JP3570531B2 - Injection mold for synthetic resin cap - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an injection mold for producing a synthetic resin cap for a container having excellent functionality and design.
[0002]
[Prior art]
Generally, a knurled structure that extends in the axial direction of the container is used for a finger portion of a screw cap that is screwed into a screw structure provided on the mouth and neck of the container. This is because, when the cap is turned to open the lid, the knurled structure extending in the axial direction of the container serves as a non-slip, making the cap easy to turn.
[0003]
However, in the case of a locking cap that locks into a concave portion or a convex portion provided in the container mouth and neck, the cap extends in the axial direction of the container at a finger-holding portion of the cap to facilitate removal of the cap from the container mouth and neck. There is a problem in applying the knurled structure. This is because the finger slips when the cap is opened by moving the cap in the axial direction of the container.
[0004]
As an example of a container using such a locking cap, FIGS. 4 and 5 show partially cutaway perspective views of a synthetic resin solid glue container. FIG. 4 shows a state where the cap is removed and the lid is opened, and FIG. 5 shows a state where the cap is attached and sealed.
[0005]
In the figure, a cap 81 has a flat ceiling portion 83, and a cylindrical skirt portion 84 hangs from the outer edge thereof. A fitting protrusion 85 is provided on the lower inner surface of the skirt portion 84 so as to protrude inward in the radial direction. The plurality of fitting protrusions 85 are provided discontinuously in the circumferential direction of the inner peripheral surface. On the outer surface of the skirt portion 84 above the position where the fitting protrusion 85 is installed, three annular knurls 86 extending in the circumferential direction are provided at regular intervals.
[0006]
The main body 82 of the container is provided on the outer surface of the upper end of the body 87 so as to prevent a thin opening 88 for fitting the cap 81 and a fitting projection 85 of the cap 81 from being accidentally pulled out. A stop portion 90, a concave groove 91 into which the fitting protrusion 85 of the cap 81 fits, and a flat portion 89 on which the lower end surface 92 of the skirt portion 84 of the cap 81 is placed and completely closed are formed. .
[0007]
The cap 81 and the main body 82 of the container are configured as described above. When the cap 81 is put on the main body 82 and pushed in, the fitting projection 85 is fitted into and engaged with the concave groove 91 as shown in FIG. can get.
[0008]
The solid glue (not shown) packed in the container is given a rotational force from a screw rod 93 that rotates by rotating the fitting base 95, and at the same time, the rotational force is regulated by the rail 94, and the body of the main body 82. It is used up and down inside 87.
[0009]
When such a container is used, the cap is pulled open in the axial direction of the container, that is, in the vertical direction, but in order to easily open and close the cap, an annular ring extending in the circumferential direction is provided on the skirt portion of the cap. It is desirable to provide knurls.
[0010]
An example of an injection mold using a split mold for manufacturing a cap having such an annular knurl is shown in a sectional view in FIGS. FIG. 6 shows a mold clamping state, and FIG. 7 shows a mold opening completed state.
[0011]
As shown, the cap 81 is formed by injecting molten thermoplastic resin into a cavity surrounded by the cavity bush 74, the split mold 72, the stripper 56, and the core 57.
[0012]
The cavity bush 74 forms the outer surface of the ceiling portion 83 of the cap 81, and the split mold 72 has a concave portion forming the annular knurl 86 of the cap 81, and forms the outer surface of the skirt portion 84 of the cap 81. The stripper 56 forms a lower end surface 92 of the cap 81. The core 57 has a concave portion that forms the fitting protrusion 85 of the cap 81, and forms the inner surface of the cap 81.
[0013]
The molten thermoplastic resin is filled from the inside of the ceiling part 83 of the cap 81 through the core 57, and when the filled resin is solidified, the mold is opened.
[0014]
In opening the mold, first, the mounting plate 20 to which the inclined slide pins 73 are fixed and the cavity plate 18 to which the cavity bush 74 is fixed are moved, and the inclined slide pins 73 are pulled out from the fitting holes 75. Subsequently, the split mold 72 is split into two and moved in the radial direction by a spring structure (not shown) provided in the stripper plate 52, and the outer surface of the cap 81 appears. Almost simultaneously, the space between the runner plate 14, the runner stripper plate 71, and the mounting plate 13 is opened, and the runner 26 is removed.
