JP3664599B2 - Plug for thermoforming, method for producing thermoformed product, and thermoforming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a thermoforming plug, a method for producing a thermoformed article, and a thermoforming apparatus.
[0002]
[Prior art]
  As disclosed in Japanese Patent Application Laid-Open No. 50-87162 (“Molding Plug”) and Japanese Patent Application Laid-Open No. 50-67370 (“Method of Molding a Thermoplastic Resin Sheet”) as a method of adjusting the wall thickness in thermoforming. Things are known.
  In the former, the plug is formed so that it can be broken into pieces along the circumferential direction, and each piece is supported so as to be pivotable on the outer peripheral side of the base, and the outer peripheral side of the upper end can be expanded and contracted. ing. The diameter is initially reduced, abuts on the thermoplastic resin sheet and is pushed into the female mold, and then the diameter is increased. By expanding the diameter, the degree of preliminary stretching of the bottom wall in the thermoformed product changes, and as a result, the wall thickness can be adjusted.
[0003]
  On the other hand, the latter is supported via an elastic support member such as a spring, and the spring is contracted by applying a plug to a female mold while contacting the thermoplastic resin plate. For this reason, the peripheral wall is preliminarily extended by an amount corresponding to the stroke of the spring in addition to the original length of the plug.
[0004]
[Problems to be solved by the invention]
  The conventional thermoforming plug described above has the following problems.
  In the former case, the configuration is complicated such that the plug is broken or pivotable. In the latter case, the plug is brought into contact with the female mold, but at this time, the wall thickness becomes thin and cannot be practically adopted.
[0005]
  The present invention has been made in view of the above problems, and allows flexible wall thickness adjustment with a simple configuration.It is possible to control the drive of the sub plug that moves forward and backward from the plug body only by the pressure difference, and it is possible to simplify the configuration and molding timingAn object is to provide a thermoforming plug, a method for producing a thermoformed product, and a thermoforming apparatus.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, the invention according to claim 1 is a plug for thermoforming, and assists wall thickness adjustment by moving forward and backward toward the female mold while being accommodated in the plug body. With sub-plugThe sub plug communicates with an airtight chamber inside the plug body while being accommodated and supported by the plug body, and advances and retreats according to a pressure difference between the airtight chamber and the outside.As a configuration.
[0007]
  In the invention according to claim 1 configured as described above, the sub plug is accommodated in the plug body and can be advanced and retracted into the female mold. Generally, when the distance between the inner peripheral surface of the female mold and the plug is reduced, the thickness of the molded product is increased in the vicinity thereof, and when the distance is increased, the thickness is reduced. Therefore, the sub plug is protruded at the portion where the thickness is to be increased.
The sub-plug is configured to communicate with an airtight chamber inside the plug body while being accommodated and supported by the plug body, and to advance and retreat according to a pressure difference between the airtight chamber and the outside.
In the invention configured as described above, an airtight chamber is formed inside the plug body, and the sub plug is accommodated and supported in the plug body so as to communicate with the airtight chamber. By performing the adjustment, the sub plug can be advanced and retracted.
For example, if the outside is kept at a constant pressure and a negative pressure is applied to the hermetic chamber, the sub plug is accommodated, and if compressed air is supplied to the hermetic chamber, the sub plug protrudes. As is well known, the atmospheric pressure outside the plug body is controlled, and the atmospheric pressure difference may be adjusted to the limit necessary for drive control of the sub plug. That is, if a high pressure is supplied to the hermetic chamber from the outside, the sub plug will protrude, but if the hermetic chamber is opened to the atmosphere from this state, the sub plug is accommodated.
[0008]
  What part of the plug main body the sub plug is accommodated in may be determined as appropriate according to the request for wall thickness adjustment. As an example, the invention according to claim 2 is the thermoforming plug according to claim 1, wherein the plug body and the sub plug are formed in a substantially concentric shape.
[0009]
  In the invention according to claim 2 configured as described above, when the plug main body and the sub-plug are formed concentrically, the area of the plug top can be changed by the advancement and retreat of the sub-plug. That is, if the sub plug does not protrude, the area of the plug body is obtained, and if the sub plug protrudes, the area of the sub plug is obtained. Further, the distance from the female inner peripheral surface changes depending on whether or not it protrudes. These act comprehensively and a partial adjustment of the wall thickness is performed.
[0010]
  Of course, the two do not necessarily have to be exactly concentric circles, and it is sufficient if the sub plug advances and retracts from the inside of the portion that can be said to be the top of the plug body..
