DESC:FIELD OF INVENTION
[0001] The present disclosure generally relates to the field of additive manufacturing. Specifically, the present disclosure relates to apparatus and method for manufacturing a three-dimensional (3D) structure using cementitious mixture.

BACKGROUND AND PRIOR ART
[0002] Additive manufacturing, which works by building parts in layers, is a process employed for manufacturing three-dimensional structures. The process of additive manufacturing is more expeditious as compared to the traditional methods of manufacturing. This process enables manufacturing of more complex and intricate structures by means of a Computer Aided Design (CAD) model.
[0003] The additive manufacturing process enables a manufacturer to obtain a three-dimensional model of any proposed structure. This process substantially reduces cost and also enhances synchronization between the design process and manufacturing, resulting in lower product cost and improved product quality.
[0004] Additive manufacturing has become more prevalent in recent years as a more viable option not only to rapidly produce prototypes, but also to manufacture final products. While more commonly used to produce polymer objects, current advancements have made it possible for this process to also be employed in manufacturing concrete structures using cementitious material.
[0005] Currently, there are a lot of problems and inefficiencies connected with the traditional methods of manufacturing concrete structures. For example, scaling, crazing, cracking, curling etc. Also, the traditional methods of manufacturing concrete structures are often very time consuming and are extremely labour intensive, with the overall efficiency being low. Manufacturing concrete structures requires concerted effort by multiple parties during its fabrication and installation. Instances of poor quality and other shortcomings, if not detected and rectified early in the process, can compromise structural safety, since the process is predominantly manual in nature and requires human intervention at every step of the process.
[0006] Therefore, there is a need for an additive manufacturing system that can manufacture good quality, robust concrete structures in an efficient and timely manner. The current invention, using additive manufacturing apparatus and method, along with the specifications of the apparatus disclosed herein, will not suffer from the same constraints as those hindering the traditional construction methods. Superior dimensional tolerances in the finished concrete structures can be achieved using the additive manufacturing process as compared to the traditional methods of manufacturing concrete structures.

OBJECTS OF THE INVENTION
[0007] One aspect of the invention is to provide apparatus and method for producing a three-dimensional concrete structure through additive manufacturing that possesses structural characteristics of concrete and refined structural features.
[0008] Another aspect of the current invention is to use a positioning apparatus, one or more linear actuators and a flow rate control apparatus, thereby leading to increased manufacturing speed as compared to traditional methods and also increasing productivity and efficiency of the manufacturing process. The process will also incur low cost as it will be automated in nature, not requiring multitudinous construction workers and also reducing wastage of the material being used. This process will also save construction materials, significantly decreasing energy consumption in construction and improving the production efficiency. Such an efficient yet less expensive process could also affect concrete construction affordability.
[0009] The current invention would make it more convenient to implement construction designs using additive manufacturing that might be hard to build in traditional ways, thus, leading to further advancements and revolutionizing the concrete structure designs using increased levels of precision and automation. The employment of this method would also encourage experimentation with novel and ingenious architectural forms and artistic expressions which are more difficult to build in conventional concrete structures. The current invention has been completed through practical knowledge acquired over the years in the said field.

SUMMARY OF THE INVENTION
[00010] In view of the foregoing, an embodiment herein provides apparatus and method for additive manufacturing of a three-dimensional model utilizing a dispensation-head having a nozzle along a longitudinal axis. The apparatus for additive manufacturing of a three-dimensional structure includes a dispensation-head positioned to a first pre-selected position, a nozzle (203) operatively coupled with the dispensation-head, the dispensation-head being configured to selectively dispense interface material in a first layer, wherein the dispensation-head is re-positioned to a subsequent position that is spaced from the first layer by a vertical distance, and wherein the vertical distance is equal to the thickness of a subsequent layer of dispensing material.
[00011] According to an embodiment of the present invention, the apparatus for additive manufacturing further includes a flow rate control apparatus that controls flow rate of viscous cementitious mixture, and instantaneously modulates the flow rate. The flow rate control apparatus includes any or a combination of single and twin-screw extruders using shear force to generate pressure to modulate flow rate of said cementitious mixture.
[00012] According to an embodiment of the present invention, the dispensation-head is attached to a positioning apparatus and controllably movable in X, Y and Z directions by one or more linear actuators.
[00013] According to an embodiment of the present invention, the method for additive manufacturing of a three-dimensional structure utilizing a dispensation-head having a nozzle (203) along a longitudinal axis includes the steps of positioning the dispensation-head to a first pre-selected position (301); selectively dispensing interface material in a first layer from said dispensation-head (302); re-positioning said dispensation-head to a subsequent position (303), wherein said subsequent position is spaced from the first layer by a vertical distance, said vertical distance being equal to thickness of a subsequent layer of dispensing material; repeating said step of selective dispensing in the subsequent layer (304); and repeating said steps of re-positioning and selective dispensing in the subsequent layer until the additive manufacturing of the three-dimensional structure is completed (309).
[00014] According to an embodiment of the present invention, the method further includes the step of selectively adjusting output from the nozzle (203) during each dispensing step to control amount of a cement material dispensed from the nozzle (203), thereby to control the thickness of each layer.
