JP2006256854A - Screw feeder and screw with blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw feeder capable of stably discharging powder and grain and a screw with a blade. <P>SOLUTION: In this screw feeder 10, a screw shaft 4 with a terminal end 3 is fitted into a cylinder-like trough 2 having one end to which the powder and grain m is introduced and the other end at which a discharge port 1 is formed in such an attitude that the terminal end 3 faces the discharge port 1, and the screw shaft 4 is rotated to carry the powder and grain m from one end of the trough 2 to the discharge port 1. The carrying direction of the powder and grain m is aligned with the thrust direction of the screw shaft 4. Further, the powder and grain m carried to the discharge port 1 is discharged to the outside of the trough 2 through the discharge port 1 while being agitated properly by the blade 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a screw feeder capable of conveying a certain amount of granular material per predetermined time, and a bladed screw.

For example, a technique for accumulating powder particles in a hopper and discharging the powder particles from the hopper by a screw feeder provided at the lower portion of the hopper is well known. Further, in order to keep the mass of the powder particles discharged per predetermined time (hereinafter referred to as “discharge amount”) constant, negative feedback control may be performed on the rotational speed of the screw shaft of the screw feeder. In this case, if the discharge amount of the granular material is small in light of the target value, the rotational speed of the feed screw is increased, or if it is large in light of the target value, the rotational speed of the feed screw is decreased. Moreover, the technique of discharging | emitting a granular material from a hopper continuously and quantitatively is disclosed by the following patent document 1. FIG.
JP 2004-075250 A

  However, when the screw shaft rotates once, the distance at which the granular material can be conveyed corresponds to one pitch when the spiral blades formed on the peripheral surface of the screw shaft have an equal pitch. Alternatively, if the screw shaft has spiral blades of unequal pitch, this distance is determined by the pitch near the end of the screw shaft. Further, in the process of conveying the granular material, the mass, volume, or bulk specific gravity of the granular material conveyed while the spiral blade rotates once is not necessarily constant. For this reason, even if the screw shaft is continuously rotated at a constant speed, the discharge amount slightly varies every rotation of the screw shaft. For example, if the process of putting the granular material discharged from the trough per predetermined time into a bag or the like and then putting the granular material into another bag or the like is repeated, the granular material is put into a plurality of bags or the like. Although it can be subdivided, variation occurs in the internal volume of each bag.

  In addition, in order to perform negative feedback control of the rotational speed of the screw shaft, it is necessary to measure the discharge amount a plurality of times at intervals of time and monitor the discharge amount that changes every moment. However, because the variation in the discharge amount due to the attribute of the screw feeder makes it difficult to accurately find the relationship between the rotational speed of the screw shaft and the discharge amount, the above control is often not performed properly.

  Further, the above-mentioned Patent Document 1 has a structure in which waste plastics and the like can be appropriately diffused so that crushed materials such as waste plastics are not hardened by a so-called cross-linking phenomenon in the vicinity of the discharge port. That is, in the technique according to Patent Document 1, a discharge port opened downward is provided directly below the rectifying blade. According to this structure, the granular material falls from the trough through the discharge port before attempting to pass between the rectifying blades in the thrust direction of the screw shaft. From this point, the technique according to Patent Document 1 is not intended for the below-described action obtained when the granular material passes between the rectifying blades (blades). Therefore, the technique according to Patent Document 1 cannot stabilize the discharge amount of the granular material by suppressing the fluctuation range of several grams.

  Then, this invention is made | formed in view of said situation, and it aims at providing the screw feeder which can discharge | emit a granular material stably, and the screw with a blade.

  In the present invention, a trough having a granular material introduced at one end and a discharge port formed at the other end is internally provided with a screw shaft, and the screw shaft is rotated to thereby remove the granular material from one end of the trough. The screw feeder according to claim 1, wherein the discharge port is opened in a thrust direction of the screw shaft, protrudes in a radial direction of the screw shaft, and is separated from each other in a rotation direction of the screw shaft. A plurality of blades disposed inside the discharge port, and rotating the blade together with the screw shaft to convey the granular material from one end of the trough toward the discharge port; The granular material passes between the plurality of blades.

