JP2011083920A - Granulating method and granulating apparatus of underwater cutting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a granulating method of an underwater cutting system having a long life of a die. <P>SOLUTION: In the granulating method of the underwater cutting system, at least one set of cutter heads 30, 30' for forward/reverse rotation are prepared. When granulation by the cutter head 30 for forward rotation is carried out for a predetermined time or when granulation of predetermined amount is carried out or when quality degradation of a shape of an obtained pellet is recognized, it is regarded that abrasion is caused at a specified part of a cured layer 11 of a dice surface and the cutter head 30 is exchanged for a cutter head 30' for reverse rotation and granulation is carried out by reversing a rotation direction of the cutter. Reverse rotation moves a position of abrasion to other and thereby life of the die 10 can be prolonged to about twice. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a state in which a molten resin continuously extruded in a strand form from an extrusion nozzle opened on the surface of a die is pressed against the surface of the die in a cutter chamber filled with temperature-controlled hot water. The present invention relates to an underwater-cut type granulation method and a granulation apparatus, in which pellets are obtained by continuous cutting with a cutter driven to rotate in a predetermined direction.

  A so-called underwater-cut granulation apparatus that obtains synthetic resin pellets by cutting a molten resin that is continuously extruded in a strand form into water from a die with a rotating cutter blade is well known in the art. It is structured as follows. That is, a cutter chamber to which water or hot water is circulated, a die that forms one side wall of the cutter chamber, a bearing casing that forms the other side wall, and a bearing casing that protrudes from the bearing casing into the cutter chamber. And a cutter holder attached to the tip of the cutter shaft, a plurality of cutter blades attached radially to the cutter holder, and the like. On the surface of the die facing the cutter chamber, a hardened layer is formed and raised in a donut shape. This hardened layer is formed from a wear-resistant alloy. A plurality of extrusion nozzles are opened on the surface of the die thus processed, and the cutter blade is rotationally driven while being pressed against the surface of the die with a predetermined pressure contact force.

  Therefore, for example, when hot water is circulated and supplied to the cutter chamber, the molten resin is continuously extruded from the extrusion nozzle into the hot water into the hot water, and the cutter shaft is driven to rotate in a predetermined direction, the molten resin is cut into pellets And sent to the separator along with hot water. The pellets separated from the hot water are dried to become a product. The hot water from which the pellets have been collected is appropriately processed and is circulated and pumped to the cutter chamber.

  When granulation is performed as described above, the cutter blade is worn because it is rotationally driven in a state of being pressed against the surface of the die at a predetermined pressure. When worn, a gap occurs between the surface of the die and the cutter blade, resulting in a cutting failure. Therefore, Patent Documents 1 and 2 propose a cutter blade adjustment method.

JP-A-6-297451 JP 2005-59411 A

  Patent Document 1 discloses an underwater cut granulating apparatus including a die for extruding molten resin and a cutter blade that is rotationally driven in a state of being in contact with the die at a predetermined pressure. This granulating apparatus is provided with a cutter blade feeding device, and the cutter blade advances and stops moving toward the die side by this device. Further, in Patent Document 2, in the underwater cut granulation apparatus as described above, the position of the cutter blade is detected to measure the amount of wear of the cutter blade, and the measured amount of wear is compared with the reference amount of wear. A cutter blade pressing pressure correction method for adjusting the pressure contact force of the cutter blade to the die based on the comparison result is shown.