[00015] According to an embodiment of the present invention, the method further includes the steps of calculating variation from the first layer formed by the dispensation of the interface material (307); and adjusting the dispensing of said interface material from the nozzle (308).
According to an embodiment of the present invention, the method further includes the step of compensating for a variation in the thickness of each layer prior to depositing the subsequent layer by selectively adjusting the output from the nozzle during each dispensing step to control the amount of said cement material dispensed from the nozzle; comparing height of last deposited layer with a reference level (306); calculating variation from said reference level (307); and adjusting the dispensing of said interface material from the nozzle (308). Until achieving the desired height, the steps are repeatedly processed in a preferred sequence.
[00016] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS
[00017] The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
[00018] Fig. 1 illustrates an exemplary model for constructing 3D concrete structures using additive manufacturing technique, in accordance with an embodiment herein;
[00019] Fig. 2 illustrates an exemplary model of an auger pump, in accordance with an embodiment herein; and
[00020] Fig. 3 illustrates the method for constructing 3D concrete structures using additive manufacturing technique, in accordance with an embodiment herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[00021] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[00022] As mentioned above, there is a need to develop apparatus and method for constructing three-dimensional concrete structures using additive manufacturing. The embodiment herein achieves this by providing apparatus and method for constructing three-dimensional (3D) concrete structures using additive manufacturing. The dispensation-head is attached to an XYZ positioning apparatus, and controllably movable in X-axis, Y-axis and Z-axis (directions) by one or more linear actuators; to print on a build platen, which may also include the build surface, using the control apparatus. Referring now to the drawings, and more particularly to FIGS. 1 through 3, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[00023] There is thus provided, in accordance with a preferred embodiment of the present invention, the apparatus for additive manufacturing of three-dimensional concrete structures. The apparatus includes a dispensation-head having a nozzle and a dispenser connected to the dispensation-head for selectively dispensing interface material in layers. The depth of each deposited layer is regulated by selectively dispensing interface material in layers from the dispensation-head.
[00024] The additive manufacturing apparatus is provided with a flow rate control apparatus that can control the flow rate of the viscous cementitious mixture, and can instantaneously modulate the flow rate. The single and/or twin screw extruders use shear force to generate pressure for this purpose. The extruder mechanism deposits the cementitious mixture in a viscous liquid form on a building platform by adding successive layers.
[00025] Furthermore, in accordance with a preferred embodiment of the present invention, the control apparatus includes a dispenser connected to the dispensation- head, a process controller coupled to the dispensation-head and a Computer Aided Design (CAD) system coupled to the process controller.
[00026] Fig. 1 illustrates an exemplary model 100 for constructing 3D concrete structures 1 using additive manufacturing technique, in accordance with an embodiment. The exemplary model for constructing 3D concrete structures 1 using additive manufacturing technique comprises of a concrete structure 101, secondary pump 102, telescopic arm 103, a stepper motor 104, a gantry 105, and a progressive cavity pump 106. The secondary pump 102 can be any positive displacement pump that includes but is not limited to an auger pump, a screw pump and so on. The stepper motor 104 is provided for arm actuation. The telescopic arm 103 is attached to the gantry 105 for moving the pump 102. Further, the telescopic arm 103 is provided for moving the secondary pump in three-dimensional (X, Y, & Z) direction using linear actuators and stepper motors 104. The progressive cavity pump 106 is provided to transfer the cementitious mixture to the secondary pump 102.
[00027] Fig. 2 illustrates an exemplary model of an auger pump 102, in accordance with an embodiment. The auger pump or secondary pump 102 comprises of a hopper 201, a barrel 202, a nozzle 203, a stepper motor 104, an auger screw 205 and a clamping plate 206. The auger pump works on the principle of positive displacement pump. The hopper 201 is an expanding cavity provided in the auger pump 102 at the suction side. The nozzle 203 is a discharge side cavity through which the cement mixture flow out to form layers in the concrete structure 101. In the barrel 202, the cement mixture from the hopper 201 can be mixed evenly. The barrel can transfer the cement mixture to flow through the nozzle 203 according to the displacement of the auger screw 205. The auger screw 205 can be activated by the stepper motor 104. Further, the clamping plate 206 is provided for attaching the auger pump 102 on to the telescopic arm 103.
[00028] According to the embodiment, the secondary pump 102 can control and regulate the flow rate of the cementitious mixture from the nozzle 203. A positive displacement pump 102 has an expanding cavity on the suction side and a decreasing cavity on the discharge side. The cementitious mixture flows into the secondary pump 102 as the cavity on the suction side expands and the mixture flows out of the discharge as the cavity collapses. The secondary pump 102 handles the viscous cementitious mixture at high flow rates and a high discharge pressure, while maintaining a smooth flow.
[00029] Exemplary method for manufacturing a three-dimensional model using additive manufacturing is described with reference to Fig 3. The methods are illustrated as a collection of operations in a logical flow graph representing a sequence of operations that can be implemented in hardware, software, firmware, or a combination thereof. The order in which the methods are described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the methods, or alternate methods. Additionally, individual operations may be deleted from the methods without departing from the spirit and scope of the subject matter described herein. In the context of software, the operations represent computer instructions that, when executed by one or more processors, perform the recited operations.