  Further, the present invention provides a screw shaft that conveys the granular material from one end of the trough to the discharge port by rotating in a trough having the granular material introduced at one end and the discharge port opened at the other end, A screw attached to the screw shaft near the discharge port and projecting in a radial direction of the screw shaft, the screw having a blade, wherein the screw shaft circulates at an equal pitch or an unequal pitch The blade includes a blade, and the blade has a dimension in a thrust direction of the screw shaft set to a length equal to or greater than a pitch of the spiral blade near the blade.

  Furthermore, the screw with a blade according to the present invention is characterized in that the screw shaft is provided with a spiral blade formed with an interval in which the powder particles are retained with respect to the blade.

  Furthermore, the screw with a blade according to the present invention is such that the screw shaft has a terminal end directed toward the discharge port, and the blade forms a blade row on an attachment / detachment piece that is detachably attached to the terminal end. It is characterized by that.

  According to the present invention, when a screw shaft is rotated in a trough having a granular material introduced at one end and a discharge port opened at the other end, the granular material can be conveyed from one end of the trough to the discharge port. Moreover, since the blade projecting in the radial direction of the screw shaft is arranged inside the discharge port, the powder can be stirred while being in contact with the blade immediately before the powder is discharged from the discharge port. As a result, even if the mass, volume, or bulk specific gravity of the granular material conveyed by the rotation of the screw shaft changes during conveyance of the granular material from one end of the trough to the discharge port, it reaches the blade in advance. Thus, it is possible to moderately mix the powder and the powder that has reached the blade, so that the fluctuation range can be reduced and the discharge amount can be stabilized.

  Therefore, when the granular material discharged from the discharge port per predetermined time is put into a bag or the like, for example, the content of the bag or the like is exactly proportional to the time when the granular material is discharged from the discharge port. Therefore, even when the process of putting the powder particles into the bags or the like is repeated to divide the powder particles into a large number of bags or the like, the contents of the individual bags or the like can be made constant. Such an effect is useful for packaging foods and the like in small sachets.

  Further, if the discharge amount is stabilized as described above, the relationship between the screw shaft rotation speed and the discharge amount can be found accurately in the process of negative feedback control of the screw shaft rotation speed. It becomes possible to quickly and accurately set a proportional constant for calculating the number of rotations of the screw shaft or a control constant such as an integration time.

  In addition, paying attention to the fact that the period of fluctuation of the discharge amount as described in the prior art coincides with the time interval of one rotation of the screw shaft, the dimension of the blade in the direction in which the granular material is conveyed is It is desirable to set the length equal to or greater than the pitch near the blade of the blade. In this case, the range of the fluctuation can be further reduced, and the discharge amount can be further stabilized.

  Also, during the process of transporting the granular material, only the portion that contacts the spiral blade of the granular material receives strong thrust, so the thrust that the spiral blade pushes the granular material toward the blade apparently increases or decreases. Will repeat. Therefore, if the spiral blades of the screw shaft are formed with an interval that allows the powder particles to stay in the blade, the fluctuation of the thrust is alleviated immediately before the powder particles reach the blade, and at the same time Can also be reduced. Thereby, since it is not necessary to press a granular material to a braid | blade with unstable force, the stirring of the granular material by a braid | blade is assisted and said effect can be achieved notably.

  Furthermore, if a blade row that is detachably attached to the end of the screw shaft is applied as the blade, the blade can be easily replaced. For example, if several blades with different dimensions or number of blades are prepared, the blades with the optimum specifications should be selected in consideration of the properties such as the angle of repose, granularity, or stickiness of the granular material. Can do.

