Apparatus with automatic balancing for mixing paint disposed in containers having different configurations

An apparatus and method are provided for mixing paint disposed in either a conventional one gallon paint container or a square paint container having a body with a handle passage extending therethrough. The apparatus includes a square bucket for holding the container. A rocker is pivotably mounted to a side wall of the bucket and includes a pair of heads aligned over a pair of openings in the side wall. A floor of the bucket has a plurality of support structures extending upwardly therefrom. When the conventional one gallon paint container is disposed in the bucket, the container rests on the floor, the vertical axis of the container is offset from the central axis of the bucket, and both heads of the rocker are disposed against the container inside the bucket. When the square paint container is disposed in the bucket, the container is supported on top of the support structures so as to be elevated above the floor, the vertical axis of the container is collinear with the central axis of the bucket, and one of the heads of the rocker is disposed in the handle passage of the container.

The present invention relates to the mixing of fluid dispersions and more specifically to apparatus and methods for mixing paint disposed in a container having either a cylindrical or a square shape.

As is well known, solids in fluid dispersions, such as paint, tend to settle in a downward direction through the force of gravity. Fluid dispersions disposed in containers for commercial sale are typically mixed in the containers before they are used by the purchasers. Many fluid dispersions can be facilely mixed in a container by manually shaking the container. Other fluid dispersions, however, such as paint, are more difficult to manually mix in a container and, thus, are often mixed in the container using a machine that shakes, rotates, vibrates or otherwise moves the container.

A variety of different types of mixing machines are known for mixing fluid dispersions disposed in containers. One type of mixing machine that is commonly used to shake individual containers is known as a vortex mixer. In a vortex mixer, the container containing the dispersion is rotated around at least one axis. Typically, the container is at least rotated about its own vertical axis. Examples of conventional vortex mixers include those disclosed in U.S. Pat. No. 3,542,344 to Oberhauser, U.S. Pat. No. 4,235,553 to Gall, and U.S. Pat. No. 4,497,581 to Miller, all of which are hereby incorporated by reference. Conventional vortex mixers such as these can only accommodate cylindrical containers. Such vortex mixers cannot properly accommodate generally square or rectangular containers. Paint, however, is beginning to be packaged in generally square or rectangular containers. Moreover, some of these containers have integral handles formed in their bodies. A commercial example of a generally square container with an integral handle molded in the body thereof is the TWIST & POUR™ container sold by The Sherwin-Williams Company, who is the assignee of the present application. Another example of such a container is disclosed in U.S. Pat. No. 6,530,500 to Bravo et al., which is assigned to The Sherwin-Williams Company.

An integral handle formed in a body of a container changes the weight distribution of the paint disposed in the container, which causes one side of the container (with reference to the vertical axis of the container) to be heavier than the other. As a result, when the container is rotated in a vortex mixer, the vortex mixer may become unbalanced, thereby causing the vortex mixer to rock or shake excessively. One known solution to this problem is to balance the weight of the container (with respect to the vertical axis of the container) by inserting a counterweight into the integral handle of the container. This solution, however, requires a separate device (the weight) and the performance of an additional step in the mixing process (placing the weight in the handle insert).

Another known method for providing balanced mixing of a container with an integral handle is to offset the vertical axis of the container from the axis of rotation of the bucket that holds the container during mixing. If the container is square and the handle is located at a corner, the axis of the container is offset by increasing the radius of curvature of one of the corners of the bucket. An example of such a bucket is sold by Ultrablend Systems Inc. and is disclosed in published U.S. Patent Application No. 2003/0142583A1. This bucket requires the container to be properly positioned in the bucket such that the handle of the container is positioned at a corner diametrically opposite to the corner with the increased radius of curvature. A visual notice is provided, indicating the proper positioning of the container in the bucket, however nothing prevents the container from being improperly positioned in the bucket. As can be appreciated, the foregoing bucket is susceptible to improper positioning of the container in the bucket.

A bucket developed by Red Devil Inc. addresses the foregoing positioning problem by including a pair of rocker arms mounted at the corner of the bucket where the handle of the container is to be placed. The rocker arms ensure the proper positioning of the container in the bucket.

The present invention is directed to a device for mixing paint disposed in a generally square container with an integral handle (as well as a conventional cylindrical container), wherein the device has an automatic balancing feature that does not require the use of a container counterweight and is not susceptible to improper positioning of the container. In accordance with the present invention, the device includes a bucket for holding the container and an electric motor for rotating the bucket. The bucket has a central axis and includes a retainer having a plurality of side walls joined together at rounded corners so as to define an interior holding space with a substantially square cross-section. The bucket further includes a base secured to the bottom of the retainer. The base has a floor with a plurality of support structures extending upwardly therefrom. The support structures at least partially define the periphery of a cylinder-receiving region of the floor that has a center that is offset from the central axis of the bucket in the direction of one of the corners of the retainer. When the container is cylindrical and is disposed in the bucket, a bottom end of the container is supported on the cylinder-receiving region of the floor and is disposed inwardly of the support structures, and the vertical axis of the container is offset from the central axis of the bucket in the direction of one of the corners of the retainer. When the container has a substantially square cross-section, the container is supported on top of the support structures so as to be elevated above the floor, and the vertical axis of the container is collinear with the central axis of the bucket.