[0011]
CareIn controlling the advancement and retreat of the sub plug by the pressure difference, various support structures for the sub plug can be considered. As an example,Claim 3The invention according toClaim 1 or claim 2The plug for thermoforming described in 1 is configured such that the plug body and the sub-plug are formed in a cylinder piston shape.
  Configured as aboveClaim 3In the invention, the sub plug and the plug main body have a cylinder piston structure, and the sub plug is housed and supported in a piston shape in a cylindrical cylindrical portion formed in the plug main body. By adjusting the atmospheric pressure with the outside, the sub plug can be moved back and forth like a piston.
[0012]
  The thermoforming plug as described above is not used alone, but is used as a part of a thermoforming apparatus to manufacture a thermoformed product. Then, a thermoformed product that can be satisfactorily adjusted in thickness is manufactured. In this senseClaim 4The present invention relates to a thermoformed product manufacturing method for manufacturing a thermoformed product by pre-stretching a softened thermoplastic resin plate by advancing and retracting a plug into a thermoforming female mold, wherein the plug is plugged The body,While being accommodated and supported by the plug body, it communicates with the airtight chamber inside the plug body and according to the pressure difference between the airtight chamber and the outside.While configuring with a sub plug that can be advanced and retracted into the female mold,By adjusting the air pressure between the airtight chamber and the outsideWith the same sub-plug protrudingAsEnter the female body for thermoforming together with the plug body, and thenBy adjusting the air pressure between the airtight chamber and the outsideThe thickness is adjusted by retracting the sub-plug.
[0013]
  Configured as aboveClaim 4In the invention according toBy adjusting the air pressure between the airtight chamber and the outsideWith the sub plug protrudingAsSince it is made to enter into the thermoforming female mold together with the plug body, the distance from the inner peripheral surface of the thermoforming female mold is narrow, and the wall thickness is increased in the vicinity thereof. And thenBy adjusting the air pressure between the airtight chamber and the outsideSince the sub-plug is retracted, even if there is a problem due to a decrease in the distance between the inner peripheral surface of the female mold for thermoforming and the plug, it can be avoided.
  Of course, there is a merit that the thickness can be adjusted without such a problem, but it is more suitable when it is necessary to eliminate the problem actually. As an example,Claim 5The present invention relates to a thermoforming apparatus having a thermoforming female mold and a plug that advances and retreats so as to push a softened thermoplastic resin plate into the thermoforming female mold. A thread bottom outer shape recess that is formed into a saddle-shaped concave shape and forms a thread bottom outer peripheral shape continuously spreading from the saddle-shaped bottom portion of the saddle-shaped concave shape, and an opening to the saddle-shaped recess in the concave portion for the thread bottom shape It is formed in a columnar shape that approximates the edge and is supported so as to be able to advance and retreat with respect to the saddle-shaped concave shape, and is located close to the opening edge from a first stop position that is retracted slightly to the rear side from the concave portion for the thread bottom outer shape. And a plug main body that can enter into the saddle-shaped recess and a column that can enter into the opening of the recess for thread bottom outer shape. While being formed into a body shape, it is the same from the bottom of the plug body. It is movably supported with respect to the mouth,While being accommodated and supported by the plug body, it communicates with the airtight chamber inside the plug body and advances and retreats according to the pressure difference between the airtight chamber and the outside,The yarn bottom inner mold has a sub-plug that is reciprocally driven without abutting corresponding to the reciprocating drive between the first stop position and the second stop position.
[0014]
  Configured as aboveClaim 5In the invention according to the present invention, the end of the end of the thermoforming female mold having a saddle-shaped concave shape is formed. For this reason, a concave portion for thread bottom outer shape having a divergent shape continuous from the saddle shape of the saddle-shaped concave shape is formed, and a column that approximates the opening edge to the saddle-shaped recess is formed in the saddle shape of the saddle-shaped recess shape. A body-like yarn bottom inner mold is accommodated so as to be able to advance and retreat. This yarn bottom inner mold is driven from the first stop position retracted slightly behind the yarn bottom outer shape concave portion to the second stop position close to the opening edge. Therefore, the softened thermoplastic resin plate must be stretched from the saddle bottom portion of the saddle type concave shape to the inner bottom of the yarn bottom through the concave portion for the yarn bottom outer shape.