  As shown in FIGS. 1 to 4, the screw feeder 10 is configured such that a screw shaft 4 having a terminal end 3 is connected to a cylindrical trough 2 in which a granular material m is introduced at one end and a discharge port 1 is provided at the other end. The powder m is transported from one end of the trough 2 to the outlet 1 by rotating the screw shaft 4 with the end 3 facing the end 1. Further, a blade 5 is attached to a location near the discharge port 1 of the screw shaft 4, and the granular material m conveyed to the discharge port 1 is trough through the discharge port 1 while being appropriately stirred by the blade 5. 2 is discharged to the outside. The screw shaft 4 to which the blade 5 is attached in this way is hereinafter referred to as “blade screw”.

  The conveyance direction of the granular material m coincides with the thrust direction of the screw shaft 4 as indicated by an arrow T in the drawing. The discharge port 1 is opened toward the thrust direction of the screw shaft 4. This means that the other end of the trough 2 may be used as the discharge port 1 as shown in the figure, but broadly means that the discharge port 1 is positioned ahead of the blade 5 in the conveying direction of the granular material m. Therefore, the granular material m may be guided below the trough 2 by using the discharge port 1 as an elbow or connecting a vertical pipe to the discharge port 1.

  One end (left side in the figure) of the screw shaft 4 is supported at an appropriate position of the trough 2 and is connected to a rotating machine M with a reduction gear. It is not essential that the screw shaft 4 has the end 3, and a portion corresponding to the end 3 may be further extended to the discharge port 1 side, and this portion may be driven by a rotating machine or the like. That is, the position at which the blade 5 is attached to the screw shaft 4 does not need to be the terminal end 3, and is not particularly limited as long as it is a location near the discharge port 1 of the screw shaft 4.

  Moreover, the screw shaft 4 forms the spiral blade 6 on the peripheral surface. The shape of the spiral blade 6 may be equal pitch or unequal pitch, but the illustrated spiral blade 6 has a specification of equal pitch. A dimension line P in FIG. 2 represents the distance per pitch of the spiral blade 6. The screw shaft 4 and the spiral blade 6 may be integrally formed by forging or the like, but the illustrated spiral blade 6 includes a plurality of spiral strips 61 provided at appropriate positions on the peripheral surface of the screw shaft 4. The support rod 62 is used. In addition, a plurality of spiral blades 6 may be formed on the screw shaft 4, and any type of screw shaft 4 can be applied to the screw feeder 10.

  The blade 5 is obtained by fixing one or more thin plate members 7 protruding in the radial direction of the screw shaft 4 to the peripheral surface of the screw shaft 4. When two or more thin plate members 7 are fixed to the peripheral surface of the screw shaft 4, the thin plate members 7 are arranged so as to be separated from each other in the direction in which the screw shaft 4 rotates. Although there is no limitation on the material, number of sheets, outer dimensions, thickness dimensions, or presence or absence of elasticity of the thin plate material 7, these conditions are as follows in the repose angle of the granular material m, or It is determined in consideration of graininess. Further, the thin plate material 7 may be welded or screwed directly to the screw shaft 4, but as shown in FIGS. 5 (a) and 5 (b), the six thin plate materials 7 are core materials. A blade row piece 9 fixed to the peripheral surface of the detachable piece 8 at a predetermined interval or an irregular interval may be detachably attached to the terminal end 3 of the screw shaft 4.

  In this case, a male screw not shown in the figure may be formed near the terminal end 3 of the screw shaft 4, and a female screw 81 formed on the detachable piece 8 may be screwed to the male screw. FIG. 6 illustrates a blade row piece 9 having eight thin plate members 7. Thus, if several blade row pieces 9 having different specifications are prepared, the blade row piece 9 having the optimum specification can be selected in consideration of the type or properties of the granular material m. Furthermore, if the hexagonal head 82 is formed on the discharge port 1 side of the detachable piece 8, a wrench inserted from the outside of the trough 2 through the discharge port 1 is hung on the hexagonal head 82 to rotate the detachable piece 8. I can stop it. For this reason, it is possible to easily replace only the blade 5 without removing the screw 20 with the blade from the trough 2.

