JP5576602B2 - Crushing device and pulverized powder ingress prevention structure - Google Patents

Description

  The present invention relates to a crushing device (or crushing device) for crushing a plastic material and the like and a pulverized powder intrusion prevention structure for preventing the pulverized powder from entering a bearing portion thereof.

At the time of molding a plastic product, the path for injecting the molten resin material into the mold is also solidified and taken out and separated from the product. The solidified portion of this path is called a sprue runner, and after being pulverized by a pulverizer or the like, it is mixed into virgin pellets and reused as a recycled material. What is pulverized by the pulverizer is called a pulverized material. Many of these pulverizers are, for example, as shown in Patent Document 1 below, a main body casing that forms a pulverization tank, and a substantially horizontal and rotatable support in the pulverization tank, and a pulverization blade is formed on the surface. A rotating blade, a bearing that supports the rotating shaft, a fixed blade having a notch blade portion through which the grinding blade can pass, and a guide plate that prevents the object to be ground from falling, When the pulverizing blade passes through the fixed blade, the object to be pulverized is pulverized.
JP 2006-122798 A

  By the way, when the object to be pulverized is pulverized, small slices and powdered pulverized powder are always generated in addition to the grains cut into a predetermined size depending on the size of the pulverizing blade. In recent years, there are many resin materials containing glass fibers and the like, and when these materials enter the bearing portion as pulverized powder, they cause various problems such as wear in a short period of time. Therefore, in order to protect the bearing from the generated pulverized powder, a side plate or a side plate and a seal ring are provided between the pulverizing blade and the bearing. In the example shown in FIG. 5 (A), the end portion of the rotary shaft 18 provided with the grinding blade 20 on the surface penetrates the through hole 16A provided in the side surface 12A of the main body casing and is supported by the bearing 30A. Between the bearing 30A and the end face 20A of the pulverizing blade 20, a side plate 200 including a flange portion 202 and a cylindrical portion 204 is provided. In the example shown in FIG. 5B, a seal ring 220 is provided in addition to the side plate 210 including the flange portion 212 and the cylindrical portion 214 having the step portion 216.

  However, in the technique using the side plate 200 or the side plate 210 and the seal ring 220 as described above, the side plates 200 and 210 and the seal ring 220 are located inside the through hole 16A. It has a structure that rotates together with the grinding blade 20 (rotating shaft 18). For this reason, a clearance (clearance) S is required between the inner peripheral surface of the through hole 16A and the side plate 200, or between the side plate 210 and the seal ring 220, and the pulverized powder enters the bearing 30A side. There is a disadvantage that it cannot be completely prevented. The pulverized powder that has entered the bearing 30A side not only causes damage to the bearing, but also flows back into the pulverizing tank when the object to be pulverized is different in material and color from that of the pulverized object. It may be a cause of defects.

  The present invention focuses on the above points, and its purpose is to provide a pulverizing apparatus capable of preventing the pulverized powder generated during pulverization from entering the bearing and a pulverized powder intrusion preventing structure thereof. is there.

In order to achieve the above object, the pulverized powder intrusion prevention structure of the pulverizing apparatus according to the present invention has a pulverizing blade formed on the surface excluding the end portion, and the end portion rotates through the through hole of the main body casing forming the pulverizing tank. A pulverized powder intrusion preventing structure of a pulverizing apparatus in which the end portion is supported by a bearing so that the shaft is substantially horizontal and rotatable in the pulverizing tank, and is positioned between the pulverizing blade and the bearing. A side plate that has a cylindrical portion that is attached to the outer peripheral surface of the rotary shaft, and a flange that has one main surface that is in close contact with substantially the entire axial end surface of the crushing blade, and rotates together with the rotary shaft; in close contact with both the inner peripheral surface of the other main surface of the flange portion of the side surface plate through hole of the main body casing, a substantially ring-shaped sealing member which does not rotate together with the rotary shaft, the seal member is rotated together with the rotating shaft Anti-rotation means for preventing Cage, wherein the seal member is made of resin, by providing a mechanism to push the outer diameter of the seal body radially, close contact with the inner peripheral surface of the through hole of the outer peripheral surface and the main casing of the seal body It is characterized by making it.