In accordance with another feature of the present invention, a side wall of the bucket has a pair of openings formed therein. A rocker having a body joined between a pair of heads is pivotally connected to the side wall and is movable between first, second, and third positions. When the container is disposed in the bucket and the container is a conventional one gallon paint container, the rocker is in the third position and the heads of the rocker extend through the openings and are disposed against the container. When the container is disposed in the bucket and the container has a handle passage and a substantially square cross-section, the rocker is in the first position and one of the heads of the rocker extends through one of the openings and into the handle passage of the container.

Also provided in accordance with the present invention, is a method of mixing paint. In accordance with the method, a cylindrical container filled with a first paint is provided. The cylindrical container is disposed between at least one pair of opposing walls. The at least one pair of opposing walls and the cylindrical container are rotated about an axis that is parallel to and spaced from the vertical axis of the cylindrical container. The cylindrical container is then removed from between the at least one pair of opposing walls.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It should be noted that in the detailed description that follows, identical components have the same reference numerals, regardless of whether they are shown in different embodiments of the present invention. It should also be noted that in order to clearly and concisely disclose the present invention, the drawings may not necessarily be to scale and certain features of the invention may be shown in somewhat schematic form.

As used herein, the term “conventional one gallon paint container” shall mean a cylindrical metal container for holding paint, having a diameter of about 6 10/16 inches, a height of about 7 11/16 inches, an interior volume of slightly greater than 1 U.S. gallon, and including a bail handle secured to a pair of mounting ears, each with a diameter of about ¾ of an inch.

Referring now toFIG. 1, there is shown a mixing apparatus10embodied in accordance with the present invention. The mixing apparatus10is operable to mix a fluid dispersion, such as paint, that is disposed in either a cylindrical container or in a generally square container. For proper operation, the mixing apparatus10should be disposed on a substantially horizontal surface, and in the following description, it will be assumed that the mixing apparatus10is so disposed.

The mixing apparatus10includes a rectangular cabinet having upstanding side walls14, a bottom wall16, an access door (not shown), an intermediate wall18and an upper wall20. The intermediate wall18divides the cabinet into a lower drive chamber22and an upper loading chamber24. The access door closes an opening (not shown) that provides access to the drive chamber22. The access door may be hinged to one of the adjacent side walls14so as to be pivotable between open and closed positions, or the access door may be removably disposed between the ends of two of the side walls14. The upper wall20has an enlarged circular opening26formed therein, which provides access to the loading chamber24. Although not shown, a hood may mounted to the cabinet, above the upper wall20.

An electric motor28is mounted toward the rear of the cabinet and extends between the drive chamber22and the loading chamber24. A rotor shaft30of the electric motor28extends downwardly and is disposed in the drive chamber22. A motor sprocket32with teeth is secured to an end of the rotor shaft30. The motor sprocket32is drivingly connected to a larger diameter drive sprocket34by an endless belt36having interior ribs. The drive sprocket34is secured to a lower end of a vertical drive shaft38that extends upwardly through a bearing mount40and into the loading chamber24through an opening (not shown) in the intermediate wall18. In the loading chamber24, the drive shaft38extends through a central passage (not shown) in a pedestal42that is disposed on an upper side of the intermediate wall18. An upper end of the drive shaft38is secured to a yoke44disposed in the loading chamber24, above the pedestal42. The bearing mount40is secured to the pedestal42, with the intermediate wall18trapped in between. The bearing mount40has a plurality of bearings (not shown) disposed therein for rotatably supporting the drive shaft38.

Referring now also toFIG. 2, the yoke44includes a mounting arm46and a balancing arm48secured together at their inner ends by a bolt50that also secures the upper end of the drive shaft38to the yoke44. The mounting arm46and the balancing arm48extend outwardly in opposing lateral directions and extend upwardly at acute angles from the vertical. The balancing arm48is bifurcated and includes a pair of spaced-apart elongated plates52. A cylindrical counterweight54is secured between outer ends of the plates52. The counterweight54balances the yoke44when a container of a fluid dispersion, such as paint, is mounted to the mounting arm46, as will be described more fully below.

A mounting shaft56rotatably extends through a passage (not shown) in the mounting arm46. Bearings (not shown) may be disposed in the passage to reduce friction between the mounting shaft56and the mounting arm46. A drive wheel58is secured to a bottom portion of the mounting shaft56, below the mounting arm46, while a mounting support60is secured to an upper portion of the mounting shaft56, above the mounting arm46. The mounting support60may circular (as shown) or square. The mounting support60includes a center passage62through which an upper end of the mounting shaft56extends. A plurality of threaded bores64are formed in the mounting support60and are disposed around the center passage62.

