JP7324258B2 - Plasticizing device and plasticizing method - Google Patents

Description

The present invention relates to a plasticization technique for plasticizing a resin material.

In the field of plastic molding, plasticizing devices are put to practical use.
A main element of many plasticizing devices is a heating cylinder with a built-in screw. A band heater is wound around the outer surface of the heating cylinder. Plasticization proceeds by the heat of the band heater and the kneading heat of the resin material itself.

However, since the heat capacity of the heating cylinder is large, there is a difference between the temperature of the heating cylinder and the temperature of the resin material, resulting in poor temperature control response.
A plasticizing device that takes measures against this problem has been proposed (see, for example, Patent Document 1 (FIG. 1)).

The plasticizing device disclosed in Patent Document 1 includes a heating cylinder having a band heater and a screw rotatably accommodated in the heating cylinder, and the screw incorporates a rod-shaped heater.

As a result of trials by the inventors of the present invention, it was found that under certain conditions, the resin material does not properly bite into the hopper near the drop opening below the hopper. Poor biting means, for example, that a semi-molten resin material clumps together and wraps around the screw. Occurrence of poor biting hinders the plasticizing operation.
Some conditions were when the weighing value was small and when the plasticizing time was long.
If the measured value is small, the amount of the resin material charged is small, and the temperature of the resin material changes in a short period of time. This temperature change causes poor bite.
If the plasticizing time is long, the temperature of the resin material will change more than expected. This temperature change causes poor bite.

In the conventional structure, it was difficult to control the temperature of the screw due to its structure, and it was not possible to sufficiently prevent the resin material from biting into the screw.
However, in recent years, as part of efforts to improve the quality of resin-molded products, there has been a strong demand for measures to prevent poor biting.
Therefore, there is a need for a plasticizing technique that can prevent the resin material from being bitten poorly.

JP 2005-262812 A

The present invention provides a plasticization technology that can prevent the resin material from being bitten poorly.

The invention according to claim 1 comprises: a heating cylinder having a bottom ; a screw inserted toward the bottom of the heating cylinder and rotatably housed in the heating cylinder; Equipped with a hopper for charging materials,
A plasticizing device that plasticizes the resin material introduced into the heating cylinder by rotation of the screw and discharges the plasticized resin material from an outlet provided at the bottom of the heating cylinder,
The screw incorporates a temperature control rod extending along the axis of the screw ,
This temperature control rod includes, from a base to a tip, a cooling portion cooled by a cooling means, a heat insulating portion, and a heating portion having a heater in this order. so as to block the transfer of heat between
The heat insulating part is provided near the drop opening,
The plasticizing device is characterized by comprising temperature control rod moving means for axially moving the temperature control rod with respect to the screw.

The invention according to claim 2 comprises a heating cylinder having a bottom , a screw inserted toward the bottom of the heating cylinder and rotatably accommodated in the heating cylinder, and a resin drop opening provided in the heating cylinder. Equipped with a hopper for charging materials,
A plasticizing device that plasticizes the resin material introduced into the heating cylinder by rotation of the screw and discharges the plasticized resin material from an outlet provided at the bottom of the heating cylinder,
The screw incorporates a temperature control rod extending along the axis of the screw ,
This temperature control rod includes, from a base to a tip, a cooling portion cooled by a cooling means, a heat insulating portion, and a heating portion having a heater in this order. so as to block the transfer of heat between
The heat insulating part is provided near the drop opening,
The plasticizing device includes first temperature control rod moving means for collectively moving the heat insulating portion, the first heating portion and the cooling portion with respect to the screw in the axial direction, and the first temperature control rod moving means. a second temperature control rod moving means for axially moving the second heating portion with respect to the screw independently of the screw.

The invention according to claim 3 is the plasticizing device according to claim 2,
The first heating unit comprises a first disk, a first claw extending from the first disk to the second heating unit, and the first heater inserted into the first disk and the first claw,
The second heating unit comprises a second disk, a second claw extending from the second disk to the first heating unit, and the second heater inserted into the second claw and the second disk,
The first claw is fitted between two adjacent second claws so as to be axially movable.

The invention according to claim 4 is the plasticizing device according to any one of claims 1 to 3,
Where L is the effective length of the screw and D is the outer diameter of the screw, L/D is in the range of 0.5 to 3.0, and D is at least 80 mm. do.

The invention according to claim 5 is a preparatory step of preparing the plasticizing device according to any one of claims 1 to 4;
a comparison step of comparing the weight value at that time and a threshold value in a scheduled plasticizing operation;
In this comparison step, when the weighed value is equal to or less than the threshold value, the temperature control rod is moved closer to the outlet, and when the weighed value exceeds the threshold value, the temperature control rod is moved. moving away from the outlet;
a plasticizing and weighing step of discharging and weighing the plasticized resin material from an outlet provided in the heating cylinder while plasticizing the resin material put into the heating cylinder by rotating the screw; It is a plasticizing method.

