston pump.
The apparatus of the present invention comprises a piston pump including a piston and a cylinder. The piston is adapted to reciprocally move within the cylinder to effect a suction stroke and a discharge stroke: A gas supplying device supplies a gas into the cylinder under a predetermined pressure and a high-viscosity material supplying device supplies a high-viscosity material into the cylinder under a predetermined pressure. A control device effects control to supply the gas and the high-viscosity material separately from each other into the cylinder in a batchwise manner so that the gas is supplied during and/or after the suction stroke of the piston pump and the high-viscosity material is supplied after the suction stroke, and to effect the discharge stroke of the piston pump after completion of the supply of the high-viscosity material in the cylinder to discharge the gas and the high-viscosity material into a pipe.
In the apparatus of the present invention, first, second and third needle valves may be provided in the cylinder of the piston pump. The first needle valve is provided at a stroke end of the discharge stroke and adapted to control discharge, the second needle valve is provided in the vicinity of the stroke end of the and discharge and discharge stroke and adapted to control supply of the gas, and the third needle valve is provided in the vicinity of a stroke end of the suction stroke and adapted to control supply of the high-viscosity material. A dead space within the cylinder may become substantially zero at the condition of completion of the discharge stroke of the piston pump.
The piston pump of the present invention comprises a cylinder and a piston which reciprocally moves within the cylinder to effect a suction stroke and a discharge stroke. First, second and third needle valves are provided in the cylinder of the piston pump, the first needle valve being provided at a stroke end of the discharge stroke and adapted to control discharge, the second needle valve being provided in the vicinity of the stroke end of the discharge stroke and adapted to control supply of the gas, and third needle valve being provided in the vicinity of a stroke end of the suction stroke and adapted to control supply of the high-viscosity material. A dead space
Okuda Shinji
Takada Masaharu
Yoshimoto Yasuyuki
Lovering Richard D.
Sunstar Giken Kabushiki Kaisha
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Method and apparatus for mixing a high-viscosity material... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for mixing a high-viscosity material..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for mixing a high-viscosity material... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3077929