The drive wheel58has a side surface with gear teeth66formed therein which are in mechanical engagement with mating gear teeth68formed in a side surface on the pedestal42. When the yoke44rotates about an axis A-A (shown inFIG. 1) extending through the drive shaft38(as will be described more fully below), the drive wheel58is moved around the pedestal42. Since the gear teeth66in the side surface of the drive wheel58are in engagement with the gear teeth68in the side surface on the pedestal42, the drive wheel58rotates around an axis B-B (shown inFIG. 1) extending through the mounting shaft56(as will be further described below). The axis B-B extends upwardly and preferably intersects the axis A-A at an acute angle of from about 20° to about 40°, more preferably at an angle of about 30°. If the mixing apparatus10is disposed on a substantially horizontal surface, the axis A-A extends substantially vertical, i.e., at about 90° from the horizontal.

It should be appreciated that in lieu of the drive wheel58and the pedestal42being in positive mechanical engagement, the drive wheel58and the pedestal42may be in frictional engagement through the use of friction surfaces on the drive wheel58and the pedestal42.

For reasons that will be explained more fully below, the polarity of the electric motor28is set so as to rotate the yoke44about the axis A-A in a counter-clockwise direction, which causes the mounting support60to rotate about the axis B-B in a counter-clockwise direction.

It should be appreciated that the present invention is not limited to the particular mechanical arrangement described above for rotating the mounting support60about a plurality of axes. Other known mechanical arrangements may be utilized for rotating the mounting support60about a plurality of axes.

Referring now toFIGS. 3 and 4, there are shown a perspective top view and a top plan view of a bucket70for holding a container of a fluid dispersion, such as paint. The bucket70includes a retaining structure72joined to a base74.

Referring now also toFIGS. 5 and 6, the base74is composed of metal and includes a floor plate76with a mount78(shown inFIG. 5) located on a bottom side thereof. The mount78may be a separate structure joined by welding or other means to a bottom surface of the floor plate76(as shown), or the mount78may be integral with the floor plate76and merely comprise an indented central portion of the floor plate76. The floor plate76has an outer periphery defined by connection regions80a,b,c,ddisposed between flanged regions86a,b,c,d. Each of the connection regions80a,b,c,dcomprises a straight edge, while the flanged regions86a,b,c,deach comprise two minor edges extending at angles from opposing ends of a major center edge. In the flanged region86a, the minor edges are disposed at very small angles, thereby almost forming a single straight edge. Since there are four connection regions80a,b,c,dand four flanged regions86a,b,c,d, the floor plate76has a generally octagonal shape. A rectangular tab or flange88extends upwardly and outwardly from each of the flanged regions86a,b,c,d. With regard to the flanged regions86a,b,c,d, the flanges88extend upwardly and outwardly from the major center edge. The flanges88are preferably integrally formed with the rest of the floor plate76and are bent upwardly at bends90. The bends90help define the periphery of a cylinder receiving region92of the floor plate76.

An axial opening94is positioned in the center of the floor plate76and extends through the base74. A plurality of mounting bores96are disposed around the axial opening94and extend through the base74as well. The mounting bores96are preferably arranged in groups located in four recessed areas that form the corners of a square pattern. One of the mounting bores96in each group can be aligned with one of the threaded bores64in the mounting support60. A plurality of the mounting bores96are provided in each of the recessed areas to permit the mounting bores to be aligned with threaded bores in mounting supports of different types of mixing machines, wherein the threaded bores are arranged in different patterns.

FIG. 6shows a top view of the base with certain dimensions indicated by letters. The dimension A represents the distance between the edges in opposing connection regions80a,c, while the dimension B represents the distance between the edges in opposing connection regions80b,d. The dimension C represents the distance between the bend90of the flange88in the flanged region86aand the bend90of the flange88in the flanged region86c, while the dimension D represents the distance between the bend90of the flange88in the flanged region86band the bend90of the flange88in the flanged region86d. The dimension C1represents the distance between the bend90of the flange88in the flanged region86aand the center of the axial opening94, while the dimension C2represents the distance between the bend90of the flange88in the flanged region86cand the center of the axial opening94. The dimension D1represents the distance between the bend90of the flange88in the flanged region86band the center of the axial opening94, while the dimension D2represents the distance between the bend90of the flange88in the flanged region86dand the center of the axial opening94. The dimensions A and B are the same, and the dimensions C and D are the same. The dimensions A, B are greater than the dimensions C, D. The dimension C2is greater than the dimension C1, whereas the dimensions D1and D2are the same.

In a first embodiment of the present invention, the distances A, B are each 6.865 inches, the distances C, D are each 6.64 inches, the distance C2is 3.470 inches, the distance C1is 3.170 inches, and distances D1, D2are each 3.320 inches.