  It should be noted that the present invention can be implemented in variously modified, modified, and modified forms based on the knowledge of those skilled in the art without departing from the spirit of the present invention. For example, FIG. 2 shows the length of the thin plate material 7 in the direction in which the granular material m is conveyed by the dimension t. The dimension t of one or all the thin plate members 7 is about 0.5 to 2 with respect to the distance (P) of one pitch of the spiral blade 6 when the spiral blade 6 of the screw shaft 4 circulates at an equal pitch. The length may correspond to the pitch range. Alternatively, when the spiral blades 6 of the screw shaft 4 circulate at an unequal pitch, the length corresponding to a range of about 0.5 to 2 pitches with respect to the pitch near the terminal end 3 of the spiral blade 6 may be used. .

  In the figure, the distance between the blade 5 and the spiral blade 6 is represented by a dimension d. The dimension d may be a width corresponding to an appropriate ratio with respect to the inner diameter of the trough 2 or a width corresponding to a range of about 0.5 to 2 pitches with respect to the pitch of the spiral blade 6. . Or you may make the braid | blade 5 and the spiral blade 6 approach, and may eliminate the space | interval between these.

  Further, in the above description, one screw shaft 4 is installed in one trough 2, but two or more screw shafts 4 may be installed in one trough 2 in series or in parallel. Further, the screw feeder 10 does not necessarily have to connect the blade row piece 9 to the screw shaft 4. For example, the blade row piece 9 may be supported as a single unit inside the discharge port 1, and the blade row piece 9 may be rotated at the same speed as the screw shaft 4 or a different speed by a rotating machine. The speed at which the screw shaft 4 is rotated is not limited.

  First, a discharge amount measurement test is performed using a device in which the blade 5 is removed from the screw shaft 4 applied to the screw feeder 10 shown in FIG. As the granular material m of the first example, a powdery synthetic resin with a repose angle of about 30 ° and a relatively good flow is prepared. This granular material m is put into the hopper h, and the screw shaft 4 from which the blade 5 has been removed is rotated while maintaining the rotational speed of 6 rpm. Thereby, the mass of the granular material m discharged | emitted from the discharge port 1 is measured for 60 second, and measurement of discharge | emission amount [g / s] of the granular material m per second is repeated every 1 second, These Are recorded as 60 data groups. The average value, standard deviation, and standard deviation% of 60 data groups are shown in Table 1 below.

  When the above measurement results are totaled, FIG. 7 is obtained. In the pie chart of the figure, one round is assigned to 60 seconds, and the distance from the center (point 0) in the radial direction is 0-8 [g / s] of the discharge amount of the granular material m. It is expressed as a range. And the discharge | emission amount of the granular material m per second measured every second is shown by the point in a circle, and each point is connected with the dotted line.

  Next, a measurement test is performed on the granular material m of the first example using the bladed screw 20 under the same conditions as described above. In this case, as shown in FIG. 2 and FIGS. 8A and 8B, the number of the thin plate members 7 constituting the blade 5 (the number of blades) is set to 8 as the screw 20 with the blade, and the individual thin plate members 7 are arranged. Those arranged at equal intervals of 45 ° to each other are applied. The dimension t of all the thin plate members 7 is a length corresponding to about one pitch with respect to a distance (P) of one pitch of the spiral blade 6 that circulates at an equal pitch. The distance (d) between the blade 5 and the spiral blade 6 is a width corresponding to 50 percent of the inner diameter of the trough 2 or about one pitch of the spiral blade 6.

  This is determined by paying attention to the fact that the fluctuation period of the discharge amount as described in the prior art coincides with the time interval of one rotation of the screw shaft 4. Specifically, in this embodiment, P = 30 mm, t = 40 mm, and d = 30 mm. Further, a gap is provided between the thin plate material 7 and the inner peripheral surface of the trough 2 to prevent the powder m from being caught. Although this gap is not essential, it is appropriate to set the dimension s of the gap to a range of 5 to 10 percent of the inner diameter of the discharge port 1. In this embodiment, s = 3 mm.