The invention according to claim 6 is a preparatory step of preparing the plasticizing device according to any one of claims 1 to 4;
a moving step of axially moving the temperature control rod with the temperature control rod moving means;
a plasticizing and weighing step of discharging and weighing the plasticized resin material from an outlet provided in the heating cylinder while plasticizing the resin material put into the heating cylinder by rotating the screw; It is a plasticizing method.

In the invention according to claim 1, the temperature control rod has a heating portion, a heat insulation portion, and a cooling portion, and is axially moved by the temperature control rod moving means.
When the weighing value is small, face the cooling part to the drop opening. Since the temperature in the vicinity of the drop port is low, there is no concern that the resin material will bite into the product. The resin material moved by the screw is plasticized in the heating section.
When the measured value is large, etc., the heating part is brought to face the drop port to promote plasticization of the resin material.
Therefore, according to the present invention, there is provided a plasticizing device capable of preventing the resin material from being bitten poorly.

The invention according to claim 2 exhibits the same effects as the invention according to claim 1, and also exhibits the following effects.
The heating section can be divided into a first heating section and a second heating section, and the two can be brought closer to each other or separated from each other. By separating, the axial length of the heating portion can be apparently extended.
Therefore, according to the present invention, finer heating control can be performed.

According to the third aspect of the invention, the first heater and the second heater can be partially overlapped (partially overlapped). By using this lap allowance, even when the second heating section is separated from the first heating section, the screw can be heated satisfactorily by the first heater and the second heater.

In the invention according to claim 4, where L is the effective length of the screw and D is the outer diameter of the screw, L/D is in the range of 0.5 to 3.0. If L/D is 0.5 or more, the required number of spiral grooves can be formed on the screw. If L/D is 3.0 or less, the overall length of the screw can be suppressed, and miniaturization of the plasticizing device can be promoted.
In addition, in the present invention, the outer diameter D of the screw is set at least 80 mm, so that the screw can accommodate a temperature control rod with a sufficiently large diameter.

The invention according to claim 5 is a plasticizing method, wherein the position of the temperature control rod is determined by comparing the threshold value and the weighing value.
When the weighing value is small, face the cooling part to the drop opening. Since the temperature in the vicinity of the drop port is low, there is no concern that the resin material will bite into the product. The resin material moved by the screw is plasticized in the heating section.
When the weighing value is large, etc., the heating part faces the drop port to promote plasticization of the resin material.
Therefore, according to the present invention, there is provided a plasticizing method capable of preventing poor biting of the resin material.

The invention according to claim 6 is a plasticizing method implemented without using a threshold value.
Since no threshold value is used, it is possible to avoid the trouble of setting the threshold value and mistakes in setting the threshold value. In addition, according to the present invention, there is provided a plasticizing method capable of preventing the resin material from being bitten poorly.

1 is a basic configuration diagram of a vertical injection molding apparatus including a plasticizing device according to the present invention; FIG. 2-2 arrow view of FIG. 1. FIG. FIG. 2 is an enlarged view of a main portion of FIG. 1 and is a basic configuration diagram of an injection device including a plasticizing device according to the present invention. It is a figure which shows the principal part of a plasticizing apparatus. FIG. 4 is a cross-sectional view of a main part of the plasticizing device; It is a figure explaining the temperature distribution of a temperature control rod. It is a figure explaining the effect|action of a temperature-control rod. It is a flow chart explaining the plasticization method concerning the present invention. FIG. 10 is a flow chart explaining a comparison process and a movement process; FIG. 4 is a flow diagram for explaining a plasticizing/weighing process and an injection process; FIG. 11 is a flow chart for explaining the changed comparison process and movement process; It is a flow figure explaining the plasticization method changed further. It is a time chart explaining a further changed plasticizing method. It is an exploded perspective view explaining the example of a change of a temperature control rod. It is a figure explaining the effect|action of the changed temperature control rod (form in which the heating part contact|connected). It is a figure explaining the effect|action of the changed temperature control rod (a form in which the heating part was separated). FIG. 10 is a cross-sectional view of a modified plasticizing device; FIG. 10 is a cross-sectional view of a main part of a further modified plasticizing device;

An embodiment of the present invention will be described below with reference to the accompanying drawings.

An embodiment of the present invention will be described below with reference to the accompanying drawings. In the cylinder, "extension" means advancing the piston rod to extend the entire length of the cylinder, and "retraction" means retracting the piston rod to shorten the entire length of the cylinder.

As shown in FIG. 1, a vertical injection molding apparatus 10 includes a mold clamping device 20 having a vertical mold clamping shaft 20a for clamping a mold 12 consisting of a lower mold 13 and an upper mold 14; The main element of this device is an injection device 50 arranged on the clamping device 20 .