Since the dimension C2is greater than the dimension C1, the axial opening94is not located in the center of the cylinder receiving region92of the floor plate76, or, to put it another way, the cylinder receiving region92is not centered on the floor plate76. Rather the cylinder receiving region92is offset toward the flanged region86c. As a result, when a conventional one gallon paint container is disposed in the cylinder receiving region92of the floor plate76, the vertical axis of the paint container is offset from the axis of rotation B-B in the direction of the flanged region86c. Thus, the center of mass of the paint container and the paint disposed therein is offset from the axis of rotation B-B, toward the flanged region86c.

The retaining structure72is comprised of a pair of parallel and substantially planar first walls100a,band a pair of parallel and substantially planar second walls102a,b. Each of the first walls100a,bis generally rectangular and includes a horizontal top edge104and a beveled bottom edge106extending between vertical side portions. Each bottom edge106includes a horizontal center portion disposed between upwardly-sloping side portions. A generally rectangular flange108extends upwardly from a center portion of each top edge104. Each of the second walls102a,bis also generally rectangular and includes a horizontal top edge110and a beveled bottom edge112extending between vertical side portions. Each bottom edge112includes a horizontal center portion disposed between upwardly-sloping side portions. A generally rectangular slot114is formed in each of the second walls102a,band extends downwardly from the top edge110. Spring clips116a,bwith downwardly-extending openings118are secured to the second walls102a,band are disposed over the slots114. The spring clip116bincludes a middle portion that bends inwardly so as to be disposed within or interior of the slot114in the second wall102a, whereas the spring clip116ahas a middle portion that bends outwardly so as to be spaced outwardly from the slot114in the second wall102b. The spring clips116a,bare operable to hold mounting ears and a bail handle of a conventional one gallon paint container.

The first and second walls100a,b,102a,bare arranged to provide the retaining structure72with a substantially square cross-section. Preferably, the side edges of the first walls100a,bare joined to side edges of the second walls102a,bat curved or rounded corners120a,b,c,d(best shown inFIGS. 4 and 5). In this manner, the retaining structure72defines an inner void or holding space122having a cross section that is square with rounded corners. The beveled bottom edges106,112of the first and second walls100a,b,102a,bpermit the bucket70to freely rotate about the axis B-B without hitting the mounting arm46of the yoke44.

The floor plate76of the base74is secured to the retaining structure72. More specifically, the center portions of the bottom edges106of the first walls100a,bare secured to the edges of the connection regions80a,cby welding or other means, while the center portions of the bottom edges112of the second walls102a,bare secured to the edges of the connection regions80b,dby welding or other means. With the base74secured to the retaining structure72in this manner, the corner120ais aligned with the flanged region86a.

In the first embodiment of the present invention, the interior distance between the first walls100a,band the interior distance between the second walls102a,bare each about 6.865 inches. The corners120a,b,c,d, however, are formed so as to reduce the distance between the centers of adjacent corners120a,b,c,dto about 6.625 inches. In this regard, the corners120a,b,c,deach have a radius of curvature of about 1.375 inches. As a result of the configuration of the corners120a,b,c,d, the retaining structure72can snugly accommodate a square container having a width of about 6.625 inches, which corresponds to the width of a conventional one gallon paint container. In so accommodating such a square container, the retaining structure72only contacts the square container at the corners120a,b,c,d, as will be further discussed below.

Since the cylinder receiving region92is not centered on the floor plate76and is offset towards the flange region86c, the cylinder receiving region92is offset toward the second wall102b. As a result, when a conventional one gallon paint container is disposed in the bucket70, the container is spaced by a gap124(shown inFIG. 11) from the second wall102a, as will be discussed further below.

A pair of clamp assemblies126are secured to the rectangular flanges108of the first walls100a,b. Each clamp assembly126comprises a clamping structure128and a casing130with an interior bore joined to a mounting plate132. The mounting plates132are secured to the rectangular flanges108by press fit pins or other means. Each clamping structure128includes a head134secured to a top end of a rod (not shown). The rods are slidably disposed in the bores of the casings130. In this manner, the clamping structures128are vertically movable between a contracted position, wherein the head134abuts the casing130, and an extended position, wherein the head134is spaced above the casing130. Bottom portions of the rods are secured to springs that are attached to the casings130and bias the clamping structures128toward their contracted positions. The heads134of the clamping structures128are provided with levers136for engaging a container disposed in the bucket70. The levers136also function as handles that may be grasped by an operator when the clamping structures128are being manipulated by the operator. In this regard, the clamping structures128are rotatable between a clamping position, (shown inFIGS. 9-11), wherein the levers136extend inwardly over the base74so as to be perpendicular to the first walls100a,b, and a released position (shown inFIG. 4), wherein the levers136extend parallel to the first walls100a,b.

