JP4791643B2 - Blow mold equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a blow mold apparatus for blow molding a synthetic resin bottle such as a polyethylene terephthalate bottle.
[0002]
[Prior art]
Conventionally, as a mold apparatus for blow-molding synthetic resin bottles such as polyethylene terephthalate bottles (hereinafter referred to as PET bottles), a pair of molds having cavities corresponding to the body parts of the bottles, and opening and closing to open and close both molds It is known that comprises means.
[0003]
The opening / closing means includes a pair of swingable holders connected to each other via a hinge, and each of the holders holds the pair of molds. Then, at the time of blow molding of the bottle, the two holders are swung in the direction of approaching each other, and both molds are closed to form a cavity corresponding to the body of the bottle inside both molds. Both holders are provided with holder connecting means for connecting the tip portions of both holders on the opposite side of the hinge, and the closed state of both molds is maintained by the holder connecting means.
[0004]
By the way, when both molds and both holders are heated to a relatively high temperature during blow molding, it is considered that thermal expansion occurs in each part. When such thermal expansion occurs in both molds, the two molds come into contact with each other prior to the connection between the two holders, which makes it difficult to connect the holders using the holder connecting means, resulting in a disadvantage in blow molding. . Alternatively, there is a risk that the two molds thermally expanded due to the connection of the two holders are excessively pressed and damaged.
[0005]
Therefore, in order to smoothly connect both holders, it is conceivable to provide both molds so that a slight gap is generated between both molds even when both holders are connected.
[0006]
However, even if the two holders are smoothly connected by providing a gap between the two molds, the gap is formed in the cavity formed by the two molds, so that there is a disadvantage that high-precision blow molding cannot be performed. For this reason, there has been a demand for a blow molding die apparatus that can form a gap between the two dies when the two holders are connected, and can eliminate the gap between the two dies at the time of blow molding.
[0007]
[Problems to be solved by the invention]
By eliminating such inconvenience, the present invention can perform smooth blow molding even when thermal expansion occurs in the mold, and can perform high-precision blow molding by preventing damage to each part. An object is to provide a blow molding die apparatus.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the present invention provides a first mold having a cavity corresponding to a part of a body part of a synthetic resin bottle, and a second mold having a cavity corresponding to the other part of the body part of the bottle. Blow molding die comprising: a die, and an opening / closing means for allowing the first die and the second die to contact each other in a freely openable and closable manner and forming a cavity corresponding to the entire circumference of the body of the bottle by both the dies. In the mold apparatus, the opening / closing means is a first holder for fixing and holding the outer periphery of the first mold, and faces the first holder, and advances and retracts the outer periphery of the second mold toward the first mold. A second holder that is freely held, and a holder connection that connects the first holder and the second holder to each other in a state where the first mold and the second mold face each other so as to contact each other. Formed in the bottle between the means, the second holder and the second mold The air to be press-fitted into the air is branched and injected to advance the second mold and bring the second mold into contact with the first mold, and the second holder and the second mold A seal member interposed between the mold and resiliently sealing the periphery of the air injection chamber when the second mold advances and retreats, both holders are connected by the holder connecting means, and air is supplied to the air injection chamber. Urging means for compressing the sealing member when not yet injected to urge the second mold in a retreating direction away from the first mold and to form a predetermined gap between the dies. , the biasing means is screwed tip to the second die, and a plurality of connecting bolts extending in moving direction of the second mold is slidably through the second holder, at least 2 One with is supported on the connecting bolt connecting bolt penetrates a, provided at the rear end of the connecting bolt And it engaged a plate member parts, coil for urging the second mold is interposed between the leaf member and a second holder in different positions and connecting bolt for supporting the plate-member in its rearward direction and a spring, the coil spring, when the air is injected into the air inlet chamber, is set to a urging force to permit abutment of the first mold second mold, the first mold When the second mold and the second mold come into contact with each other, a predetermined gap is maintained between the plate member and the second holder.
[0009]
According to the present invention, when air is not injected into the air injection chamber, the sealing member is compressed between the second mold and the second holder by the urging force of the urging means, so that the second mold is used. Is maintained away from the first mold. Thereby, even if thermal expansion occurs due to heating in both molds, the first holder and the second holder can be reliably and accurately connected, and the first holder and the second holder are connected. It is possible to prevent excessive compression of both molds.
