| Title of Invention | SMART DOUBLE RIBBON SCREW MIXER |
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| Abstract | Present disclosure relates to a smart double ribbon screw mixer, which provides end relief to each ribbon as well as to both the vertical walls of the drum holding mixer shaft, without creating any dead spot. The outer ribbon has a straight ending at the last ribbon holder arm, while the inner ribbon finishes at mixer shaft, before touching the last ribbon holder arm. The inner and outer ribbons are designed with variable dimensions, especially with variable area of cross-section at various portions of the entire length of ribbons, wherever needed. |
| Full Text | Smart double ribbon screw mixer 1. Introduction: The proposed invention relates to a smart double ribbon screw mixer which has several novel and unique useful features. Due to substantial changes and innovative improvements in the design and dimensions of the ribbons applied in the mixer, the proposed device is almost a completely new and unique invention. The background of the invention, summary of the invention, detailed description of the invention with the help of certain drawings and finally claims about the proposed invention- every aspect of the invention is substantially mentioned below one-by-one. 2. Background of the Invention: In commercial world, certain horizontal mixers are used for homogenous mixing of bulk quantity of powdered materials or certain substances in granule form (like pulses, pebbles, sand, grain-splits etc). For mixing food grains and grains- splits, generally horizontal mixers of different power/capacity, with U- Shaped trough are used. A shaft, having blades, paddles or ribbons of different designs, is mounted inside the drum, which when rotates, perform mixing. Double ribbon screw mixer or double spiral mixer is also a type of horizontal mixer, being used in the industry to perform mixing. In such mixtures, two ribbons in helix shape are mounted at different pitch circle diameters in such a way that once the shaft starts moving, along with the rotational motion of inner and outer ribbons, the material in the drum moves in two opposite directions. Outer ribbon pushes the material in the drum in one direction, towards the vertical wall of the drum and the inner ribbon directs the material towards other opposite direction, i.e. towards another vertical wall of the drum. Thus, all types of materials present inside the mixer drum, becomes homogeneously mixed, within very small span of time. For effective mixing, the quantity of ingredients being pushed by outer ribbon towards say right side should be equally balanced by the inner blade, which pushes the ingredients, say towards left. 2.1 About the Conventional Design : It is a general fact about all horizontal mixers, especially double ribbon horizontal mixers that the design of mixing shaft decides the mixing accuracy — that is, rpm of shaft, pitch of ribbons, cross- section (surface area) of blades etc. Mechanical efficiency of the complete such instrument, depends on the type of gear box (helical or worm) being used--whether belt driven or directly coupled etc. Here only the mechanical losses inside the mixing drum are matter of consideration and not the mechanical efficiency of the machine, out side its mixing drum. The common conventional design of ribbons, all over the world, generally has following feature: a. Both the ribbons are of uniform breadth and cross-section. It means if a ribbon starts with say 2" width, it has same width throughout its helix till the end point. b. Both the ribbons start from 1st arm at one side (say in left) and end at last arm at other side of the shaft (say in right). c. Therefore, in any of the existing known double ribbon screw mixer, there is no provision of end relief at the sides of mixing drum. It means, ribbons start from one end of drum and continues till other end, and therefore, when they revolve pushing phenomenon, near the side-walls of the drum. 2.2 Due to above mentioned features of conventional double ribbon screw mixer they encounter several drawbacks/flaws, such as: • As they don't have end relief facility at the sides of mixing-drum, they produce considerable mechanical losses, in terms of energy and structural components. • The ribbons undergo frequent breakage. • The mechanical abrasion, generated near both the sides of walls of mixing drum, acts as prominent factor for quality degradation of several material (especially food), processed through mixing in such screw mixers. • Due to uniform breath of both types of ribbons, throughout their length, they do not have ability of fast carrying of materials, under mixing, from the regions near the sidewalls of the mixing drum, so that to reduce the excess pressure of materials, pushed towards the walls. 