With reference toFIGS. 3,7and9, a pair of elliptical openings140a,bare formed in the second wall102a. The opening140bis disposed toward the lateral center of the second wall102aand toward the bottom edge112of the second wall102a, whereas the opening140ais disposed toward the corner120aand toward the top edge110of the second wall102a. In this manner, the openings140a,bare arranged in a downwardly extending angle in the direction of the first walls100a,b. A holding guide142is secured to an exterior surface of the second wall102a. The holding guide142includes a yoke144and a rocker146. The yoke144comprises a pair of spaced-apart holding arms148extending outwardly from an attachment plate150. Openings are formed in outer end portions of the arms148. The rocker146includes an elongated body152joined between enlarged first and second heads154,156. The body152includes interior and exterior sides. An arcuate pivot mount158protrudes outwardly from the exterior side of the body152and has a passage160extending therethrough. The pivot mount158is disposed toward the second head156. The first head154has a sloping outer surface162, while the second head156has a sloping inner surface164. The rocker146is disposed between the arms148of the yoke144, with the first head154aligned with the opening140a, the second head156aligned with the opening140band the passage160in the pivot mount158aligned with the openings in the arms148. A pin166extends through the passage160and the openings, thereby pivotally mounting the rocker146to the yoke144. The rocker146is movable between a first position and a second position. In the first position, the first head154extends through the opening140asuch that a major portion of the first head154is disposed in the holding space122, whereas no portion or only a small portion of the second head156is disposed in the holding space122. In the second position, the second head156extends through the opening140bsuch that a major portion of the second head156is disposed in the holding space122, whereas no portion or only a small portion of the first head154is disposed in the holding space122. Between the first position and the second position, the rocker146may be oriented in a third position, wherein the first and second heads154,156extend through the openings140a,bsuch that substantial portions of both the first and second heads154,156are disposed in the holding space122. Since the pivot mount158is disposed toward the second head156, the rocker146is normally disposed in the first position.

A weight bar168is secured to the first wall100a, toward the corner120a. The weight bar168is preferably solid and composed of a metal, such as steel. The weight bar168is secured to the first wall100aby screws, bolts, or press fit pins that extend through aligned openings in the weight bar168and the first wall100a. Alternately, the weight bar168may be secured to the first wall100aby welding or other means. The weight bar168is positioned to extend longitudinally along the length of the corner120a. The weight bar168and to a lesser extent the holding guide142comprise an added weight that increases the weight of the bucket70at the corner120a, thereby shifting the center of mass of the bucket70toward the corner120a. As will be discussed further below, the amount of the added weight is selected so as to be substantially equal to the weight of paint displaced by an integral handle in a corner of a square paint container.

The retaining structure72may be constructed from a single piece of sheet metal that is bent and joined together at a spot-welded seam (not shown), which is preferably located in one of the first walls100a,b. The sheet metal may powder coated to enhance the appearance of the retaining structure72and to protect it from corrosion.

Although the bucket70is described above as being constructed from two separate metal structures, namely the retaining structure72and the base74, it should be appreciated that the bucket70could be a unitary structure composed of plastic, such as high density polyethylene.

In the first embodiment, the bucket70is adapted for holding a conventional one gallon paint container, as well as a generally square paint container having an integral handle and a width of about 6 10/16 inches. An example of such a square paint container is shown inFIG. 8. The paint container170comprises a plastic body172defining an interior volume for holding a fluid dispersion, such as architectural paint. The body172is preferably blow molded from high density polyethylene and has a generally square shape with four generally square side walls, including a first handle side wall174and a second handle side wall (not shown). The side walls are joined at two rounded side corners176, a handle corner178and a sloping front corner (not shown), which is disposed opposite to the handle corner178. The body172also includes a bottom wall (not shown) and a top wall180with an enlarged opening formed therein. A collar184with an external thread186is disposed around the opening in the top wall180and extends upwardly therefrom. The collar184terminates in an upper rim184adefining an access opening188, which is sized to permit a conventional paint brush to extend therethrough. More specifically, the access opening188preferably has a diameter greater than about 4 inches, more preferably greater than about 5 inches.

The body172has a plurality of inner walls190defining a handle passage192that extends through the first handle side wall174and the second handle side wall. The first handle side wall174and the second handle side wall are joined at the handle corner178. The first handle side wall174is joined to the bottom wall at a rounded bottom edge. A handle194is formed at the handle corner178of the body172and extends vertically across the handle passage192. An innermost one of the inner walls190that defines the handle passage192is disposed laterally inward from the collar184. In this manner, a portion of the handle passage192is disposed laterally inward from the collar184. The handle passage192and the handle194are integrally formed with the rest of the body172during the blow molding of the body172. Thus, the handle194is an integral handle formed in the body172of the paint container170.

