HIGH DENSITY PNEUMATIC TRANSPORT METHOD FOR USE IN POWDER OR GRANULAR MATERIAL AND SYSTEM FOR PRACTISING THE METHOD

Abstract: An improved method and the related system for pneumatically transporting a powder or granular material placed in an airtight storage container through a transport pipe in high density. Pressurized gas is being intermittently supplied to the airtight storage container (1) containing the material therein so as to take out of the container and a transport plug (16) is being synchronously fed into the base of the transport pipe (4), whereby the powder or granular material is successively formed into a long column inside the transport pipe and is pneumatically transported at very slow speed.

Description: Field of the Invention The present invention relates to an improved method of, and a system for, transporting a powder or granular material to a collector by the use of pressurised gas. The invention is more specifically, but not exclusively, related to the transportation of medicine tablets. Prior Art Figure 8 shows a conventional powder or granular pneumatic transport system. The system is of the kind in which, in use, a powder or granular material placed in an airtight storage container 100 is transferred from the container to a lower pipe 102a of a transport pipe 102 by gas supplied from a gas feed pipe 101. The material is formed into a plug shape by supplying pressurized gas from a pressure nozzle 103 disposed on the lower pipe 102a, and then the plug-shaped material is pneumatically transported inside an upper pipe 102c of the transport pipe 102 through an inclined pipe 102b and is finally received by a collector 104. One disadvantage of this arrangement is that when the powder or granular material is pneumatically transported along the pipe 102 in the form of a plug, clearance 106 is often formed between the plug-shaped material and the transport pipe 102 as shown in Fig. 9, with the result that the material A on the surface of the plug-shaped material 105 is transferred from the plug and the plug shape is broken. This eventually results in unsatisfactory transfer. Moreover, since the conventional system as described above transfers the plug-shaped material at an extremely high speed, for example several meters per second, the material undergoes strong shock forces when being received by collector 104, thus easily incurring severe damage or disintegration of the material. Futhermore, that effect causes another problem of mutual collision between the powder or granular materials inside the transport pipe 102. Accordingly, the application of this conventional method to the transport of materials, such as medicine tablets, of which high production quality is demanded tends to increase the number and rate of production defects in the product. It is accordingly, a primary object of the invention to provide a method capable of pneumatically transporting a powder or granular material in high density without imparting impulse to the material or causing segregation of the material. Another object of the invention is to provide an improved system capable of pneumatically transporting a powder or granular material without imparting impulse to the material or causing segregation of the material. Another object of the invention is to provide an improved system capable of pneumatically transporting a powder or granular material in high density efficiently without imparting impulse to the material or causing segregation thereof. Summary of the Invention In one aspect, the invention relates to a high density pneumatic transport method of pneumatically transporting a powder or granular material from an airtight storage container (1) to a collector (5) through a transport pipe (4) by the use of pressurized gas, the method comprising the steps of: supplying pressurized gas intermittently to said airtight storage container (1) containing a powder or granular material therein so as to take the material out of said container (1) and feed the material into said transport pipe (4); in the time between each successive supply of gas feeding a transport plug (16) into a base end of the transport pipe (4) so as to section the material, whereby the material is successively formed into a long column (P) at high density and transported to said collector (5) by the action of the gas on said plug (16) at a very low speed; and finally receiving the material which has been transported in the form of a long column (P) into said collector (5). Such a method is known from JP-A-54-67984. According to the invention the method is characterised in that hollow and elongated transport plugs are used, and in that the speed of the material is reduced at the terminal end of the transport pipe, such that the material is received in the collector (5) in a state of substantially gravitational fall. In another aspect, the invention relates to a high density transport system for transporting a powder or granular material by the use of pressurised gas the system comprising on airtight storage container (1); means for intermittently supplying pressurized air to said storage container; a collector (5) and a transport pipe (4) connecting said container (1) to said collector (5). Such a system is known from JP-A-54-67984. According to the invention the system is characterised in that the transport pipe (4) includes a horizontal pipe portion (42), a conical tube (9) disposed at the upstream end of said horizontal portion (42) with the caliber of the tube (9) increasing in the direction of transportation, and speed reduction means (10), disposed