JP4163148B2 - Breaker plate for plastic extruder - Google Patents

Description

  The present invention relates to an improvement in a breaker plate used, for example, for a plastic insulated extruder.

  Conventionally, for example, a plastic extruder has been used for insulatingly coating a conductor with a plastic such as polyethylene or vinyl chloride. A breaker plate is attached to the tip of the screw of this plastic extruder, that is, the tip of the cylinder, and a screen used for removing foreign substances in the plastic to be pushed out inside (the screw side) of this breaker plate. A mesh (wire mesh) is held.

  Incidentally, the breaker plate mechanically holds the screen mesh as described above, and also has a role of removing large foreign matters in the plastic and a function of assisting adjustment of the kneading degree of the resin in the extruder. .

  By the way, the breaker plate for the plastic extruder and the screen mesh are in the positional relationship as described above, and specifically, in the positional relationship as shown in FIG. The breaker plate is provided with a large number of resin passage holes having the same hole diameter uniformly and over the entire breaker plate.

JP-A-5-245906

  Now, as described above, the conventional breaker plate disclosed in Patent Document 1 has a plurality of resin passage holes having the same diameter as the entire breaker plate, that is, the center portion and the peripheral portion of the breaker plate. It is worn uniformly.

  Using such a breaker plate, the present inventors extruded a certain engineering plastic or a thermoplastic resin comprising a polyolefin resin containing a flame retardant having magnesium hydroxide or aluminum hydroxide. As a result, the load of the motor for driving the extruder and the torque increased, and the plastic could not be extruded safely.

  Accordingly, an object of the present invention is to reduce a resin pressure in a plastic extruder, to reduce a load or torque of a motor that drives the extruder, and to extrude a plastic having a satisfactory quality, and to break a plastic extruder. To provide a plate.

In order to achieve the above object, the breaker plate for a plastic extruder according to claim 1 of the present invention is provided with a single resin passage hole in the central part, and a plurality of inner diameters are smaller than the resin passage hole in the central part. In addition, resin passage holes having the same diameter are circumferentially arranged at equal intervals, and an opening ratio of the resin passage holes in the central portion is 23% to 33%, and is arranged around the resin passage holes in the central portion. The opening ratio of the plurality of resin passing holes having the same diameter is 39% to 42% .
According to the breaker plate for a plastic extruder as described in claim 1, the resin pressure in the plastic extruder can be lowered, and the load or torque of the motor driving the extruder can be lowered, and it is sufficiently satisfactory. It is possible to obtain a plater plate for a plastic extruder that can extrude various types of plastic.
In the present invention, when the aperture ratio is referred to, the total area of all resin passage holes provided in the plater plate is defined as the area of the surface of the breaker plate where the resin passage holes are provided (resin passage holes). The area is also expressed in%.

  As described above, according to the present invention, the plastic pressure in the plastic extruder can be lowered, the load or torque of the motor for driving the extruder can be lowered, and the plastic capable of extruding a sufficiently satisfactory plastic A breaker plate for an extruder can be provided.

Hereinafter, the process of obtaining the breaker plate for a plastic extruder according to the present invention will be described in detail with reference to FIGS.
By the way, it goes without saying that the resin extruded through the breaker plate is more likely to flow out as the opening ratio of the breaker plate increases, so that the resin pressure in the plastic extruder naturally decreases.

  Accordingly, the present inventor made the opening ratio of the breaker plate constant, the number of screen meshes to be mounted on the breaker plate, the type of resin to be extruded, the set temperature of the extruder cylinder when extruding the resin, etc. The inner diameter of a plurality of resin passage holes provided in the breaker plate was changed between the central portion and the peripheral portion of the breaker plate, and changes in the resin pressure and the motor load were examined. In other words, the influence of the size and arrangement of the resin passage holes provided in the breaker plate on the resin pressure and the motor load was investigated.

  A plan view of the breaker plate used in this experiment is shown in FIG. The aperture ratios of the breaker plates A to C shown in FIG. 1 are all constant at 62%. The breaker plate A is provided with 19 resin passage holes 1 with an inner diameter of 7.2 mm uniformly throughout the breaker plate 2, and the breaker plate B has a resin passage hole 3 with an inner diameter of 3.5 mm at the center. Nineteen and 12 resin passage holes 1 having an inner diameter of 7.2 mm are provided in the periphery. The breaker plate C is provided with one resin passage hole 4 having an inner diameter of 19.1 mm at the center and twelve resin passage holes 1 having an inner diameter of 7.2 mm.

Extrusion experiments were conducted using the breaker plates A to C. The main extrusion conditions other than the breaker plate are as follows.
Extruder: 40mm (inner diameter of cylinder)
Extruded resin: Engineering plastic (PBT resin)
Screen mesh: Use a total of 3 sheets from 60-200 to 60

  The result is shown in FIG. FIG. 2 shows the load current (A) of the extruder drive motor in the breaker plates A to C on the vertical axis. As shown in FIG. 2, the breaker plates A to C all have the same aperture ratio of 62%, but have one large resin passage hole 4 with an inner diameter of 19.1 mm at the center and an inner diameter of 7 around the center. The motor load current of the breaker plate C provided with twelve small resin passage holes 1 of 2 mm is the lowest.

  3 shows the resin pressure (MPa) in the extruder in the breaker plates A to C on the vertical axis, it is clear from FIG. 3 that the resin pressure of the breaker plate C is lower than the others. It is.