The formation of the handle194reduces the interior volume of the body172in the vicinity of the handle corner178and thus, the amount of paint disposed in the vicinity of the handle corner178when the paint container170is filled with paint. In other words, the formation of the handle194displaces a certain amount of paint from the vicinity of the handle corner178. The weight of this displaced paint shifts the center of mass of the filled paint container170toward the front corner.

A pouring insert196is provided for removable mounting in the access opening188of the paint container170. The pouring insert196comprises an annular mounting ring198having a skirt for disposal over the upper rim150aof the paint container170. A pour spout200is disposed radially inward from the mounting ring198and is joined thereto by a curved wall202. The pour spout200is arcuate and extends above the upper rim184a. The apex of the pour spout200is spaced about ½ an inch from the upper rim184awhen the pouring insert196is properly disposed in the access opening188. The curved wall202slopes downwardly as it extends rearwardly, toward the handle194. The curved wall202, the mounting ring198and the pour spout200define a drainage groove204that collects paint drips from the pour spout200and permits the collected paint to flow back into the paint container170.

A tiered lid206is provided for closing the access opening188. The lid206comprises a cylindrical top portion208joined to a larger cylindrical bottom portion210. A pair of grip lugs212extend radially outward from an outside surface of the bottom portion210. The bottom portion210has an internal thread (not shown) for engaging the thread186of the collar184to threadably secure the lid206to the collar184. The external thread186of the collar184and the internal thread of the lid206are configured such that rotation of the lid206in a clock-wise direction tightens the lid206to the collar184and conversely, rotation of the lid206in a counter clock-wise direction loosens the lid206from the collar184.

The width of the paint container170is substantially the same as the diameter of a conventional one gallon paint container, namely about 6 10/16 inches. The height of the paint container170, up to the top of the lid206(when it is securely threaded to the collar184) is about 8 inches. The interior volume of the paint container170is slightly greater than 1 U.S. gallon.

The paint container170includes a bail handle structure216composed of plastic and comprising a bail handle218integrally joined at opposing ends to an annular band220. The bail handle218is generally rectangular and has two legs joined to opposing ends of a central member so as to be generally perpendicular thereto. Preferably, the band220is constructed to be expandable so that the band220can be snapped over the collar184and trapped under a lowermost turn of the thread186. The band220can be rotated around the collar184between a flush position, wherein the legs and central member are substantially parallel to and flush with the side walls of the body172, and an extended position, wherein the legs and the central member are disposed at oblique angles to the side walls, thereby forming protruding loops. The bail handle218can be flexed to a carrying position, wherein the bail handle218is substantially perpendicular to the band220.

In the following description of the positioning of the paint container170in the bucket70and the subsequent operation of the mixing apparatus10, the paint container170will be considered to be filled with an architectural paint.

The paint container170may be disposed in the bucket70by holding the paint container170(through the bail handle218or otherwise) over the holding space122such that the handle corner178is aligned with the corner120a. The paint container170is then moved downwardly so as to enter the holding space122. As the paint container170moves downward, the bottom edge of the paint container170along the first handle side wall174contacts the outer surface162of the first head154of the rocker146and pushes it outwardly, which causes the rocker146to pivot from the first position to the second position. The outward movement of the first head154permits the bottom edge of the paint container170to pass below the opening140aand continue its downward movement. As the paint container170continues to move downward, the bottom edge of the paint container170contacts the inner surface164of the second head156of the rocker146and pushes it outwardly, which causes the rocker146to pivot back to the first position. When the rocker146moves back to the first position, the first head154moves into the handle passage192of the paint container170. The movement of the first head154into the handle passage192permits the second head156to move outwardly enough to enable the bottom edge of the paint container170to clear the second head156and pass below the opening140b. The paint container170continues to move downward (with the first head154of the rocker146disposed in the handle passage192) until the bottom wall of the paint container170contacts the flanges88of the base74. At this point, the paint container170is fully disposed in the bucket70.

Once the paint container170is fully disposed in the bucket70, the levers136of the clamping structures128are manipulated by an operator to place the clamping structures128in the clamping positions, wherein the levers136are disposed over the bottom portion210of the lid206of the paint container170. In this manner, the paint container170is trapped between the flanges88and the levers136, thereby securing the paint container170in the bucket70.

With the paint container170positioned in the bucket70as described above, the paint container170is supported on the flanges88and is spaced above the floor plate76. In addition, the vertical axis of the paint container170is aligned with the axial opening in the base74. Thus, the vertical axis of the paint container170is disposed coaxially with the axis B-B. Since the paint container170is disposed coaxially with the axis B-B and since the center of mass of the paint container170is disposed toward the front corner of the paint container170(due to the paint displaced by the formation of the handle194), the center of mass of the paint container170is offset from the axis B-B and is disposed toward the corner120c. The weight of the weight bar168(and the holding guide142), however, are specifically selected to counterbalance this offset in the center of mass of the paint container170. More specifically, the weight of the weight bar168(and the holding guide142) are selected such that the combination of the bucket70and the paint container170has a center of mass aligned with the axis B-B. In this manner, when the paint container170is being shaken by the mixing apparatus10and is being rotated about the axis B-B, the combination of the bucket70and the paint container170is balanced with respect to the axis B-B, thereby avoiding excess shaking and rocking of the mixing apparatus10.