[00030] In accordance with a preferred embodiment of the present invention, a method for manufacturing a three-dimensional model using additive manufacturing. The method includes the steps of:
- positioning a dispensation-head to a first pre-selected position;
- having a nozzle along a longitudinal axis;
- selectively dispensing interface material in layers from the dispensation-head;
- re-positioning the dispensation-head to a subsequent layer; and
- repeating the step of selective dispensing.
[00031] The second pre-selected position is displaced axially along the longitudinal axis from the first pre-selected position. The method further includes the step of: selectively adjusting the output from the nozzle to control the flow rate of cementitious mixture dispensed from the nozzle.
[00032] Fig. 3 illustrates the method 300 for constructing 3D concrete structures 1 using additive manufacturing technique, in accordance with an embodiment. The method for constructing 3D concrete structures 1 using additive manufacturing technique comprising the steps of,
[00033] At block 301, the dispensation-head is positioned to a first pre-selected position for constructing the 3D cement structure;
[00034] At block 302, the dispensation-head is selectively started to dispense the interface material in the first layer;
[00035] At block 303, the dispensation-head is then re-positioned to a subsequent position.
[00036] At block 304, the dispensation-head is then started to selectively dispense the interface material in the subsequent layer.
[00037] At block 305, the height of the last deposited layer is compared with a reference level using a displacement sensor;
[00038] At block 306, the displacement sensor can check whether the required height is achieved or not;
[00039] At block 309, if the condition is true then the process may complete the construction of 3D structure;
[00040] At block 307, if the condition states false then the variation from the reference level is calculated and the difference or error signal can be sent to the stepper motor;
[00041] At block 308, the dispensing of the interface material from the nozzle is adjusted using the stepper motor; and after that, the process may continue to repeat the step from selectively dispensing interface material in the subsequent layer 304. The steps are repeated to obtain the desired 3D concrete structure 1.
[00042] According to an embodiment of the present invention, the method can provide the opportunities to save construction time and achieve a greater flexibility in design and functionality for large structural parts or even entire buildings. The method can enable the manufacturer to obtain a three-dimensional model of any proposed structure. The method substantially can reduce the cost and also can enhance the synchronization between the design process and manufacturing, resulting in lower product cost and improved product quality. Superior dimensional tolerances in the finished concrete structures can be achieved using this method as compared to the traditional methods of manufacturing concrete structures.
[00043] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
,CLAIMS:
1. An apparatus for additive manufacturing of a three-dimensional structure, the apparatus comprising:
a dispensation-head positioned to a first pre-selected position;
a nozzle (203) operatively coupled with said dispensation-head, said dispensation-head being configured to selectively dispense interface material in a first layer, wherein the dispensation-head is re-positioned to a subsequent position that is spaced from the first layer by a vertical distance, and wherein the vertical distance is equal to the thickness of a subsequent layer of dispensing material.
2. The apparatus of claim 1, wherein the apparatus for additive manufacturing comprises a flow rate control apparatus that controls flow rate of viscous cementitious mixture, and instantaneously modulates the flow rate.
3. The apparatus of claim 2, wherein the flow rate control apparatus comprises any or a combination of single and twin-screw extruders using shear force to generate pressure to modulate flow rate of said cementitious mixture.
4. The apparatus of claim 1, wherein the dispensation-head is attached to an XYZ positioning apparatus and controllably movable in X, Y and Z directions by one or more linear actuators.
5. A method for additive manufacturing of a three-dimensional structure utilizing a dispensation-head having a nozzle (203) along a longitudinal axis, the method comprising the steps of:
positioning the dispensation-head to a first pre-selected position (301);
selectively dispensing interface material in a first layer from said dispensation-head (302);
re-positioning said dispensation-head to a subsequent position (303);
wherein said subsequent position is spaced from the first layer by a vertical distance, said vertical distance being equal to thickness of a subsequent layer of dispensing material;
repeating said step of selective dispensing in the subsequent layer (304); and
repeating said steps of re-positioning and selective dispensing in the subsequent layer until the additive manufacturing of the three-dimensional structure is completed (309).
6. The method in accordance with claim 5, wherein the method further comprises the step of:
selectively adjusting output from the nozzle (203) during each dispensing step to control amount of a cement material dispensed from the nozzle (203), thereby to control the thickness of each layer.
7. The method in accordance with claim 5, wherein the method further comprises the steps of:
calculating variation from the first layer formed by the dispensation of the interface material (307); and
adjusting the dispensing of said interface material from the nozzle (308).
8. The method in accordance with claim 5, wherein the method further comprises the step of:
compensating for a variation in the thickness of each layer prior to depositing the subsequent layer by selectively adjusting the output from the nozzle during each dispensing step to control the amount of said cement material dispensed from the nozzle.
9. The method in accordance with claim 8, wherein the method further comprises the steps of:
comparing height of last deposited layer with a reference level (306);
calculating variation from said reference level (307); and
adjusting the dispensing of said interface material from the nozzle (308).