JP3798121B2 - Extrusion machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an extrusion molding machine.
[0002]
[Prior art]
In this type of extrusion molding machine, in order to supply synthetic resin raw material pellets into the cylinder from the raw material pellet supply port, and to convey the raw material pellets in the axial direction of the screw without rotating in the cylinder by the rotation of the screw In particular, a hopper ground area in which several square grooves are engraved in parallel in the axial direction is arranged near the raw material pellet supply port, and the bottom of these square grooves is formed shallower toward the downstream side. (See Japanese Utility Model Publication No. 58-62623).
[0003]
[Problems to be solved by the invention]
In general, there are various shapes of raw material pellets such as a spherical shape, a cylindrical shape, and a square disk shape, the sizes thereof are various in size, and the hardness varies depending on the material pellets made of synthetic resin. If a plurality of types of hopper ground areas having square grooves are prepared, the cost increases. In order to avoid this high cost, a common hopper ground area is usually used regardless of the type of raw material pellets. However, when a common hopper gland area is used, the square groove dimensions are formed so as to be suitable for transferring a specific raw material pellet. When trying to transfer the material, the raw material pellet fits into the square groove, and the raw material pellet simply rolls in this square groove, and the rotation of the screw may not transfer the desired amount of raw material pellet in the extrusion direction. As a result, the amount of discharged resin becomes insufficient, and extrusion molding, inflation molding or blow molding may become impossible. In addition, when the raw material pellet is soft, the raw material pellet is divided in the rotation direction of the screw at the corner portion of the square groove to be a small size, and the desired amount is obtained by rotating the screw in the same manner as the small raw material pellet. There are cases where raw material pellets cannot be transferred.
[0004]
In order to solve the above-mentioned problem, there is Japanese Utility Model Publication No. 4-135316 as a special shape of the groove in the hopper ground area. However, when the screw diameter is small, it is possible to sufficiently secure the transfer amount of the raw material pellets. However, when the diameter is increased, the raw material pellets tend to slip. The present invention is an extrusion molding machine capable of kneading without excessively increasing the melted resin pressure by appropriately improving the screw diameter, appropriately conveying the raw material pellets, by improving the shape of the screw. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the specific invention is such that the length of the screw corresponding to the hopper ground area of the cylinder in the extruder is at least 3 pitches from the hopper center position. The groove depth of the pitch is the same, and the remaining 1 pitch groove depth is formed in a taper that becomes shallower in front of the 2 pitch groove depth, and the screw in the extruder is From the hopper ground area of the cylinder to the discharge port of the extrusion molding machine, it includes a supply part, a melting acceleration part, a homogenous part, and a metering part, and a first screw is formed from this supply part to the central part of the melting acceleration part In the remaining portion of the melting promoting portion, a second screw having a narrower pitch than the pitch of the first screw is formed, and the first screw and the second screw are formed. The kneading part is formed in the separation part, and a kneading part is formed in the separation part. In the first screw, the supply part corresponding to the hopper ground region and one of the melting promotion parts located near the separation part are provided. The groove depths located in the respective portions are substantially the same, and the groove depths of the screws located between them are located in the supply portion and a part of the melting promoting portion located near the separation portion, respectively. The extruder is characterized by being shallower than the depth, and the groove depth of the communicating portion between the deep portion and the shallow portion is tapered in the axial direction.
[0006]
In order to solve the above-mentioned problem, the related invention has the same pitch as the pitch of the first screw of the screw in the extruder, and the spiral groove is formed in a reverse screw relationship with respect to the first screw. The hopper ground region is formed as a forced cooling region, and a barrel portion located in the vicinity of the hopper ground region in the pellet transfer direction is a natural cooling region.