  According to the invention described in Patent Document 1, when the cutter blade is worn and a gap with the die is generated, the cutter blade is moved forward toward the die, and the cutter blade and the die are brought into contact with each other. Can be recovered. Therefore, the relative positional relationship is automatically maintained without detecting the relative positional relationship between the cutter blade and the die. However, the wear in the above-described underwater-cut type granulating apparatus is generated not only on the cutter blade but also on the surface of the die, more precisely in the vicinity of the opening of the extrusion nozzle. More specifically, although the hardened layer is formed on the surface of the die so that it is difficult to wear, the die surface is driven by the mechanical friction because it is driven at a high speed while a plurality of cutter blades are pressed against each other. The vicinity of the opening of the extrusion nozzle is worn. In addition, since the cutter blade is rotationally driven at a high speed, it may cause problems such as turbulence and cavitation, but the die surface is locally worn. Such local wear tends to occur as a step on one side of the nozzle opening. That is, in the periphery of the nozzle opening on the surface of the die, the downstream side in the traveling direction of the cutter blade is worn, and there is a tendency that a step is generated in this portion. If such a wear step, that is, a dent, occurs, the product is adversely affected. Therefore, it is necessary to polish the hardened layer on the die surface until the dent disappears. However, the invention described in Patent Document 1 Is not considered. Further, the invention described in Patent Document 2 detects the amount of wear of the cutter blade and adjusts the pressing pressure of the cutter blade, so that the life of the cutter blade is extended and the replacement frequency of the cutter blade is reduced. It can be said that the problem has been solved for the wear of the cutter blade. However, like the invention described in Patent Document 1, no special measures are taken against local wear on the surface of the die as described above.

  Accordingly, an object of the present invention is to provide an underwater cut type granulation method and a granulation apparatus that solve the problem of wear on the surface of the die in the above-described under water cut type granulation apparatus. . In other words, an object is to provide a granulation method and a granulation apparatus having a long die life. Another object of the present invention is to provide a granulation method and a granulation apparatus that can be easily applied to an existing underwater cut granulation apparatus.

  The above-described wear on the surface of the die occurs at a specific position or a specific part because it is driven to rotate at a high speed in a predetermined direction with the cutter blade pressed. When the direction of rotation of the cutter blade is reversed, the wear moves to another specific part. During this time, the wear of the former specific part does not proceed. Thus, it is not necessary to change the die until the same degree of wear occurs in other parts, and it is not necessary to polish until the depression is eliminated. Therefore, in order to achieve the above-mentioned object, the present invention sets the rotation direction of the cutter after granulating for a predetermined time, or after cutting a predetermined amount, or when deterioration of the shape quality is recognized in the obtained pellet. Configured to reverse. When the rotation direction is reversed, a cutter head having a cutter blade shape and a mounting direction for reverse rotation is used. In the present specification, the cutter head means a portion composed of a cutter holder, a plurality of cutter blades fixed to the cutter holder, and a disc-shaped cutter support for positioning the cutter blade. Yes.

  Thus, in order to achieve the above-mentioned object, the invention according to claim 1 continuously extrudes into a cutter chamber filled with temperature-controlled hot water in a strand form from an extrusion nozzle opened on the surface of the die. When the molten resin is continuously cut by a cutter that is rotationally driven in a predetermined direction while being pressed against the surface of the die to obtain pellets, a cutter head for normal rotation and a cutter head for reverse rotation When one of the cutter heads is rotationally driven in a predetermined direction and granulated for a predetermined time, the other cutter head is replaced and granulated with the cutter head rotating in the reverse direction. Configured as follows.

  According to the second aspect of the present invention, a molten resin that is continuously extruded in a strand form from an extrusion nozzle that is open to the surface of the die is inserted into a cutter chamber that is filled with temperature-controlled hot water. In order to obtain pellets by continuously cutting with a cutter head that is driven to rotate in a predetermined direction while being pressed against the cutter head, a cutter head for reverse rotation is prepared in addition to the cutter head. When the head is rotationally driven in a predetermined direction and granulated for a predetermined time, the cutter head is replaced with the reverse rotation cutter head, and the cutter head is rotated in the reverse direction for granulation. The invention according to claim 3 is the granulation method according to claim 1 or 2, wherein the granulation after the predetermined time granulation starts granulation and the granulation amount reaches a predetermined amount. And the wording when the deterioration of the shape of the resulting pellet is recognized.