One of the main forms is characterized in that the seal body is brought into close contact with the flange portion of the side plate by using an elastic body that applies a load in the axial direction of the rotating shaft .

In another embodiment, a gap is provided between the inner peripheral surface of the seal body and the cylindrical portion of the side plate, and between the outer peripheral surface of the flange portion of the side plate and the inner peripheral surface of the through hole of the main body casing. It is characterized by that.

  A pulverizing apparatus according to the present invention includes the pulverized powder intrusion prevention structure according to any one of the above. The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

  The present invention suppresses the ingress of pulverized powder and rotates together with a rotating shaft, and prevents the pulverized powder from entering by adhering to the side surface plate and the inner peripheral surface of the through hole of the main body casing. A seal body that does not rotate with the shaft is provided between the grinding blade on the surface of the rotating shaft and the bearing. For this reason, the side plate protects the sealing body and suppresses the entry of pulverized powder, and the sealing body closes the axial and radial gaps of the rotating shaft, so that the pulverized powder from the pulverizing blade side to the bearing side The effect of completely preventing the entry of can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

  First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a view showing a crushing apparatus of the present embodiment. (A) is a plan view of the main part cut along the rotation axis and viewed from above, and (B) shows the above (A). It is sectional drawing cut | disconnected along the A- # A line and seeing in the arrow direction. FIG. 2 is an enlarged cross-sectional view of the pulverized powder intrusion prevention structure, and FIG. 3 is an exploded perspective view of the pulverized powder intrusion prevention structure.

  First, the configuration of the crusher 10 will be described with reference to FIG. In the pulverizing apparatus 10, a pulverization tank 14 is formed by a main body casing 12, and between the opposing side surfaces 12 </ b> A and 12 </ b> B of the main body casing 12, the pulverization apparatus 10 is substantially horizontal and rotatable in the pulverization tank 14. A rotating shaft 18 having a crushing blade 20 and a claw 22 on its surface is provided. The rotating shaft 18 has a pair of bearings 30A and 30B fixed to the main body casing 12 with both end portions where the crushing blade 20 is not formed passing through the through holes 16A and 16B provided in the side surfaces 12A and 12B. It is rotatably supported. The rotating shaft 18 is rotatable by transmitting the rotation of a speed reducer 24 provided outside the main casing 12.

  In the crushing tank 14, a fixed blade 26 in which a notch blade portion (not shown) through which the crushing blade 20 and the claw 22 can pass is formed at a position opposed to the crushing blade 20, and crushing A guide plate 28 for preventing the object to be crushed before falling down is fixed so as to form an inclined surface, and when the pulverizing blade 20 passes through the fixed blade 26, the pulverization is performed. The object is crushed. In the present embodiment, in such a pulverizing apparatus 10, pulverized powder intrusion preventing structures 50A and 50B are provided between the axial end surface 20A of the pulverizing blade 20 and the bearings 30A and 30B.

  The pulverized powder intrusion prevention structures 50A and 50B will be described in detail with reference to FIGS. 2 and 3 illustrate one of the pulverized powder intrusion prevention structures 50A, the other pulverized powder intrusion prevention structure 50B has the same structure. The pulverized powder intrusion prevention structure 50A includes a side plate 52, a seal ring 70, a seal support 80, an O-ring 90, a seal ring presser 92, and a detent pin 38 provided on the bearing 30A. The bearing 30A is composed of a bearing body 32 having a through hole 34 and a bearing casing 36, and a plurality of detent pins 38 are provided at appropriate intervals on the end face of the cylindrical portion 36A of the bearing casing 36 (example shown in the figure). There are two).

  First, the side plate 52 is mounted on the outer peripheral surface of the rotary shaft 18 and includes a flange portion 54, a cylindrical portion 56, and a through hole 60, and is formed of, for example, metal. The through hole 60 is formed with a key groove 62 that can be fitted to a convex key 18A provided on the outer peripheral surface of the rotary shaft 18, and by fitting the key groove 62 and the key 18A, The side plate 52 can rotate together with the rotary shaft 18. One end surface 54A of the flange portion 54 can be in close contact with the end surface 20A of the crushing blade 20, and the outer peripheral surface 54C is rotationally frictioned between the inner peripheral surface of the through hole 16A of the main body casing side surface 12A. It is formed in such a size as to form a clearance (clearance) S1 for reducing the resistance. When the metal side plate 52 and the metal main body casing 12 come into contact with each other, metal powder may be generated and mixed into the product. However, by providing the gap S1, such a problem can be prevented. . Further, the cylindrical portion 56 is provided with a step portion 58, and the step portion 58 is formed with a plurality of screw holes 64 at appropriate intervals into which screws 98 for tightening seal ring pressers 92 to be described later are screwed. Has been.