[0007]
The length of the first screw in this extruder is at least 13 pitches from the hopper center, and corresponding to the hopper grant area, 3 pitches are located from the hopper center position among these 13 pitches. The groove depth of 2 pitches is constant from the center of the hopper, and the groove depth of 2 pitches following this is formed into a taper that becomes shallower as it goes forward from the groove depth of 2 pitches. The two-pitch groove depth following the groove portion is constant and shallower than the two-pitch groove depth from the hopper center position, and the two-pitch groove depth following the shallow groove depth portion becomes deeper as it goes forward one after another. The remaining 5 pitch groove depth following the taper portion is constant and is the same as or slightly the same as the 2 pitch groove depth from the hopper center position. Which is preferably Ku formed.
[0008]
A spiral groove having the same pitch as that of the first screw of the screw in the extruder is formed in the hopper ground region. In the first screw, a ratio h between the groove depth h and the screw diameter D is set. / D is 0.11 to 0.12 in the supply portion corresponding to the hopper ground region and the portion located in the melting promotion portion on the side of the separation portion, and the ratio h / D in the intermediate portion is 0.09. It is preferable that it is -0.093.
[0009]
The ratio of the pitch of the second screw to the pitch of the first screw in this extruder is preferably 0.77 to 0.85.
It is preferable that the size of the spacing portion in this extrusion molding machine is 8 to 10 mm. In order to solve the above-mentioned problems, the screw diameter in this extruder is 50 mm to 90 mm.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
A typical embodiment of the invention described in claims 1 and 2 will be described. 1 to 4, A represents the entire extrusion molding machine, and a screw 10 in the extrusion molding machine A is a die (for example, an inflation) connected to the discharge port of the extrusion molding machine A from the hopper ground region G of the cylinder 15. A film forming die) 20 includes a supply part B, a melting promoting part C, a homogeneous part D, and a measuring part E. A first screw 11 is formed from the supply part B to the center of the melting promotion part C. A second screw 12 having a pitch P2 narrower than the pitch P1 of the first screw 11 is formed in the remaining portion of the melting promoting portion C. The first screw 11 and the second screw 12 are separated from each other by a predetermined dimension (for example, 10 mm), and a kneading portion F is formed at the separation portion 13. In the first screw 11, the hopper ground region G The groove depth h1 located in each of the supply part B corresponding to the above and a part of the melting promotion part C located closer to the separation part 13 is substantially the same, and the groove depth h2 located therebetween is the groove depth h2 It is made shallower than the groove depth h1 located in the supply part B and a part of the fusion promoting part C located near the separating part 13, and the screw of the communicating part between the deep part and the shallow part The depth of the groove changes smoothly and tapers in the axial direction.
[0011]
More specifically, corresponding to the hopper ground area G of the cylinder in the extruder A, the groove depth h of the first screw 11 of the screw 10 extends from the rear end of the hopper ground area G to the front end. It has a tapered portion that becomes shallower. More preferably, the length of the screw 10 in the hopper ground region G is set to a dimension of at least three pitches of the first screw 11 from the hopper center position G1, and of these three pitches, the groove depth is two pitches from the hopper center position. The length h1 is the same, and the remaining one-pitch groove depth is formed as a taper that becomes shallower and tapered toward the front than the two-pitch groove depth h1, and becomes the groove depth h2. The length of the first screw 11 is 13 pitches from the hopper center. Corresponding to the hopper grant area G, 3 pitches from the hopper center position G1 are located among these 13 pitches. The groove depth of 2 pitches from G1 is constant, and the groove depth of 2 pitches following this is formed into a taper that becomes shallower as it goes forward from the groove depth of 2 pitches, and this taper part The two-pitch groove depth that follows is shallower than the two-pitch groove depth from the center of the hopper and is constant, and the two-pitch groove depth that follows the shallow part of this groove depth gradually increases toward the front. The remaining 5-pitch groove depth following the tapered portion is constant, and is the same as or slightly deeper than the 2-pitch groove depth from the hopper center position.