The mold clamping device 20 includes a bed 21 fixed to a floor (or a machine base) 16, a pressure receiving plate 22 fixed to the bed 21, a turntable 23 placed on the pressure receiving plate 22, and a platen below the pressure receiving plate 22. a traction board 25 arranged in the pressure receiving board 22 and raised and lowered by a half nut position adjusting means 24 provided on the pressure receiving board 22; a half nut 26 arranged under the traction board 25; A movable platen 28 which is moved up and down by the provided mold opening/closing means 27, a tie bar 31 which is lowered from the movable platen 28 and passes through the pressure receiving plate 22 and the traction platen 25, pressure to the half nut position adjusting means 24, the mold opening/closing means 27 and the like. A pump motor unit 32 is provided for the controlled supply of oil.

The half nut position adjusting means 24 is preferably a half nut position adjusting hydraulic cylinder 24A. Similarly, the mold opening/closing means 27 is preferably a mold opening/closing hydraulic cylinder 27A.

The pressure receiving plate 22 can be removed from the bed 21 by loosening bolts or the like. Therefore, "fixation" in the present invention includes not only complete fixation but also separably bonded forms.
Also, the half nut position adjusting means 24 and the mold opening/closing means 27 may be provided on the bed 21 without any problem.

The traction board 25 has, for example, a mold clamping cylinder 33 that opens upward. A piston portion 34 extending downward from the pressure receiving platen 22 is accommodated in the mold clamping cylinder 33 . A pressure oil chamber 35 is formed between the mold clamping cylinder 33 and the piston portion 34 . When pressure oil is supplied to the pressure oil chamber 35, the traction board 25 is lowered.

The tie bar 31 is provided with an engaging portion 36 at its lower end. This engaging portion 36 is, for example, a sawtooth portion. Hereinafter, the engaging portion 36 is read as the sawtooth portion 36 .
The half nut 26 is a half-split nut that engages (engages) with the sawtooth portion 36 as an engaging portion. The half nut 26 is opened and closed by half nut opening/closing means 37 provided on the traction board 25 . The half nut opening/closing means 37 is preferably a half nut opening/closing hydraulic cylinder 37A.

It is preferable that the teeth of the saw-toothed portion 36 are arranged at regular pitches like bamboo knots. The teeth may be rectangular, trapezoidal, or triangular in cross section. The half nut 26 is provided with corresponding teeth.

Tie bars 31 and half nuts 26 are made of strong, hard steel. Grease lubrication is provided between the serrations 36 and the half nut 26 to facilitate steel-to-steel contact. Grease is applied to the outer peripheral surface of the tie bar 31 at a position higher than the sawtooth portion 36 . The grease runs down and reaches the serrations 36 . Greasing may be automatic or manual.

Preferably, a half nut operation monitoring mechanism 38 for monitoring the operation of half nut 26 is provided near half nut 26 . However, on the condition that the mold opening/closing means 27 and the half nut position adjusting means 24 can be accurately controlled, the half nut operation monitoring mechanism 38 may be omitted.

Arbitrary sensors, such as a proximity switch and a limit switch, can be used for the half nut operation monitoring mechanism 38 . Proximity switch is a non-contact sensor that determines "object is present" when the mating metal approaches within a certain distance, and "no object" when the mating metal is beyond a certain distance. The half nut 26 is wet with waste grease, but if it is a non-contact type sensor, there is no fear of erroneous detection. Moreover, it is inexpensive. Proximity switches are therefore recommended.

A tray 41 is preferably positioned below the halfnuts 26 and on the floor 16 to receive the waste grease. The tray 41 is a dish-shaped container. Regularly or as needed, the tray 41 is pulled out and accumulated waste grease is treated to prevent the floor 16 from being soiled.

Preferably, bed 21 is surrounded by cover 42 . This cover 42 serves as a safety cover. By surrounding the bed 21 with the cover 42, the appearance of the mold clamping device 20 is improved. However, the cover 42 is not essential because it can be replaced by a safety fence or the like.

FIG. 2 is a view taken along arrow 2-2 in FIG.
As shown in FIG. 2, the tie bars 31 are arranged at the vertices of the triangle. Among them, one tie bar 31 constitutes the center of rotation of the turntable 23 .
At the product take-out position 17 , the resin molded product is taken out from the lower mold 13 . The empty lower mold 13 is moved to the mold clamping position 18 by rotating the turntable 23 by 180°.
Since the work of removing the product and the work of clamping the mold can be performed in parallel, the use of the turntable 23 can improve productivity.

However, the turntable 23 can be replaced with a carriage that reciprocates between the mold clamping position 18 and the product unloading position 17 . In this case, it is desirable to use four tie bars 31 .
Alternatively, the turntable 23 and the carriage may be omitted. Also in this case, it is desirable to use four tie bars 31 .

Therefore, in the mold clamping device 20, the number of tie bars 31 can be freely determined, and whether or not to provide the turntable 23 and whether or not to provide a carriage is optional.

In the mold clamping device 20 of FIG. 1, the half nut 26 is opened and separated from the serrated portion 36 . Next, the mold opening/closing means 27 is extended to raise the movable platen 28 . As the movable platen 28 rises, the upper die 14 separates from the lower die 13 and the tie bars 31 rise.