  The seal ring 70 is for preventing the pulverized powder from entering from the pulverizing blade 20 side to the bearing 30A side, and is formed in a substantially ring shape having a through hole 72 and a stepped portion 74. It can be in close contact with both the main surface 54B of the face plate flange 54 and the inner peripheral surface of the through hole 16A. The inner peripheral surface 70B of the seal ring 70 is set to a dimension that forms a gap S2 (see FIG. 2) between the inner peripheral surface 70B and the outer peripheral surface of the cylindrical portion 56 of the side plate 52. The gap S2 is for reducing rotational frictional resistance and avoiding excessive thermal expansion. Further, the main surface of the seal ring 70 on the bearing 30A side is provided with recesses 76 (two locations in the illustrated example) for receiving the detent pin 38. As such a seal ring 70, for example, resin is used, and in this embodiment, particularly, a resin having thermal expansibility is used to achieve close contact with the inner peripheral surface of the through hole 16A.

  The seal support 80 includes a flange portion 82, a cylinder portion 84, and a through hole 86. When the O ring 90 is attached to the outer peripheral surface of the cylinder portion 84 and overlaps the seal ring 70, the seal ring 70 is provided. The O-ring 90 is sandwiched between the step portion 74 and the flange portion 82 of the seal support 80. In addition, a hole 88 through which the detent pin 38 can pass is formed in the flange 82 at a position corresponding to the recess 76 of the seal ring 70. The seal ring retainer 92 has a substantially ring shape that can come into contact with the flange portion 82 of the seal support 80, and has a through hole 94. The seal ring 70 is attached to the side plate 52 through the seal support 80. A plurality of screw holes 96 to be screwed with screws 98 for tightening are provided at appropriate positions. As a material for forming the seal support 80, for example, a resin is used. In this embodiment, the O-ring 90 is used as an elastic body for bringing the seal ring 70 into close contact with the side plate 52. However, other known elastic bodies such as rubber and wave washers are used. It may be. As the seal ring presser 92, for example, metal is used.

  Next, the operation of this embodiment will be described. In each of the above-described parts, for example, first, the seal ring 70 is fitted to the side of the flange main surface 54 </ b> B of the side plate 52, and then the seal support 80 in which the O-ring 90 is mounted on the cylindrical part 84 is overlaid on the seal ring 70. Fit like so. Next, the seal ring retainer 92 is placed on the stepped portion 58 of the side plate 52, the screw hole 64 of the stepped portion 58 and the screw hole 96 of the seal ring retainer 92 are aligned, and the screw 98 is screwed together. The seal ring 70 is brought into close contact with the flange main surface 54 </ b> B of the side plate 52 using the elastic force of the O-ring 90. The side plate 52, the seal ring 70, the seal support 80, the O-ring 90, and the seal ring presser 92 assembled as described above are aligned so that the key groove 62 of the side plate 52 and the key 18A of the rotary shaft 18 are aligned. Attached to the end of the rotating shaft 18. Then, the detent pin 38 is inserted into the recess 76 of the seal ring 70 and the hole 88 of the seal support 80 to mount the bearing 30A. The other crushed powder intrusion prevention structure 50B is assembled in the same manner.