[0012]
A spiral groove G2 having the same pitch as the pitch P1 of the first screw 11 in the screw 10 and having a triangular cross-section and a relationship between the first screw 11 and the reverse screw is provided in the hopper ground region G in six or more lines. Eight strips are formed. The hopper ground area G is a forced cooling area, and the barrel portion G3 located in the vicinity of the hopper ground area G in the pellet transfer direction is a natural cooling area. In the first screw 11, the ratio h / D of the groove depths h1 and h2 to the screw diameter D is h1 / D = 0.11 in the supply part B and the melting promotion part C corresponding to the hopper ground region G. It is preferable that the ratio h2 / D in the intermediate portion is 0.09 to 0.093. The ratio P2 / P1 of the pitch P2 of the second screw 12 to the pitch P1 of the first screw 11 is 0.77 to 0.85. The spacing portion 13 has a dimension of 8 to 10 mm, and the screw diameter D is 50 to 90 mm.
[0013]
A molding die 20 is provided so as to be freely connected to a discharge port of the extruder A at the tip of the cylinder 15. An air ring 32 having two upper and lower annular outlets 30 and 31 concentrically with the die 20 is provided in the vicinity of the annular outlet 21 of the molding die 20. The outer lip of the lower annular outlet 30 near the annular discharge port 21 is formed by a lower end portion 41 a of the bubble-side inclined inner surface 41 of the annular block body 40 having a high height. The bubble-side inclined inner surface 41 is an annular inner surface whose diameter increases toward the upper end that guides the air flow along the entire outer peripheral surface of the bubble B. An inner lip 33 of the upper annular outlet 31 is formed at the upper end of the annular block body 40, and the tip of the inner lip 33 of the upper annular outlet 31 extends in the flow direction (outside) of the bubble B. Have been killed along.
[0014]
Of the outer lips 33, 34, the tip of the outer lip 34 is bent inwardly toward the inner lip 23, and the outer lip 34 moves vertically on the outer circumferential surface of the outer lip 34. An adjustable auxiliary lip 35 is provided, and an annular pressure chamber 36 having a variable capacity is formed between the outer lip 34 and the auxiliary lip 35 so as to open toward the bubble B side.
[0015]
A cylindrical body 37 extending above the rectifying pressure adjusting chamber 36 is provided at the upper part of the air ring 32, and a chamber 38 communicating with the outside air is formed between the cylindrical body 37 and the air ring 32. At the upper end of the cylindrical body 37, an auxiliary valve guide body 39 that can be adjusted up and down is provided. The horizontal ridge lines 43 are formed in the upper and lower layers by the adjacent depressions 46 formed in the stepped shape on the inclined inner surface 41 of the block body 40, and the extension line connecting these ridge lines 43 forms the guide surface of the valve B. Yes. The outer surface on the opposite side of the bubble of the annular block body 40 is a substantially vertical surface 44, and a vertical annular wall continuous with the annular blowout port 31 at the upper end together with an annular vertical wall body 48 having an outer lip 34 of the annular blowout port 31 at the upper end. In the connecting portion between the first horizontal annular air passage 46 that forms the air passage 45 and communicates with the blower P, and the vertical annular air passage 45, the first horizontal annular air passage 46 is the annular block body. The air rectifying and pressure regulating chamber 47 is formed spreading toward the end 40. The first horizontal annular air passage 46 is formed between an annular horizontal wall 49 having the annular vertical wall 48 at the inner end and an annular substrate 50 having the lower annular outlet 30 at the inner end. Yes. A horizontal second annular air passage 51 branched from the rectifying / pressure adjusting chamber 47 communicates with the lower annular outlet 30. The horizontal second annular air passage 51 is formed between the bottom surface 40 a of the annular block body 40 and the annular substrate 50.
An auxiliary air ring (not shown) is disposed above the air ring 32 with a space therebetween.
[0016]
The operation of the extruder A will be described as a case where it is applied to inflation film molding. The raw material pellets rotated from the hopper 10 and supplied from the hopper are, in the supply part B, the groove 61 in the hopper ground region G of the cylinder 15 and the groove depth of the first screw 11 in the supply part B of the screw 10. With the deep flight of h1, the solid is transferred forward while inclining its posture, and the gap between the raw material pellets is slightly reduced successively at the tapered portion where the groove depth becomes shallower from the rear end to the front end of the hopper ground region. At this time, the pellets are forcibly cooled in the hopper ground region G, and the barrel portion G3 in the vicinity of the hopper ground region G is naturally cooled. That is, the heat transferred from the melting promoting portion C is naturally cooled in the barrel portion G2. The temperature of the barrel part G3 is about room temperature to the softening temperature of the used pellets. Therefore, at the time of transferring the solid, the raw material pellets are sent to the melting promoting part C without being forcedly cooled and hardened to such an extent that the surface of each particle is slightly softened.