Next, the injection device 50 will be described.
As shown in FIG. 3, the injection device 50 includes an injection positioning means 51 extending upward from the movable platen 28, an injection platen 52 supported by the injection positioning means 51, and an injection cylinder 53 suspended from the injection platen 52. , a first bracket 54 and a second bracket 55 which are appropriately erected on the injection platen 52, a plasticizing device 70 supported by the injection platen 52 and the like, and a heating tube 71, which is a main part of the plasticizing device 70, extending downward from the resin material. and a branch member 58 branching from the middle of the height of the material storage member 57 and extending to the injection cylinder 53 are main elements.

The material storage member 57 has a nozzle 59 at its lower end and a shut valve 61 in the vicinity of this nozzle 59 . The shut valve 61 is opened and closed by shut valve opening/closing means 62 .
A plunger 63 is movably accommodated in the branch member 58 and driven by the injection cylinder 53 .
The material storage member 57 including the branch member 58 and the heating cylinder 71 are heated by the band heater 64 .
An outlet 65 for discharging the resin material and an outlet valve 66 for opening and closing the outlet 65 are provided at the bottom of the heating cylinder 71 . The outlet valve 66 is driven by outlet valve driving means 67 provided near the heating cylinder 71 .

The detailed structure of the plasticizing device 70 will be described later with reference to FIGS. 4 and 5. A heating cylinder 71 is supported by an injection platen 52, and a screw 72 is rotatably supported by a first bracket 54 via a bearing 73. , the temperature control rod moving means 74 and the hopper 75 are fixedly supported by the second bracket 55 , and the screw rotating means 76 for rotating the screw 72 is fixed to the injection platen 52 .
The temperature control rod moving means 74 is a mechanism for moving the temperature control rod (FIG. 5, reference numeral 90) in the axial direction (along the rotation axis of the screw 72).

A large-diameter pulley 77 is integrally formed on the screw 72, a small-diameter pulley 78 is provided on the rotating shaft of the screw rotating means 76, and a belt 79 is stretched between the large-diameter pulley 77 and the small-diameter pulley 78, so that the screw The rotating means 76 can rotate the screw 72 in a predetermined direction at a predetermined speed.
The large-diameter pulley 77 may be replaced with a large-diameter gear, and the small-diameter pulley 78 may be replaced with a small-diameter gear.

As shown in FIG. 4, the heating cylinder 71 has an outlet 65 and an outlet valve 66 at the bottom. A bottom portion 81 may be removable to facilitate installation of the outlet valve 66 .
The heating cylinder 71 has a drop port 82 at the top. This drop port 82 is connected to a hopper (Fig. 3, reference numeral 75). The resin material introduced from the drop port 82 spreads in the gap between the inner peripheral surface of the heating cylinder 71 and the outer peripheral surface of the screw 72 . Therefore, the vicinity of the drop port 82 becomes the supply portion 83 .

As shown in FIG. 5, a temperature control rod 90 is accommodated in the screw 72 so as to be axially movable.
The temperature control rod 90 consists of a lower end block 91, a heat insulating plate 92 mounted on the lower end block 91, a tubular sleeve 93 mounted on the heat insulating plate 92, and a cooling means 94 provided on the sleeve 93. Consists of
The cooling means 94 is, for example, a cooling tube 95 wrapped around the sleeve 93 . A liquid supply pipe 96 and a drain pipe 97 are connected to the cooling tube 95 .

In addition, the cooling means 94 may be a refrigerant passage directly opened in the sleeve 93 by a long drill. In this case, since the cooling tube 95 is omitted, the outer diameter of the sleeve 93 is set to be the same as that of the heat insulating plate 92 and the lower end block 91 . Since the sleeve 93 has a sufficiently large diameter, the refrigerant passage is easily formed. A liquid supply pipe 96 and a drain pipe 97 are connected to the refrigerant passage.

A plurality of heaters 98 are fitted in the lower end block 91 . A sheathed wire 99 feeding the heater 98 extends upward through the sleeve 93 .
The heater 98 is preferably a rod-shaped heater in which a heating wire is covered with an insulating material, but may be a plate-shaped heater, a surface heater, a ceramic heater, an IH (electromagnetic induction heating) heater, or a halogen lamp heater. Any known heating means can be used.

Lower end block 91 , heat insulating plate 92 and sleeve 93 are integrated by lowering hexagon socket bolt 101 from sleeve 93 and screwing into lower end block 91 .
Also, the drive rod 102 is lowered through the center of the sleeve 93 and the lower end of the drive rod 102 is screwed into the lower end block 91 . The drive rod 102 is moved up and down a predetermined distance by temperature control rod moving means (74 in FIG. 3).

Preferably, a ring 103 is fitted to the lower end block 91 to prevent the lower end block 91 from swinging with respect to the sleeve 93 in the direction perpendicular to the axis. The ring 103 may be a piston ring, and any type of annular member may be used as long as the ring 103 is an annular member that prevents the lower end block 91 from swinging to the left and right.