[0015]
  At this time, since the conventional plug can only be pushed inward from the heel of the thermoforming female mold, the distance from the plug to the thread bottom outer shape recess and the thread bottom inner mold does not necessarily increase. I do not get. However, in the case of this plug, in addition to the plug main body that can enter into the saddle-shaped recess, a sub plug formed in a columnar shape that can enter into the opening of the thread bottom outer shape recess is provided. , The thermoplastic resin plate is pushed to a position close to the concave portion for the bottom of the yarn bottom and the inner bottom of the yarn bottom.
[0016]
  By the way, the thread-bottom inner mold is supported so as to be able to advance and retreat. For the thread-bottom contour that extends from the edge of the opening to the opening side by pushing the thermoplastic resin plate that has been extended to the back of the heel once. This is to form a heel that continues without a large step from the saddle-shaped recess while forming the yarn bottom with the recess. Since the yarn bottom inner forming mold moves from the first stop position to the second stop position in this way, interference may occur if the sub plug is protruding. Moreover, if the distance is large enough not to interfere, the thickness cannot be increased.
[0017]
  For this reason, the sub-plugWhile being accommodated and supported by the plug body, it communicates with the airtight chamber inside the plug body and advances and retreats according to the pressure difference between the airtight chamber and the outside,The yarn bottom inner mold is reciprocated without contact in correspondence with the reciprocating drive between the first stop position and the second stop position, thereby increasing the thickness to the maximum. become able to.
[0018]
【The invention's effect】
  As described above, according to the present invention, it is possible to easily assist partial thickness adjustment by having a sub-plug that advances and retracts from the plug body.The drive of the sub plug can be controlled only by the pressure difference, and the configuration and molding timing can be simplified.A thermoforming plug can be provided.
[0019]
  According to the second aspect of the present invention, the wall thickness can be adjusted by changing the bottom area and changing the distance by forming the plug body and the sub-plug substantially concentrically..
further,Claim 3According to the invention, the sub plug and the plug body can be simply configured as a cylinder piston configuration.
[0020]
  further,Claim 4According to the invention concerning the thickness adjustmentEasyPossible to doThe drive of the sub plug can be controlled only by the pressure difference, and the configuration and molding timing can be simplified.A method for manufacturing a thermoformed product can be provided.
  further,Claim 5According to the invention, it is possible to easily form a yarn bottom having a large thickness.The drive of the sub plug can be controlled only by the pressure difference, and the configuration and molding timing can be simplified.Can be provided.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
  FIG. 1 is a schematic sectional view showing a deformation operation of a thermoforming plug according to an embodiment of the present invention, and FIG. 2 is a principal sectional view showing a thermoforming apparatus to which the thermoforming plug is applied. FIG. 3 is a timing chart showing an operation sequence of the thermoforming apparatus.
[0022]
  First, the thermoforming apparatus will be described. The upper substrate 11 and the lower substrate 31 are fixed to an upper table and a lower table (not shown), and can be moved up and down within a predetermined stroke range by the driving devices M1 and M2. A cabinet base 12 is bolted to the upper substrate 11 at a predetermined distance. A cabinet holder 13 is bolted to the cabinet base 12, and a plurality of main cavities 21 are mounted on the cabinet holder 13.
[0023]
  The thermoforming female mold 20 is composed of a main cavity 21 and a bottom mold 22 as shown in an enlarged view in FIG. The main cavity 21 is formed in a generally bowl-shaped concave shape, but has a through hole 21a formed at the bottom thereof, so that the substantially cylindrical bottom mold 22 can move up and down so as to close the through hole 21a. It is supported.
  The shape of the ridge continues from the opening end through the peripheral wall surface to the bottom wall surface, but the through-hole 21a is formed in the bottom wall surface, and the opening diameter once narrowed from the peripheral wall surface becomes wider toward the back. After the diameter is increased, the diameter is again reduced to about the initial opening diameter, and thereafter, the diameter is constant. The part which expands in a divergent shape here is a part which forms the outer shape of the yarn bottom formed at the bottom of the heel, and forms an undercut with respect to the die cutting direction.
[0024]
  The bottom mold 22 forms the concave bottom surface, and a two-stepped portion 22a formed concentrically on the bottom surface. The outer shape of the bottom mold substantially coincides with the constant inner diameter portion of the through hole 21a, but the opening end diameter of the through hole 21a is slightly smaller than the same constant inner diameter portion.