[0017]
Next, in the flight part having a shallow groove having a groove depth h2 which is an intermediate part of the first screw 11, the gap between the raw material pellets is further slightly reduced between the inner wall of the cylinder 15 and the screw 10, and the gap between the raw material pellets is reduced. In a state where the gap is reduced, the raw material pellets are transferred forward while being melted again with a slightly larger melting cross-sectional area than the intermediate portion by a deep flight with a groove depth h1 near the spacing portion 13 in the first screw 11, After the forward transfer is temporarily interrupted and kneaded in the separating portion 13, the melting of the raw material pellets is further promoted by the flight of the second screw 12. Thereafter, the melted resin is extruded from the discharge port of the extrusion molding machine A to the die 20 through the homogeneous part D and the metering part E as in the known one. When the single blower P is started, cooling air is blown out from the two upper and lower outlets 30 and 31 and the bubble B is pushed out from the annular discharge port 21 of the die 20.
[0018]
The cooling air blown out from the lower air outlet 30 in the air ring 32 preliminarily cools the molten resin extruded from the annular discharge port 21 of the die 20 in the vicinity of the annular discharge port, preliminarily solidifies the resin, and increases the stretch ratio. The melt tension is increased to the extent that it is not impaired. After this pre-cooling, the air flows at high speed in the bubble flow direction through the gap between the outer surface of the bubble B which is expanded by internal pressure and the bubble side inclined inner surface 41 of the block body 40, and a part of the air flows. It flows into and diffuses into the step-like depression on the bubble-side inclined inner surface 41 to reduce the wind speed. It is lifted and supported from the outside without contacting the bubble-side inclined inner surface 41 of the body 40 to eliminate the sagging, and since the wind speed is low, there is little vibration, and wave-like sag occurs on the surface of the bubble B completely. To prevent. The air that has flowed into the recess and temporarily retained is agitated in the recess by the cooling air flow that blows out from the lower outlet 30 of the air ring 32, and a part of the air rides on the air flow that sequentially flows along the bubble. Since it flows out from the leverage to the upper outlet 31 side, the air in the recess is always kept at a low temperature.
[0019]
The speed of the cooling air flow blown out from the lower outlet 30 is rapidly reduced by the inflow of the air flow into the respective depressions, and the flow velocity is further reduced by the mixed extrusion of the air from the depressions. The speed of the air flow in the gap between the outer surface of the lower air outlet 30 and the outer lip 33 tip surface of the lower outlet 30 is reduced, and the degree of the venturi action generated by this air flow is not increased so much. There is no risk of contact with the front end surface of the outer lip 33, and there is no risk of uneven thickness molding at this portion.
[0020]
Next, the air that flows out to the upper air outlet 31 side merges with the air that blows out from the upper air outlet 31, further cools the bubbles, and is supported from the outside in the rectifying pressure adjusting chamber 36, While the outside airflow that is gradually expanded and then sucked into the cylindrical body 37 is blown from the chamber 38 toward the bubble B, the auxiliary bubble guide body 39 increases the blow ratio to stabilize the bubble, and a part of the bubble is Without making contact with the auxiliary lip 35, the resin is stably molded with a wide width and a vertical and horizontal stretch ratio of approximately the same, and a high blow ratio.