2.3 Object of the Invention: In light of above mentioned drawbacks of conventional double ribbon screw mixer, a new and improved screw mixer is proposed which can facilitate: • Better mixing due to: a) Provision of variable width for inner as well as outer ribbons; b) Provisions of end-relief with the help of straighter flat at the end of outer ribbon and by finishing the inner ribbon, before reaching the last arm on other end. At the same time, ribbons with variable width also support in this purpose. • Better product quality: It produce better quality of products due to proposed uniform environment for mixing in the mixing drum, as there is no mechanical abrasion near both the sidewalls, mounted with shaft. • Better energy management per unit mixing volume: It manages to save energy and its efficient and calculated use due to considerably minimized mechanical energy loss, as the proposed mixer has a provision for end-relives & ribbons with variable width/cross section. • Faster mixing process.: Because it allows much wider ribbons which means larger total area of working on material resulting fast mixing • Lesser mechanical loss/breakage in the ribbons and no frequent replacements of various parts/components of proposed machine. 3. Summary of the Invention:- The present invention is related with certain novel and very useful modifications in the design and method of installation of ribbons in the double ribbon screw mixer. Two ribbons, in helix shape, mounted with the shaft are chosen with variable width. It means if inner ribbon starts with 6" width from one end, it will be gradually decreasing and say 4" at the other end. These ribbons with variables width at various portions of each ribbons (generally increasing or decreasing width from one side to other side, along with its length) are installed on the mixing shaft, in such a way that both of them facilitate end relief at the region near the vertical wall of the drum. Actually due to movement of ribbons the materials, loaded in the mixing drum for homogenous mixing, start moving towards both opposite vertical walls of the drum. Suppose the outer ribbon, due to its rotational motion, pushes the material from left to right side wall of the drum and at the same time, the inner ribbon carries the material from right-side of the drum. In such continuous process of opposite movement, the material undergoing mixing as well as the components of the drum, namely ribbons, joints, walls of the drum etc., experience undue pressure. This unwanted pressure in the regions near the sidewalls of the mixing drum is reduced by proper installation of ribbons on the proposed invention, starts from one end of the drum (say in the left side), i.e. fixed at 1st arm of the mixing shaft, but not reaches the other end (say in right side) in same helix shape. Depending upon the size of drum, 174th or 1/2 of pitch length of the ribbon is straightened to give relief without making any dead spot. Actually a straight and flat stop acts, as the end part of material flow towards the right end of the drum. In the similar way the inner ribbon which stands suppose from right end of the drum and ends in the left side, is also provided with facility for end-relief, without causing any dead- spot. For this purpose, the inner ribbon starts from one end (say from right side's 1st arm) but does not reaches the other end (say to the left side's last arm or the shaft). Depending on size of drum, 174th or 1/2 of pitch- length of inner ribbon is kept missing. Actually in new design of the drum, the material, moving along with the inner ribbon, from right side to left side of the drum, falls freely down so that the outer ribbon carries it for next round of rotation. 3.1 Thus, the proposed modifications in the design of ribbons and therefore in the inside of the mixing drum of the proposed double ribbon screw mixer are:- 1. End relief is given at both the sides-walls of the drum, ensuring no dead spot too. a. Outer ribbon is provided with straighter flat at its end portion and it does not finish in the same helix shape. b. Inner ribbon is designed to start from that arm where outer ribbon finishes. But it is allowed to get finished without reaching other end, missing its 174th or 1/2 of pitch-length, depending on size of the drum. 2. Ribbons of the proposed invention are provided with variable width, throughout its length, especially with decrease/change in ribbon width from its starting point to its end-point. 4. Detailed Description of the Invention:- 4.1 Horizontal mixers: These mixers are used to mix homogenously different powders in a U-shaped trough. A shaft having blades, paddles or ribbons of different designs are mounted inside the drum, which when rotates performs mixing. 4.2 Double ribbon Screw mixer or a double spiral mixers are being used in the industry to perform mixing. In double-ribbon screwed mixer, two ribbons (see figure-1) in helix shape are mounted at different pitch circle diameters, which when rotates pushes the material towards opposite sides. First ribbon at outer side close to drum (at outer pitch circle diameter) pushes the material to one side (say right side), and second ribbon at inner side (between outer ribbon and shaft) pushes the material to other side (say left side). 