[0015]
Next, the core plate 53 to which the core 57 is fixed is moved, and the core 57 is extracted from the stripper plate 52. During the removal, the cap 81 is removed from the core 57 because the lower end surface 92 of the cap 81 is engaged with the stripper 56.
[0016]
[Problems to be solved by the invention]
Incidentally, the above-mentioned injection mold has a complicated structure because the split mold 72 and the inclined slide pin 73 are used, and a plurality of the above-described injection molds are attached to a 180-ton class injection molding machine to obtain a diameter. When trying to form a 30 mm cap, the mold area of one mold is about 500 × 600 m / m, so the number of attachments is about 12 and the time required for mold clamping and mold opening takes a long time. Therefore, the production amount per unit time is small, and therefore, the product price increases.
[0017]
In addition, since the split mold 72 is used to form the annular knurl 86, an axial parting line appears on the outer surface of the skirt portion 84 of the cap 81, which makes the appearance poor and is evaluated as unsatisfactory. There is.
[0018]
SUMMARY OF THE INVENTION An object of the present invention is to provide an injection molding die for a synthetic resin cap provided with an annular knurl that does not have an axial parting line on the outer surface of the cap and has a large output per unit time.
[0019]
[Means for Solving the Problems]
According to the present invention, as shown in FIGS. 1 to 3, a cylindrical skirt portion 84 hangs down from an outer edge of a flat ceiling portion 83, and an annular knurl 86 extending in a circumferential direction is provided on an outer surface of the skirt portion 84. In a mold for injection-molding a synthetic resin cap 81 having a fitting projection 85 on the inner surface near the lower end of the portion 84, the mold includes an inner mold 2 and an outer mold 3.
[0020]
The inner mold 2 accommodates the moving plate 11 therein by moving the inner cavity plate 17 and the inner core plate 15 in contact with the outer mold 3 and the two plates by a block 16 and moves the moving plate 11 up and down. The inner core plate 15 is provided with an inner core 21 provided with a molten resin runner 21a therein so as to form a space to fit the inner core plate 15, the inner cavity plate 17, and the movable plate 11. An inner cavity bush 23 is attached to the inner cavity plate 17, and the outer core 22 and the inner cavity plate 17 are inserted into the movable plate 11 while slidably contacting the inner core 21 and sliding inside the inner cavity bush 23. And a slide pin 12 that comes into contact with the outer mold 3 is attached.
[0021]
The outer mold 3 accommodates the moving plate 27 therein by moving the outer cavity plate 18 and the mounting plate 20 in contact with the inner mold 2 with the mounting plate 20 by a block 19 and moves the moving plate 27 up and down. A space is formed, and an outer cavity bush 24 is attached to the outer cavity plate 18. A stripper pin 25 sliding in the outer cavity bush 24 and the outer cavity plate 18 are inserted into the movable plate 27 to contact the inner mold 2. It is configured by attaching a slide pin 28 in contact therewith.
[0022]
In the above-mentioned injection mold, an injection port for molten resin is provided at the top end of the inner core 21.
[0023]
In the injection molding die of the synthetic resin cap thus configured, the inner core 21, the outer core 22, the inner cavity bush 23, the outer cavity bush 24, and the stripper pin 25 form a cavity having the shape of the cap 81. Form.
[0024]
In the cavity thus formed, a portion corresponding to the outer surface of the ceiling portion 83 of the cap 81 is formed by the top end of the stripper pin 25, and a portion corresponding to the inner surface of the ceiling portion 83 of the cap 81 is defined by the inner core 21 and the outer core. A top outer surface of the outer core 22 forms a portion corresponding to an inner surface of the cap 81 including the fitting protrusion 85 of the skirt portion 84 of the cap 81, and a portion from the lower end surface 92 of the skirt portion 84 to the annular knurl 86. The portion corresponding to the outer surface of the skirt portion 84 is formed by the inner cavity bush 23, and the portion corresponding to the outer surface of the skirt portion 84 from the annular knurl 86 to the outer edge of the ceiling portion 83 is formed by the outer cavity bush 24.
