Patent Application
20210237310
The present invention relates in general to a mixer and, in particular, to a portable mixer that hydrates and mixes prepackaged cementitious mix in a continuous process.
Concrete is a building material commonly used in a variety of construction applications. In many cases, the volume of concrete required for a particular application and/or the number of personnel available to handle the uncured concrete does not warrant delivery of the concrete via a mixer or ready-mix truck. Instead, for small jobs, concrete is often prepared in batches by emptying one or more sacks of prepackaged concrete mix into a wheelbarrow, adding water in various amounts, and then mixing the resulting slurry by hand utilizing tools such as a hoe or shovel until the desired consistency is reached. For slightly bigger jobs, concrete can be mixed from bags of concrete mix or from raw materials (e.g., aggregates, cement, and water) in a rotating drum mixer, which can be powered, for example, by electricity or a gasoline or diesel motor.
The present disclosure recognizes that conventional techniques for mixing concrete have significant drawbacks. For example, the concrete slurry is frequently too wet or too dry, which can lead to a need to repetitively add more water and/or dry mix to the slurry to achieve a desired consistency. Depending upon the skill and/or experience of the individual doing the mixing, the consistency of different batches of concrete often differs significantly. Further, the work involved in cleaning the tools and the drum mixer utilized in preparation of the concrete is laborious. In fact, it is common for a drum mixer to be discarded after mixing several hundred sacks of concrete mix due to the difficulty and labor required to remove the dried and hardened concrete from the crevices and small spaces in and around the internal paddles inside the drum.
The present disclosure also recognizes that continuous process mortar mixers are currently available for mixing bags of prepackaged mortar mix for brick and stone laying, joint pointing, and other applications. Although the contents of these prepackaged mortar mixes vary depending upon the intended application and required mortar properties, prepackaged mortar mixes do not include aggregate ingredients larger in grain size than “sand,” which is defined herein according to the Wentworth scale as a granular material having a grain size of between 0.062 mm and 2.0 mm. In general, prepackaged mortar mixes commonly include silica sand having a relatively homogenous grain size of about 0.5 mm. Because continuous process mortar mixers are specifically designed to exclusively mix commercial prepackaged mortar mixes, these continuous process motor mixers cannot accept or mix commercially available prepackaged concrete mixes due to their inability to accommodate the gravel aggregates present in concrete mixes, where “gravel” is defined according to the Wentworth scale as a granular material having a grain size ranging from 2.0 mm to 64.0 mm.
According to one or more embodiments, an improved portable mixer is provided that hydrates and mixes sacks of prepackaged cementitious mix, which may contain gravel aggregate, in a continuous process.
In one or more embodiments, a portable mixer includes a frame, a hopper for receiving therein dry cementitious mix, and a chute rigidly coupled to the hopper that communicates with the hopper via an aperture. The hopper and chute are pivotally coupled to the frame. The portable mixer further includes an auger extending from the hopper into the chute via the aperture, a water supply system configured to apply water to cementitious mix, and a motor coupled to the auger and configured to rotate the auger to mix the dry cementitious mix with the water.
In some embodiments, the frame of the portable mixer includes a first plate, and the portable mixer further includes a second plate pivotally coupled to the first plate by a pivot assembly. In some embodiments, the pivot assembly includes a spring that biases the second plate away from the first plate.
In some embodiments, the auger includes a first body portion and a second body portion, where the second body portion comprises a shaftless helical auger body portion. In some embodiments, the second body portion is disposed in the chute, and the second body portion has a greater pitch than the first body portion.
In at least some embodiments, the portable mixer is configured to facilitate ease of cleanup, thus reducing or eliminating the cleaning issues common to drum mixers.
