Patent Application
20210268687
The present invention relates generally to spin casters for depositing a surfacing material on a surface and, more particularly, to a device and method for integrating an activator with the surfacing material prior to deposition of the surfacing material on the surface.
Spin casting (also referred to as centrifugal casting) has been used in the repair of culverts and for installation of a surfacing material, such as concrete layers, inside a pipe or other tubular-shaped structure. Spin casting is based on pumping a fine grain concrete-type mix to a head that is spinning at high speed. The head, using centrifugal force, projects the concrete outward and toward the surface of the pipe to be coated. A head of the spin caster is centered within the pipe to be coated and the head is driven by a motor, normally pneumatic or electric. As the layer of concrete builds up, the spin caster is moved down the pipe, thereby depositing a consistent layer of concrete that repairs/coats the inside surface of the pipe.
While spin casting is widely used, it is limited to a rather thin thickness of concrete per pass, e.g., less than 2 inches thick per pass. For thicknesses greater than 2 inches the concrete may fall from overhead portion of the pipe or the weight of the concrete may cause it to flow downward. To address this problem, concrete manufactures provide rapid setting concrete formulations. However, such rapid setting formulations can increase the likelihood that the pumped material stiffens or hardens in the transport pipes and hoses between the pump and the spin caster, particularly, if there is an installation delay. This can cause plugging of the transport lines, requiring the process to be discontinued and all lines removed and cleaned or replaced, which can increase cost and time.
In view of the above limitations, for linings thicker than 2 inches multiple passes are made. For example, a first layer may be deposited and allowed to cure (often 12 or more hours), and then a second pass is made depositing an additional layer. This process can be repeated to achieve the desired thickness. As will be appreciated, such multiple passes substantially increase the time required to achieve the desired thickness and thus is reduces efficiency.
Aspects of the invention are directed to methods and devices for delivering an activator to hardenable materials, such as cement or refractory materials, prior to the hardenable materials being deposited on a surface. More specifically, the activator is delivered to the hardenable material as the hardenable material is expelled from an aperture of an applicator to a spin head that casts the hardenable material onto a target surface. Mixing of the activator with the hardenable material occurs in an air space between the applicator and the spin head and during application itself.
An advantage of the invention is that since the activator is added as the hardenable material is being expelled, the likelihood of plugging of transport lines and delivery tubes that provide the hardenable material to the applicator is significantly reduced.
According to one aspect of the invention, a spin caster for spraying a surfacing material upon an interior surface of a vessel includes: a spin head configured to rotate about an axis, the spin head including an input port; and a supply line coupled to the input port and configured to convey a first material to the spin head and a second material to the spin head, wherein the supply line comprises a first channel configured to convey the first material to the spin head and a second, different channel configured to convey the second material to the spin head.
In one embodiment, the supply line outputs the first material and the second material into the spin head, whereby the second material is applied to the first material through rotation of the spin head.
In one embodiment, the first channel and the second channel are concentric with each other.
In one embodiment, the first channel is inside the second channel.
In one embodiment, an outer surface of the first channel and an inner surface of the second channel define a gap therebetween, the gap forming the second channel.
In one embodiment, the second channel comprises a plurality of channels arranged adjacent to the first channel.
In one embodiment, the plurality of second channels are attached to an inner wall of the first channel.
In one embodiment, the plurality of second channels are attached to an outer wall of the first channel.
In one embodiment, the spin head comprises a plurality of vanes arranged radially outward from the input port, and a deflector arranged opposite the input port, the deflector configured to disperse the first material and the second material toward the plurality of vanes.
According to another aspect of the invention, a method for spin casting refractory concrete via a spin caster having a spin head, the refractory concrete including a wet mix and separate activator that is applied to the wet mix, the method including: transmitting both the wet mix and the activator to the spin head through separate channels; and applying the activator to the wet mix at the spin head.
In one embodiment, transmitting through separate channels comprises transmitting the wet mix through a first channel and transmitting the activator through a second channel, the second channel arranged inside the first channel.
In one embodiment, the second channel is arranged on an inner wall of the first channel.
In one embodiment, transmitting through separate channels comprises transmitting the wet mix through a first channel and transmitting the activator through a second channel, the second channel arranged on an outside surface of the first channel.
In one embodiment, transmitting through separate channels comprises transmitting both the wet mix and the activator to the spin head through a double-wall tube defining a first and second channels, wherein the wet mix is transmitted through the first channel and the activator is transmitted through the second channel.
In one embodiment, the activators comprise at least one of hydrated lime, alkali chlorides, alkali silicates, alkali phosphates, hydroxyethylcellulose, lithium accelerators, lithium sulfate, lithium carbonate, lithium citrate, lithium fluoride.
In one embodiment, the activator comprises a foaming agent.
In one embodiment, the foaming agent comprises at least one of a foaming additives in a range of 0.1 wt % to 3.0 wt %.
In one embodiment, the foaming agent comprises at least one of alkylbenzene sulfonates, alkene sulfonates, and hydroxylalkane sulfates.
In one embodiment, the method includes adding an air-entraining additive to the foaming agent.