4.3 How ribbons push ingredients: Principle:- Ingredients inside the mixer are pushed according to Newton's first law of motion which predicts: substance want to retain its position of rest or motion (Inertia) until external force act on it. When shaft rotates, the helical shaped ribbon will try to rotate the ingredients with it and if ingredients are slipped on ribbon surface these will be pushed along shaft towards sides of drum. Friction between surface of ribbon and ingredients affects amount of material being pushed. Ingredients pushed by Inner ribbon has only one friction surface i.e., between ingredients and ribbons, while Ingredients pushed by outer ribbon has two surfaces i.e., one between ribbon & ingredients and second between ingredients & inside surface of drum. The friction will depend on:- 1. Surface finish of ribbons & inside (and sides) of drum. 2. Type & characteristics of ingredients being mixed i.e. flow ability, particle size, cohesion & adhesion characteristics etc. 3. Formulation-Mixing of powders only or powders with liquids, oils etc.. For efficient mixing the quantity of ingredients being pushed by outer ribbon towards say right side should be equally balanced by the inner blade, which pushes the ingredients say left side. 4.4 Common Design:- The design of mixing shaft decides the mixing accuracy-i.e., rpm of shaft, pitch of ribbons, cross-section (surface are) of blades etc. Mechanical efficiency will depend on type of gear box (helical or worm) being used, whether belt driven or direct coupled etc. Here we are not considering the mechanical efficiency outside the mixing drum; we will take into consideration mechanical losses inside the mixing drum only. 4.5 The common design of ribbons all over the world is as follows:- 1. No. end relief is given at sides of Drum: It means ribbons start from one end of drum and continues till other end of drum (see Figure No.l). 2. Both Ribbons are of uniform cross-section:- It means if a ribbon starts with 2" width, it will be of same width throughout its helix till end (see Figure. No. 2). 4.6 Our modification in design of ribbons is as follows:- 1. End relief is given at sides of drum: a) Outer ribbon starts from one end of drum but not reach the other end in same helix shape, (see figures 3). Depending on size of drum, 174th or '/2 of pitch length of ribbon is straightened (flat is provided in place of helix) to give relief without making dead spot. Dead Spot:_lf a part of outer ribbon is removed at one end of mixer drum to give relief, ingredients in that corner of drum will not be moved either way, hence mixing variation will occur. b) Inner ribbon starts from one end but not reach the other end. Depending on size of drum, l/4th or 1/2 of the pitch length of ribbon is missing. 2. Ribbons are not of uniform cross-Section: It means if inner ribbon starts with 6" width from one end, it will be gradually decreasing and say 4" at the other end. 4.7Comparative Results of common design and our modified design:- (i) In common design, because no end relief is given on either ribbon, both the ribbons keep on pushing the material being mixed towards sides of the drum i.e. exerting undue pressure on sides of drum. This undue pressure on sidewalls directly wastes mechanical energy without performing any appreciable mixing. In proposed design due to relief provided in both the ribbons at the ends, wastage of energy is controlled considerably. (ii) When the movement of ingredients inside the mixing drum was analyzed, it was observed that the outer ribbon pushed the material towards right side. Ingredients then return back towards left side. If cross section (width) of inner blade was made wider (the proposed design) at start, it pushed extra ingredients from right to left to ease the return of ingredients from right to left. But if all the cross-section of inner blade was made wider till end (common design) it would imbalance the quantity of ingredients being pushed towards left resulting in more material pushed towards left and exerting undue pressure on left side of drum. So if inside ribbon cross-section was reduced gradually from left to right, it would help to let the material take a return from start easily (due to larger cross section) but at the end it would not exert any pressure on side walls. Similarly, variable cross-section (dimension/width) design works for outer ribbon also. 4.8 How much variation; How much variation in cross section is required depends on total volume of drum, characteristic of ingredients (which decides fiictional forces) etc. 4.9 Benefits of the proposed modifications; 1) Better mixing accuracy with considerable reduction in mixing time. 2) Reduction in power consumption per unit mixing volume. 3) Reduction in product degradation due to mechanical abrasion. 4) Problems of frequent breakage of ribbons/arms/ main shaft are greatly solved. 4.10 Discussion with help of certain schematic drawing with certain numerals, as symbols; Figure 1: Schematic front view of the internal arrangement of mixing shaft, arms and ribbons inside the mixing drum of conventional double ribbon screw mixer. Figure 2: (i) & (ii) represent the schematic segments of conventional outer ribbon and inner ribbon depicting their uniform width, throughout their total length. Figure 3: (i) & (ii) represent the schematic segments of proposed outer and inner ribbons, depicting their variable width, throughout their total length. Figure (4): Schematic front view of the internal arrangement of mixing shaft, arms and ribbons inside the mixing drum of proposed new double ribbon screw mixer. The meaning of several numerals, used in the drawing are mentioned below:- 1. Mixing shaft L. Left side-end/region of the mixing drum/shaft. R. Right side-end/region of the mixing drum/shaft. 