[0021]
Further, the cooling air flow supplied from the blower is branched into the outlet 30 on the lower end and the outlet 31 on the upper stage in the block body 40, and the vertical formed on the outer surface of the block body 40 on the opposite side of the bubble. The cooling air flow supplied to the upper air outlet 31 through the annular air passage 45 is rectified in a horizontal annular air passage 46 that spreads toward the block body 40 near the lower end of the vertical annular air passage 45. Then, after adjusting the pressure, a cooling air flow having a constant pressure is blown out from the entire upper outlet 31 to stably support and blow the entire circumference of the bubble B, thereby reducing the pressure loss. When changing the blow ratio, the height of the auxiliary lip 35 is changed in accordance with the blow ratio, the capacity of the rectifying pressure adjusting chamber 36 is changed, and the amount of air blown out from the chamber 38 is adjusted. When the opening area of the chamber 38 is enlarged, the position of the auxiliary bubble guide body 39 is adjusted in the vertical direction.
[0022]
【The invention's effect】
In the specific invention, regardless of the screw diameter, the raw material pellets can be transported in a solid state while reducing the gap between the raw material pellets in the axial direction of the screw by flight in the first screw in the hopper ground area supply unit, and the shallow Smoothly melt and transfer the raw material pellets without increasing the internal pressure of the cylinder along with the expansion of the melt cross-sectional area in the portion where the groove depth h1 of the portion located closer to the separation portion is deeper than the portion of the groove depth h2. Therefore, the load applied to the screw, that is, the drive motor thereof can be reduced as compared with the conventional one in which the raw material pellets are transferred over the entire supply section having a constant groove depth of the screw. In addition, after that, the first screw in the melting promoting portion is kneaded with the semi-molten raw material pellet at the separation portion which is the cut portion of the second screw, and the kneaded resin is mixed by the flight of the second screw. Furthermore, since it is melted and transferred to the homogeneous part and the weighing part, the raw material pellets can be homogeneously kneaded, and when the same transfer force as that of a conventional extrusion molding machine is used, the amount of extrusion can be increased from the conventional one. .
[0023]
In the invention according to claim 2, in addition to the effect of the invention according to claim 1, it has the same pitch as the pitch of the first screw of the screw, and the relation of the reverse screw to the first screw. A spiral groove is formed in the hopper ground region, the hopper ground region is a forced cooling region, and the barrel portion located in the pellet transfer direction in the vicinity of the hopper ground region is a natural cooling region. Therefore, the surface of the raw material pellets in the barrel portion communicating with the hopper ground region is only slightly softened, and the above can be smoothly carried out without causing damage to the flight due to hardening of the raw material pellets during solid transfer, and increasing the solid transfer force. The raw material pellets supplied from the hopper can be supplied to the melting promoting portion by the spiral groove and the flight of the first screw.
[0024]
The effects common to the above-mentioned claims are that the raw material pellets do not rapidly increase the internal pressure of the barrel when moving from the hopper ground area to the melting section, and the internal pressure of the barrel in the melting section is made substantially constant. It can be melted and the load applied to the screw of the raw material pellet can be reduced. In other words, the raw material pellet can be semi-forcedly transferred.
[0026]
As an effect when applied to the inflation film molding in the embodiment, after the preliminary cooling, the air is expanded by the internal pressure, and the bubble B inclined inner surface 41 of the block body 40 and the bubble side inclined inner surface 41 And a part thereof flows into and diffuses into the stepped recess 46 of the inclined inner surface 41 to reduce the wind speed, and the internal pressure in the recess 46 and the internal pressure of the bubble B In this balance, the bubble B having a low melt tension is lifted and supported from the outside without bringing it into surface contact with the bubble-side inclined inner surface 41 of the lower block body 40, and the drooping is eliminated. It is possible to completely prevent the wavy slack from occurring on the surface of the bubble B. The air that has flowed into the recess 46 and temporarily retained is agitated in the recess 46 by the cooling air flow that blows out from the lower outlet 30 of the air ring 32, and a part of the air flow that sequentially flows along the bubble. The air flows out from the recess 46 to the upper blower outlet 31 side, so that the air in the recess can be kept at a low temperature at all times.
