Liner for a mixing container and an assembly and method for mixing fluid components

A liner for use in a mixing container which is adapted to receive a mixing shaft having an open tubular distal end and having mixing members mounted thereon for mixing materials disposed in the container, includes a tubular sleeve substantially closed at a first end thereof by an end wall and open at a second end thereof, and an elongated substantially rigid protrusion fixed to the interior of the sleeve end wall centrally of the sleeve end wall, extending toward the second end of the sleeve, and adapted to receive thereon the open tubular distal end of the shaft.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to the mixing of fluid components and is directed
 more particularly to a liner for use with mixing containers, and an
 assembly and method for mixing fluid components in a liner-equipped mixing
 container.
 2. Description of the Prior Art
 The mixing of paint in facilities wherein paint is used on a large scale,
 as, for example, in automotive production plants, often is conducted in
 metal drums, e.g., common 55 gallon drums, equipped with a short
 upstanding post fixed to the center of the interior bottom surface.
 Referring to FIG. 1, it will be seen that a typical prior art mixing
 assembly includes a 55 gallon cylindrical container 10 having a closed end
 wall 12 and an open end 14. A post 16 is affixed to and upstands about
 21/4 inches, or so, from the interior surface 18 of the closed end wall
 12.
 The assembly further includes a mixing shaft 20 to which there are fixed
 mixing elements, such as blades 22. Mixing shaft 20 is hollow, or else it
 has a cavity 24 at its bottom end so as to permit the mixing shaft to be
 rotatably mounted on post 16. The shaft 20 extends through a central
 opening 26 in a cover member 28.
 In operation, a fluid, typically comprising two or more paint components,
 is introduced into the container 10 to a suitable level. The mixing shaft
 20, with cover member 28 thereon, is then placed in the container 10. The
 bottom end 24 of the shaft 20 is positioned so that post 16 is received by
 the shaft bottom end. Cover member 28 is secured to the top of the
 container 10 to close the otherwise open end 14 thereof. This results in
 the shaft 20 being generally aligned with the longitudinal axis of
 container 10. The blades 22 are rigid and extend close to, and are spaced
 from, the interior surface of side wall 15 of container 10.
 The top end 32 of the mixing shaft 20 is then engaged by an
 electrically-powered turning device (not shown) which turns the shaft 20,
 thereby moving the blades 22 through the fluid. Alternatively, the upper
 end of the shaft can be coupled to a manually-operated turning mechanism
 (also not shown).
 Upon completion of the mixing operation, cover member 28 and mixing shaft
 20 with blades 22 are removed from the container 10. The mixed paint is
 then transferred to other containers or used directly from the container
 10. In either case, the container 10 is not suitable for further like use
 and hence must be discarded. Disposal of the 55 gallon metal containers is
 objectionable because (1) the modified 55 gallon drums are expensive
 (typically costing more than $20 per drum) and (2) the drums are
 relatively large and disposing of thousands of drums involves a large
 disposal volume.
 In an effort to render the mixing containers reusable, there has been
 provided a liner 40 (FIG. 2) for use with the mixing container 10 (FIG.
 3). The liner 40 comprises a sleeve 42 closed off by a bottom end wall 44
 thereof and having an open top end 46. Liner 40 is of a configuration
 generally complementary to the interior configuration of container 10.
 Sleeve 42 is of a flexible fluid-impervious material, preferably
 polyethylene or another flexible fluid-impervious plastic material.
 A fitment 50 is fixed to an interior surface 48 of the bottom end wall 44
 of the sleeve 42 and is open at a bottom end 52 (FIG. 2) thereof, and
 closed at a top end thereof. The fitment 50 is of an elongated
 configuration generally complementary to the configuration of the post 16.
 The bottom end wall 44 of the sleeve 42 defines a hole 56 (FIG. 2) in
 alignment with the fitment open bottom end 52. The fitment 50 may be
 provided with a flange portion 58 by which the fitment 50 is affixed to
 the interior surface 48 of the sleeve bottom end 44, as by adhesive,
 ultra-sonic welding, heat sealing, or other bonding process.
 Fitment 50 preferably is of a plastic material or a high density elastomer.
 The fitment 50 is relatively stiff so as to resist twisting in response to
 rotation of shaft 20.
