JP4043318B2 - Biaxial stretch blow molding method and molding machine therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a cylindrical parison extruded from a crosshead die of an extruder provided in a biaxial stretch blow molding machine is molded into a bottomed preform in a preform molding die, and then the preform is formed into a molded product. TECHNICAL FIELD The present invention relates to a biaxial stretch blow molding method and a molding machine for forming a hollow molded product by blowing secondary air and stretching a stretch rod in a molding die, and in particular, a lowering speed of a secondary air blowing nozzle and a lowering speed of a stretch rod. In a biaxial stretch blow molding method for molding a hollow molded product in synchronism with the above and a molding machine therefor.
[0002]
[Prior art]
Conventionally, after feeding a cylindrical parison extruded from a crosshead die of an extruder provided in a hollow molding machine and dropping into a preform molding die having a preform molding cavity, the preform molding die is The mold is closed, the cylindrical parison is cut with a parison cutting device, one end of the cylindrical parison is closed, a primary air blowing nozzle is inserted into the cylindrical parison, and primary air is blown through the nozzle. A bottomed preform was molded, the preform mold was opened, and the bottomed preform was suspended by a primary air blowing nozzle and supplied into a molded product mold having a molded product molding cavity. After that, the mold for molding the molded product is closed, the secondary air blowing nozzle and the stretch rod are inserted into the bottomed preform, and the secondary air blowing nozzle and the bottomed preform are inserted. Biaxial stretch blow molding method and biaxial stretching in which secondary air is blown through the stretch rod and the stretch rod is stretched to stretch the bottomed preform in the transverse and longitudinal directions to form a hollow molded product. Blow molding machines are known (see Tadahiko Katsura, “Practical Blow Molding Easy to understand” published by the Industrial Research Committee, November 20, 2000, P.6-10, P.28-29).
[0003]
In this biaxial stretch blow molding method and molding machine therefor, a hollow molded product is molded by molding a molded product mold having a molded bottomed preform suspended from a primary air blowing nozzle and having a molded product molding cavity. After the mold is closed and the primary air blowing nozzle is released, the stretch rod is lowered at a predetermined lowering speed and inserted into the bottomed preform, and then the secondary The air blowing nozzle is lowered at a predetermined lowering speed to seal the vicinity of the opening of the bottomed preform, and then the secondary air is introduced into the bottomed preform via the secondary air blowing nozzle and the stretch rod. And a stretched rod is stretched to stretch the bottomed preform in the transverse and longitudinal directions to form a hollow molded article.
[0004]
In this biaxial stretch blow molding machine, a secondary air blowing nozzle drive mechanism that lowers the secondary air blowing nozzle at a predetermined lowering speed and a stretch rod drive mechanism that lowers the stretch rod at a predetermined lowering speed. Each is provided with a hydraulic or compressed air drive source, and this drive source is operated separately to operate the secondary air blowing nozzle drive mechanism and the stretch rod drive mechanism, and the secondary air blowing nozzle is lowered. Sealing in the vicinity of the opening of the bottomed preform and insertion into the bottomed preform by lowering the stretch rod are performed.
[0005]
[Problems to be solved by the invention]
However, in the above biaxial stretch blow molding method and molding machine, a secondary air blowing nozzle drive mechanism that lowers the secondary air blowing nozzle at a predetermined lowering speed and a stretch rod that lowers the stretch rod at a predetermined lowering speed. Each drive mechanism is provided with a hydraulic or pneumatic drive source, and the drive sources are operated separately in cooperation with each other so that the secondary air blowing nozzle drive mechanism and the stretch rod drive mechanism function. It is difficult to synchronize the operation of the secondary air blowing nozzle and the operation of the stretch rod, and if the secondary air blowing nozzle is operated first, it may cause damage to the stretch rod. Then, the secondary air blowing nozzle is lowered to seal the vicinity of the bottomed preform opening. By extending the rods is performed to prevent damage.