  When the granular material m of the first example is put into the hopper h and the bladed screw 20 is rotated, the granular material m is conveyed from one end of the trough 2 toward the discharge port 1. In this step, immediately before the powder m is discharged from the discharge port 1, the eight thin plate members 7 that are separated from each other in the direction of rotation of the bladed screw 20 are moved along the thrust direction of the screw shaft 4. Pass through. Then, when the granular material m comes into contact with the individual thin plate material 7 rotating together with the screw shaft 4, the granular material m is scraped by the individual thin plate material 7 and rotates around the screw 20 with the blade. While stirring.

  In addition, by providing a gap between the blade 5 and the spiral blade 6, the powder m can be retained between them to some extent. Thereby, the fluctuation of the force with which the spiral blade 6 tries to push the granular material m toward the blade 5, in other words, the fluctuation of the thrust that the granular material m receives from the helical blade 6 is alleviated and simultaneously the thrust is reduced. You can also. Therefore, the powder m need not be strongly pressed against the thin plate material 7 with an unstable force, so that the stirring of the powder m by the thin plate 7 as described above is assisted.

  Due to the above-described action, the mass, volume, or bulk specific gravity of the granular material m that is conveyed every rotation of the screw shaft 4 varies in the process in which the granular material m is conveyed from one end of the trough 2 to the discharge port 1. Even so, it is possible to satisfactorily mix the granular material m that has reached the individual thin plate material 7 constituting the blade 5 and the granular material m that has reached the individual thin plate material 7 thereafter. The fluctuation range of the emission amount can be reduced. This result is as shown by connecting the discharge amount of the granular material m per second indicated by dots every second in the pie chart of FIG. 7 by solid lines. That is, the solid line in FIG. 7 clearly shows that the discharge amount is stable as compared with the case where the screw shaft 4 without the blade 5 is applied (dotted line).

  Therefore, the discharge amount of the granular material m is accurately proportional to the time when the granular material m is discharged from the discharge port 1, and, for example, by repeating the step of charging the granular material into a bag or the like, When the granular material is subdivided into bags or the like, the internal volume of each bag or the like can be made constant. If stabilization of the discharge amount of the granular material m is realized, the rotational speed of the bladed screw 20 and the granular material in the process of negative feedback control of the rotational speed of the bladed screw 20 using, for example, a computer. Since the relationship with the discharge amount of m can be found accurately, the computer can quickly and accurately set a control constant such as a proportional constant or an integration time for calculating the number of rotations of the bladed screw 20. It becomes.

  First, the granular material m of the 2nd example which is a powdery synthetic resin with a repose angle of about 60 degrees or more with a comparatively poor flow is prepared. For this granular material m, a measurement test is carried out in the same manner as in Example 1 using an apparatus in which the blade 5 is removed from the screw shaft 4 of the screw feeder 10 shown in FIG. And the mass of the granular material m discharged | emitted from the discharge port 1 is measured for 60 second, and discharge | emission amount [g / s] of the granular material m per second is recorded for every second. This result is indicated by a dotted line in the pie chart of FIG. FIG. 9 shows the discharge amount per second by dots as in FIG. 7. Next, a measurement test is performed on the granular material m of the second example using the bladed screw 20 having the same specification as that of the first example. This result clearly shows that the discharge amount is stable as compared with the case where the screw shaft 4 not provided with the blade 5 is applied, as represented by the solid line in the pie chart of FIG. 9.

  First, the granular material m of the 3rd example which consists of a granular piece about 2-7 mm in diameter obtained by grind | pulverizing a synthetic resin lump is prepared. For this granular material m, a measurement test is carried out in the same manner as in Example 1 using an apparatus in which the blade 5 is removed from the screw shaft 4 of the screw feeder 10 shown in FIG. And the mass of the granular material m discharged | emitted from the discharge port 1 is measured for 60 second, and discharge | emission amount [g / s] of the granular material m per second is recorded for every second. This result is indicated by a dotted line in the pie chart of FIG. FIG. 10 shows the discharge amount of the granular material m per second by dots as in FIG.