 In operation, the liner 40 is inserted into the container 10, with the
 fitment 50 fitting over and receiving post 16 through the hole 56 and open
 bottom end 52 of the fitment 50. The fluid (e.g. paint components) is then
 poured into the open end of liner 40, causing the liner 40 to be pressed
 against the side and bottom end walls 15, 12 of the container 10. The
 mixing shaft 20 is inserted into the container 10 over the fitment 50 and
 post 16. The cover 28 is pressed down over the open end 46 of sleeve 42
 and a complementary rim 49 of container 10 to lock the cover 28 to the
 upper end 14 of the container 10, to close the assembly (FIG. 3). The
 mixing shaft 20 is then rotated by a rotative apparatus engaged with the
 shaft top end 32.
 Upon completion of the mixing operation, cover 28 and mixing shaft 20 are
 removed from the container 10, and the mixed paint (or other fluid) is
 removed form the container. Upon emptying the container, the liner 40 is
 stripped from the container, the interior of which has been protected by
 the removed liner from contact with the fluid.
 The liner may be made with a relatively small wall thickness. Since it also
 is flexible, the liner 40 may be folded into a relatively small volume of
 space for disposal purposes, while the container may be re-used. The cost
 of liner 40 is much less than the cost of the container 10, and the space
 required for disposal of the liner 40 is very much less than the space
 required for disposal of the container 10.
 The above-described liner and associated assembly and method is shown and
 described in U.S. Pat. No. 5,727,878, issued Mar. 17, 1998 to Joseph J.
 Sullivan, Jr. While the liner has successfully rendered mixing drums, even
 paint mixing drums, reusable, providing for the post 16 contributes
 substantially to the cost of the drum and, once done, limits the market
 for the drum to essentially purchasers having need for mixing containers.
 That is, the expense added to the manufacture of the drum tends to remove
 the drum from the general market and confine sales of the drum to a
 specialty niche. From the perspective of the users of mixing drums, the
 drums with posts mounted therein are substantially more expensive than the
 standard drum.
 There is thus a need for a mixing assembly wherein the mixing container is
 an ordinary unmodified drum, and the cost of a mixing enabler is less
 expensive.
 SUMMARY OF THE INVENTION
 Accordingly, an object of the invention is to provide a plastic liner which
 may be inserted into a mixing container prior to a fluid mixing operation,
 which liner constitutes a barrier between the container and the fluid
 components therein, and which liner is provided with a protrusion thereon
 on which a mixer shaft may be mounted.
 A further and more specific object is to provide a liner as set forth
 immediately above for use with a paint mixing container.
 A still further object of the invention is to provide an assembly for
 mixing fluid components, wherein a liner constitutes a barrier between the
 container and the fluid therein and serves to support a mixing device in
 the container.
 A still further object is to provide a method for mixing fluid components
 in a container wherein a liner constitutes a barrier between the container
 and the fluid therein, and further provides support for a mixing device in
 the container.
 With the above and other objects in view, as will hereinafter appear, a
 feature of the present invention is the provision of a liner for use in a
 mixing container, the container being adapted to receive a mixing shaft
 having an opening in its distal end and having mixing members mounted
 thereon for mixing materials disposed in the container. The liner
 comprises a tubular sleeve substantially closed at a first end thereof by
 an end wall and open at a second end thereof, and an elongated
 shaft-retaining member in the form of a substantially rigid protrusion
 fixed to the interior of the sleeve end wall centrally of the sleeve end
 wall, extending toward the second end of the sleeve and adapted to
 telescopically receive thereon the tubular distal end of the shaft.
 In accordance with a further feature of the invention, there is provided a
 liner for use with a paint mixing container having a bottom wall and an
 upstanding circular side wall, and adapted to receive a mixing shaft
 having an opening at its distal end and mixing members extending outwardly
 from the shaft. The liner comprises a flexible fluid-impervious sleeve
 substantially closed at a bottom end thereof and open at a top end
 thereof, the sleeve being of a configuration generally complementary to
 the interior configuration of the container. The liner further comprises a
 substantially rigid shaft-retaining member fixed to and upstanding from
 the interior bottom end of the sleeve, the shaft-retaining member being of
 a configuration compatible with the opening in the distal end of the
 mixing shaft. The liner is insertable into the container and is configured
 to conform substantially to the interior configuration of the container.
 The shaft-retaining member receives the distal end of the mixing shaft.
 The mixing shaft is turnable on the shaft-retaining member to move the
 mixing members through paint in the container, to mix the paint.