[0010]
Then, air is injected into the air injection chamber at the time of blow molding, so that the second mold can be rapidly advanced in synchronization with the blow molding, and the second mold and the first mold are reliably brought into contact with each other. Can be touched. Thereby, since the cavity by a 1st metal mold | die and a 2nd metal mold | die can be formed without a clearance gap, highly accurate blow molding can be performed. At this time, the sealing member elastically extends in the restoring direction, and the sealed state of the air injection chamber is maintained.
[0012]
The present invention can simplify the structure in which the second mold is provided in the second holder so as to be movable forward and backward by connecting the second mold to the second holder via the connecting bolt of the urging means. Not only can the assembly work of the second mold to the second holder be facilitated. In addition, since a coil spring is employed as the biasing means and biased in the backward direction of the second mold through the connecting bolt, a desired biasing force can be easily set on the coil spring itself. be able to.
[0013]
By the way, when air is injected into the air injection chamber during blow molding, the second mold moves toward the first mold by the air pressure and the elastic force of the seal member. At this time, if the air pressure and the elastic force of the seal member exceed the urging force of the urging means, the coil spring reaches the compression limit, and the stress concentrates on the connecting bolt. When used in such a state for a long period of time, or when the seal member is replaced with one having a strong elastic force, the connecting bolt cannot withstand the stress and may break.
[0014]
Therefore, in the present invention, the coil spring is set to an urging force that allows the second mold to come into contact with the first mold when air is injected into the air injection chamber. As a result, when air is injected into the air injection chamber during blow molding, the second mold can be reliably brought into contact with the first mold to perform high-precision blow molding. The stress applied to the connecting bolt can be relaxed, and the connecting bolt can be prevented from being broken.
[0015]
In the present invention, the connecting bolt includes a screw part that is screwed into the second mold, and a diameter-enlarged part that regulates a screwing amount of the screw part into the second mold. When screwed into the second mold, the distance from the second mold to the head of the connecting bolt is maintained at a predetermined dimension.
[0016]
In the present invention, when the screw portion is screwed into the second mold, the screwing amount is regulated by the enlarged diameter portion. Thereby, the screwing amount of the connecting bolt into the second mold can be maintained at an appropriate amount, and the urging force set in the coil spring can be maintained with high accuracy.
[0017]
That is, for example, when the first holder and the second holder are connected and air is not injected into the air injection chamber, the distance between the first mold and the second mold is set to a predetermined dimension (for example, 0.1 mm). ˜0.2 mm). The distance between the first mold and the second mold is formed by retracting the second mold while compressing the seal member by screwing the connecting bolt into the second mold. At this time, if the screwing amount of the connecting bolt into the second mold exceeds an appropriate amount and is excessively large, the head of the second holder and the connecting bolt is larger than the distance between the first mold and the second mold. It is conceivable that the second mold is not brought into contact with the first mold even when air is injected into the air injection chamber.
[0018]
On the other hand, in the present invention, the screwing amount becomes an appropriate amount only by screwing the threaded portion of the connecting bolt into the second mold until it is regulated by the enlarged diameter portion. It can be reliably prevented that the distance between the second holder and the head of the connecting bolt is smaller than the distance between the second mold and the second holder to the second holder via the connecting bolt. The operation of connecting the molds can be performed very easily and with high accuracy.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view schematically showing a configuration and operation of a main part of the present apparatus in a partially broken view, and FIG. 2 is an explanatory view showing the main part of the present apparatus in plan view.
[0020]
The blow molding die apparatus 1 of this embodiment is used when blow-molding a PET bottle (not shown). As shown in FIG. 1 (a), a block-shaped second mold for molding a body portion of a PET bottle. A first mold 2 and a second mold 3 are provided. The first mold 2 and the second mold 3 constitute a so-called split mold, and a cavity 4 corresponding to the body portion of the PET bottle is formed in contact with each other. A bottle preform (not shown) is put in a state where the first mold 2 and the second mold 3 are in contact with each other and closed, and blow molding of the PET bottle is performed. Moreover, the molded PET bottle is taken out by opening the first mold 2 and the second mold 3.