  The bottom mold 22 penetrates the cabinet base 12 and is supported by the bottom mold base 14 held between the cabinet base 12 and the upper substrate 11. The bottom mold base 14 can be moved up and down within a predetermined stroke range by the driving device M3, and the stroke of the bottom mold base 14 from the position retracted from the end of the yarn bottom (upward in FIG. 2) by the height of the yarn bottom. It is the distance that the bottom surface of the bottom mold 22 reciprocates up to the starting end (downward in FIG. 2).
[0025]
  A large number of vacuum / release holes 23 are arranged on the inner peripheral surface of the female mold 20 for thermoforming, and are concentrated particularly on the bottom of the heel, which is a part for forming the above-described undercut. Referring to FIG. 4, it can be seen that it is formed in a portion that continues from the peripheral wall surface to the heel bottom, a portion at the outermost peripheral end of the yarn bottom, and a portion of the two-stepped portion 22 a. Regarding the number and arrangement of the vacuum / release holes 23, when compressed air is supplied from the vacuum / release holes 23 as will be described later, in addition to the minimum condition that the vacuum / release holes 23 are in close contact with each other along the inner peripheral shape of the bowl shape In addition, it is determined under such conditions that the bottom part of the molded product can be bent inward.
[0026]
  These vacuum / release holes 23 are connected to control valves V1 and V2 with respect to an external pressure control mechanism (not shown) through a hollow path provided in the bottom mold 22 and a hollow path formed in the bottom mold base 14. The negative pressure is supplied or the compressed air is supplied as shown in the timing chart of FIG. 3 by the same pressure control mechanism.FakeIt has become so. The timing for supplying the negative pressure to the vacuum / release hole 23 is indicated as “vacuum / release hole (vacuum)”, and the timing for supplying the pressure release air is “vacuum / release hole (release)”. ) ”Is displayed.
  On the other hand, such a vacuum / release hole 23 is not formed at the opening end of the main cavity 21, and instead, an air communication hole 24 is formed in the recess along the opening end shape. Therefore, no air pocket is formed between the molded body and the main cavity 21 even when pressure is applied from the plug side during molding as will be described later.
[0027]
  In addition, a knockout plate 15 is disposed on the side of the lower substrate 31 in the cabinet holder 13, and can be separated and moved by a predetermined stroke when the mold is released by the driving device M4.
  On the lower substrate 31 side, a plug base 32 is bolted with a spacer 33 in between to form a closed pressure air box as a whole. A plug 40 is bolted to the plug base 32 at a position facing the main cavity 21, and a communication port 32 a is formed around the site where the plug 40 is implanted.
[0028]
  The plug 40 is formed in a substantially mushroom shape around the vertical axis, with the upper half portion inserted into the thermoforming female mold 20 when the mold is closed. FIG. 1 shows the cross-sectional structure of the plug 40 in more detail than the other figures. The plug 40 includes a plug main body 41 serving as an outer frame, and a sub plug 42 accommodated and supported by the plug main body 41. The plug body 41 is formed in a hollow shape whose upper surface is open, and is composed of an upper plug body 41a and a lower plug body 41b so that the sub plug 42 can be accommodated in the opening. The hollow portion 41a1 is formed in a substantially columnar shape, the upper side has a small diameter, and the lower side has a large diameter. Correspondingly, the upper side of the sub plug 42 has a diameter corresponding to the small diameter portion of the hollow portion 41a1, and a flange 42a corresponding to the large diameter portion of the hollow portion 41a1 is formed at the lower end portion. An annular groove 42a1 continuous along the circumferential direction is formed on the outer periphery of the flange 42a, and a sealing O-ring 42a2 is accommodated. That is, the plug body 41 and the sub plug 42 are formed as a cylinder piston structure in which the former corresponds to the cylinder and the latter corresponds to the piston.
[0029]
  The upper plug body 41a is formed in a cylindrical shape, and the lower end opening is closed by the lower plug body 41b. On the upper surface side of the lower plug main body 41b, a short columnar convex portion 41b1 having a diameter capable of entering the lower end opening of the upper plug main body 41a is formed, and an annular groove 41b2 is formed on the outer peripheral surface thereof and an O-ring 41b3. Is housed. The lower plug body 41b is mounted by allowing the protrusion 41b1 to enter the upper plug body 41a from below the upper plug body 41a, and is fixed by bolts (not shown). Here, the upper side of the hollow portion 41a1 is sealed by the O-ring 42a2 of the sub plug 42, and the lower side is sealed by the O-ring 41b3 of the convex portion 41b1, thereby forming an airtight region. This hermetic zone is connected to a spare chamber 41b4 communicating with the hollow portion 41a1 and a plug AD43, which is an electromagnetic switching valve, via a predetermined air communication path.44It is connected to a constant pressure supply source 45. Note that this communication path is also omitted in the drawings below.