However, interposing the ring 103 makes it easier for the lower end block 91 to rotate together with the rotating screw 72 . As a countermeasure, a flat portion 104 is provided on the upper portion of the sleeve 93 . The plane portion 104 is formed by cutting a part of the outer circumference of the cylinder to make it flat. A rotation stopping plate 105 is brought into contact with this flat portion 104 . This prevents the sleeve 93 from co-rotating.

In order to accommodate (incorporate) the temperature control rod 90 having such a configuration, the screw 72 needs to have a large diameter to some extent.
Therefore, in FIG. 4, when the distance between the lower end of the screw 72 and the drop port 82 is the effective length L, and the outer diameter of the screw 72 is D, L/D is between 0.5 and 3.0. range and D should be at least 80 mm.

If D is 80 mm, a sufficiently large temperature control rod 90 can be easily set.
If L/D is less than 0.5, the effective length L becomes small, and a sufficient number of spiral grooves cannot be formed on the outer circumference. Further, when L/D exceeds 3.0, the plasticizing device 70 shown in FIG. 3 extends vertically, and the injection device 50 becomes large.
If L/D is in the range of 0.5 to 3.0, a sufficient number of spiral grooves can be formed in the screw 72, and the axial dimension of the plasticizing device 70 can be reduced.

As shown in FIG. 6A, the lower end block 91 has a built-in heater (reference numeral 98 in FIG. Since the sleeve 93 is wound with the cooling tube 95 , it becomes the cooling portion 107 . The heat insulating plate 92 serves as the heat insulating portion 108 and plays a role of blocking heat transfer from the heating portion 106 to the cooling portion 107 and a role of preventing the heating portion 106 from being cooled by the cooling portion 107 .
As shown in FIG. 6B, the heating section 106 becomes high temperature, the cooling section 107 becomes low temperature, and the heat insulation section 108 becomes intermediate temperature between high temperature and low temperature.

In FIG. 7(a), the temperature control rod 90 is in the advanced (lowered) position.
As shown in FIG. 7(b), the screw temperature has a curve similar to that in FIG. 6(b). The center of the supply portion 83 (corresponding to reference numeral 83 in FIGS. 4 and 5) attached to the horizontal axis is in the low temperature range, and the supply portion 83 as a whole is substantially in the low temperature range.
The forms of FIGS. 7A and 7B are suitable when a small amount of resin material is supplied to the supply portion 83 or when the resin material is slowly plasticized.

A small amount of resin material is synonymous with a small measured value or a small volume.
If the weighed value is small or the volume is small, the resin material quickly becomes hot and tends to cause poor bite. can be prevented from becoming

In contrast, in FIG. 7(c), the temperature control rod 90 is in the retracted (raised) position.
As shown in FIG. 7(d), the temperature curve shifts to the right. As a result, the center of the supply section 83 is in the high temperature range, and the supply section 83 as a whole is substantially in the high temperature range.
The forms of FIGS. 7(c) and (d) are suitable when a large amount of resin material is supplied to the supply section 83 or when the resin material is quickly plasticized.

A large amount of resin material is synonymous with a large metric value or a large volume.
That is, if the measured value is large or the capacity is large, the resin material will not reach a high temperature immediately and will not bite into the resin material. By heating the resin material in the supply section, the resin material can be quickly plasticized.

A plasticizing method performed using the plasticizing apparatus 70 having the above configuration will be described with reference to FIGS. 8 to 10. FIG.
At ST 10 in FIG. 8 (ST indicates a step number; the same applies hereinafter), the plasticizing device 70 described in FIGS. 3 to 5 is prepared.
In the comparison step of ST20, the planned metric value is compared with the threshold value.
In the movement step of ST30, the temperature control rod is moved based on the comparison result.
In the plasticizing/measuring step of ST40, the resin material introduced into the heating cylinder is plasticized by rotating the screw, and the plasticized resin material is discharged from the outlet provided in the heating cylinder and weighed.
The above ST20, ST30 and ST40 will be described in detail below.

Details of ST20 (comparing step) and ST30 (moving step) will be described with reference to FIG.
At ST21 in FIG. 9, a threshold value is set. This threshold is a value that determines whether the temperature control rod is advanced or retracted, and is determined based on injection molding trials and empirical rules.

In ST22, the planned weighing value is read.
In ST23, it is determined whether the planned weight value is below or exceeds the threshold value.
The above ST21 to ST23 constitute a comparison process.

When it is determined in ST23 that the planned weight value is equal to or less than the threshold value, in ST31, the temperature control rod is advanced to take the form shown in FIG. 7(a).
Further, when it is determined in ST23 that the planned weighing value exceeds the threshold value, in ST32, the temperature control rod is retracted to the configuration shown in FIG. 7(c).