  In the pulverizing apparatus 10 to which the pulverized powder intrusion prevention structures 50A and 50B assembled as described above are attached, the O-ring 90 is crushed by tightening the seal ring presser 92 with the screw 98. A load is applied to the seal ring 70, and the seal ring 70 can be continuously brought into close contact with the flange main surface 54 </ b> B of the side plate 52. Further, since the seal ring 70 and the seal support 80 are made of resin and are fixed so as not to rotate by the anti-rotation pin 38 of the bearing casing 36, the seal ring 70 which is in close contact with the side plate 52 has rotational friction. Causes frictional heat. Since the resin seal ring 70 having a higher coefficient of thermal expansion than metal expands due to this frictional heat, the inner peripheral surface of the through-hole 16A of the main casing 12 and the outer peripheral surface 70A of the seal ring 70 are connected to each other. Even if a gap is generated due to processing accuracy, the gap is completely closed by thermal expansion, and the intrusion of pulverized powder is prevented. A gap S2 is provided between the inner peripheral surface 70B of the seal ring 70 and the inner peripheral surface 80A of the seal support 80 and the outer peripheral surface of the side plate cylinder portion 56, and the outer peripheral surface 54C of the side plate flange portion 54 and the penetrating holes are provided. Since the gap S1 is provided between the inner peripheral surfaces of the holes 16A, the rotational frictional resistance is reduced and excessive thermal expansion is avoided.

Thus, according to the first embodiment, there are the following effects.
(1) The side plate 52 that suppresses the ingress of pulverized powder and rotates together with the rotary shaft 18 and the side plate 52 and the inner peripheral surface of the through holes 16A and 16B of the main body casing 12 are in close contact with each other to prevent the crushed powder from entering. The seal ring 70 that does not rotate with the rotary shaft 18 by the rotation prevention pin 38 is provided between the grinding blade 20 and the bearings 30A and 30B. For this reason, the side plate 52 protects the seal ring 70 and suppresses the ingress of pulverized powder, and the seal ring 70 closes the axial and radial gaps of the rotary shaft 18 from the side of the pulverization blade 20 to receive a bearing. It is possible to completely prevent the pulverized powder from entering the 30A and 30B sides.

(2) Since the O-ring 90 capable of applying a load in the axial direction is provided, even if the seal ring 70 is worn due to rotational friction with the side plate 52, the close contact state can be maintained.
(3) A clearance S1 is provided between the flange outer peripheral surface 54C of the side plate 52 and the inner peripheral surface of the through hole 16A, and the outer peripheral surface of the cylindrical portion 56 of the side plate 52 and the inner peripheral surface of the seal ring 70 and the seal support 80. Since the clearance S2 is provided between the surface and the surface, the rotational frictional resistance can be reduced.
(4) Since the seal ring 70 is thermally expanded by frictional heat, the inner peripheral surfaces of the through holes 16A and 16B and the outer peripheral surface 70A of the seal ring 70 are brought into close contact with each other. Even if a gap due to accuracy occurs, it is possible to prevent the pulverized powder from entering by closing the gap.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. In addition, the same code | symbol shall be used for the component which is the same as that of Example 1 mentioned above, or respond | corresponds. 4A is an enlarged cross-sectional view showing the pulverized powder intrusion prevention structure of the present embodiment, and FIGS. 4B-1 and 4B-2 show the close contact mechanism between the seal ring and the main body casing. It is a cross-sectional enlarged view. In the above-described embodiment, the thermal expansion of the seal ring 70 is used to achieve close contact with the inner peripheral surface of the through hole of the main body casing. However, in this embodiment, the outer periphery of the seal ring is arranged in the radial direction. This is an example in which a mechanism for spreading the film is provided.

  The pulverized powder intrusion prevention structure 100 according to this embodiment includes a side plate 52, a seal ring 102, a seal ring presser 110, anti-rotation pins 116 and 120, and a spring 122. The configuration of the side plate 52 is the same as that of the first embodiment. The seal ring 102 is substantially ring-shaped, and one main surface 102A is in close contact with the flange main surface 54B of the side plate 52, and the other main surface 102B has an outer periphery shown in FIG. ) And a plurality of recesses 106 are formed on the inner peripheral side. Similar to the first embodiment, the seal ring 102 is formed of resin.

  Next, the seal ring presser 110 is formed in a substantially ring shape from resin, metal, or the like, and has a tapered convex surface 112 inserted into the groove 104 of the seal ring 102 on the outer peripheral side of one main surface 110A. Is provided. As shown in FIG. 4 (B-1), the convex surface 112 is formed to have a taper larger than the groove 104 of the seal ring 102. By fitting the convex surface 112 into the groove 104, the seal ring The outer peripheral surface 102 </ b> C of the main body casing 12 can be spread and the gap between the through-hole 16 </ b> A of the main body casing 12 and the inner peripheral surface can be closed. A through hole 114 is provided on the inner peripheral side of the seal ring presser 110 through which a rotation prevention pin 116 that fits into the recess 106 of the seal ring 102 passes.