  According to a fourth aspect of the present invention, there is provided a die that constitutes one side of a cutter chamber that is filled with temperature-controlled hot water, a cutter shaft having a tip portion facing the cutter chamber, and the cutter shaft The cutter head is detachably mounted on the tip of the die, and the cutter head is rotationally driven in a predetermined direction in a state where the cutter head is pressed against the surface of the die having an extrusion nozzle open with a predetermined pressure. The granulation apparatus is configured to further include another cutter head having a configuration opposite to the configuration of the cutter head in a line-symmetric manner, and the cutter shaft. Is configured to be rotationally driven in other directions. According to a fifth aspect of the present invention, in the granulating apparatus according to the fourth aspect, the cutter head includes a cutter holder attached to a tip end portion of the cutter shaft, and a plurality of sheets fixed to the cutter holder by bolts. And a disc-shaped cutter support for positioning the cutter blade, and the cutter head is configured to be detachably attached to the cutter shaft.

  As described above, according to the present invention, when a cutter blade is rotationally driven in a predetermined direction while being pressed against the surface of a die and granulated, only a specific portion of the surface is worn, but as a countermeasure, the reverse configuration Since the granulation is carried out by rotating the cutter head having the reverse direction in the reverse direction, the part to be worn moves to another part. That is, the worn portion is biased to one side of the periphery of the die nozzle hole, but moves to the opposite side. Therefore, an effect peculiar to the present invention can be obtained that granulation can be performed without exchanging the dies until both the specific part and the other specific part are worn. In addition, according to the present invention, the above-described effects can be obtained only by applying a cutter head having a reverse configuration in the rotation direction to an existing granulation apparatus having a cutter head that is rotationally driven in one direction.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the granulation apparatus which concerns on embodiment of this invention, The (a) is sectional drawing which shows the whole, The (a) is a cutter blade when a cutter is driven in the clockwise direction seeing from a die side FIG. 8C is a plan view showing the attachment state of the cutter blade when the cutter is driven in the counterclockwise direction as viewed from the die side.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. The underwater-cut granulation apparatus 1 according to the present embodiment is also generally configured similarly to the conventional one. That is, the granulating apparatus 1 includes a cutter case 2 having a predetermined size. A die 10 is liquid-tightly attached to an opening on the left side of the cutter case 2 in FIG. The surface of the die 10 and the side wall 3 of the cutter case 2 constitute a cutter 5 chamber. A hot water supply pipe 6 is connected below the cutter chamber 5 and a hot water discharge pipe 7 is connected above. Although not shown in the drawing, a pellet separation device is interposed downstream of the hot water discharge pipe 7, and the temperature of the hot water from which the pellets have been collected is appropriately adjusted, and is circulated to the cutter chamber 5 by the hot water supply pipe 6. It is supposed to be returned.

  As is well known in the art, the die 10 is connected to the extruder via a die holder (not shown). A hardened layer 11 swelled in a donut shape is formed on the side of the die 10 facing the cutter chamber 5. The surface of the hardened layer 11 is a portion rotated by contact with a cutter blade described later, and a hardened layer is formed from a wear-resistant alloy such as tungsten carbide or titanium carbide, or by heat treatment. A plurality of extrusion nozzles 12, 12,..., So-called land ends that are connected to the discharge port of the extruder are opened on the surface of the cured layer 11 that has been cured in this way.

  The left end portion of the bearing casing 8 is attached to the side wall of the cutter case 2 with bolts 9 and 9. As is well known in the art, a cutter shaft 20 is provided inside the bearing casing 8 so as to be movable in the axial direction in a sealed state and rotatable in the forward and reverse directions. The right end portion of the cutter shaft 20 exits from the bearing casing 8 to which the electric motor 21 is attached via a rotary joint such as a ball joint 33, for example. The electric motor 21 is connected to a three-phase power source via a switch whose phase rotation is reversed. The other end of the cutter shaft 20 faces the cutter chamber 5. Such a cutter shaft 20 is driven in a direction in which the cutter blade is in contact with and away from the surface of the hardened layer 11 of the die 10. For example, the hydraulic or pneumatic mechanism is in the bearing casing 8 and / or outside of the casing 8. Although not shown in detail in FIG.