In one embodiment, the air-entraining additive comprises at least one of methylcellulose, methylhydroxypropylcellulose or hydroxyethylcellulose.
Examples of the specific embodiments are illustrated in the accompanying drawings. While the invention will be described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to such specific embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in details so as to not unnecessarily obscure the present invention.
These and other advantages will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings and the appended claims.
The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein:
Various aspects now will be described more fully hereinafter. Such aspects may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art.
Where a range of values is provided, it is intended that each intervening value between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the disclosure. For example, if a range of 1 mm to 8 mm is stated, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm are also intended to be explicitly disclosed, as well as the range of values greater than or equal to 1 mm and the range of values less than or equal to 8 mm.
All percentages, parts and ratios are based upon the total weight of the topical compositions and all measurements made are at about 25° C., unless otherwise specified.
The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a “polymer” includes a single polymer as well as two or more of the same or different polymers; reference to an “excipient” includes a single excipient as well as two or more of the same or different excipients, and the like.
The word “about” when immediately preceding a numerical value means a range of plus or minus 10% of that value, e.g., “about 50” means 45 to 55, “about 25,000” means 22,500 to 27,500, etc., unless the context of the disclosure indicates otherwise, or is inconsistent with such an interpretation. For example, in a list of numerical values such as “about 49, about 50, about 55, “about 50” means a range extending to less than half the interval(s) between the preceding and subsequent values, e.g., more than 49.5 to less than 52.5. Furthermore, the phrases “less than about” a value or “greater than about” a value should be understood in view of the definition of the term “about” provided herein.
As used herein, the term “refractory materials” refers to inorganic nonmetal materials that are utilized in various high-temperature equipment, e.g., steel production and the like. Refractory materials are characterized by a high melting point, and when exposed to high temperatures they do not lose their strength and of form.
Spin casting is used for the installation of cement-bonded or other bonding systems such as phosphate, silicate, colloidal oxides and others as is often used. In certain applications, it is desirable for concrete or refractory materials expelled by the spin caster to provide a thick lining, e.g., greater than 2 inches, inside a culvert, duct, pipe or other circular vessel like a steel ladle or rotary kiln. In both concrete and refractory concrete, long setting formulations allow for long working time and are very forgiving to delays. Such long-setting formulations, however, require multiple passes with lengthy delays between passes to allow the concrete or refractory material to set before another layer is deposited.
Various embodiments of the invention are directed to methods and devices for centrifugally casting hardenable materials such as cement or refractory materials onto the inside of conduits, pipes, and circular vessels. In such embodiments, an activator is delivered to a hardenable material as it is expelled from an aperture of an applicator to a spin head that casts the hardenable material onto the target conduit, pipe, or circular vessel. Mixing of the activator with the hardenable material occurs in the air space between the applicator and the spin head and during application itself, reducing the likelihood of plugging of the transport lines and delivery tubes in the applicator.
Delivery of the activator can be carried out by various means. For example, in some embodiments, the activator may be delivered to the aperture by a spray ring larger than the spinhead that sprays the activator 360 degrees around the spin head. In other embodiments, one or more delivery tubes inside the hardenable material delivery tube carries the activator to the aperture, and in still other embodiments, an additive delivery tube may be affixed to the delivery tube that expels activator at the aperture. The addition of activator allows for rapid gelling and hardening of the hardenable materials after expulsion from the applicator, thereby allowing for thicker linings to be produced without layering.
“Hardenable materials” can include any type of material that hardens or cures in air and which hardening can be accelerated by, for example, a chemical activator. Examples of hardenable materials include, but are not limited to, composite materials, such as cement, concrete, asphalt, refractory materials, asphalt concrete, polymer concrete, mastic asphalt, mastic roller hybrid, dental composite, syntactic foams, and the like, and polymer like foams and casting polymers.
The motor 110 may include an exhaust cap 111, a rotational base 112, and an end cap 113. The rotational base 112 may rotate about the stationary exhaust cap 111, providing rotation that is transferred through the end cap 113 to the spin head 13. In some embodiments, an air fitting 114 may extend through the support base 102 and fits into the exhaust cap 111 to provide a supply of air to the motor 110.
A delivery tube 12 may extend through the length of applicator 10, providing a means for transferring hardenable material to the spin head 13 where it can be applied to a target surface. The delivery tube 12 may terminate at a head tube 121 that rotates together with the rotational base 112 and end cap 113. The head tube 121 may include an exterior threaded portion 122 or an interior threaded portion (not shown) that provides a means for fastening to spinner head 13 to the applicator 10.
The spin head 13 may include a spin head base 132 operably connected to a spin head connector 131, which may include threads can be operably attached to the threaded portions of the head tube 121. A spin head aperture 133 that is operably coupled to the spin head connector 131 may be positioned in the spin head base 132 and allow the hardenable material to be expelled from the device 1. Vanes 134 may be connected to spin head base 132 and a spin head top plate 135. An interior 139 of spin head top plate 135 may direct hardenable material toward the vanes 134. A spinner head nut 136 may engage spinner head bolt 137, which is adjacent to spinner head washer 138 and permit adjustment of the flow characteristics of the hardenable material flowing during operation of the device 1.