[0021]
As shown in FIG. 2, the first mold 2 and the second mold 3 are opened and closed by an opening / closing means 5. The opening / closing means 5 includes a first holder 6 having a substantially U-shape in plan view that contains and holds the first mold 2, and a second holder 7 having a substantially U-shape in plan view that contains and holds the second mold 3. And. The first holder 6 and the second holder 7 are connected by holder connecting means. That is, as shown in FIG. 2, one side end of the first holder 6 and one side end of the second holder 7 are connected via the hinge 8, and the first mold 2 and the second mold are connected. The mold 3 is swingable in the direction in which the molds 3 are attached to each other. Further, the other end of the first holder 6 and the other end of the second holder 7 are formed with connecting holes 9 and 10 having the same diameter, and the axial centers of both the connecting holes 9 and 10 coincide with each other. In addition, the first mold 2 and the second mold 3 can be maintained in a state of being attached to each other by inserting the connection pins 11 into both the connection holes 9 and 10.
[0022]
As shown in FIG. 1 (a), the first holder 6 fixes and holds the first mold 2 integrally. The second holder 7 holds the second mold 3 so as to be able to advance and retract toward the first mold 2. The second holder 7 is provided with an air injection chamber 13 surrounded by an annular sealing member 12 between the second holder 3 and the second mold 3. Blow air at the time of blow molding is branched and injected into the air injection chamber 13 through a pipe (not shown). Therefore, the pressure of the air injected into the air injection chamber 13 is equal to the air pressure injected into the bottle preform during blow molding.
[0023]
The sealing member 12 that surrounds the air injection chamber 13 is formed of a member having sealing properties and elasticity. The sealing member 12 elastically expands and contracts to maintain the sealing property of the air injection chamber 13 over the range of the second mold 3. Further, the second mold 3 is held by the second holder 7 via a biasing means 14 that biases the second mold 3 away from the first mold 2. The urging means 14 retracts the second mold 3 by the urging force to compress the seal member 12, and a first gap formed between the second mold 3 and the first mold 2. Maintain a at a predetermined dimension.
[0024]
As shown in FIG. 1A, the urging means 14 includes a connection bolt 15 that connects the second mold 3 to the second holder 7 and a plate member that is locked to the head 16 of the connection bolt 15. 17, and a coil spring 18 interposed between the plate member 17 and the second holder 7.
[0025]
As shown in FIG. 1A, the connecting bolt 15 slidably penetrates the second holder 7, and its tip is screwed to the second mold 3. The connecting bolt 15 includes a threaded portion 19 only at the tip, and includes a diameter-enlarged portion 20 that regulates the screwing amount when screwed into the second mold 3. Thereby, when connecting the 2nd metal mold | die 3 to the 2nd holder 7, just screwing in the screw part 19 of the connection bolt 15 until it is regulated by the enlarged diameter part 20, and it will be connected from this 2nd metal mold 3 to this connection bolt. The distance to 15 heads 16 is maintained at a constant dimension. The enlarged diameter portion 20 extends to the head 16 and has the same diameter, and guides the second mold 3 in the advancing / retreating direction along a guide hole 21 provided in the second holder 7.
[0026]
The plate member 17 locked to the head portion 16 of the connecting bolt 15 includes a recess 22 for holding the coil spring 18 to prevent the coil spring 18 from dancing during expansion and contraction, and the coil spring 18 is dropped off. To prevent. A second gap b set larger than the first gap a is provided between the plate member 17 and the second holder 7.
[0027]
Next, the operation of the present embodiment having the above configuration will be described. First, prior to the blow molding of the PET bottle, the first mold 2 and the second mold 3 are heated, and the first holder 6 and the second holder 7 are connected by the connecting pin 11 as shown in FIG. Connected together. At this time, as shown in FIG. 1 (a), the sealing member 12 of the air injection chamber 13 is compressed and the second mold 3 is retracted by urging by the coil spring 18 of the urging means 14. And As a result, a first gap a is formed between the first mold 2 and the second mold 3, and even if thermal expansion occurs between the first mold 2 and the second mold 3, The connection between the first holder 6 and the second holder 7 by the connection pin 11 (shown in FIG. 2) can be performed smoothly.