2. 1st arm from left. 3. 1st arm from right 4. The contact point on the shaft or an arm, perpendicular to the arm 2. 5. Outer ribbon in conventional double ribbon screw mixer. 6. Inner ribbon in conventional double screw mixer. 7. Uniform width of the outer ribbon in the conventional double ribbon screw mixer. 8. Uniform width of the inner ribbon in the conventional double ribbon screw mixer. 9. Outer ribbon in proposed invention 10. Inner ribbon in proposed invention 11. Variable width dimension of the outer ribbon in proposed invention. 12. Variable width dimension of the inner ribbon in proposed invention. 13. Straight flat at the end in place of the helical outer ribbon in the proposed invention, which provides end-relief, without creating any dead area. 14. The wide portion of the inner ribbon of proposed invention, which is at the starting point of the ribbon, on arm 3. 15. The comparatively thinner portions of the inner ribbons of proposed invention, which are at their termination point, at 4, next to 2. 16. The enclosed region shows the absence of inner ribbons, in the proposed invention, missing at the end to give provide end to provide end-relief. 17. Depicts the thinner portion a schematic segment of proposed outer ribbon with variable 18. Depicts the wider portion of a schematic segment of proposed outer ribbon with variable width. 19. Depicts the thinner portion of a schematic segment of proposed inner ribbon with variable width. 20. Depicts the wider portion of a schematic segment of proposed inner ribbon with variable width. Figure-1 Depicts the schematic view of the inner region of the mixing drum of conventional double ribbon screw mixer. It shows the horizontal mixing shaft 1 of the mixing drum, mounted on the vertical & parallel walls of the drum. All the other components inside the drum are mounted on the shaft 1. There are a number of arms 2, mounted on the shaft 1. Actually arm 2 is the first arm from the left side (L) of the shaft 1 and there is arm 3, mounted as the first arm from right side (R) of the shaft 1. Numeral 4 represents either the contact point joint on the shaft 1 or the arm, which is at just perpendicular to those arms represented by 2 & 3. Outer ribbons, shown by 5, which start from arm 2, goes upto last arm 3 in the right side end R. Similarly inner ribbons, shown by 6, which start from arm 3 in right side end R, get finished on the last arm 2 in the left side end. Numeral 7 & 8 represent width of outer ribbons 5 and inner ribbon 6, respectively when the mixing shaft 1 rotates, ribbons 5 and 6 perform the mixing of materials present in the mixing drum. The helical shape and installation of these ribbons are such that they push the material in two opposite directions. The outer ribbons 5, say starting from arm 2 in left side end (L), push the material towards right side end (R) in the mixing drum. Again the inner ribbons 6, which suppose start at arm 3 in the right side end (R), carry the material from the end, near the vertical wall of the drum and start pushing towards the left side end (L). Thus the material inside the drum move in a specific fashion and gets homogeneously mixed. But the main problem arises at left side end (L) and right side end (R), regions close to vertical walls. Due to vertical walls in L & R sides, the moving material, continuously pushed by the ribbons 5 & 6, generate unwanted pressure, which not only damage the structural component of the mixing drum, namely ribbons 5,6, joints, walls etc. but also degrade the quality of the final product material. Figure-2 Shows small segments of outer and inner ribbons, in the conventional machine. In figure 2 (i) the outer ribbon 5 has uniform width, shown by numeral 7, throughout its length. Similarly in figure 2 (ii), the inner ribbon 6 has uniform width, shown by numeral 8. Figure-3 Shows the variable width of outer and inner ribbons, of the proposed smart double ribbon screw mixer. In figure 3 (i) there is a small segment of outer ribbon 9 of proposed invention, which has non-uniform width throughout its length. From the portion 18 towards portion 17 of ribbon 9, there is regular decrease in the width. Similarly figure 3 (ii) shows that from point 20, there is a continuous decrease/change in the width of the inner ribbon 10, till it reaches its end point 19. Thus the proposed modification in the width of ribbons prominently highlights the variable width dimension of the ribbon. Figure-4 Provides a schematic view about the proposed invention. It actually represents the complete from view of the inside of the region of the mixing drum. On shaft 1, the arms 2, 3, 4 etc are mounted in the same way as in figure 1. Numeral 9 represents the outer ribbons of the smart double ribbon screw mixer and numeral 10 represents the inner ribbons of the same. The outer ribbon 9 and outer ribbons 10 have variable width, as shown in figure 3. Not only the width, depending upon the needs (i.e. the ingredient of the materials to be mixed) the other structural parameters like thickness of