In addition to providing weight to help balance the combination of the bucket70and the paint container170, the holding guide142also helps ensure that the paint container170is properly positioned in the bucket70, i.e., positioned such that the handle corner178is disposed in the corner120a. If the handle corner178of the paint container170is not aligned with the corner120aof the bucket70when the paint container170is being inserted into the bucket70, the first head154of the rocker146cannot move into the handle passage192when the second head156is contacted by the bottom edge of the paint container170. This inability of the first head154to move into the handle passage192prevents the second head156from moving sufficiently outward to enable the bottom edge of the paint container170to clear the second head156and pass below the opening140b. As a result, the second head156blocks further downward movement of the paint container170, thereby providing an indication that the paint container170is positioned incorrectly.

In addition to holding the paint container170, the bucket70is adapted for holding a conventional one gallon paint container, such as a conventional container224filled with an architectural paint that is partially shown inFIGS. 10 and 11. The conventional container224may be disposed in the bucket70by holding the conventional container224(through its bail handle226or otherwise) over the holding space122such that the conventional container224is aligned with the cylinder-receiving region92of the floor plate76of the base74and the mounting ears of the conventional container224are aligned with the spring clips116a,b. The conventional container224is then moved downwardly so as to enter the holding space122. As the conventional container224moves downward, a bottom edge of the conventional container224contacts the outer surface162of the first head154of the rocker146and pushes it outwardly, which causes the rocker146to pivot from the first position toward the second position. The outward movement of the first head154permits the bottom edge of the conventional container224to pass below the opening140aand continue its downward movement. As the conventional container224continues to move downward, the bottom edge of the conventional container224contacts the inner surface164of the second head156of the rocker146and pushes it outwardly, which causes the rocker146to pivot back toward the first position. Since the conventional container224does not have a handle passage, the first head154contacts the conventional container224before the first head reaches the first position, thereby halting the inward movement of the first head154of the rocker146. At this point, the rocker146is in the third position and both the first and second heads154,156are in contact with or close proximity to the conventional container224. Since the cylinder receiving region92is offset toward the second wall102b(as described above), the conventional container224is spaced by the gap124from the second wall102a. The gap124accommodates the first and second heads154,156of the rocker146and permits the conventional container224to move past the first and second heads154,156of the rocker146and continue to move downward until a bottom end wall of the conventional container224contacts the floor plate76within the cylinder receiving region92. At this point, the conventional container224is fully disposed in the bucket70.

With the conventional container224positioned in the bucket70as described above, the conventional container224is supported on the floor plate76within the cylinder receiving region92. The first and second heads154,156of the rocker146are disposed in the gap124and are positioned against or in close proximity to the conventional container224, thereby preventing an upper portion of the conventional container from moving toward the second wall102awhen the bucket70is rotating. In this manner, the holding guide142helps to hold a conventional one gallon paint container in the bucket70during the operation of the mixing apparatus10.

Since, the conventional container224is disposed in the cylinder receiving region92, the vertical axis of the conventional container224is offset from the axis of rotation B-B in the direction of the corner120c(and the flanged region86c), i.e., the vertical axis of the conventional container224is parallel to, but is spaced from, the axis of rotation B-B. Thus, the center of mass of the conventional container224and the paint disposed therein is offset from the axis of rotation B-B, toward the corner120c. The weight of the holding guide142and the weight bar at the opposing corner120a, however, counterbalance this offset. In this manner, when the conventional container224is being shaken by the mixing apparatus10and is being rotated about the axis B-B, the combination of the bucket70and the conventional container224is balanced with respect to the axis B-B, thereby avoiding excess shaking and rocking of the mixing apparatus10.

It should be appreciated that the distance the cylinder receiving region92is offset toward the flanged region86c(the offset distance) is determined by the weight of the weight bar168(and to a lesser extent the holding guide142), which, in turn, is determined by the weight of paint displaced by the formation of the handle194in the paint container170. More specifically, the weight of the displaced paint in the paint container170determines the amount of weight (the offset weight) of a conventional one gallon paint container and the paint contained therein that must be offset toward the flange region86c(and the corner120c). Using a standard density for paint and the weight of a conventional one gallon paint container, the offset distance of the cylinder receiving region92is calculated to produce the offset weight.