between the terminal end of said horizontal pipe portion (42) and said collector (5), for reducing the speed of the transported material such that the material falls into the collector (5) substantially under gravitational fall; and in that the system includes hollow elongated transport plugs (16) adapted to be fed into a base end of said transport pipe to section said material. The invention is suited for use with capsules, powder, granules, and other solid substances in addition to compression moldings such as medicine tablets, candies, electrical or electronic parts, ie materials which are required to have no cracks or chips. Brief Description of the Drawings Other objects and advantages of the invention will be apparent from the following description, the appending claims and the accompanying drawings, wherein: Fig. 1 is a schematic diagram of a preferred embodiment of the invention; Fig. 2 is a sectional view to an enlarged scale, illustrating the construction of a hollow elongated transport plug loading portion of the arrangement of Fig. 1; Fig. 3 (a), (b) are time charts explaining supply timing of transport gas and a transport plug, respectively; Fig. 4 shows an embodiment of transport plug; Figs. 5 and 5a show another embodiment of transport plug; Figs. 6, 6a and 6b show yet another embodiment of transport plug; Figs. 7 shows a long column formed in the transport pipe; Fig. 8 shows a conventional system; and Fig. 9 shows a plug formed of the powder or granular material in the conventional system. Detailed Description of the Invention A description will now be given of one embodiment of the invention with reference to the drawings. The embodiment shown herein uses pressurised air to transport medicine tablets. Fig 1 is a schematic diagram of the system of the invention. The numeral 1 designates an airtight storage container. Tablets supplied from compression molding 15 are received in the container 1 through a feeder 12. The tablets thus received in the container 1 are transferred into a transport pipe 4 by means of pressurised air supplied intermittently to the container 1 via an air feed pipe 3 by a gas supply means 2. In each time period between successive supplies of pressurised air, transport plug 16 (17), eg as shown in Figs. 4, 5 to 6b, is fed into the base end of the pipe 4. Fig. 2 shows the construction of a transport plug loading portion 6 formed at the base end of the pipe 4. The portion 6 has a loading opening 18a open at one end of a branch pipe 18 communicating with the pipe 4 extending from the container 1. The portion 6 illustrated is such that the plug is manually loaded, but the invention is not limited to the embodiment shown and may include a loading portion which is such as to permit automatic loading from a cassette containing a multiplicity of plugs therein which are to be transported by the pressurized gas. Figs. 3 (a), (b) are time charts explaining supply timing of pressurized gas and transport plugs, respectively. A plug is fed at the end of every period of supply of pressurized gas, and the next supply of air is carried out every time a sensor to be described later detects a plug disposed at a suitable position in the pipe 4. Referring again to Fig. 1, a feeder 12 is designed to feed tablets into the airtight storage container 1 by using a magnetic vibrator 13 which is driven to vibrate a hopper 11 containing tablets sent from compression molding machine 15. The container 1 is provided with a hopper 14 and is adapted to contain tablets fed from a feeder 12 by controlling a valve 14a disposed below the bottom of the hopper 14. The amount of tablets stored in the container 1 is detected by a level switch and when the level of tablets falls below a predetermined lower limit, the valve 14a is opened and at the same time the magnetic vibrator 13 is driven to start automatic feeding. The transport pipe 4 comprises a riser portion 41 rising at a suitable gradient from the airtight storage container 1 and a horizontal pipe portion 42 extending from the riser portion 41. The pipe 4 is provided at the initial end of the pipe portion 42 with a pipe 9 comprising a conical tube. At the terminal end of the portion 42 with an elbow-shaped pipe 10 which has a larger caliber than that of pipe 42 and is connected to a collector 5. The pipes 9 and 10 each constitute a speed reduction means, respectively. The speed reduction means 10 may be provided in various constructions other than the elbow-shaped pipe of the type described, such that the means can reduce the speed of a material which has been transported by pressurised air. Accordingly, besides the above mentioned construction, a pipe of simple construction such as, for example a perforated pipe may be employed. The horizontal pipe 42 is provided at a suitable portion with a sensor 8 for detecting the passage of the transport plug. The sensor 8 sends a detection signal to a controller 7 when it detects the plug 16 (17), and the controller 7, upon receipt of the signal, drives a gas supply means 2 to supply the next charge of pressurised air to the storage container 1 (see Fig. 3). The sensor 8 of the kind described is such as to be capable of discriminating between the material to be transported and the transport plug. For example, a color sensor may be used. The length of the transport pipe 4 may be left to users' discretion. In addition to the construction described above, a pressure booster 19 may be employed to compensate for reduced transport pressure in the pipe 4, when the pipe is long. Next, an embodiment of a hollow elongated transport