the ribbon can also be varied. Therefore the term with broad meaning, dimension is applied here. In this figure, Numerals 11 &12 represent the variable width dimension of ribbons 9 & 10 respectively. The outer ribbons 9 have starting point at arm 2 in left side end (L) of the drum. Theses ribbons do not end in the right side end in the normal helical shaped ribbon, but they are straightened like flat strip 13. This straighter flat strip 13, at the end part of ribbon 9, provides the end relief at the right side end (R), near the vertical wall of the mixing drum, by simply disturbing and retarding the movement of the materials. The inner ribbons 10, start from the right side end (R) of the mixing drum. At arm 3 of side R, such ribbons 10/14 have very large width, in comparison to the subsequent parts in its length. Gradually the width of ribbons 10, decrease, as it moves left word. Ribbons 10, do not reach to the actual end point in the left side (L) of the drum, that is arm 2, and they terminate much before on the shaft 1 or on arm 4. In this way, there is creation of a void region 16, where there is no action of inner ribbons 10 actually takes place. Thus the material carried & pushed by the inner ribbon from right side to left side end, does not experience any force in region 16. In region 16, material just fall near the outer ribbon 9 and thus the ribbon 9 restart the mixing cycle for the material, by driving & pushing it from left side end (L) to right side end (R). At side R, the straighter flat strips 13, perform the action for end relief & minimize the mechanical abrasion and mechanical energy loss. We Claim 1. An smart double ribbon screw mixer which comprises with: a) Inner ribbon with variable width/dimension; b) Outer ribbon with variable width/ dimension; c) An straight flat strip as the end: part of outer ribbon; d) A horizontal shaft mounted on the parallel vertical walls of the mixing drum; and where, i) The said ribbons are installed on the said mixing shaft; ii) Inside the drum the said drum, near the said vertical walls, there is no dead area; and iii) Inside the said mixing drum, near the vertical walls, there are provisions of end-relief to the drum-components & the material under mixing. 2. An smart double ribbon screw mixer, as claimed in claim 1, wherein the said ribbons are not of uniform cross-section & width, especially that the width of said inner as well as said outer ribbons preferably undergo decrease/change throughout its length — starting from the starting point of the ribbon till its end point. 3. An smart double ribbon screw mixer, as claimed in claim 1, wherein the ribbons, with improved design, are parallel vertical on the mixing shaft mounted on the parallel vertical walls of the drum and are supported with arms & contact points/joints on the said shaft, in such a balanced and accurately calculated positions that the integration of inner ribbon, outer ribbon, shaft and arms from a single unit. 4. An smart double ribbon screw mixer, as claimed in claim 1, wherein the said outer ribbon starts from one end of the mixing drum but reaches the other end in the form of a straighten flat strip, in spite of its helix shape ribbon part. 5. An smart double ribbon screw mixer, as claimed in claim 1, wherein the said inner ribbon starts from that end of the mixing drum, where outer ribbon ends and finishes on the mixing shaft/arm, in the opposite direction, before reaching the end point/last arm of the shaft. 6. An smart double ribbon screw mixer, as claimed in claim1, wherein the inside region of said mixing drum has no dead area and has provisions for end-relief nor both the vertical walls, mounting the said horizontal shaft. 7. An smart double ribbon screw mixer, as claimed in claims 1, and 4, wherein the length of the outer ribbon, which is straighten as a flat strip, depends on the size of mixing drum, preferably lies between 1/4* to half of pitch length of the said outer ribbon. 8. An smart double ribbon screw mixer, as claimed in claims 1 and 5, wherein the total length of the inner ribbon depends on the size of the mixing drum and it finishes & preferably l/4th or half of its pitch length, before touching the end point of the shaft or last arm. 9. An smart double ribbon screw mixer, as claimed in claim 1 and 2, wherein the variation in width/dimension of ribbons depend on the total volume of mixing drum and characteristics of ingredient to be mixed (which decide the fictional force). |
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| Patent Number | 279572 | ||||||||
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| Indian Patent Application Number | 1544/DEL/2007 | ||||||||
| PG Journal Number | 05/2017 | ||||||||
| Publication Date | 03-Feb-2017 | ||||||||
| Grant Date | 25-Jan-2017 | ||||||||
| Date of Filing | 23-Jul-2007 | ||||||||
| Name of Patentee | SH. SATBIR SINGH | ||||||||
| Applicant Address | H NO.245, EAST BHATIA NAGAR, NEAR MOHAN BAKERI, YAMUNANAGAR-135 002 | ||||||||
Inventors:
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| PCT International Classification Number | C08F2/02; C08F2/44 | ||||||||
| PCT International Application Number | N/A | ||||||||
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