[0006]
For this reason, the molding cycle becomes long, and it is difficult to control the two in cooperation with each other, and it is difficult to obtain suitable production efficiency.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a first aspect of the present invention, a tubular parison hanging through f Ddodai, once applied to the preform in the molding die having a preform molding cavity, the preform The mold is closed and cut with a parison cutting device, one end of the cylindrical parison is closed, a primary air blowing nozzle is inserted into the cylindrical parison, and primary air is blown through the nozzle. Molded into a bottomed preform, opened the preform molding die, suspended the bottomed preform with a primary air blowing nozzle, and supplied it into a molded product mold having a molded product molding cavity. After that, the mold for molding the molded product is closed, and the secondary air blowing nozzle and the stretch rod are inserted into the bottomed preform to blow the secondary air, and the stretch rod is extended to expand the bottomed mold. In the biaxial stretch blow molding method in which the foam is expanded until it matches the cavity of the molded product molding die, a secondary air blowing nozzle for sealing the vicinity of the opening of the bottomed preform and blowing secondary air is provided. A drive mechanism for a secondary air blowing nozzle that moves up and down, and a drive mechanism for a stretch rod that stretches and contracts a stretch rod that is inserted into the bottomed preform to blow secondary air and extend in the vertical direction. Driven by an electric motor, the secondary air blowing nozzle and the stretch rod are lowered simultaneously or substantially simultaneously from the lowering start position above the respective molding die, and the secondary air blowing nozzle is moved to the molding die. The timing of sealing the vicinity of the opening of the bottomed preform in the mold and the distance moved longer than the moving distance of the secondary air blowing nozzle Toretchiroddo is simultaneous and the timing reaching a predetermined position of the bottomed-flops preform, after, blowing the secondary air through the secondary air blowing nozzle and the stretch rod to the bottomed-flops preform with writing, and characterized in that said by extending the stretch rod extends the bottomed preform vertically and horizontally.
[0008]
According to a second aspect of the invention, flop having a parison cutting device for cutting the tubular parison hanging through f Ddodai, the preform molding cavities tubular parison is formed into a bottomed preform is supplied Reform molding die, primary air blowing nozzle that is positioned above the preform molding die and inserted into a cylindrical parison and blows primary air to form a bottomed preform, and a primary that raises and lowers the nozzle A primary air blowing device having a drive mechanism for an air blowing nozzle, a secondary air blowing nozzle and a bottom having a secondary air blown through the bottomed preform located above the molding die Stretch rod that is elongated in the vertical direction in a cylindrical preform, and a nozzle and rod drive mechanism that raises, lowers, and stretches / shrinks the nozzle and the rod In the biaxial stretch blow molding machine for hollow molded article comprising a biaxially oriented device provided, each equipped with an electric motor to the secondary air blowing nozzle drive mechanism and a stretch rod drive mechanism, in which the motor, the secondary air The blowing nozzle and the stretch rod are simultaneously or substantially simultaneously lowered from the lowering start position above the respective molded product molding dies, and the secondary air blowing nozzle is disposed on the bottomed preform in the molded product molding dies. A control unit that simultaneously seals the vicinity of the opening and the timing at which the stretch rod that has moved a distance longer than the moving distance of the secondary air blowing nozzle reaches a predetermined position in the bottomed preform It is characterized by having.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the biaxial stretch blow molding method of the present invention, a cylindrical parison is molded from an extruder and a cross head die, a bottomed preform is blow molded from the cylindrical parison, and this is blown into a hollow molded product. An embodiment of the present invention will be specifically described below with reference to the drawings.
[0010]
1 to 4 schematically show a biaxial stretch blow molding machine according to the present invention. An extruder 1 having a raw material charging hopper 12 for extruding a thermoplastic synthetic resin by softening and melting, A crosshead die 11 that hangs down the molten raw resin attached to the discharge portion as a cylindrical parison p, a parison cutting device 3 that cuts the cylindrical parison p that hangs down via the crosshead die 11, and a crosshead A preform molding die 2 having a preform molding cavity 21 which is positioned below the die 11 and into which a cylindrical parison p is inserted and molded into a bottomed preform P;
A molded product molding die 5 having a molded product molding cavity 51 which is supplied with a bottomed preform P and molded into a hollow molded product S, and located above the preform molding die 2 and in the cylindrical parison p And a primary air blowing nozzle 41 for forming a cylindrical parison p into a bottomed preform P by blowing in primary air and a primary air blowing nozzle drive mechanism 42 for raising and lowering the nozzle 41. A primary air blowing device 4, a secondary air blowing nozzle 61 that is positioned above the molding die 5 and is inserted into the bottomed preform P and blows secondary air, and the longitudinal direction in the preform P And a stretch rod drive mechanism 63 for elongating / reducing the rod 62, a secondary air blowing nozzle drive mechanism 63 for raising / lowering the nozzle 61, and a stretch rod drive mechanism 64 for elongating / reducing the rod 62. Between the biaxial stretching device 6, a clamping device (not shown) for clamping the molding dies 2, 5, the crosshead die 11, the primary air blowing device 4, and the biaxial stretching device 6 A molding die moving device (not shown) for alternately moving the molding dies 2 and 5 is used.