plug used in the invention will be described. Fig. 4 shows an embodiment of the transport plug used in a transport pipe whose inlet and outlet caliber are substantially the same as those of a straight pipe (transport pipe). The plug 16 has a spool-like shape with a flat mushroomlike front portion 16a and a rear portion 16b. The front portion 16a is connected to a rear portion 16b by a stem 16d. Formed in about the centre of the rear portion 16b is a hollow hole 16c leading to the stem 16d. The outer peripheral edge of the front portion 16a is substantially the same as that of the rear portion 16b and the transport plug 16 is formed of a soft material such as silicone rubber and is so sized as to come in close contact with the inside surface of the transport pipe 4. The plug 16 is propelled along the inside of the pipe 4 by pressurised gas applied to the hollow hole 16c. Fig. 5 shows another embodiment of the plug used in a pipe (transport pipe) different in its inlet and outlet caliber. The plug 16 shown is similar in shape to that shown in Fig. 4, but the rear portion 16b is larger in diameter than the front portion 16a, so that when the plug 16 passes through a smaller caliber portion of the pipe, both the front portion 16a and the rear portion 16b are deformed so as to bring their peripheral edges into close contact with the inside surface of the pipe 4. Fig. 5a shows the transport plug 16 as seen from the rear side thereof. The transport plug 17 shown in Fig. 6 has a form similar to that of a badminton shuttlecock. The plug 17 has a plurality of rear feathers 17b made of thin Teflon (Teflon is a Trade Mark) material and formed like a petal and has a flat top, made of Teflon, in the head portion 17a. When the plug receives gas pressure from behind the rear feathers 17b, the feathers 17b being folded as shown in Fig. 6a, the feathers 17b are opened to come in close contact with the inside surface of the pipe 4 as shown in Fig. 6b and receive a propelling force. Further, a description will now be given of a transport method. Materials are taken out of the container 1 into the transport pipe 4 by supplying pressurized air from gas supply means 2. A transport plug 16 (17) is fed into a base end of the pipe 4 and pressurized air is supplied for a specified time by driving the gas supply means 2. The length supply time t of pressurized air into the container 1 is set to be of sufficient duration for a sufficient amount of powder or granular material to be fed into the transport pipe 4 to form a suitable length of a column. The next supply of pressurised air to move the plug 16 is commenced shortly after a detection signal from the sensor 8 disposed in a horizontal pipe portion 42 is generated. In this manner, the powder or granular material is taken in suitable amounts out of the storage container 1, passes through a riser portion 41 of the transport pipe 4, rises and thereafter reaches a horizontal pipe portion 42 accompanied with the transport plug 16 (17), whereupon the material is reduced in speed by means of a pipe 9 with a gradually enlarged outlet caliber disposed at the initial end of the horizontal pipe portion 42, before blocking up the horizontal pipe portion 42. Then, the material is pushed by the transport plug 16 (17) and is forcedly moved forward through the horizontal pipe portion 42, with the result that the material is formed into a long column material P inside the pipe 42 as shown in Fig. 7. The material P thus formed into a long column is transported intact at very low speed through the pipe 42 and is again reduced in speed by means of the speed reduction means 10 at the terminal end of the pipe 42 and finally falls into the collector 5 in the state of substantially gravitational free fall. The powder or granular material in the storage container 1 is successively sectioned by the plug 16 (17) on the principle described above and is transported at very low speed in the form of a long column until it finally drops into the collector 5 substantially gravitationally. Therefore, the material is not only free from impact but is also free from segregation while being pneumatically transported. In experiments conducted by the inventors, in the case of a transport pipe five meters in length, a column about one meter long was formed and the speed of transport was as very slow as 0.1 m/sec. It was also confirmed that there was no change in the speed of transport even in the case of a 20m transport pipe and that the length of a column was increased to about 5 meters. As is clear from the above description, since the method of the invention makes it possible to transport a powder or granular material in high density, namely in the form of a long column, through the horizontal upper pipe 42 at very low speed, there is no danger of giving an impact to the material or causing segregation while the material is pneumaticaly transported through the transport pipe 4. Therefore, according to the invention, the problem of producing cracks and chips which is inherent in the conventional pneumatic transport, may be completely solved. Accordingly, the method of the invention is suited for transporting tablets of medicine which need to be of high quality during production and compression moldings of specified shape. Consequently, it is not too much to say that the present invention securely provides industries with more substantial profit potentials in that the problem which is inherent in the conventional pneumatic methods has been completely solved. The invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description.