  Further, on the outer peripheral side of the other main surface 110 </ b> B of the seal ring presser 110, a concave portion 118 is formed in which a detent pin 120 fixed to the cylindrical portion 36 </ b> A of the bearing casing 36 is fitted. A spring 122 is attached to the outer peripheral surface of the rotation prevention pin 120, and when the spring 122 contacts the main surface 110 </ b> B of the seal ring presser 110, an axial load is applied to the seal ring presser 110. It can be transmitted to the seal ring 102 via the contact hole, and the seal ring 102 can be kept in close contact with the side plate 52. At the same time, the convex surface 112 of the seal ring presser 110 is inserted into the groove 104 formed in the seal ring 102, so that the outer periphery of the seal ring 102 is expanded as shown by the broken line in FIG. Thus, the gap between the inner peripheral surface of the through hole 16A of the main body casing 12 and the outer peripheral surface 102C of the seal ring 102 can be completely closed. As a result, even if a gap due to the processing accuracy between components is generated on the inner peripheral surface of the through hole 16A and the outer peripheral surface 102C of the seal ring, the gap can be completely eliminated.

  Thus, according to the second embodiment, the seal ring 102 is brought into close contact with the side plate 52 via the seal ring presser 110 by the spring 122 attached to the rotation prevention pin 120 of the bearing casing 36. At the same time, the gap between the outer peripheral surface 102C of the seal ring and the inner peripheral surface of the through-hole 16A is closed by inserting and pushing the convex surface 112 provided on the seal ring presser 110 into the groove 104 provided on the seal ring 102. Therefore, the same effect as in the first embodiment can be obtained. Also in this embodiment, a gap S1 is provided between the flange outer peripheral surface 54C of the side plate 52 and the inner peripheral surface of the through hole 16A, and the inner peripheral surface 102D of the seal ring 102 and the inner periphery of the seal ring presser 110 are also provided. The clearance S <b> 2 is provided between the surface 111 and the outer peripheral surface of the side plate cylinder portion 56 to reduce the rotational frictional resistance and suppress excessive thermal expansion, as in the first embodiment described above.

In addition, this invention is not limited to the Example mentioned above, A various change can be added in the range which does not deviate from the summary of this invention. For example, the following are also included.
(1) The shape and size of each part shown in the above-described embodiment is an example, and can be appropriately changed as necessary.
(2) The configuration of the pulverizing apparatus 10 shown in the above embodiment is also an example, and the design may be changed as necessary as long as the pulverized powder intrusion prevention structure of the present invention is provided.
(3) The O-ring 90 shown in the first embodiment and the spring 122 shown in the second embodiment are also examples, and other known various types can be used as long as a load can be applied to the side plate 52 in the axial direction. The elastic body may be used.

  (4) The above-described assembly procedure is also an example, and may be changed as appropriate to achieve the same effect.

(5) The method of tightening the seal ring presser 92 in the first embodiment is also an example. A screw portion is provided on the inner diameter side of the seal ring presser 92 and the outer peripheral surface of the cylindrical portion 56 of the side plate 52, and the seal ring presser You may change suitably so that there may exist the same effect, such as rotating 92 and tightening.
(6) In Example 2, the outer peripheral portion of the seal ring 102 is pushed and widened by the difference in taper between the groove 104 of the seal ring 102 and the convex surface 112 of the seal ring presser 110, but this is also an example. As shown in FIG. 4 (B-2), the design is appropriately changed so that the seal ring 102 is provided with a non-tapered groove 104A, and a tapered convex surface 112 is inserted into the groove 104A. Good.