With reference now to the figures and, in particular, with reference to
In the depicted embodiment, portable mixer 100 has a frame 102, which can be formed out of a durable material, such as fiberglass, plastic, wood, and/or tubular steel. Frame 102 has a handle portion 104 by which portable mixer 100 can be manually pushed or pulled to position portable mixer 100 at a desired position on a job site. In at least some embodiments, as seen, for example, in
When portable mixer 100 is parked on a level substrate 101 as shown in
Portable mixer 100 further includes a hopper 120 for receiving therein dry prepackaged cementitious mix (e.g., Sakrete™, Quikrete™, or mortar mix), which typically includes predetermined proportions of cement, accelerants, retardants, binders, possibly aggregate (e.g., gravel and/or sand), and other proprietary chemicals to enhance final product performance. Prepackaged concrete mixes commonly include locally sourced natural or crushed rock or recycled concrete aggregate having a grain size greater than 0.19 inches (about 3 mm), and more commonly, between 0.375 and 1.5 inches. This gravel aggregate commonly forms between 60% and 75% of the total volume of a prepackaged concrete mix. Hopper 120 is preferably formed out of a durable material, such as fiberglass, plastic, or sheet metal (e.g., steel). As shown, hopper 120 has a rim 122, one or more inwardly sloping sidewalls 124 with a slope appropriate to ensure smooth delivery/discharge recognizing the repose angle of the prepackaged cementitious mix being utilized, and a base 126 to which concrete mix placed in hopper 120 is uniformly funneled/dispensed under gravitational force. Near base 126, a sidewall 124 has an aperture 128 formed therein through which an auger 700 extends and through which prepackaged cementitious mix is transported by the rotation of the auger 700, as discussed further below.
As shown, hopper 120 can conveniently include a bag opener 125, which in the illustrated embodiment comprises an upwardly arched serrated blade. In a preferred embodiment, the sidewall(s) 124 of hopper 120 are spaced such that the leading surface of an unopened sack of prepackaged cementitious mix dropped into hopper 120 will be deformed convexly and placed under tension through the contact of the sack with the sidewall(s) 124 of hopper 120. Bag opener 125 is preferably located substantially centrally front-to-back within hopper 120 and at a height relative to the inward slope of sidewall(s) 124 such that bag opener 125 will perforate the tensioned, leading convex surface of the sack, allowing the cementitious mix contained therein to spill into hopper 120 under the urging of gravity. Once perforated, the sack is preferably left in hopper 120 until a majority of the sack's contents have spilled out in order to reduce the amount of air-borne silica dust. After the sack is mostly emptied, the sack can be lifted by its ends to completely empty its contents into hopper 120 and can then be removed from the top of hopper 120.
Hopper 120 can have a variety of shapes and/or sizes in different embodiments. For example, hopper 120 can have an ovoid or rectangular or other cross-section. Further, the cross-sectional shape of a hopper 120 can vary between rim 122 and base 128. In the illustrated embodiment in which hopper 120 has a generally rectangular cross-section at rim 122, hopper 120 has maximum orthogonal dimensions HD1 and HD2 between about 12 and 24 inches across at rim 122, and more particularly, between about 15 and 20 inches, and still more particularly, between about 16 and 18 inches. Further, in some embodiments, hopper 120 is between about 8 and 25 inches deep measured between rim 122 and base 128, and more particularly, between about 10 and 20 inches deep. In these embodiments, hopper 120 can be sized to hold approximately 100 pounds of dry cementitious mix.
In at least some preferred embodiments, it is desirable for portable mixer 100 to be easy for one or two person work crews to lift, transport, deploy, and use. For example, in some embodiments, an unloaded portable mixer 100 can be less than about 100 pounds, and still more preferably, less than about 80 pounds. In addition, frame 102, wheels 110, and hopper 120 are sized and configured such that the load height (LH) of rim 122 of hopper 120 is less than about four feet above the underlying substrate 101, and more preferably, in the range of between about 24 inches and 42 inches above the underlying substrate 101. This height range makes the task of lifting sacks of cementitious mix and loading their contents into the top of hopper 120 much easier and safer than loading a conventional barrel mixer.
Aperture 128 of hopper 120 communicates with a chute 130 that extends between a sidewall 124 of hopper 120 and an open end 136. In one exemplary embodiment, chute 130 is between about 16 and 30 inches in length, and more particularly, between about 16 and 24 inches, and still more particularly, between about 16 and 20 inches in length. These ranges of lengths allow portable mixer 100 to remain compact, while providing sufficient opportunity for the cementitious mix to be thoroughly mixed with water as it traverses chute 130. In some embodiments, these ranges of chute lengths result in portable mixer 100 having an overall length (OL) of between about 50 and 72 inches, and more particularly, between about 60 and 70 inches. When rests 106 of portable mixer 100 are resting on a level substrate 101, chute 130 can have an inclination or declination relative to substrate 101 from aperture 128 of hopper 120 to open end 136 or can be substantially parallel with substrate 101 (as shown). In various embodiments, open end 136 of chute 130 can have a range of chute heights (CH) when rests 106 of portable mixer 100 are resting on a level substrate 101. For example, in some embodiments, portable mixer 100 can have a chute height (CH) of between about 12 and 24 inches, and more particularly, between about 12 and 20 inches.