[0011]
In the biaxial stretch blow molding machine configured as described above, a raw material resin such as polyethylene terephthalate or polypropylene is supplied to a raw material charging hopper 12 provided in the extruder 1, and as shown in FIG. 1 is dripped as a cylindrical parison p through the crosshead die 11 in a state where the raw material resin is melted and softened, and the mold temperature of the cylindrical parison p having the preform molding cavity 21 is 5 to 50 ° C. It supplies in the preforming metal mold | die 2 currently set.
[0012]
The preform molding die 2 is closed with the cylindrical parison p contained therein, one end of the cylindrical parison p is closed with the preform molding die 2, and the parison cutting device 3 is disposed above the cylindrical parison p. Disconnect with.
[0013]
The primary air blowing nozzle 41 provided in the primary air blowing device 4 is lowered with respect to the cylindrical parison p supplied into the preform molding die 2 in a range of a descending speed of 10 to 1000 mm / sec. The primary air blowing nozzle 41 is inserted into the upper opening, and then primary air is blown through the primary air blowing nozzle 4 to blow 0.4 to 1.5 MPa of primary air to swell the cylindrical parison p into the preform molding cavity 21. It is made to take out and shape | molds in bottomed preform P as shown in FIG. 2, FIG.
[0014]
The molded bottomed preform P is composed of an opening provided with screws, a body part, and a bottom part. As shown in FIG. 2, an excess part (upper beam) is provided in the opening part, and a joint part of the bottom part is provided. A surplus part (bottom beam) has occurred. These surplus portions are removed when the bottomed preform P is formed.
[0015]
The molded bottomed preform P is supplied into a molded product molding die 5 having a molded product molding cavity 51 and molded into a hollow molded product S.
[0016]
After the bottomed preform P is brought to a temperature in the vicinity of the glass transition point at a suitable stretching temperature, the preform molding die 2 is opened and the bottomed preform P is suspended from the primary air blowing nozzle 41. Then, it is fed into a molded product molding die 5 having a molded product molding cavity 51 opened and having a mold temperature set to 5 to 70 ° C.
[0017]
After the bottomed preform P is supplied into the molded product molding die 5, the primary air blowing nozzle 41 is lifted to be detached from the opening of the bottomed preform P and molded as shown in FIG. The bottom-shaped preform P is contained in the molded product molding die 5.
The primary air blowing nozzle 41 is raised and lowered by the electric motor 43 of the primary air blowing nozzle drive mechanism 42 communicating with the primary air blowing nozzle 41.
[0018]
Next, as shown in FIG. 4, the molding die moving device is moved from the position where the molded product molding die 5 having the bottomed preform P is molded to the hollow molded product S to the position where it is molded into the hollow molded product S. (Not shown).
[0019]
Thereafter, the two both the axial stretching device secondary air blowing nozzle 61 provided in the 6 and the stretch rod 62 drop-off below, the top surface of the opening portion of the edge of the secondary air blowing nozzle 61 bottomed preform P And the vicinity of the opening of the bottomed preform P is sealed in a watertight manner, and at least the tip of the stretch rod 62 is inserted into the bottomed preform P.
[0020]
The lowering of the secondary air blowing nozzle 61 and the stretch rod 62 is caused by the motor 65 of the secondary air blowing nozzle drive mechanism 63 communicated with the secondary air blowing nozzle 61 and the electric motor of the stretch rod driving mechanism 64 communicated with the stretch rod 62. 66 are driven in cooperation by the control unit to lower the secondary air blowing nozzle 61 and the stretch rod 62 simultaneously or substantially simultaneously , and control the lowering speed within a range of 300 to 1500 mm / sec. It is done by moving in. Moreover, as shown in FIG. 4, the timing at which the secondary air blowing nozzle 61 seals the vicinity of the opening of the bottomed preform P in the molded product molding die 5 and the movement distance of the secondary air blowing nozzle 61. Control is performed simultaneously with the timing at which the tip of the stretch rod 62 that has moved a longer distance reaches the vicinity of the inner bottom of the bottomed preform P.