  According to the present invention, the side plate that suppresses the intrusion of the pulverized powder and rotates together with the rotating shaft, the side surface plate and the through hole of the main body casing are in close contact with each other to prevent the pulverized powder from entering, and the rotation preventing means. The sealing body that does not rotate with the rotating shaft is provided between the end face of the grinding blade on the surface of the rotating shaft and the bearing. For this reason, it is applicable to the use of the pulverized powder intrusion prevention structure for preventing the pulverized powder from entering the bearing side from the pulverizing blade side. In particular, it is suitable as an application of a pulverized powder intrusion prevention structure for a pulverizer for pulverizing plastic materials and the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the grinding | pulverization apparatus of Example 1 of this invention, (A) is the top view which cut | disconnected the main part along the rotating shaft and looked at the whole from upper direction, (B) is said (A) #A -A cross-sectional view taken along line #A and viewed in the direction of the arrow. It is sectional drawing which expands and shows the pulverized-powder intrusion prevention structure of the said Example 1. FIG. It is a disassembled perspective view of the pulverized-powder intrusion prevention structure of the said Example 1. FIG. It is a figure which shows Example 2 of this invention, (A) is sectional drawing which expands and shows the pulverized-powder invasion prevention structure, (B-1) and (B-2) are the close_contact | adherence mechanism of a seal ring and a main body casing side FIG. It is a figure which shows an example of background art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Crushing device 12: Main body casing 12A, 12B: Side surface 14: Crushing tank 16A, 16B: Through-hole 18: Rotating shaft 18A: Key 20: Crushing blade 20A: End face 22: Claw 24: Reducer 26: Fixed blade 28: Guide plate 30A, 30B: Bearing 32: Bearing main body 34: Through hole 36: Bearing casing 36A: Tube portion 38: Non-rotating pin 50A, 50B: Ground powder intrusion prevention structure 52: Side plate 54: Gutter portion 54A, 54B: Main Surface 54C: Outer peripheral surface 56: Tube portion 58: Step portion 60: Through hole 62: Key groove 64: Screw hole 70: Seal ring 70A: Outer peripheral surface 70B: Inner peripheral surface 72: Through hole 74: Step portion 76: Recessed portion 80 : Seal support 80A: Inner peripheral surface 82: Gutter part 84: Tube part 86: Through hole 88: Hole 90: O-ring 92: Seal ring retainer 94: Through hole 96: Screw hole 98: Screw 100: Ground powder intrusion prevention structure 102: Seal ring 102A, 102B: Main surface 102C: Outer peripheral surface 102D: Inner peripheral surface 104, 104A: Groove 106: Concave portion 110: Seal ring retainers 110A, 110B: Main surface 111: Inner peripheral surface 112: Convex surface 114: Through hole 116, 120: Non-rotating pin 118: Concave portion 122: Spring 200, 210: Side plate 202, 212: Gutter 202A, 212A, 220A: Outer peripheral surface 204, 214 : Cylinder part 216: step part 220: seal ring S, S1, S2: gap

Claims (4)

A crushing blade is formed on the surface excluding the end portion, and the end is arranged such that a rotary shaft penetrating a through hole of a main body casing in which the end portion forms a crushing tank is substantially horizontal and rotatable in the crushing tank. The pulverized powder intrusion prevention structure of the pulverization apparatus, the part of which is supported by a bearing
A cylindrical portion mounted on the outer peripheral surface of the rotating shaft so as to be positioned between the pulverizing blade and the bearing, and a flange portion in which one main surface is in close contact with substantially the entire axial end surface of the pulverizing blade. A side plate that rotates together with the rotating shaft,
A substantially ring-shaped sealing body which is in close contact with both the other main surface of the flange portion of the side plate and the inner peripheral surface of the through hole of the main body casing and does not rotate with the rotating shaft;
Anti-rotation means for preventing the seal body from rotating with the rotary shaft;
With
The sealing body is made of resin,
By providing a mechanism for expanding the outer diameter portion of the seal body in the radial direction, the outer peripheral surface of the seal body and the inner peripheral surface of the through hole of the main body casing are brought into close contact with each other. Prevention structure. By the use of the elastic body for adding a load to the axial direction of the rotary shaft, pulverized powder entry preventing structure of the grinding apparatus according to claim 1, wherein the to adhere the seal member to the flange portion of the side plate. A gap is provided between the inner peripheral surface of the seal body and the cylindrical portion of the side plate, and between the outer peripheral surface of the flange portion of the side plate and the inner peripheral surface of the through hole of the main body casing. The structure for preventing pulverized powder from entering the pulverizing apparatus according to claim 1 or 2 . Milling apparatus comprising the pulverized powder entering prevention structure according to any one of claims 1-3.

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