JP2006231788A - Die for forming film sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a minute adjustment in a narrow pitch and to form a film sheet of a highly accurate thickness. <P>SOLUTION: The die for forming a film sheet comprises a choker section spacing adjustment mechanism which performs the spacing adjustment of a choker section by moving a choker bar 31 arranged in the middle of a melting resin passage 17 by means of a plurality of choker adjusting bolts 32 arranged in a predetermined pitch in the width direction of the die, thereby the spacing adjustment of the choker section 30 is performed, wherein thermal conductors 36 are arranged in each of the choker adjusting bolts 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a die used for film / sheet molding, and more particularly to a film / sheet molding die having a choker (choke) gap adjusting mechanism.

  In film / sheet molding using a die (T-die), in order for the film / sheet to be formed to have a uniform thickness, the flow rate distribution of the molten resin flowing out from the slit-shaped die outlet is uniform in the width direction of the die and the die stagnation The time distribution must also be uniform in the width direction of the dice.

  On the other hand, the shape of the manifold and pressure loss adjustment land of the film / sheet forming die can be determined by analysis and analysis using a computer so that a uniform flow rate distribution and a uniform die stagnation time distribution can be obtained. Has been done. In this case, the shape of the manifold and the pressure loss adjusting land is a considerably complicated curved surface shape, but complicated curved surface shapes can be processed by high-precision numerical control machining.

  However, since the resin characteristics change depending on the operating conditions of the film / sheet molding machine, the film / sheet thickness is uniform under all operating conditions even if the manifold and pressure loss adjustment land are optimally set as described above. It ’s difficult.

  As a conventional technology, a lip gap adjustment mechanism and a choker part are provided on a film / sheet forming die, and the lip gap adjustment mechanism is used to adjust the lip gap at the die outlet or change the choker part gap according to the operating conditions. Thus, the film / sheet thickness is made uniform for each operating condition.

  The clearance adjustment of the choker part is performed by turning the choker adjustment bolt and moving the choke cover in the vertical direction (direction in which the cross-sectional area of the molten resin flow path inside the die is changed). The choker adjusting bolt is a general die, and a plurality of choker adjusting bolts are provided with a pitch of about 30 to 60 mm in the die width direction.

  In order to make the film and sheet thickness uniform, these choker adjustment bolts are operated, and the gaps of the choker portions are adjusted for each arrangement portion of the choker adjustment bolts. The cho cover generally has a square bar structure and is made of the same kind of steel as the die body.

  The choker section gap adjustment performed by turning each choker adjustment bolt to change the amount of movement of the chocover is to bend the chocover at every several choker adjustment bolt pitches and change the choker section gap in its shape. The choker cover cannot be bent in a wavy manner for each choker adjustment bolt. That is, it is difficult to finely adjust the choker portion gap at a narrow pitch, and it is impossible to adjust the thickness at a narrow pitch.

  There is a system in which a rotation actuator is attached to each choker adjustment bolt, film / sheet thickness is automatically measured, each rotation actuator is feedback-controlled based on the measured value, and film / sheet thickness is automatically controlled.

  In this case, the gap adjustment of the choker part is automatic, but the fine choker part gap adjustment at a narrow pitch cannot be performed and the thickness adjustment at a narrow pitch cannot be performed, as in the case of manual operation.

  In addition, a cartridge heater is embedded near the manifold part or lip of the die body, the viscosity characteristics of the molten resin in the die are changed by heating the heater, and the film / sheet thickness is adjusted by adjusting the flow rate of the molten resin. Is also known.

  Multiple cartridge heaters are arranged at a predetermined pitch in the die width direction from the back of the die, and in the method of adjusting the film and sheet thickness by changing the flow characteristics of the resin in the manifold by adjusting the temperature of each heater, the manifold heater from the center of the die When the molten resin flowing into the die spreads in the die width direction in the manifold, the influence controlled by the heater at the die center side reaches the molten resin flowing toward the die end side.

  For this reason, in the film / sheet thickness adjustment, complicated control in consideration of the control influence on the upstream side of the die center is required on the die end side. Due to the resin properties, it may be difficult to make the film and sheet thickness uniform due to mutual interference between temperature control on the upstream side and downstream side.

  A plurality of cartridge heaters arranged at a predetermined pitch in the width direction of the lip outlet, and with a system in which the temperature of each heater is adjusted, can be controlled individually in the width direction, so it is effectively used for forming films and thin sheets. ing. However, in the case of a thick sheet, sufficient control is difficult due to insufficient heat quantity of the heater, and it is rarely used.

  The problem to be solved by the present invention is to enable fine adjustment at a narrow pitch and to form a film / sheet having a high precision thickness.