Details of ST40 (plasticizing/measuring step) and the injection step in FIG. 8 will be described with reference to FIG.
At ST41 in FIG. 10, the outlet valve is opened. That is, in FIG. 3, outlet valve 66 is moved to open outlet 65 .
At ST42, the shut valve is closed. That is, in FIG. 3, the shut valve 61 is turned to close the nozzle 59 .
In ST43, back pressure control of the injection cylinder is performed. That is, in FIG. 1, the back pressure control of the injection cylinder 53 is started by the pump motor unit 32 so that a predetermined reaction force (resistance force) is applied to the plunger.

At ST44, the resin material is plasticized while rotating the screw. In FIG. 3, the resin material fills the material storage member 57 and the branch member 58 . Due to this filling, the plunger 63 gradually retreats (moves to the right in the figure). The movement distance of the plunger 63 is measured by well-known means such as an encoder.

The resin material is weighed according to the following equation: cross-sectional area of plunger 63 x moving distance of plunger 63 = weighed value.
In ST45, completion of metering is checked, and when metering is completed, back pressure control is ended and the outlet valve is closed (ST46).
The above steps ST41 to ST46 constitute the plasticizing/weighing process.

In ST47, it is confirmed that the clamping of the molds has been completed, and when the confirmation is completed, the shut valve 61 is opened (ST48).
After the shut valve 61 is opened, the plunger 63 is advanced to inject the resin material from the nozzle 59 (ST49).
When it is confirmed in ST50 that the injection has ended, the shut valve 61 is closed (ST51).
The above ST47 to ST51 constitute the injection process.

In the above description, the threshold is set in ST21 of FIG. 9, but a plurality of thresholds may be set. A specific example thereof will be described with reference to FIG.
FIG. 11(a) is a drawing in which first to fourth positions P1 to P4 are added to FIG. 7(c).
A fourth position P4 indicates the retraction limit position of the lower end block 91 (that is, the temperature control rod 90).
The first position P1 indicates the forward limit position of the lower end block 91 (temperature control rod 90).

A second position P2 and a third position P3 indicate intermediate positions between P1 and P4, the second position P2 is closer to the first position P1 than the third position P3, and the third position P3 is closer to the second position P2. It is located closer to the fourth position P4 than.

A flow corresponding to FIG. 11(a) will be described with reference to FIG. 11(b).
At ST61 in FIG. 11(b), the first to third threshold values are set.
At ST62, the planned weighing value is read.
At ST63, the planned metric value is compared with the first to third threshold values.
The above ST61 to ST63 constitute a comparison step.

When it is determined in ST63 that the planned weighed value is equal to or less than the first threshold value, in ST64 the temperature control rod is moved to the first position P1.
When it is determined in ST63 that the planned weight value exceeds the first threshold value and is equal to or less than the second threshold value, in ST65 the temperature control rod is moved to the second position P2.
When it is determined in ST63 that the planned weight value exceeds the second threshold value and is equal to or less than the third threshold value, in ST66 the temperature control rod is moved to the third position P3.
When it is determined in ST63 that the planned measured value exceeds the third threshold value, in ST67 the temperature control rod is moved to the fourth position P4.
The above steps ST64 to ST67 constitute the moving process.

As described above, setting a plurality of threshold values enables finer temperature control.
Although the number of thresholds is set to three in this specific example, the number of thresholds may be set to two or four or more. The number of positions of the temperature control rod is the number of thresholds plus one.

It should be noted that the method of the present invention can be implemented without using a threshold as well as using a threshold. A specific example thereof will be described with reference to FIG.
At ST10 in FIG. 12, the plasticizing device 70 described with reference to FIGS. 3 to 5 is prepared.
In the movement step of ST30, the temperature control rods are moved based on external information. The details of this ST30 (moving step) have already been explained with reference to FIG. 9 or FIG.

The external information includes a planned weighing value, a planned plasticizing time, a type of resin material, and the like.
When the weighed value is small, the plasticizing time is long, or the resin material has a low melting temperature, the temperature control rod moving means advances the temperature control rod.
When the weighed value is large, the plasticizing time is short, or the resin material has a high melting temperature, the temperature control rod moving means retracts the temperature control rod.

In the plasticizing/measuring step of ST40, the resin material introduced into the heating cylinder is plasticized by rotating the screw, and the plasticized resin material is discharged from the outlet provided in the heating cylinder and weighed.
The details of ST40 (plasticizing/weighing step) have already been described with reference to FIG. 10, so description thereof will be omitted.

In the above-described embodiment, the temperature control rod is axially moved in the moving step, and is kept stationary during the plasticizing and metering steps without being axially moved.
However, depending on the type of material (difference in crystallinity/amorphism, difference in ease of melting/difficulty in melting resin, difference in easiness/difficulty in occurrence of poor bite, etc.), plasticization may occur.・Moving the temperature control rod during the weighing process may provide better results.

Position control of the temperature control rods when they are moved will be described with reference to FIG.
As shown in FIG. 13(a), at a small capacity (when the weighed value is small), the temperature control rod is moved from the advanced (lowered) position to the retracted (raised) position at the beginning of the plasticizing and weighing process. Most of the plasticization is performed in the retracted position. At the end of the plasticizing and metering process, the temperature control rod is moved from the retracted position to the advanced position.