  A cutter head 30 according to the present embodiment is attached to the tip of the cutter shaft 20. The cutter head 30 includes a cutter holder 25, a plurality of cutter blades 31, 31,..., And a disk-shaped cutter support 32 that positions the cutter blades 31, 31,. A cutter holder 25 is attached to the distal end portion of the cutter shaft 20 by an axial key 22 and a bolt 23. The cutter holder 25 is integrally formed from a disk portion 26 to which a plurality of cutter blades are attached, and a boss portion 27 that fits into a small diameter portion at the distal end portion of the cutter shaft 20. Since the boss portion 27 is attached to the cutter shaft 20 by the key 22 and the bolt 23, the cutter holder 25 is detachable from the cutter shaft 20.

  FIG. 1A shows an embodiment of a cutter head 30 for forward rotation when the cutter holder 25 is driven to rotate clockwise, that is, in the right direction as viewed from the left in FIG. ing. As shown in this figure, the plurality of cutter blades 31, 31,... Are formed in such a manner that the radial straight line R passing through the center O of the disk portion 26 and the axis r of the cutter blade 31 are at a predetermined angle near the attachment portion. It is attached so as to be inclined. That is, it is attached at a predetermined angle to the downstream side in the rotational direction with respect to the radial axis R. Therefore, the cutter blades 31, 31,... Hit the molten resin extruded in a strand shape so as to be obliquely cut and are well cut. Further, the cut pellets are sent out of the radius. A cutter head 30 is constituted by the cutter holder 25 and a plurality of cutter blades 31, 31,.

  According to the present embodiment, the cutter shaft 20 is also driven to rotate in the reverse direction. An embodiment of a cutter head 30 'for reverse rotation when driven in the reverse direction is shown in FIG. As is clear when (c) and (b) in FIG. 1 are compared, the cutter blades 31, 31,... For forward rotation and the cutter blades 31 ′, 31 ′,. It has become. That is, the size and shape of each cutter blade, the mounting position, the angle, and the like are line symmetric. Also, the number is the same. According to the present embodiment, at least one set of the cutter heads 30 and 30 'for forward and reverse rotation as described above is prepared. Alternatively, at least one reverse rotation cutter head 30 ′ is prepared for an existing granulation apparatus including a forward rotation cutter head 30.

  Next, the operation of the above embodiment will be described. For example, the cutter head 30 for forward rotation is first attached to the tip of the cutter shaft 20 and driven in the forward rotational direction by the electric motor 21. At this time, the cutter blades 31, 31,... Are pressed against the surface of the hardened layer 11 of the die 10 with a predetermined pressure contact force. The molten resin is continuously extruded in a strand form into the cutter chamber 5 from the extrusion nozzles 12, 12,. The molten resin to be extruded is cut into a predetermined size by cutter blades 31, 31,... That are driven to rotate in the forward direction in warm water, and is pelletized by being pumped together with the warm water from the warm water discharge pipe 7 to the separator. Is separated and recovered. Processing such as drying is performed to obtain a pellet product. The hot water from which the pellets have been collected is subjected to processing such as filtration and temperature adjustment, and is returned to the cutter chamber 5. Thereafter, pellets are continuously obtained in the same manner.

  When granulating as described above, the relationship between the granulation time or the amount of pellets obtained and the amount of wear on the surface of the hardened layer 11 of the die 10 is examined. If it is obtained, it is considered that a predetermined amount has been worn, and the operation is stopped. Or, when observing the physical quality such as the shape and size of the resulting pellet and observing the deterioration of the quality (the shape of the pellet), or when it is time to expect the deterioration Stop operation. The predetermined portion of the hardened layer 11 is worn by a predetermined amount due to the operation in the forward rotation direction. Next, it is replaced with a reverse rotation cutter head 30 '. The phase rotation is reversed by the changeover switch to drive the electric motor 21 in the reverse rotation direction. The granulation is performed as described below.