[0025]
Further, for opening the mold, the inner core 21 and the inner cavity bush 23 are simultaneously separated in the axial direction, then the outer core 22 is separated in the axial direction, and the cap 81 held by the outer cavity bush 24 is removed by a stripper pin. It is configured to extrude at the top end of 25.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 3 show sectional views of an injection mold for manufacturing a synthetic resin cap according to the present invention. 1 shows a mold clamping state, FIG. 2 shows a mold opening intermediate state, and FIG. 3 shows a mold opening completed state.
[0027]
In the injection molding die 1 of the present invention, a molten thermoplastic resin from a mounting plate 13 fixed to an injection molding machine (not shown) is connected to a runner plate 14 which branches into a cavity of each die 1. . The runner plate 14 is installed movably in the axial direction of the mold.
[0028]
The mold 1 of the present invention has a structure in which the cavity bush is divided into an inner cavity bush 23 and an outer cavity bush 24, and the core also has a structure in which the core is divided into an inner core 21 and an outer core 22. I have.
[0029]
Further, the mold 1 of the present invention is constituted by an inner mold 2 and an outer mold 3, and the inner mold 2 and the outer mold 3 can be respectively moved in the axial direction by a moving mechanism (not shown). With this movement and the configuration described later, the inner mold 2 operates the inner cavity bush 23, the inner core 21, and the outer core 22, and the outer mold 3 operates the outer cavity bush 24 and the stripper pin 25.
[0030]
The inner mold 2 includes an inner core plate 15 on which an inner core 21 is fixed, and an inner cavity plate 17 on which an inner cavity bush 23 is fixed, and these plates 15 and 17 are connected by a block 16. Have been. The moving plate 11 is provided in a space surrounded by the plates 15 and 17 and the block 16. An outer core 22 and a slide pin 12 are fixed to the moving plate 11, and the outer core 22 is guided by the slide pin 12 and can move in the axial direction by a moving mechanism (not shown).
[0031]
The outer mold 3 includes an outer cavity plate 18 to which an outer cavity bush 24 is fixed, a spacer 29, a block 19, and a mounting plate 20, which are fixed to each other. In a space surrounded by the spacer 29, the block 19, and the mounting plate 20, a moving plate 27 in which a stripper pin 25 and a slide pin 28 are fixed is provided so as to be movable in the axial direction by a mechanism (not shown). The stripper pin 25 is guided by the slide pin 28 and operates in the axial direction.
[0032]
FIG. 1 shows a mold clamping state of the mold 1. The inner cavity plate 17 of the inner mold 2 and the outer cavity plate 18 of the outer mold 3 abut on a joining surface orthogonal to the axis of the mold 1. ing.
[0033]
In the figure, the moving plate 11 of the inner mold 2 comes into contact with the inner core plate 15 and stops, and the moving plate 27 of the outer mold 3 also comes into contact with the mounting plate 20 and stops. A cavity 81 a having the shape of a cap 81 is formed between the mold 2 and the outer mold 3.
[0034]
In this cavity, a portion corresponding to the outer surface of the ceiling portion 83 of the cap 81 is formed by the top end of the stripper pin 25, and a portion corresponding to the inner surface of the ceiling portion 83 of the cap 81 is formed by the inner core 21 and the outer core 22. The top end is formed, and the top outer surface of the outer core 22 forms the inner surface side including the fitting protrusion 85 of the skirt portion 84 of the cap 81.
[0035]
The inner cavity bush 23 forms a cylindrical outer surface of the skirt 84 from the lower end surface 92 of the skirt 84 to the annular knurl 86, and the outer cavity bush 24 extends from the annular knurl 86 to the outer edge of the ceiling 83. The outer surface of the skirt 84 is formed.
[0036]
Therefore, the parting lines of the inner cavity bush 23 and the outer cavity bush 24 are annularly located on the side of the outer peripheral surface of the annular knurl 86 closest to the lower end surface 92 of the cap 81 near the lower end surface 92 and are not noticeable. . When the annular knurl is a concave groove, the parting line is annularly located at the boundary between the annular knurl closest to the lower end surface 92 of the cap 81 and the cylindrical skirt portion, and is also inconspicuous.
[0037]
A runner 21 a is provided at the center of the inner core 21 so as to communicate with the runner of the runner plate 14, and a subsequent outlet is opened at the top end of the inner core 21. Is injected into the cavity 81a of the cap 81 formed by clamping as described above.