As shown in FIG. 13(b), the medium volume (capacity between the small volume and the large volume) requires a longer time for the plasticizing/weighing process than the small volume. Then, as with the small volume, the temperature control rod is moved from the advanced position to the retracted position at the beginning of the plasticizing and metering process. Most of the plasticization is performed in the retracted position. At the end of the plasticizing and metering process, the temperature control rod is moved from the retracted position to the advanced position.

As shown in Fig. 13(c), at a large capacity (when the weighing value is large), the temperature control rod is moved from the intermediate position (intermediate between forward and backward) to the retracted (rising) position at the beginning of the plasticizing and weighing process. do. Most of the plasticization is performed in the retracted position. At the end of the plasticizing and metering process, the temperature control rod is moved from the retracted position to the intermediate position.

In addition, in FIGS. 13(a) to 13(c), it is permissible to change the position of the temperature control rod at the intermediate position of the plasticizing/measuring process. That is, in the present invention, the temperature control rod can be moved by the temperature control rod moving means, so that the position of the temperature control rod can be controlled at any time or at will.

By the way, in FIG. 7(c), the no-heater area 109 appears in front of the lower end block 91 by retracting the temperature control rod (the lower end block 91). Considering that the resin material is melted, the non-heater region 109 should be absent. An example of countermeasures will be described below.

As shown in FIG. 14, the lower end block 91 is divided into a first heating section 111 and a second heating section 112 .
The first heating unit 111 includes a first disk 113 , four columnar first claws 114 extending from the first disk 113 to the second heating unit 112 , and a first heater 115 inserted into the first claws 114 . Consists of

The second heating section 112 includes a second disk 116 , four columnar second claws 117 extending from the second disk 116 to the first heating section 111 , and a second heater 118 inserted into the second claws 117 . Consists of
The sum of the height dimension of the first disk 113 and the height dimension of the 22nd disk 116 is the minimum height dimension of the lower end block 91 .

15 and 16, the operation of the modification divided into the first heating section 111 and the second heating section 112 will be described.
As shown in FIG. 15( a ), one first claw 114 is closely fitted between two adjacent second claws 117 . Since it fits, the first heating section 111 does not rotate with respect to the second heating section 112 . That is, the first heating section 111 can only move in the axial direction with respect to the second heating section 112 .
The first heater 115 overlaps the second heater 118 by L2.

As shown in FIG. 15B, the second heating section 112 is housed in the screw 72 in contact with the first heating section 111 .
As shown in FIG. 15(c), the heating section 106 becomes hot.

As shown in FIG. 16A , the first heating unit 111 is relatively moved so that the first heating unit 111 is separated from the second heating unit 112 . Due to this movement, the lap allowance (FIG. 15(a), symbol L2) becomes almost zero. Apparently, the first heating unit 111 and the second heating unit 112 are heated just enough by the first heater 115 and the second heater 118 .

As shown in FIG. 16(b), the first heating section 111 and the second heating section 112 are accommodated in the screw 72 in a form separated from each other.
As shown in FIG. 16(c), the heating section 106 becomes hot. That is, the non-heater region 109 shown in FIG. 7(c) is eliminated.

As shown in FIG. 17, the lower end of the drive rod 102 is screwed into the second heating portion 112 (FIG. 14, second disk 116). The drive rod 102 is driven up and down by the first temperature control rod moving means 121 .

In addition, the first heating section 111 is vertically driven by the second temperature control rod moving means 122 together with the heat insulating plate 92 , the sleeve 93 and the cooling means 94 .
Other components are the same as those in FIG. 5, so the reference numerals in FIG. 5 are used and detailed descriptions thereof are omitted.

In addition to the form of FIG.15(b), the following form is obtained by the above.
By advancing (lowering) the first temperature control rod moving means 121 and the second temperature control rod moving means 122 together, the same configuration as in FIGS. 7(a) and 7(b) can be obtained.
By retracting (raising) the first temperature control rod moving means 121 and the second temperature control rod moving means 122 together, the same configuration as in FIGS. 7(c) and (d) can be obtained.

Next, another modified example of the temperature control rod 90 will be described with reference to FIG.
As shown in FIG. 18, the lower block 91 is entirely made of a heat insulating material and consists of a flange 91a and a cylindrical portion 91b having a diameter smaller than that of the flange 91a. Then, a heater 98 is wound around the cylindrical portion 91b.
As described above, the brim 91 a made of heat insulating material constitutes the heat insulating portion 108 and the heater 98 constitutes the heating portion 106 .

As is clear from the above description, the heat insulating portion 108 can be configured by a heat insulating plate (FIG. 5, reference numeral 92) or by a flange 91a made of a heat insulating material. Therefore, the structure of the heat insulating portion 108 is not limited to the examples (including modified examples) as long as it exhibits heat insulating performance.

Also, the heater 98 can be built in the lower end block 91 or wound around the lower end block 91 . Therefore, the form of the heating unit 106 is not limited to the embodiment (including modified examples) as long as it exhibits heating performance.