Claims: A high density pneumatic transport method of pneumatically transporting a powder or granular material from an airtight storage container (1) to a collector (5) through a transport pipe (4) by the use of pressurized gas, the method comprising the steps of: supplying pressurized gas intermittently to said airtight storage container (1) containing a powder or granular material therein so as to take the material out of said container (1) and feed the material into said transport pipe (4); in the time between each successive supply of gas, feeding a transport plug (16) into a base end of the transport pipe (4) so as to section the material, whereby the material is successively formed into a long column (P) at high density and transported to said collector (5) by the action of the gas on said plug (16) at a very low speed; and finally receiving the material which has been transported in the form of a long column (P) into said collector (5) characterised in that hollow and elongated transport plugs are used, and in that the speed of the material is reduced at the terminal end of the transport pipe, such that: the material is received in the collector (5) in the state of substantially gravitational fall. A high density transport system for transporting a powder or or granular material by the use of pressurised gas, the system comprising an airtight storage container (1); means (2,3) for intermittently supplying pressurized air to said storage container; a collector (5) and a transport pipe (4) connecting said container (1) to said collector (5) characterised in that the transport pipe (4) includes a horizontal pipe portion (42), a conical tube (9) disposed at the upstream end of said horizontal portion (42) with the caliber of the tube (9) increasing in the direction of transportation, and speed reduction means (10), disposed between the terminal end of said horizontal pipe portion (42) and said collector (5), for reducing the speed of the transported material such that the material falls into the collector (5) substantially under gravitational fall; and in that the system includes hollow elongated transport plugs (16) adapted to be fed into a base end of said transport pipe to section said material. A high density pneumatic transport system according to claim 2, characterized in that said said speed reduction means (10) comprises an elbow-shaped pipe with a larger caliber than that of said transport pipe (4). A high density pneumatic transport system according to claim 2 or 3, characterized in that said transport plug has a shape similar to that of a shuttle cock, comprising a front portion (17a) and a plurality of rearward extending feather-like members (17b). A high density pneumatic transport system according to claim 2 or 3, characterized in that said transport plug is of a spool-like shape with a flat mushroom-like front portion (16a). A high density pneumatic transport system according to claim 5, characterized in that said front portion (16a) and a back portion (16b) of the spool-like shape are of substantially the same diameter. A high density pneumatic transport system according to claim 5, characterized in that a back portion (16b) of said spool-like shape is of a diameter larger than a diameter of said front portion (16a). A high density pneumatic transport system according to any one of claims 2 to 7, characterized in that said transport plug is made of silicone rubber. A high density pneumatic transport system according to claim 4, characterized in that said transport plug is made of Teflon®.

Inventors: IWAMOTO, AKIKAZU, MORIMOTO, KIYOSHI, MORIYAMA, MASUO, SONODA, ATSUROH C/O OSAKA WORKS
Applicants: KABUSHIKI KAISHA MATSUI SEISAKUSHO, KYOWA HAKKO KOGYO CO., LTD.
Application year: 1987
Main classification: B65G53
IPC codes: B65G53