  In the film / sheet forming die according to the present invention, a choke cover is arranged in the middle of the molten resin flow path, and the choke cover is moved by a plurality of choker adjusting bolts arranged at a predetermined pitch in the die width direction. In a film / sheet forming die having a choker part gap adjusting mechanism for adjusting a gap, a thermal conductor is provided on each choker adjusting bolt.

  In the film / sheet forming die according to the present invention, preferably, the choker adjusting bolt is constituted by a hollow bolt, and a thin rod-shaped thermal conductor is inserted into the hollow portion of the hollow bolt so as to reach the cho cover portion.

The film / sheet forming die according to claim 1.

  In the film / sheet forming die according to the present invention, preferably, the thermal conductor is provided with a temperature sensor.

  The film / sheet forming die according to the present invention further includes a lip gap adjusting mechanism for adjusting the lip gap at the die outlet.

  In the film / sheet forming die according to the present invention, the surface temperature of the cho cover can be controlled by the arrangement pitch of the choker adjusting bolts by the thermal conductor. When the surface temperature of the choker part is high, the molten resin in the choker part flows more by lowering the viscosity due to the resin characteristics, and the film / sheet thickness of the part corresponding to that part becomes thicker. When the surface temperature of the cho cover is low, the flow is reduced, and the film / sheet thickness of the part corresponding to that part is reduced. Therefore, fine adjustment at a narrow pitch is possible with thermal conductor control, and high accuracy. A film or sheet having a proper thickness can be formed.

  One embodiment of a film / sheet forming die according to the present invention will be described with reference to FIG.

  The film / sheet forming die of this embodiment has a die body 10 formed by a fastening body of an upper die body 11 and a lower die body 12 that are fastened to each other by fastening bolts 13.

  The die body 10 has a resin inlet channel 14 on the back side at the center in the die width direction. The die body 10 has a manifold portion 15 that is long in the die width direction. The resin inlet channel 14 communicates with the manifold portion 15 at the center in the die width direction.

  On the outlet side of the manifold portion 15, similarly to the manifold portion 15, a pressure loss adjustment land 16 and a molten resin flow path 17 that are long in the die width direction are formed. The shapes of the pressure loss adjusting land 16 and the molten resin flow path 17 are optimally set by computer simulation.

A die outlet 20 that is long in the die width direction is formed on the front side of the die body 10 by an upper lip portion 18 formed by the upper die body 11 and a movable lower lip member 19 attached to the lower die body 12 so as to be movable in the vertical direction. Is defined. The outlet side of the manifold portion 15 communicates with the die outlet 20 via the pressure loss adjusting land 16 and the molten resin flow path 17.

  The movable lower lip member 19 can be changed in its vertical position by an adjustment bolt 21 provided on the lower die body 12 and an adjustment nut 23 screw-engaged with the adjustment bolt 21 via a cap member 22. The bolt 24 is fixed to the lower die main body 12 at the adjustment position, and the slit width (lip gap) of the die outlet 20 can be variably set. This structure is a lip gap adjusting mechanism. By this lip gap adjusting mechanism, the thickness of the film or sheet to be molded can be variably set.

  A plurality of lip adjustment bolts 25 are attached to the upper die body 11 at a predetermined pitch in the die width direction. An adjustment nut 26 is threadedly engaged with the lip adjustment bolt 25. By turning the adjustment nut 26, the upper lip portion 18 is elastically deformed for each lip adjustment bolt 25, and the lip gap at the die outlet 20 can be finely adjusted.

  In each of the upper die body 11 and the lower die body 12, die heating cartridge heaters 27 and 28 are embedded and mounted at a predetermined pitch in the die width direction.

  A cho cover 31 is disposed in the middle of the molten resin flow path 17. The cho cover 31 is on the upper die body 11 side, and the choke portion 30 is constituted by the lower die body 12.

  In the upper die body 11, a plurality of hollow choker bolts (choker adjusting bolts) 32 are arranged at a predetermined pitch (about 20 to 60 mm) in the die width direction. The hollow choker bolt 32 is connected to the cho cover 31. An adjustment nut 34 is threadedly engaged with the hollow choker bolt 32 via a cap member 33. By turning the adjustment nut 34, the hollow choker bolt 32 moves up and down, whereby the cho cover 31 moves up and down, and the clearance of the choker portion 30 is adjusted. This is the choker part gap adjusting mechanism.

  In addition, the choker adjustment bolt for the choke cover 31 may be constituted by a heat medium bolt, and the choker adjustment bolt itself may be a thermal conductor. Further, the hollow choker bolt 32 may be a direct acting type screw engaged with the upper die body 11.