[0038]
When the molten resin is injected into the cavity 81a and the time required for the resin to harden passes, the mold opening is started.
[0039]
To open the mold, first, the moving plate 11 of the inner mold 2 starts to move toward the outer mold 3, and the slide pins 12 move the outer mold 3 outward. At this time, since the inner core 21 does not move, the resin at the injection port is cut from the inside of the ceiling portion 83 of the cap 81. Since the cut marks are located inside the ceiling portion 83 of the cap 81, they are not noticeable and do not impair the design of the cap 81.
[0040]
Since this movement is performed while holding the cap 81 with the outer core 22, the outer cavity bush 24, and the stripper pin 25, the cap 81 is not damaged. By this operation, the cylindrical skirt portion 84 extending from the annular knurl 86 of the cap 81 to the lower end surface 92 of the cap 81 is smoothly removed from the inner cavity bush 23 without any deformation. Eventually, when the moving plate 11 comes into contact with the inner cavity plate 17, this movement stops, and the positional relationship between the inner mold 2 and the outer mold 3 shown in FIG.
[0041]
Next, in this state, the inner mold 2 and the outer mold 3 are both moved outward, and the runner 26 is taken out to be in the state shown in FIG.
[0042]
Subsequently, although not shown, only the outer mold 3 is further moved outward from the state of FIG. Then, along with the movement, the outer core 22 gets over the fitting protrusion 85 of the cap 81 and is pulled out of the cap 81.
[0043]
During the step of removing the outer core 22, the cylindrical skirt portion 84 extending from the annular knurl 86 of the cap 81 to the lower end surface 92 of the cap 81 is not held from the outside. When the outer core 22 gets over the fitting protrusion 85 provided, the cylindrical skirt portion 84 can elastically deform outward.
[0044]
Therefore, the outer core 22 can be smoothly removed without damaging the cap 81. Then, the cap 81 is held by the outer cavity bush 24 and the stripper pin 25.
[0045]
Next, the movable plate 27 of the outer mold 3 moves inward until it comes into contact with the spacer 29. By this movement, the stripper pin 25 pushes the cap 81 held by the outer cavity bush 24, and the pushed cap 81 is locked to the outer cavity bush 24 by the annular knurl 86, but the inside is in a hollow state. , Can be freely elastically deformed in the radial direction, and the annular knurl 86 of the cap 81 easily comes off the outer cavity bush 24 without being damaged, and the cap 81 is pushed out as shown in FIG. Complete the opening.
[0046]
When the mold opening is completed in this way, the runner 26 and the cap 81 are discharged by a sweeper (not shown), and the mold 1 returns to the mold clamped state shown in FIG. 1, and the same operation is repeated.
[0047]
【Example】
As an example of the present invention, 16 injection molding dies 1 of a synthetic resin cap 81 were attached to a 180-ton class injection molding machine, and a cap having a diameter of 30 mm was manufactured in one cycle time of 25 seconds. No problems occurred with the cap 81 and the device.
[0048]
As a comparative example of the present invention, an injection mold using the conventional split mold shown in FIGS. 6 and 7 was attached to a 180-ton class injection molding machine to produce a cap having a diameter of 30 mm. The limitation was that only 12 molds were attached to the molding machine for molding, and the one cycle time at that time was 30 seconds.
[0049]
【The invention's effect】
As described above, according to the injection mold of the present invention, a split mold and an inclined slide pin are not used, and therefore, the structure can be simplified and reduced in size, and the operation time is shorter than that of the comparative example. The one-cycle time can be reduced by 15% or more, and the number of pieces can be increased. Therefore, it is possible to mass-produce a highly functional synthetic resin cap having an annular knurl extending in the circumferential direction in a short time.
[0050]
Further, according to the mold of the present invention, a parting line that can be a seam or the like becomes inconspicuous, and therefore, an excellent cap having a beautiful appearance can be manufactured in terms of design.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a closed state of an injection mold for a synthetic resin cap of the present invention.
FIG. 2 is a sectional view showing an intermediate state of the mold opening of the mold of FIG. 1;
FIG. 3 is a sectional view showing a state in which the mold opening of the mold of FIG. 1 is completed.