In at least some embodiments, chute 130 is a curved, at least partially enclosed tube. In some embodiments, the top of chute 130 can be at least partially open along its length to facilitate cleaning and maintenance. In such embodiments, the open top of chute 130 is optionally but preferably covered during rotation of auger 700 by a guard 140, which reduces the likelihood of injury due to the inadvertent contact of a user's body or clothing with a rotating auger 700. In at least some preferred embodiments, guard 140 is pivotally or otherwise coupled to chute 130 so that a user can move guard 140 up and away from the top of chute 130 for ease of cleaning. In some embodiments, a grill 127 can similarly be disposed in hopper 120. For example, in one example, grill 127 may include a series of rods penetrating through holes in the sidewall(s) 124 of hopper 120.
In at least some embodiments, chute 130 may be formed integrally (i.e., as a unitary piece) with hopper 120, for example, by injection molding. In at least some embodiments, chute 130 may optionally further include a hold down strap (not illustrated) that limits the axial displacement of auger 700 (e.g., as it is displaced from axial alignment by contact with gravel aggregate in the concrete mix).
Portable mixer 100 additionally includes a motor 150 for rotating auger 700. In the depicted example, motor 150 is an electric motor, which is removably coupled (e.g., by bolts) to the lower back surface of hopper 120. In this arrangement, a small through hole in hopper 120 (not specifically illustrated) allows a motor shaft of motor 150 to be coupled to and axially rotate auger 700. For example, in some embodiments, the motor shaft of electric motor 150 is coupled to auger 700 by a left hand Acme thread. In other embodiments, the motor shaft and auger 700 can be coupled by a clevis pin that passes through corresponding through holes in the motor shaft and auger 700. In some embodiments, electric motor 150 can be powered by standard 110-230 V AC mains power, which, if electric motor 150 is a DC motor, can be transformed into DC power of suitable voltage, for example, by a power transformer disposed within electrical enclosure 152. In other embodiments, electric motor 150 can alternatively or additionally be powered by a battery, such as a standard 12 V DC automobile battery. In at least some embodiments, the power system of portable mixer 100 includes a manual multi-position switch 200 that allows to auger 700 to be selectively operated by a user in a forward direction in which cementitious mix is moved by auger 700 from hopper 120 in chute 130 or in a reverse direction or stopped. Although the illustrated embodiment employs an electric motor (e.g., a fixed or variable speed DC or AC motor), it should be appreciated that motor 150 can alternatively be implemented with a gasoline or diesel-powered engine.
Portable mixer 100 additionally includes a water supply system best seen in
Although in various embodiments, the water supply system can introduce water into the dry cementitious mix in various locations, including inside hopper 120, in at least some preferred embodiments like that depicted in
In some embodiments like that illustrated in
In some embodiments, hopper 120 and chute 130 may be coupled in fixed relation to frame 102. However, in other embodiments, at least chute 130 may be movable in relation to frame 102. For example, in the embodiment depicted in
In the depicted embodiment, portable mixer 100 additionally includes an upper plate 216 (see, e.g.,
Referring now to
In the embodiment depicted in
In at least some embodiments, second body portion 806 of auger body 800 takes the form of a shaftless open helix (also referred to as a shaftless flight) continuously curving in single direction (e.g., a right-handed helix like flighting 810). Second body portion 806 may in some embodiments have a length AL3 between about 18 and 42 inches, and more particularly, between about 20 and 30 inches. Second body portion 806 may be rigidly coupled to first body portion 804, for example, by one or more welds between flighting 810 of first body portion 804 and second body portion 806. In other embodiments, second body portion 806 can be formed as a unitary piece with flighting 810. The absence of a central shaft in second body portion 806 promotes more thorough mixing of the water with the cementitious mix and eliminates the numerous joints and crevices where slurry can more easily escape the cleaning process and thus build up and eventually retard the advancement of the slurry down the chute and degrade the ultimate mixing effectiveness of auger 700. The absence of a central shaft in second body portion 806 also allows the portable mixer 100 to accommodate the use of prepackaged concrete mixes with large gravel aggregates (e.g., 0.75 to 1.0 inch). In some embodiments, second body portion 806 has a substantially uniform outer diameter AOD2 measured orthogonally to the long axis X of auger 700 of between 2.25 and 3.25 inches, and more particularly, between about 2.5 and 3.0 inches. In general, it is preferred if AOD2 is greater than AOD1.