[0021]
Subsequently, as shown in FIGS. 4 and 5, secondary air is blown into the bottomed preform P through the secondary air blowing nozzle 61 and the stretch rod 62, and the stretch rod 62 is extended to The bottom preform P is stretched in the vertical and horizontal directions to form a hollow molded product S.
[0022]
The secondary air blowing of the secondary air blowing nozzle 61 and the extension of the stretch rod 62 are performed by sealing the bottom of the bottomed preform P by the secondary air blowing nozzle 61 and the bottomed shape of the stretch rod 62. Almost simultaneously with the completion of the insertion to the predetermined position in the reform P , 0.4-3 MPa via the blow hole provided in the secondary air blow nozzle 61 and the blow hole provided in the stretch rod 62 in the bottomed preform. Secondary air is blown, and the stretch rod 62 is stretched while controlling the stretch rod 62 at a stretch speed of 300 to 1500 mm / sec, and the bottomed preform P is vertically stretched to 1.5 to 3.0. It is stretched by 2.0 to 5.0 times laterally and bulged into a molded product molding cavity 51 of the molded product molding die 5 to be molded into a hollow molded product S shown in FIGS.
[0023]
After being molded into the hollow molded product S, the molded product molding die 5 is opened, and the molded hollow molded product S is suspended from the secondary air blowing nozzle 61 from the molded product molding die 5. The mold is released and transferred to a predetermined position to accumulate the hollow molded product S.
[0024]
In the present invention, the secondary air blowing nozzle that descends at a predetermined lowering speed and seals the vicinity of the opening of the bottomed preform and the stretch rod inserted into the bottomed preform are used for the operation of the reference axis. In addition, this is performed by biaxial linear interpolation control in which the interpolation symmetrical axis follows and operates . In other words, the stretch rod that moves a relatively long moving distance is taken as the reference axis with the control method of the long axis of the graph, and the secondary air blowing nozzle that moves a relatively short moving distance is the short axis of the graph. taken interpolation axis of symmetry, by setting the set and lowering speed of the stretch rod de made to the reference axis of the downward end point of the secondary air blowing nozzles composed of a stretch rod and interpolation target axis is a reference axis (destination address), the reference axis The stretch rod is controlled according to the positioning data set in (2), and the secondary air blowing nozzle, which is the interpolation target axis set as the reference axis, is drawn so as to draw a straight locus according to the reference axis .
[0025]
In the biaxial stretch blow molding of the present invention, a drive mechanism for a secondary air blowing nozzle that seals the vicinity of the opening of the bottomed preform and raises and lowers the secondary air blowing nozzle that blows secondary air; The secondary air blowing nozzle and stretch are driven by an electric motor driven by a stretch rod drive mechanism that stretches and contracts a stretch rod that extends in the vertical direction while blowing secondary air through the bottomed preform. The rods are started to descend at the same time or almost simultaneously and are lowered at a predetermined lowering speed, and the vicinity of the opening of the bottomed preform is sealed by the secondary air blowing nozzle, and the stretch rod is placed in the bottomed preform . insert simultaneously Tamingu in place later, but is intended to draw the bottomed preform to vertical and horizontal, lowered prior slightly stretch rod The secondary air blowing nozzles or each other so as to descend to follow at a distance the rod, or the secondary air blowing nozzles so as both result lowered so as to push the stretch rod Fall There may be.
[0026]
【The invention's effect】
The present invention relates to a drive mechanism for a secondary air blowing nozzle that seals the vicinity of the opening of a bottomed preform and raises and lowers a secondary air blowing nozzle that blows secondary air, and a bottomed preform. The secondary air blowing nozzle is lowered at a predetermined lowering speed by driving with a motor a stretch rod driving mechanism that extends and contracts a stretch rod that extends in the vertical direction while blowing secondary air through and sealing abolish filter timing the vicinity of the opening of the bottomed preform, the secondary air blow downward simultaneously with the start of the nozzle or the stretch rod substantially brought down simultaneously started reaches a predetermined position of the bottomed-flops preform and the timing and simultaneously, since after the bottomed preform is intended to extend in vertical and horizontal, both falling completion from the lowered starting position above the secondary air blowing nozzle and the stretch rod The time required for installation can be shortened, the molding cycle can be further shortened, and the coordinated operation of the secondary air blowing nozzle and the stretch rod can be easily and functionally controlled to obtain suitable production efficiency. This leads to the molding of a good quality hollow molded article.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a method for forming a cylindrical parison.