During operation of the device 1, wet hardenable material mix is pumped through the delivery tube 12 and the motor 101 to head tube 121 and spin head connector 131. The hardenable material then passes through spin head aperture 133 where the wet mix engages interior 139 of the spin head top plate 135. The interior spin head top plate deflects the wet mix outward toward the vanes 134. The spin head 13 rotates during operation whereby the vanes 134 spray a coating of wet mix radially outward.
In accordance with the invention, an activator is injected at or near the spin head aperture 133 as the wet mix enters the head of the spin caster, and the spin head mixes the activator into the wet mix. The activator may be a liquid or an aqueous suspension that is pushed into the material with air causing the concrete to begin to set or gel very quickly, allowing build-up of a thick layer of cast material on the substrate, even when the wet mix is applied overhead. As will be appreciated, the specific activator that is utilized will depend on the type of hardenable material that is to be deposited on the surface. Exemplary activators include hydrated lime, alkali chlorides, alkali silicates, alkali phosphates, hydroxyethylcellulose, lithium accelerators, lithium sulfate, lithium carbonate, lithium citrate, lithium fluoride. The activator may include a foaming agent that facilitates the formation of foam, and may be a surfactant or a blowing agent. Exemplary foaming agents include alkylbenzene sulfonates, alkene sulfonates, and hydroxylalkane sulfates or an air entraining additive. The foaming agent can include a foaming additive in a range of 0.1 wt % to 3.0 wt %.
In some embodiments, sprayers may be attached to the applicator and directed toward the spin head. The sprayers may deliver the activator to the wet mix as it is expelled from the spin head aperture, allowing mixing of the activator with the wet mix.
The type and arrangement of sprayer can vary among embodiments. For example, the sprayer may be individual sprayers or the sprayer can be combined into a spray apparatus such as a spray ring 24 illustrated in
In some embodiments, the activator may be transported through the applicator 30 with the wet mix. For example, as illustrated in
In some embodiments, devices such as those described above may be part of systems that include a wet mix pump 560 that introduces wet mix into the inner delivery tube 52a and a hose or pipe 561 that transfers wet mix from the pump to 56 the device. Such systems may further include an activator pump 562 and hoses or piping 563 that transfers activator to the gap between the inner delivery tube 52a and outer delivery tube 52b, and an air pump 564 and hoses or piping 565 that transfers air into the gap between the inner delivery tube 52a and outer delivery tube 52b. A seal may be positioned between the outer delivery tube 52b and the inner delivery tube 52b near the lower terminus of the outer delivery tube to ensure activator and, in some embodiments, air are transferred toward the spin head aperture. In some embodiments, the activator pump 562 and air pump 564 may be combined into a single device, and an air and activator mixture may be pumped through a single hose or pipe. In other embodiments, the activator may be pumped into the gap between the gap between the inner delivery tube 52a and outer delivery tube 52b.
The spin head aperture 633 may be composed of the opening of the circular channel 651 and the opening of the canal 652 created by the inner delivery tube. The circular channel 651 and the canal 652, therefore, allow simultaneous passage of activator and wet mix to the spin head 63 where it is expelled from the outer delivery tube 62b and the inner delivery tube 62a. A deflection cone 640 may be positioned in the spin head 63 to intercept expelled activator and wet mix cause mixing of these materials and deflect the materials toward the vanes 634. Mixing of activator and wet mix can occur within the space between the spin head base 632 and spin head top plate 635, and the area surrounding the spin head 63 as these materials are contacted by the vanes 634. In certain embodiments, the circular channel 651 may be composed of several smaller tubes positioned along an inner wall of the inner delivery tube 62a eliminating the need for the outer delivery tube 62b while affecting delivery of activator to the spin head aperture 633, or in some embodiments, such tubes may be arranged within the circular channel 651.
Referring to
Moving to
While the embodiments illustrated in
In various embodiments described above, activator may be a liquid or suspension that, in some embodiments, can be mixed with air or other gases in the delivery tube. The activator may be delivered as a spray that mixes with the wet mix. This may cause the wet mix to begin to set or gel very quickly, allowing build up a thick layer of material without the problems related to a rapid setting formulations that must remain uncured as it is pumped into the spin head and cures more slowly upon delivery to the coated surface. Delivering activator separately from the wet mix and mixing in the air within or surrounding the spin head allows high concentrations of the activator to be mixed into the wet mix, and rapid curing of the hardenable material upon delivery to the coated surface. Rapid curing allows for thicker layers of wet mix to be applied to the surface in a single step, reducing the time necessary to apply sufficient material and eliminating curing within the delivery tube and spin head.
Some embodiments are directed to methods for centrifugally casting a hardenable material that include the step of mixing a wet mix of the hardenable material with an activator in air in or around a spin head. In some embodiments, the activator may be pumped into the spin head, and in certain embodiments, the activator may be mixed with air or another gas before being mixed with the wet mix.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
This application claims the benefit of U.S. Provisional Patent Application No. 62/983,596 filed Feb. 28, 2020, which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62983596 | Feb 2020 | US |