 In accordance with a further feature of the invention, there is provided an
 assembly for mixing fluid components. The assembly comprises a mixing
 container having a closed first end and an open second end. A liner is
 provided for disposition within the container. The liner comprises a
 sleeve substantially closed at a first end thereof and open at a second
 end thereof, the sleeve having a configuration generally complementary to
 the interior configuration of the container, and a substantially rigid
 shaft-retaining member fixed to and upstanding from the closed first end
 of the sleeve. A mixing shaft is mountable over the shaft-retaining member
 and is provided with mixing members fixed thereon. The shaft is rotatable
 on the shaft-retaining member to move the mixing members in the liner. The
 sleeve constitutes a barrier between the container and the fluid
 components, and a support for the mixing shaft.
 In accordance with a still further feature of the invention, there is
 provided a method for mixing fluid components, the method including the
 steps of providing a mixing container having a closed bottom end and an
 open top end, providing a cover member for the container, the cover member
 having a hole centrally thereof, providing a mixing assembly including a
 rotatable shaft and mixing members fixed to the shaft, the shaft having an
 open tubular bottom end, and providing a liner comprising a sleeve having
 a substantially closed bottom end and an open top end, the sleeve having a
 configuration generally complementary to the interior configuration of the
 container, the sleeve including a substantially rigid shaft-retaining
 member fixed to the bottom end of the sleeve and upstanding therefrom. The
 method further includes the steps of inserting the liner in the container,
 admitting the fluid components to the liner causing the liner to lie
 against the inner surfaces of the container, positioning the mixing
 assembly shaft in the liner on the shaft-retaining member, closing the
 open top end of the container with the cover member, the shaft extending
 through the hole in the cover member, and rotating the shaft on the liner
 rigid shaft-retaining member such that the mixing members move through and
 mix the fluid components.
 The above and other features of the invention, including various novel
 details of construction and combinations of parts, and combinations of
 method steps, will now be more particularly described with reference to
 the accompanying drawings and pointed out in the claims. It will be
 understood that the particular devices and method steps embodying the
 invention are shown by way of illustration only and not as limitations of
 the invention. The principles and features of this invention may be
 employed in various and numerous embodiments without departing from the
 scope of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT
 Referring to FIG. 4, it will be seen that a liner 60 for use with the
 mixing container 10 comprises a sleeve 62 closed at a bottom, or first,
 end thereof by an end wall 66 and open at a top, or second, end 68
 thereof. The sleeve preferably is made of a suitable plastics material,
 e.g., polyethylene, with its sidewall 70 having a circular cross-sectional
 configuration generally complementary to the container 10. Preferably the
 sleeve is made of a flexible plastic, e.g., a low density polyethylene.
 The liner also may be made of another material, including by way of
 example but not limitation, polypropylene or a high density polyethylene
 (if the latter material is used, it is preferred that its thickness be
 minimized so that the sleeve will have some flexibility).
 The liner 60 further comprises an elongated substantially rigid protrusion
 72 fixed to the interior of the sleeve end wall 66 and extendible toward
 the open end 68 of the sleeve 62. The protrusion 72 preferably is a solid
 member of a high density polyethylene and is located at the center of end
 wall 66.
 Referring to FIGS. 5 and 6, it will be seen that the protrusion 72 is an
 integral extension of a disk 74 which is fixed to the sleeve end wall 66
 (FIG. 4), with the protrusion and disk constituting an shaft-retaining
 member. The sleeve end wall 66 is provided with a plurality of holes 76
 therethrough (FIG. 4). The disk 74 is similarly provided with holes 78
 (FIG. 6), each of which is alignable with one of the holes 76.
 Pins 80 (FIGS. 7 and 8) are used for securing the shaft-retaining member to
 the sleeve end wall 66. Pins 80 are adapted to fit in aligned liner holes
 76 and holes 78 of disk 74. The pins 80 may be "tight-fit" pins 80, as
 shown in FIGS. 7 and 8, which are sized to make a tight friction
 connection to disk 74. Alternatively, the pins may be of a "ring-snap"
 type 80a (FIG. 12) or a "hook snap" type 80b (FIG. 13), or any fastener
 suitable for securing members together. The "ring-snap" pins 80a are
 provided with opposed arc-shaped segments which may be squeezed toward one
 another to pass through the holes 76, 78 and are biased to snap outwardly
 to secure the pins 80a in place. Similarly, the "hook snap" pins 80b are
 provided with opposed hook-shaped segments which may be squeezed toward
 one another to pass through the holes 76, 78 and are biased to snap
 outwardly to secure the pins 80b in place. The pins 80, 80a and 80b may be
 made of various materials. Preferably, for reasons of cost and
 suitability, they are made of a high density polyethylene.
 The pins 80, 80a, 80b are each provided with an enlarged head portion 82.