Once the conventional container224is fully disposed in the bucket70, the levers136of the clamping structures128are manipulated by an operator to place the clamping structures128in the clamping positions, wherein the levers136are disposed over a chime lid228of the conventional container224. In this manner, the conventional container224is trapped between the floor plate76of the base74and the levers136, thereby securing the conventional container224in the bucket70. The mounting ears of the conventional container224are held by the spring clips116a,band lower portions of the bail handle226are disposed in the openings118of the spring clips116a,b, thereby securing the bail handle226from movement when the conventional container224is being rotated. Since the conventional container224is offset toward the second wall102b, the mounting ear of the conventional container224on the side facing the second wall102bfully extends through the slot114in the second wall102b, whereas, the mounting ear of the conventional container224on the side facing the second wall102adoes not extend into the slot114in the second wall102aor only does so slightly. The construction of the spring clips116a,b, however, accommodates this offset in the positioning of the mounting ears. More specifically, since the middle portion of the spring clip116bbends inwardly, the middle portion of the spring clip116bis able to contact the mounting ear of the conventional container114on the side of the second wall102awithin or interior of the slot114, and since the middle portion of the spring clip116abends outwardly, the middle portion of the spring clip116ais able to accommodate the mounting ear of the conventional container224on the side of the second wall102band to contact the mounting ear exterior to the slot114.

Referring back toFIG. 1, the bucket70is secured to the mounting support60by disposing the bucket70on the mounting support60such that the mounting shaft56extends through the axial opening94in the base74and the mounting bores96are aligned with the bores64in the mounting support60. Bolts (not shown) are inserted through the bores96and are threaded into the bores64. With the bucket70secured to the mounting support60in the foregoing manner, the bucket70extends upwardly, through the circular opening26in the cabinet, thereby making the bucket70readily accessible to an operator. The central axis of the bucket70is collinear with the axis B-B and, thus, preferably intersects axis A-A at an angle of from about 20° to about 40°, more preferably at an angle of about 30°.

The mixing apparatus10is especially suited for mixing paint in the paint container170. Typically, the mixing apparatus10is located in a retail store where paint is sold. A paint manufacturer supplies the retail store with the paint container170filled with a base paint composition. When a customer selects a particular color for paint, an employee at the retail store determines the required amount of tinting concentrate(s) for producing the selected color. The employee then unscrews the lid206from the collar184and adds the tinting concentrate(s) to the base paint composition disposed in the body172of the paint container170. The employee then tightly screws the lid206back onto the collar184and places the paint container170in the bucket70in the manner described above. With the paint container170securely disposed in the bucket70as shown inFIG. 1, the employee activates a start switch or button that provides the electric motor28with power, which causes the rotor shaft30and, thus, the motor sprocket32to rotate. The belt36transfers the rotation of the motor sprocket32to the drive sprocket34, thereby causing the drive sprocket34and, thus, the drive shaft38to rotate. The rotation of the drive shaft38causes the yoke44to rotate about the axis A-A in a counter-clockwise direction which, in turn, causes the drive wheel58and the mounting support60to rotate about the axis B-B in a counter-clockwise direction. As a result, the bucket70and, thus, the paint container170are simultaneously rotated about the axis A-A and the axis B-B, thereby mixing the paint in the paint container170.

It has been observed that when the paint container170is rotated about the axes A-A and B-B in a clockwise direction, paint sometimes leaks from the juncture between the lid206and the collar184. Conversely, it has been observed that when the paint container170is rotated about the axes A-A and B-B in a counter-clockwise direction, paint does not leak from the juncture between the lid206and the collar184. Without being limited by any particular theory, it is believed that when the paint container170is rotating, the movement of the architectural paint disposed in the interior volume of the paint container170lags behind the movement of the paint container170due to the viscous nature of the paint. As a result, it is believed that the paint creates a force against the lid206that is directed opposite to the direction the paint container170is rotating. If the paint container170is rotating counter-clockwise, it is believed that the force against the lid206is directed clockwise, which tends to tighten the lid206to the collar184. If the paint container170is rotating clockwise, it is believed that the force against the lid206is directed counter-clockwise, which tends to loosen the lid206from the collar184. Accordingly, it is preferred to have the polarity of the electric motor28set so as to rotate the yoke44about the axis A-A in a counter-clockwise direction, which causes the paint container170to rotate about the axis B-B in a counter-clockwise direction.

The mixing apparatus10is very effective in mixing fluid dispersions disposed in either a cylindrical container or in a generally square container. In fact, Applicant has found that the mixing apparatus10is significantly more effective in mixing a fluid dispersion disposed in a generally square container, such as the paint container170, than in a cylindrical container, such as a conventional paint container. This result was surprising and unexpected. Without being limited by any particular theory, it is believed that the side walls of the paint container170act like paddles to increase agitation of the paint disposed in the interior volume of the paint container170.

While the invention has been shown and described with respect to particular embodiments thereof, those embodiments are for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein described will be apparent to those skilled in the art, all within the intended spirit and scope of the invention. Accordingly, the invention is not to be limited in scope and effect to the specific embodiments herein described, nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.