  A thin bar-like thermal conductor 36 is inserted into the hollow portion 35 of each of the plurality of hollow choker bolts 32 up to the chocover 31 portion. That is, the tip of the thermal conductor 36 is inserted into the hollow portion 35 of the hollow choker bolt 32 so as to reach the cho cover 31 portion.

  The thermal conductor 36 can be composed of a cartridge heater, a double pipe type heat medium pipe, or the like, and has a built-in temperature sensor 37 at the tip portion on the side of the cho cover 31 that can accurately measure the temperature. Temperature controlled.

  By controlling the current of the thermal conductor 37 according to the temperature measured by the temperature sensor 37, the temperature of each thermal conductor 37 can be individually and precisely controlled. The temperature sensor 37 can be omitted depending on the required film / sheet thickness accuracy.

  When the resin flow characteristics are different from the conditions when the die flow path is simulated by a computer, or when the resin flow is different from that used during simulation, the flow in the entire die width direction is greatly undulated. It changes with. This large swell is adjusted and compensated by operating the hollow choker bolt 32.

  The heat of the thermal conductor 37 is conducted to the cho cover 31, and the surface temperature of the cho cover 31 is determined by the thermal conductor 37. The molten resin in the choker portion 30 flows at a portion where the surface temperature of the cho cover 31 is high by decreasing the viscosity due to the resin characteristics, and the film / sheet thickness of the portion corresponding to the portion increases. Contrary to this, at the portion where the surface temperature of the cho cover 31 is low, the flow of the molten resin is reduced, and the film / sheet thickness at the portion corresponding to the portion is reduced.

  Since the choker portion 30 has a narrow flow path structure, it is sufficiently achievable to control the flow characteristics of the resin in the flow path with temperature. Thereby, adjustment at a narrow pitch that cannot be adjusted by adjustment of the choker portion clearance by the hollow choker bolt 32 can be performed by temperature control of the thermal conductor 37.

  Therefore, it is preferable that the choker portion clearance adjustment by the hollow choker bolt 32 is manual, and the thermal conductor control (temperature control) by the thermal conductor 37 is automatic.

  Therefore, the film / sheet forming die according to the present invention is preferably used in a film / sheet molding machine of an automatic control system that performs feedback control by automatic measurement of the film / sheet thickness. Depending on the result, thermal conductor control (temperature control) can be performed so that the film and sheet thickness are uniform.

  In the simple machine, the set temperature of each thermal conductor 37 may be manually input based on the automatic measurement result of the film / sheet thickness.

  When the thermal conductor 37 is a heat medium type, the surface temperature of the cho cover 31 can be forcibly set to a low temperature, so that the control amount according to the temperature can be set in a large range.

  When the choker section clearance adjustment with the hollow choker bolt 32 and the thermal conductor control with the thermal conductor 37 are used in combination, even if the operating conditions differ greatly or the resin type changes, a highly accurate film or sheet is formed. It becomes possible.

  In the case of the same resin type, a highly accurate film / sheet can be formed by thermal conductor control by the thermal conductor 37 and lip gap adjustment by the lip adjustment bolt 25.

It is a longitudinal cross-sectional view which shows one Embodiment of the die for film sheet | seat formation by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Die main body 11 Upper die main body 12 Lower die main body 13 Fastening bolt 14 Resin inlet flow path 15 Manifold part 16 Pressure loss adjustment land 17 Molten resin flow path 18 Upper lip part 19 Movable lower lip member 20 Die exit 21 Adjustment bolt 22 Cap member 23 Adjustment nut 24 Fastening bolt 25 Lip adjustment bolt 26 Adjustment nut 30 Choker part 31 Choker 32 Hollow choker bolt 33 Cap member 34 Adjustment nut 35 Hollow part 36 Thermal conductor 37 Temperature sensor

Claims (4)

A choke cover is arranged in the middle of the molten resin flow path, and has a choker part gap adjustment mechanism for adjusting the choker part gap by moving the choke cover with a plurality of choker adjustment bolts arranged at a predetermined pitch in the die width direction. In film and sheet forming dies,
Film / sheet forming dies with thermal conductors on each choker adjustment bolt.   The film / sheet forming die according to claim 1, wherein the choker adjusting bolt is constituted by a hollow bolt, and a thin rod-shaped thermal conductor is inserted into a hollow portion of the hollow bolt so as to reach the cho cover portion.   The film / sheet forming die according to claim 1, wherein a temperature sensor is provided on the thermal conductor.   The film / sheet forming die according to any one of claims 1 to 3, further comprising a lip gap adjusting mechanism for adjusting a lip gap at a die outlet.

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