FIG. 2 is a partially enlarged explanatory view of a method for forming a bottomed preform.
FIG. 3 is an explanatory view of a bottomed preform.
FIG. 4 is a partially enlarged explanatory view of extending a bottomed preform in the longitudinal direction.
FIG. 5 is an explanatory view of a partly enlarged main part for extending a bottomed preform in the transverse direction.
FIG. 6 is an explanatory view of a hollow molded product.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Extruder 2 ... Preform molding die 3 ... Parison cutting device 4 ... Primary air blowing device 5 ... Molded product molding die 6 ... Biaxial stretching device 11 ... Crosshead die 12 ... Raw material feeding hopper 21 ... Preform Molding cavity 41 ... Primary air blowing nozzle 42 ... Primary air blowing nozzle drive mechanism 43 ... Electric motor 51 for primary air blowing nozzle drive mechanism ... Molded product molding cavity 61 ... Secondary air blowing nozzle 62 ... Stretch rod 63 ... Two Next air blowing nozzle drive mechanism 64 ... Stretch rod drive mechanism 65 ... Secondary air blow nozzle drive mechanism motor 66 ... Stretch rod drive mechanism motor p ... Cylindrical parison P ... Bottomed preform S ... Hollow Molding

Claims (2)

A tubular parison hanging through f Ddodai, once applied to the preform in the molding die having a preform molding cavity, with cut with parison cutting device closed mold preform mold, tubular One end of the parison is closed, a primary air blowing nozzle is inserted into the cylindrical parison, and primary air is blown through the nozzle to form a bottomed preform, and the preform mold is opened. The bottomed preform is suspended in the primary air blowing nozzle and supplied into a molded product mold having a molded product molding cavity, and then the molded product mold is closed and the bottomed preform is closed. Insert the secondary air blowing nozzle and stretch rod into the secondary air, and extend the stretch rod until the bottomed preform matches the cavity of the molded product mold. In the biaxial stretch blow molding method for out,
A secondary air blowing nozzle drive mechanism that seals the vicinity of the opening of the bottomed preform and raises and lowers the secondary air blowing nozzle that blows secondary air, and is inserted into the bottomed preform. The secondary air blowing nozzle and the stretch rod are respectively molded into the molded metal by driving a stretch rod driving mechanism that blows secondary air and stretches / shrinks a stretch rod that extends in the vertical direction with an electric motor. A timing at which the secondary air blowing nozzle seals the vicinity of the opening of the bottomed preform in the molded product molding die at the same time or substantially simultaneously from the lowering start position above the mold, and the secondary air the timing of the stretch rod to travel long distances from the moving distance of the blow nozzle reaches a predetermined position of the bottomed-flops preform and simultaneously, after, before Wherein the bottomed-flops preform through the secondary air blowing nozzle and the stretch rod secondary air with blown, said by extending the stretch rod extends the bottomed preform to vertical and horizontal A biaxial stretch blow molding method. A parison cutting device for cutting the tubular parison hanging through f Ddodai,
A preform mold having a preform molding cavity to which a cylindrical parison is supplied and molded into a bottomed preform;
A primary air blowing nozzle that is positioned above the preform molding die and inserted into a cylindrical parison to blow primary air into a bottomed preform, and a drive mechanism for the primary air blowing nozzle that raises and lowers the nozzle. A primary air blowing device comprising:
A secondary air blowing nozzle that is located above the molding die and is inserted into the bottomed preform and blows secondary air, and a stretch rod that extends in the vertical direction in the bottomed preform, and In a biaxial stretching blow molding machine for a hollow molded article comprising a nozzle and a biaxial stretching device equipped with a drive mechanism for a nozzle and a rod for raising / lowering and extending / reducing the rod,
The secondary air blowing nozzle drive mechanism and the stretch rod drive mechanism are each equipped with an electric motor, and the secondary air blowing nozzle and the stretch rod are simultaneously installed in the electric motor from the lowering start position above the respective molding dies. Or it is lowered almost at the same time, and the timing when the secondary air blowing nozzle seals the vicinity of the opening of the bottomed preform in the molded product molding die and the distance longer than the moving distance of the secondary air blowing nozzle A biaxial stretch blow molding machine comprising a control unit that simultaneously sets a timing at which the stretch rod that has moved the position reaches a predetermined position in the bottomed preform .

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