 As shown in FIGS. 7 and 8, sealing rings 84 of an elastomeric material are
 preferably disposed between the pin head portions 82 and the bottom end
 wall 66 of sleeve 62. Additionally or alternatively, sealing rings 84 may
 be disposed between the upper surface of sleeve end wall 66 and the planar
 bottom surface 86 of disk 74.
 An upper surface 88 of the disk 74 may be provided with reinforcing
 structure 90 which preferably includes an upstanding ring 92 (FIGS. 6 and
 7) around each of the disk holes 78 and an annular flange 94 surrounding
 the inner or base end of the protrusion 72. The reinforcing structure 90
 may further include reinforcing ribs 96 upstanding from the upper surface
 88 of the disk 74. In a preferred arrangement, shown in FIGS. 6 and 7, the
 ribs 96 extend from the flange 94 radially outwardly to the periphery of
 the disk 74.
 In addition to reinforcing the disk 74, the reinforcing rings 92 provide
 flat upper surfaces 98 for engagement by the resilient legs 100 of the
 ring snap and hook snap types of pins 80a, 80b (FIGS. 12 and 13) to snap
 onto in fabrication of the liner 60.
 The protrusion 72 and disk 74 forming the retaining member for mixing shaft
 20 preferably are molded integrally as a single, unitary shaft-retaining
 member. High density polyethylene has been found to be a suitable material
 for the entire shaft-retaining member. A high density hard rubber may be
 used in place of high density polyethylene. Polypropylene, nylon or a
 polyester, also may be used for making the shaft retaining member 72, 74.
 Still other suitable materials will be obvious to persons skilled in the
 art.
 Referring to FIG. 14, it will be seen that the protrusion 72 may be
 provided with a corrugated exterior surface 104, characterized by lands
 106 and intervening grooves 108. Such a configuration reduces the area of
 contact between the protrusion 72 and the interior surface of the tubular
 distal end 24 of the mixing shaft 20, permitting the shaft 20 to turn on
 the protrusion 72 with less friction therebetween.
 Referring to FIG. 11, it will be seen that an assembly 102 for mixing fluid
 components includes the mixing container 10 and the mixing shaft 20 and
 attached components 22, 28 described hereinabove. The assembly 102 further
 includes the liner 60 which serves as a barrier between the container 10
 and the fluid therein and, through the protrusion 72, serves as a mount
 for rotatably supporting the mixing shaft 20 and attached components.
 In operation, the liner 60 is inserted into the container 10. The fluid
 components to be mixed are then admitted to the liner, causing the liner
 to be pressed against the inner surfaces of the container. The mixing
 assembly shaft 20 is then positioned in the liner on the protrusion 72.
 The cover member 28 is then pressed onto the top end 46 of the liner 60
 and container rim 49 to close the assembly 102. The exposed upper end 32
 of the shaft 20 is then rotated, to cause rotation of the shaft 20 on the
 protrusion 72 and movement of the mixing blades 22 through the fluid in
 the liner. Since the disk portion 74 of the shaft-retaining member is
 fixed to the bottom wall of the liner by pins 80, 80a or 80b, the
 protrusion 72 serves to retain the shaft 20 against lateral movement while
 also serving as a bearing to facilitate shaft rotation.
 As is the case with liner 40, the liner 60 may be fabricated with a
 relatively small wall thickness, typically about 0.004 inch. Depending on
 the flexibility of the material of which the liner 60 is made, the liner
 may be folded into a relatively small volume for disposal purposes, while
 the container 10 may be reused for any purpose for which such containers
 find use. The cost of the liner 60 constitutes a fraction of the cost of
 the container 10 and the space required for disposal of the liner is very
 much less than the space required for disposal of the container. Further,
 inasmuch as the mixer-support protrusion 72 is part of the liner and not
 required in the container, the acquisition cost of the container is
 substantially reduced.
 It is to be understood that the present invention is by no means limited to
 the particular construction herein disclosed and/or shown in the drawings,
 but also comprises any modification or equivalent within the scope of the
 claims. Thus it is contemplated that the disk 74 of the shaft retaining
 member may be secured to the bottom wall of the liner by means other than
 pins 80, 80a or 80b, e.g. by some other form of mechanical attachment
 means or by bonding with a high strength bonding agent or by heat sealing.
 It is envisioned further that the protrusion 72 need not be solid but
 instead may be hollow with its inner end closed off. A further possible
 modification is to form protrusion 72 separately from disk 74 and then to
 affix it to the disk so as to provide a shaft retaining member similar in
 appearance to that shown at 72 and 74 in FIGS. 4-8 and 14. Still other
 modifications will be obvious to persons skilled in the art from the
 foregoing description.