  If the granulation operation by the reverse rotation is performed as much as the granulation operation by the normal rotation, other predetermined portions of the hardened layer 11 are worn by the same amount. Alternatively, it is considered worn by the same amount. Therefore, the operation is stopped. In this way, during the granulation by rotating in the reverse direction, local wear that occurs when the granulation is always performed by rotating in the normal direction as in the past does not proceed. When the granulation operation by the reverse rotation is performed as described above, the wear portions are alternately left and right, so that continuous wear in only one direction is eliminated as in the prior art. That is, the wear rate of the hardened layer 11 of the die 10 is halved.

  As described above, according to the present embodiment, the life of the die can be extended approximately twice. In addition, the present invention can be easily applied to a conventional granulator simply by preparing a reverse rotation cutter head 30 '. At this time, reversing the direction of rotation of the cutter shaft can be easily achieved by simply changing the connection of the three-phase AC.

DESCRIPTION OF SYMBOLS 1 Granulator 5 Cutter chamber 10 Dies 11 Hardened layer 12 Extrusion nozzle (land) 20 Cutter shaft 22 Key 23 Bolt 25 Cutter holder 30 Cutter head 30 'Cutter head 31 Cutter blade 31' Cutter blade 32 Cutter support 32 'Cutter support

Claims (5)

In a cutter chamber filled with temperature-controlled hot water, molten resin that is continuously extruded in a strand form from an extrusion nozzle that opens on the surface of the die is pressed in a predetermined direction while being pressed against the surface of the die. When continuously cutting with a rotationally driven cutter to obtain pellets,
Prepare a cutter head for forward rotation and a cutter head for reverse rotation, and rotate one of the cutter heads in a predetermined direction and granulate for a predetermined time. A granulation method of an underwater cut method, characterized in that the granulation is performed while replacing and reversing the rotation direction of the cutter head. In a cutter chamber filled with temperature-controlled hot water, molten resin that is continuously extruded in a strand form from an extrusion nozzle that opens on the surface of the die is pressed in a predetermined direction while being pressed against the surface of the die. When continuously cutting by rotary driven cutter head to obtain pellets,
In addition to the cutter head, a cutter head for reverse rotation is prepared separately, and when the cutter head is rotated in a predetermined direction and granulated for a predetermined time, the cutter head is replaced with the cutter head for reverse rotation and the cutter head An underwater-cut granulation method characterized by granulating with the direction of rotation reversed. In the granulation method according to claim 1 or 2, in the wording after the predetermined time granulation, the wording when the granulation amount reaches a predetermined amount after starting granulation and the shape of the pellet obtained An underwater-cut granulation method that includes wording when deterioration is recognized. , A die forming one side of a cutter chamber filled with temperature-controlled hot water, a cutter shaft having its tip facing the cutter chamber, and a detachable attachment to the tip of the cutter shaft With the cutter head being
The cutter head is a granulating device adapted to be rotationally driven in a predetermined direction in a state of being pressed with a predetermined pressure on the surface of the die having an extrusion nozzle open,
The granulating apparatus further includes an exchangeable cutter head having a configuration opposite to that of the cutter head, and the cutter shaft is rotationally driven in other directions. An underwater-cut granulator characterized by 5. The granulating apparatus according to claim 4, wherein the cutter head includes a cutter holder attached to a tip end portion of the cutter shaft, a plurality of cutter blades fixed to the cutter holder by bolts, and the cutter blade. An underwater-cut granulating apparatus comprising a disc-shaped cutter support for positioning, and the cutter head is detachably attached to the cutter shaft.

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