  Next, a measurement test is performed on the granular material m of the third example using the bladed screw 20. In this case, a bladed screw 20 is used in which the number of the thin plate members 7 constituting the blade 5 is 6, and the individual thin plate members 7 are arranged at equal intervals of 60 °. Other conditions are the same as in the first embodiment. And the discharge amount of the granular material m discharged | emitted from the discharge port 1 is measured, putting the granular material m of a 3rd example in the hopper h, and rotating the screw 20 with a blade. This result clearly shows that the discharge amount is stable as compared with the case where the screw shaft 4 not provided with the blade 5 is applied, as represented by the solid line in the pie chart of FIG.

In the above Examples 1 to 3, the degree to which the discharge amount of the granular material m can be stabilized is shown numerically in Table 1 below. Table 1 compares the average value, standard deviation, and standard deviation% of the 60 data groups obtained for each of the weighing tests performed individually in Examples 1 to 3.

  INDUSTRIAL APPLICABILITY The present invention can be applied to the technical field of supplying all the granular materials in addition to being applicable to supply of granular solid fuel to a boiler or supply of granular synthetic resin to an extruder.

Sectional drawing of the screw feeder which concerns on embodiment of this invention. The side view of the screw with a blade concerning the embodiment of the present invention. (A) is sectional drawing which looked at FIG. 1 from the direction of arrow AA, (b) is the end elevation seen from the direction of arrow BB of FIG. The side view which fractured partially the screw with a blade concerning the embodiment of the present invention. (A) is sectional drawing of the cascade element applied to the screw feeder which concerns on embodiment of this invention, (b) is the end elevation. The end elevation which shows the modification of the blade row piece applied to the screw feeder which concerns on embodiment of this invention. The pie chart which shows the effect of the screw feeder concerning Example 1 of the present invention. (A) is an end view of the screw with a blade concerning Example 1 of the present invention, and (b) is the sectional view. The pie chart which shows the effect of the screw feeder which concerns on Example 2 of this invention. The pie chart which shows the effect of the screw feeder which concerns on Example 3 of this invention.

Explanation of symbols

1: Discharge port 2: Trough 3: Termination 4: Screw shaft 5: Blade 6: Spiral blade 9: Blade row piece 10: Screw feeder 20: Screw with blade m: Granule

Claims (4)

A trough having a granular material introduced at one end and a discharge port formed at the other end includes a screw shaft, and the screw shaft is rotated to convey the granular material from one end of the trough to the discharge port. A screw feeder,
The discharge port is opened toward the thrust direction of the screw shaft;
A plurality of blades protruding in the radial direction of the screw shaft and spaced apart from each other in the direction of rotation of the screw shaft are disposed inside the discharge port,
By rotating the blade together with the screw shaft, the granular material passes between the plurality of blades in the step of conveying the granular material from one end of the trough to the discharge port. Screw feeder. A screw shaft that conveys the granular material from one end of the trough to a discharge port by rotating in a trough with the granular material introduced at one end and the discharge port opened at the other end,
A bladed screw provided with a blade attached near the discharge port of the screw shaft and protruding in a radial direction of the screw shaft,
The screw shaft includes spiral blades that circulate at an equal pitch or an unequal pitch, and the blade has a dimension in the thrust direction of the screw shaft set to a length equal to or greater than the pitch of the spiral blade near the blade. A bladed screw characterized by   The screw with a blade according to claim 2, wherein the screw shaft is provided with a spiral blade formed with an interval for retaining the powder particles with respect to the blade.   5. The screw shaft according to claim 2, wherein the screw shaft has a terminal end directed toward the discharge port, and the blade forms a blade row on a detachable piece removably attached to the terminal end. The bladed screw according to any one of the above.

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