  Therefore, the present inventor concluded that the breaker plate 2 in which one large resin passage hole is provided at the center and the smaller resin passage holes are uniformly arranged in the periphery thereof lowers the load of the motor and lowers the resin pressure more effectively. Next, based on this concept, the aperture ratio is changed. Further, two breaker plates D and E as shown in FIG. 4 are prepared, and the motor load current and the resin pressure of the breaker plates C, D, and E are set. It was measured. The main extrusion conditions including the resin used in the experiment are the same as the previous experiment.

Incidentally, as described above, the breaker plate C is provided with one resin passage hole 4 having an inner diameter of 19.1 mm in the center and twelve resin passage holes 1 having an inner diameter of 7.2 mm around the center. The aperture ratio is 62%.
The breaker plate D is provided with one resin passage hole 5 having an inner diameter of 23.0 mm in the center and twelve resin passage holes 1 having an inner diameter of 7.5 mm. The opening ratio is 75%. I used one.
The breaker plate E has a resin passage hole 5 having an inner diameter of 23.0 mm at the center, and a substantially elliptical resin passage hole in which a portion between the resin passage holes having an inner diameter of 7.5 mm is cut around the resin passage hole 5. 6 having 6 pieces and having an aperture ratio of 85% were used.

  The results are shown in FIGS. FIG. 5 shows the motor load current (A) on the vertical axis, and FIG. 6 shows the resin pressure (MPa) in the extruder on the vertical axis. Here, the leftmost point in both figures indicates the value related to the breaker plate 2 having a conventional aperture ratio of 47%. Incidentally, in the conventional breaker plate 2, 61 resin passage holes 3 having an inner diameter of 3.5 mm are uniformly bored in the entire breaker plate.

As shown in FIG. 5, the motor load current decreases in the order of the breaker plates C, D, E. That is, the motor load current decreases in inverse proportion to the aperture ratio. Similarly, the resin pressure in the extruder decreases as the breaker plates C, D, E increase in order, that is, the opening ratio increases.
Therefore, simply, if a relatively large resin passage hole is provided at the center, a plurality of smaller resin passage holes are provided at regular intervals in the periphery, and the aperture ratio is increased, the motor load current is also increased. It can be seen that it can be made smaller.

More specifically, compared with a conventional breaker plate having an aperture ratio of 47%, the motor load current is reduced by about 10% in the breaker plate C having an aperture ratio of 62%, and in the breaker plate D having an aperture ratio of 75%. In the breaker plate E having about 14% and an aperture ratio of 85%, the motor load current was as low as about 17%.
However, when a breaker plate having an opening ratio of 85% was used, the resin kneading state was slightly worse because the resin pressure was too low. Therefore, the breaker plate C with an aperture ratio of 62% and the breaker plate D with an aperture ratio of 75%, which effectively reduce the motor load current and the resin pressure in the extruder and have no problem in the resin kneading state, are actually manufactured. Turned out to be suitable.

As can be seen from the above, in the breaker plate for a plastic extruder, if the resin passage hole diameter in the central part is made larger than that in the peripheral part and the opening ratio is in the range of 60 to 75%, the resin pressure can be reduced. Therefore, it is possible to reduce the load on the drive motor for the extruder, and it is possible to perform plastic extrusion without any problem in the quality of the resin to be extruded.
By the way, in the said experiment, although the extruder of 40 mm is used as an extruder and engineering plastics (PBT resin) is used as resin to extrude, an extruder is not limited to this, For example, various extruders, such as 65 mm and 90 mm, are used. The present invention can be applied to the breaker plate, and the resin is not limited to the PBT resin but can be applied to other resins. However, the diameter of the resin passage hole at the center and the size of the resin passage hole having a smaller diameter disposed in the periphery thereof may be appropriately adjusted so that the opening ratio is in the range of 60 to 75%.

  As described above, according to the present invention, the plastic pressure in the plastic extruder can be lowered, the load or torque of the motor for driving the extruder can be lowered, and a plastic of sufficient quality can be extruded. Breaker plates can be provided.

It is a top view of breaker plate AC which made the aperture ratio constant and changed the magnitude | size and arrangement | positioning of the resin passage hole. It is a graph which shows the magnitude | size of the motor load electric current at the time of using the breaker plate shown in FIG. It is a graph which shows the magnitude | size of the resin pressure in an extruder at the time of using the breaker plate shown in FIG. It is a top view of the breaker plates C-E which changed the aperture ratio by changing the magnitude | size of the resin passage hole of a center and a periphery. It is a graph which shows the magnitude | size of the motor load electric current at the time of using the breaker plate shown in FIG. It is a graph which shows the magnitude | size of the resin pressure in an extruder at the time of using the breaker plate shown in FIG.

Explanation of symbols

1 Resin passage hole 2 Breaker plates 3-6 Resin passage hole

Claims (1)

With one of the resin passing hole in the center, the inner diameter is more smaller than the resin passing hole of the central portion, and the resin passing holes having the same diameter are arranged at regular intervals circumferentially around the said center The opening ratio of the resin passage holes in the central portion is from 23% to 33%, and the opening ratio of the plurality of resin passage holes having the same diameter arranged around the resin passage hole in the central portion is from 39% to 42%. A breaker plate for a plastic extruder.

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