Fluid sprinkling – spraying – and diffusing – Unitary plural outlet means
Reexamination Certificate
2000-01-07
2003-02-18
Yuen, Henry C. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Unitary plural outlet means
C239S553000, C239S556000, C239S566000, C239S568000
Reexamination Certificate
active
06520429
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns an extruding equipment with multi-tubes which can be used for extrusion of fluid plastic materials to make various formed products or for coating of fluid chemicals onto the web surface.
The typical conventional extrusion dies used for making plastic films among many types are as follows:
Coat hanger type (normally called as “T-Die”) which is explained in details hereinafter
Manifold type of which die is equipped with holding chambers (called as “Manifold”)
Same as above Manifold type but with a built-in agitating roll inside each manifold. This agitating roll prevents deterioration of the fluid materials.
Hereinafter, the outline of the T-Die of Coat hanger type is described with reference to Drawing
24
. The illustration (A) in the drawing shows the section when viewing from the front and (B) shows the U—U section of the illustration (A). This extrusion die
200
has such a T-shape construction die
201
as shown in the illustration (A). The plastic material melted by the heater in the preceding fluid supply equipment (not shown) is sent to the die via the pipe
202
and coupling
203
by a gear-pump or an extruder (not shown). As shown in the illustration (A), the fluid plastic material flows and spreads from the center of the die
201
in the cross machine direction along the internal wall, then goes through the slit
204
to the slice lips where the material is extruded out into a film of a pre-determined width.
On the other hand, a so called “co-extrusion” product is sometime produced by this Coat hanger type extrusion die. The “co-extrusion” is such a process where more than two different plastic materials are extruded from the die to form, by lamination, certain layers of a multi-layer product. The extrusion die for production of this kind of product is basically similar to
201
die. What is different is the so-called “feed blocks” mounted just before the extrusion die
201
. At this “feed blocks”, some pre-adjustment of the melted plastic material can be made before going to the extrusion die, for purpose of getting a more uniform thickness for each layer of the product. Of course, it is very important to keep a stable uniform flow of stock for all of the layers.
Basic problems in the flow of raw materials before or inside the extrusion die have not yet been solved while various improvements of the die itself for extrusion of one or more different plastic materials have been made. It is hard to produce uniform extruded products by such an extrusion die as shown in Drawing
24
because the amount of raw material extruded from the outlet of the die per hour in the cross machine direction could vary from location to location due to the difference in the velocity of raw materials flow inside the die, for example, the velocity in the flow line “a” and that of the flow line “b” are different. Another problem is some deterioration of quality of the products caused by the shearing force to the fluid raw materials and different retention time of the raw materials in the die due to the difference in the velocity among the locations. In addition, the relatively large internal volume of such die requires a bigger volume and more time in refilling of the raw materials at each strat-up time, which results in a bigger loss of such raw material. More time and detergent for washing is required, too, because of the large internal volume.
As the die of this design has such a slit portion as shown in (B) of Drawing
24
, some deformation of the slit portion takes place by so called “Clam-shell phenomenons (the die lips being opened)”. Such deformation is variable from time to time by the change in the fluid viscosity and the fluid volume extruded. A sophisticated automatic control system to adjust the lips opening is available for installation so that a balanced flow of the fluid raw material in the die could be secured for producing an uniform layer. However, the high cost of such a control system is another problem. On top of the above mentioned problems, this die has another problem, that is, the change of the coating width takes time and is not so easily done.
As for the co-extrusion type, unsolved problems due to multi-layers structure still remain even though a lot of improvements of the die itself have been made by many people. The major reasons for this problem are the unstable flow of the fluid raw materials among layers and the cross machine direction profile of thickness of each layer could be easily deteriorated. The cause for unstable flows among layers is the large influence of the shearing force at the contacting surface between two layers which is called as “Welded line” where the lamination of the two layers is very poor because of less dispersion of high molecule chains. The instability among layers results in the uneven wave and reduces the value of the product. The cross machine direction thickness profile of each layer easily gets uneven and causes a so-called “wrapping phenomenon”, that is, the higher viscosity fluid is wrapped by the lower viscosity fluid. Such a technology to make a pre-adjustment of melted plastic materials in order to avoid the above mentioned “wrapping phenomenon” has been developed but it is not enough to completely stop the wrapping phenomenon. The method of the pre-adjustment must be also developed for each specific features of the phenomenon respectively and is not practical for use in the industry.
OBJECTS AND SUMMARY OF THE INVENTION
The first object of the invention is to make an extruding equipment available to the industry of which manufacturing cost is low and capable to reduce the raw material and time required for the initial filling at the time of start-up and to reduce the loss of the raw material, too. The second object of the invention is to make an extruding equipment available to the industry which is capable to produce products of uniform and good quality. The third object of the invention is to make an extruding equipment available to the industry which is capable to produce the film with almost nil variation of thickness in the cross machine direction. The fourth object of the invention is to make an extruding equipment available to the machinery manufacturers which allows more tolerance for machining and requires less skill in manufacturing.
In order to achieve the above mentioned objects, this Multi-tube extruding equipment of which patent is claimed under the first claim hereinafter comprises
a joint to connect the bunched tubes and the material supply equipment by a hose etc.
multi-tubes of which one ends at the material inlet side are bunched and securely inserted into the joint, and the other ends at the material outlet side are lined up in a plane in the cross machine direction.
The secure fastening of the other ends of the lined up tubes in a plane means not only the fastening of the ends of the whole tubes lined up in a plane and in the cross machine direction to the extrusion die but also the fastening of the ends of each divisional bunch of tubes also lined up in a plane and in the cross machine direction,bunch by bunch, to the extrusion die. The unfastened ends of the tubes could be used in some applications.
The advantages of an extruding or coating equipment having such components as mentioned hereinabove are as follows:
1) the manufacturing cost is cheaper than that of conventional equipment which is fabricated from the casted or forged metal block and finished by fine machining
2) less amount of the material & time for the initial filling and a minimized loss of the material at the time of start-up due to its smaller internal volume (total of the internal volume of the tubes) than such conventional extruding die as
101
of Drawing
24
3) less consumption of the detergent and time for washing of the equipment due to the same reason as that of above 2)
4) quicker work in case of a change of the product.
As the above mentioned tubes are used on this equipment it is possible to have the direction of the material inflow and the direction of the outflow at ri
Hwu Davis
Young & Thompson
Yuen Henry C.
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