Auger body 800 also preferably has an uneven pitch. In particular, flighting 810 of first body portion 804 preferably has a lesser first pitch, while the shaftless flight of second body portion 806 preferably has a greater second pitch. In various embodiments, the greater pitch of second body portion 806 can either be fixed or can increase uniformly or step-wise over some or all of the length of second body portion 806 as it extends from first body portion 804 toward open end 136. As one example, first body portion 804 may have a pitch-to-diameter ratio of between about 0.2 and 0.9, and more particularly, between about 0.5 and 0.8, and more particularly, of about 0.7 (e.g., a pitch of 1.6 inches for an AOD1 of 2.2 inches). In this example, second body portion 806 can have a pitch-to-diameter ratio at open end 136 of chute 130 in the range of between about 0.4 to 1.8, and more particularly, of between about 0.6 to 1.0, and more particularly, of between about 0.7 to 0.8 (e.g., a pitch of 2.1 for an AOD2 of 2.7 inches).
As further illustrated in
In one embodiment of auger 700 in which second body portion 806 is about 27 inches long and has an outer diameter of about 2.75 inches, second body portion 806 includes four fingers 820a-820d, with the first (i.e., finger 820a) spaced between about 7 and 8 inches from the end of shaft 808 (which in some embodiments, extends through aperture 128 into chute 130), the second (i.e., finger 820b) positioned between about six to seven inches further down chute 130 toward open end 136, the third (i.e., finger 820c) positioned between about five to six inches further down chute 130, and the fourth (i.e., finger 820d) positioned between about six to seven inches further down chute 130. Each of fingers 820a-820d is preferably substantially orthogonal to the long axis X of auger 700. The increased pitch of second body portion 806 is preferably selected to counter the resistance in flow (and velocity) offered by fingers 820a-820d. The increase in pitch of the helix in second body portion 806 moves the cementitious mix along chute 130 with enough relative velocity to reduce or eliminate unwanted material build-up in chute 130. As best seen in
As further depicted in
Although the portable mixer 100 described herein is capable of continuous operation, it should be appreciated that the flow of cementitious slurry from chute 130 is continuous for only as long as the operator desires. If desired, the operator can stop the rotation of auger 700 for perhaps 15 or 20 minutes with partially mixed cementitious mix in chute 130 and then resume operation without any problem in the working properties of the resulting cementitious slurry.
As has been described, in at least some embodiments, a portable mixer includes a portable mixer includes a frame, a hopper for receiving therein dry cementitious mix, and a chute rigidly coupled to the hopper that communicates with the hopper via an aperture. The hopper and chute are pivotally coupled to the frame. The portable mixer further includes an auger extending from the hopper into the chute via the aperture, a water supply system configured to apply water to cementitious mix, and a motor coupled to the auger and configured to rotate the auger to mix the dry cementitious mix with the water.
While various embodiments have been particularly shown and described, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the appended claims and these alternate implementations all fall within the scope of the appended claims. References herein to an embodiment or embodiments do not necessarily refer to the same embodiment or embodiments. It should also be appreciated that various of the disclosed embodiments or features thereof may be utilized in combination. The terms “about” or “approximately,” when used to modify quantities or ranges, are defined to mean the stated value(s) plus or minus 10%. The term “coupled” is defined to mean that elements are unitary or are attached, possibly through one or more intermediate members. Further, the term “exemplary” is defined herein as meaning one example of the described feature, but not necessarily the only or preferred example of the feature.