[0027]
The speed of the cooling air flow blown out from the lower outlet 30 is rapidly reduced by the inflow of the air flow into each depression, and the flow velocity is further reduced by the mixing and extrusion of the air from the depression. The speed of the air flow in the gap between the outer surface of the lower air outlet 30 and the outer lip 33 tip surface of the lower outlet 30 is reduced, and the degree of the venturi action generated by this air flow is not increased so much. There is no fear of coming into contact with the distal end surface of the outer lip 33, and there is no risk of uneven thickness molding at this portion.
[0028]
Further, the air flowing out to the upper air outlet 31 side merges with the air blown out from the upper air outlet 31 to further cool the bubble, and is supported from the outside in the rectifying pressure adjusting chamber 36, While the outside airflow that is gradually expanded and then sucked into the cylindrical body 37 is blown from the chamber 38 toward the bubble B, the auxiliary bubble guide body 39 increases the blow ratio to stabilize the bubble, and a part of the bubble is Without coming into contact with the auxiliary lip 35, the resin can be stably molded with a wide width and a vertical and horizontal stretch ratio of approximately the same and a high blow ratio.
[0029]
Further, the cooling air flow supplied from the blower P is branched into the lower outlet 30 and the upper outlet 31 in the block 40, and the block body 40 is formed on the outer surface opposite to the bubble. In the horizontal annular air passage 46 that spreads toward the block body 40 near the lower end of the vertical annular air passage 45, the cooling air flow that passes through the vertical annular air passage 45 and is supplied to the upper outlet 31 is expanded. After rectifying and adjusting the pressure, a cooling air flow having a constant pressure is blown out from the entire upper outlet 31 to stably support and blow the entire circumference of the bubble B, and the pressure loss can be reduced. When changing the blow ratio, the capacity of the rectifying pressure adjusting chamber 36 can be changed by changing the height of the auxiliary lip 35 corresponding to the blow ratio, and the amount of air blown out from the chamber 38 The position of the auxiliary bubble guide body 39 can be adjusted in the up-down direction when the opening area of the chamber 38 is enlarged. In the above example, the example in which the blow molding die is connected to the blow molding die or the flat T die is used. However, the present invention does not change at all even if the extruder A is connected to the blow molding die.
[Brief description of the drawings]
FIG. 1 is a schematic front view showing a screw of an extrusion molding machine in an embodiment.
2 is a schematic plan view showing a relationship between a hopper ground area and a screw of the extrusion molding machine in FIG. 1. FIG.
FIG. 3 is a half-longitudinal longitudinal end view showing this use state.
4 is a cross-sectional view showing a hopper ground area of a cylinder in FIG. 2. FIG.
[Explanation of symbols]
11 First screw 12 Second screw 13 Spacing portion

Claims (2)

  The length of the screw corresponding to the hopper ground area of the cylinder in the extruder is at least 3 pitches from the hopper center position. Of these 3 pitches, the groove depth of 2 pitches from the hopper center position is the same, and the rest The groove depth of 1 pitch of this is formed in a taper which becomes shallower as it goes forward from the groove depth of 2 pitches, and the screw in the extruder is discharged from the hopper ground area of the cylinder. A first screw is formed from the supply part to the central part of the melting promotion part, and the remaining part of the melting promotion part is included in the remaining part of the melting promotion part. A second screw having a narrower pitch than the pitch of the first screw is formed, and the first screw and the second screw are separated by a predetermined dimension. In the first screw, the groove depths positioned in the supply portion corresponding to the hopper gland region and the part of the melting promoting portion located near the separation portion are substantially the same in the first screw. The groove depth of the screw located between them is shallower than the groove depth located in each of the supply portion and a part of the fusion promoting portion located near the separation portion. An extrusion molding machine characterized in that the groove depth of the communicating portion between the deep portion and the shallow portion is tapered in the axial direction.   The screw has the same pitch as that of the first screw of the screw, and a spiral groove is formed in the hopper ground region in a reverse screw relationship with respect to the first screw. The hopper ground region is a forced cooling region. The extrusion molding machine according to claim 1, wherein the barrel portion located in the pellet transfer direction in the vicinity of the hopper ground region is a natural cooling region.

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