FIG. 4 is a partially cutaway perspective view of a solid glue container as an example of a synthetic resin container.
FIG. 5 is a partially cutaway perspective view of the container of FIG. 4 in a sealed state.
FIG. 6 is a cross-sectional view showing a closed state of an injection mold using a conventional split mold.
FIG. 7 is a cross-sectional view showing a completed state of the opening of the injection mold of FIG. 6;
[Explanation of symbols]
REFERENCE SIGNS LIST 1 injection molding die 2 inner die 3 outer die 11,27 moving plate 12 28 slide pin 13,20 mounting plate 14 runner plate 15 inner core plate 16,19 block 17 inner cavity plate 18 outer cavity plate 21 inner core 22 Outer core 23 Inner cavity bush 24 Outer cavity bush 25 Stripper pin 26 Runner 29 Spacer 52 Stripper plate 53 Core plate 56 Stripper 57 Core 71 Runner stripper plate 72 Split mold 73 Inclined slide pin 74 Cavity bush 75 Fitting hole 81 Cap 81a Cavity 82 Container main body 83 Ceiling 84 Skirt 85 Fitting projection 86 Ring knurl 87 Body 88 Mouth 89 Flat part 90 Locking part 91 Groove 92 Lower end face 93 Screw rod 94 Rail 9 5 Insertion base

Claims (2)

A cylindrical skirt portion 84 hangs down from an outer edge of the flat ceiling portion 83, and an annular knurl 86 extending circumferentially is provided on an outer surface of the skirt portion 84, and a fitting protrusion 85 is provided on an inner surface near a lower end of the skirt portion 84. In the mold for injection-molding the synthetic resin cap 81, the mold includes an inner mold 2 and an outer mold 3,
The inner mold 2 accommodates the moving plate 11 therein by moving the inner cavity plate 17 and the inner core plate 15 in contact with the outer mold 3 and the two plates by a block 16 and moves the moving plate 11 up and down. The inner core plate 15 is provided with an inner core 21 provided with a molten resin runner 21a therein so as to form a space to fit the inner core plate 15, the inner cavity plate 17, and the movable plate 11. An inner cavity bush 23 is attached to the inner cavity plate 17, and the outer core 22 and the inner cavity plate 17 are inserted into the movable plate 11 while slidably contacting the inner core 21 and sliding inside the inner cavity bush 23. And a slide pin 12 which comes into contact with the outer mold 3 is attached,
The outer mold 3 accommodates the moving plate 27 therein by moving the outer cavity plate 18 and the mounting plate 20 in contact with the inner mold 2 with the mounting plate 20 by a block 19 and moves the moving plate 27 up and down. A space is formed, and an outer cavity bush 24 is attached to the outer cavity plate 18. A stripper pin 25 sliding in the outer cavity bush 24 and the outer cavity plate 18 are inserted into the movable plate 27 to contact the inner mold 2. Attached slide pin 28 is attached and configured,
The inner core 21, the outer core 22, the inner cavity bush 23, the outer cavity bush 24, and the stripper pin 25 form a cavity having the shape of the cap 81,
The top end of the stripper pin 25 forms a portion corresponding to the outer surface of the ceiling portion 83 of the cap 81 in the cavity, and the top end of the inner core 21 and the outer core 22 forms a portion corresponding to the inner surface of the ceiling portion 83 of the cap 81. The top outer surface of the outer core 22 forms a portion corresponding to the inner surface side including the fitting projection 85 of the skirt portion 84 of the cap 81, and is formed on the outer surface of the skirt portion 84 from the lower end surface 92 of the skirt portion 84 to the annular knurl 86. A corresponding portion is formed by the inner cavity bush 23, a portion corresponding to the outer surface of the skirt portion 84 from the annular knurl 86 to the outer edge of the ceiling portion 83 is formed by the outer cavity bush 24,
Further, for opening the mold, the inner core 21 and the inner cavity bush 23 are simultaneously separated in the axial direction, then the outer core 22 is separated in the axial direction, and the cap 81 held by the outer cavity bush 24 is removed by a stripper pin. 25. An injection molding die for a synthetic resin cap, which is configured to be extruded at the top end of the mold. The injection molding die for a synthetic resin cap according to claim 1, wherein a molten resin injection port is provided at the top end of the inner core 21.

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