In FIG. 1, the plasticizing device 70 of the present invention is applied to the vertical injection molding apparatus 10 in which the mold clamping shaft 20a is vertical. It can be applied to a certain horizontal injection molding machine.
When applied to a horizontal injection molding apparatus, the attitudes of the injection cylinder 53, the heating cylinder 71 and the screw 72 shown in FIG. 3 remain as shown in FIG. be.

In FIG. 1, the half nut position adjusting means 24, mold opening/closing means 27, and half nut opening/closing means 37 are preferably hydraulic cylinders, but may be electric cylinders, air cylinders, or equivalent means.
Similarly, the injection positioning means 51, the shut valve opening/closing means 62, the outlet valve driving means 67 and the temperature control rod moving means 74 are preferably hydraulic cylinders, but may be electric cylinders or air cylinders or equivalent means.

INDUSTRIAL APPLICABILITY The present invention is suitable for a plasticizing device that plasticizes a resin material.

50... Injection device, 65... Exit (exit provided in heating tube), 70... Plasticizing device, 71... Heating tube, 72... Screw, 74... Temperature control rod moving mechanism, 75... Hopper, 82... Falling port, 90 temperature control rod 92 heat insulating plate 94 cooling mechanism 98 heater 106 heating unit 107 cooling unit 108 heat insulating unit 111 first heating unit 112 second heating unit 113 1st disk 114 1st claw 115 1st heater 116 2nd disk 117 2nd claw 118 2nd heater 121 1st temperature control rod moving mechanism 122 2nd temperature Control rod moving mechanism, D... outer diameter of screw, L... effective length of screw.

Claims (6)

A heating cylinder having a bottom , a screw inserted toward the bottom of the heating cylinder and rotatably accommodated in the heating cylinder, and a hopper for throwing a resin material into a drop opening provided in the heating cylinder. ,
A plasticizing device that plasticizes the resin material introduced into the heating cylinder by rotation of the screw and discharges the plasticized resin material from an outlet provided at the bottom of the heating cylinder,
The screw incorporates a temperature control rod extending along the axis of the screw ,
This temperature control rod includes, from a base to a tip, a cooling portion cooled by a cooling means, a heat insulating portion, and a heating portion having a heater in this order. so as to block the transfer of heat between
The heat insulating part is provided near the drop opening,
The plasticizing device is characterized by comprising temperature control rod moving means for axially moving the temperature control rod with respect to the screw.
A heating cylinder having a bottom , a screw inserted toward the bottom of the heating cylinder and rotatably accommodated in the heating cylinder, and a hopper for throwing a resin material into a drop opening provided in the heating cylinder. ,
A plasticizing device that plasticizes the resin material introduced into the heating cylinder by rotation of the screw and discharges the plasticized resin material from an outlet provided at the bottom of the heating cylinder,
The screw incorporates a temperature control rod extending along the axis of the screw ,
This temperature control rod includes, from a base to a tip, a cooling portion cooled by a cooling means, a heat insulating portion, and a heating portion having a heater in this order. so as to block the transfer of heat between
The heat insulating part is provided near the drop opening,
The plasticizing device includes first temperature control rod moving means for collectively moving the heat insulating portion, the first heating portion and the cooling portion with respect to the screw in the axial direction, and the first temperature control rod moving means. and a second temperature control rod moving means for axially moving the second heating portion with respect to the screw independently of the screw.
The plasticizing device according to claim 2,
The first heating unit comprises a first disk, a first claw extending from the first disk to the second heating unit, and the first heater inserted into the first disk and the first claw,
The second heating unit comprises a second disk, a second claw extending from the second disk to the first heating unit, and the second heater inserted into the second claw and the second disk,
A plasticizing device, wherein the first claw is axially movably fitted between two adjacent second claws.
The plasticizing device according to any one of claims 1 to 3,
Where L is the effective length of the screw and D is the outer diameter of the screw, L/D is in the range of 0.5 to 3.0, and D is at least 80 mm. Plasticizing device to do. A preparation step of preparing the plasticizing device according to any one of claims 1 to 4;
a comparison step of comparing the weight value at that time and a threshold value in a scheduled plasticizing operation;
In this comparison step, when the weighed value is equal to or less than the threshold value, the temperature control rod is moved closer to the outlet, and when the weighed value exceeds the threshold value, the temperature control rod is moved. moving away from the outlet;
a plasticizing and weighing step of discharging and weighing the plasticized resin material from an outlet provided in the heating cylinder while plasticizing the resin material put into the heating cylinder by rotating the screw; plasticization method. A preparation step of preparing the plasticizing device according to any one of claims 1 to 4;
a moving step of axially moving the temperature control rod with the temperature control rod moving means;
a plasticizing and weighing step of discharging and weighing the plasticized resin material from an outlet provided in the heating cylinder while plasticizing the resin material put into the heating cylinder by rotating the screw; plasticization method.

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