[0028]
Next, when a bottle preform is inserted into the cavity 4 of the first mold 2 and the second mold 3 and high-pressure air for blowing is injected into the bottle preform, the blowing air is simultaneously injected into the bottle preform. It is also injected into the air injection chamber 13. Thereby, the 2nd metal mold | die 3 is advanced against the urging | biasing by the coil spring 18, and as shown in FIG.1 (b), the 1st metal mold | die 2 and the 2nd metal mold | die 3 contact | abut. At this time, the coil spring 18 is compressed between the plate member 17 and the second holder 7, but an urging force is set so as not to reach the compression limit. Moreover, even if the first mold 2 and the second mold 3 are brought into contact with each other and the first gap a disappears, the second gap b between the plate member 17 and the second holder 7 is maintained. ing. Thereby, even if the air pressure injected into the air injection chamber 13 or the elastic force of the seal member 12 is applied to the connection bolt 15, the stress on the connection bolt 15 is relieved by the coil spring 18 and the connection bolt 15 is relieved. 15 breakage can be prevented.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory view schematically showing a partially broken configuration and operation of a main part of an apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory plan view showing a main part of the present embodiment in cross-section.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Blow molding die apparatus, 2 ... 1st metal mold, 3 ... 2nd metal mold, 4 ... Cavity, 5 ... Opening / closing means, 6 ... 1st holder, 7 ... 2nd holder, 11 ... Connection pin (holder connection) Means), 12 ... Sealing member, 13 ... Air injection chamber, 14 ... Biasing means, 15 ... Connection bolt, 16 ... Head, 18 ... Coil spring, 19 ... Screw part, 20 ... Diameter expansion part.

Claims (3)

A first mold having a cavity corresponding to a part of the body of the synthetic resin bottle; a second mold having a cavity corresponding to the other part of the body of the bottle; the first mold and the first In a blow molding die apparatus comprising: 2 molds that can be freely opened and closed, and open / close means that forms a cavity corresponding to the entire circumference of the body of the bottle by both molds;
The opening / closing means holds a first holder for fixing and holding the outer periphery of the first mold, and faces the first holder, and holds the outer periphery of the second mold so as to freely advance and retract toward the first mold. A second holder and a holder connecting means for connecting the first holder and the second holder to each other in a state where the first mold and the second mold face each other so as to contact each other. An air formed between the second holder and the second mold and pressed into the bottle is branched and injected to advance the second mold, and the second mold is moved to the first mold. An air injection chamber to be brought into contact with the mold, and a seal member interposed between the second holder and the second mold to elastically seal the periphery of the air injection chamber when the second mold is advanced and retracted, When both holders are connected by the holder connecting means and air is not injected into the air injection chamber, the seal member is compressed. Biasing the second die in the backward direction away from the first mold, and a biasing means for forming a predetermined gap between the dies,
Wherein the biasing means is screwed tip to the second die, and a plurality of connecting bolts the second is slidably penetrate the holder extending in the moving direction of the second die, at least two The connecting bolt penetrates and is supported by the connecting bolt , and a plate member locked to the head provided at the rear end of each connecting bolt, and the connecting bolt that supports the plate member at a position different from that of the connecting bolt. A coil spring interposed between the plate member and the second holder and biasing the second mold in its retreating direction,
The coil spring is set to a biasing force that allows the second mold to come into contact with the first mold when air is injected into the air injection chamber .
When the first mold and the second mold come into contact with each other, a predetermined gap is maintained between the plate member and the second holder.   The connecting bolt includes a screw part that is screwed into the second mold, and a diameter-enlarged part that regulates a screwing amount of the screw part into the second mold, and the screw part is screwed into the second mold. 2. The blow molding die apparatus according to claim 1, wherein when combined, the distance from the second die to the head of the connecting bolt is maintained at a predetermined dimension.   The blow mold apparatus according to claim 1, wherein the plate member includes a concave portion that holds the coil spring.

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