  The constant pressure supply source 45 is connected to the pressure air source 45a via the pressure adjustment valve 45b so that the pressure air of the set pressure can be supplied. Of course, if the airtight area is connected to the constant pressure supply source 45 by the plug AD43, the compressed air is supplied into the airtight area, and the silencer is supplied by the plug AD43.44When the sub-plug 42 is stored, the compressed air supplied to the inside is released to the atmosphere and exhausted. In addition, in order to adjust the pressure of this airtight area | region independently, it connects to the independent constant pressure supply source 45. FIG.
  FIG. 1 shows a state in which the sub-plug 42 protrudes most on the left side, and shows a state in which the sub-plug 42 sinks most on the right side so that the movable range of the sub-plug 42 can be seen.
  In FIG. 2 and subsequent figures, the configuration of the plug 40 is simplified in order to prevent comprehension.
[0030]
  Returning to FIG. 2, the upper substrate 11 and the lower substrate 31 are close to each other by disposing a seal plate 34 that surrounds the plug 40 so as to face the open end of the main cavity 21 and has a through hole. In this state, a sealed space communicating with the compressed air box is formed while sandwiching a thermoplastic resin plate between the seal plate 34 and the main cavity 21. The pressure box is also communicated with the pressure control mechanism via control valves V3 and V4. The pressure control mechanism is supplied with compressed air as shown in the timing chart of FIG. Exhausted)FakeIt has become so.
  Note that the drive devices M1 to M4, the control valves V1 to V4, and the plug AD43 described above are subjected to drive control corresponding to the timing chart of FIG. 3 by the drive control device C1 including a sequencer or the like.
[0031]
  Next, the operation of the present embodiment configured as described above will be described with reference to the timing chart of FIG. In addition, although a heater, a feeder, etc. are arrange | positioned in the front | former stage of this thermoforming apparatus, since a general thing can be used, description is abbreviate | omitted.
  First, at the timing T1, the upper table starts to descend, and the upper substrate 11 and the thermoforming female mold 20 fixed to the upper table begin to descend. The lowering of the upper table ends at timing T3, but the lower table starts to rise from timing T2 prior to that, and after the lowering of the upper table is completed, the raising is completed at timing T4 that is slightly delayed. When the lower table starts to rise, the plug AD43 is switched to the constant pressure source 45 side, and a predetermined compressed air is supplied to the airtight region. At this time, since the periphery of the plug 40 communicates with the atmosphere, the internal pressure in the airtight region is higher, and the sub-plug 42 is in a state of popping out due to the atmospheric pressure difference.
[0032]
  FIG. 5 shows each configuration in the mold-closed state at the timing T4, but only the thermoplastic resin plate is omitted in this figure. At this time, the bottom mold 22 is in a position (upward position) that is recessed from the main cavity 21. As shown in FIG. 6, the thermoplastic resin plate is sandwiched in a circular shape by the opening end of the main cavity 21 and the seal plate 34, and the plug 40 is extended to the inside of the main cavity 21 at the center. Since the bottom mold 22 is located at a position recessed from the main cavity 21, the collar bottom portion of the bowl-shaped recess is also located at a deeper position to form a hollow portion, but the sub-plug 42 protrudes from the plug body 41. Up to this hollow part. Of course, the thermoplastic resin plate is extended to the upper surface side of the sub-plug 42 and is located near the lower surface of the bottom mold 22.
[0033]
  At timing T50, compressed air is supplied from the compressed air box side, and at the same time, negative pressure is supplied to the vacuum / release hole 23. Then, the thermoplastic resin plate is sucked into the vacuum / release hole 23 while being pressed into the main cavity 21 from the side of the plug 40, and is surely formed even in the deep shape of the inner peripheral surface of the female die. . Further, a step shape is also formed in the portion of the main cavity 21 near the opening end, but the vacuum / release hole 23 is concentrated on the bottom of the ridge and is not formed in the step portion. However, an air communication hole 24 is formed instead in the step portion, and when the compressed resin is pressed against the step portion near the opening end when pressurized air is supplied from the plug 40 side, The residual air remaining in the air is exhausted to the outside through the atmosphere communication hole 24. Therefore, it adheres and hardens along the inner peripheral surface shape of the main cavity 21.
[0034]
  By the way, the pressurized air supplied at this time is set higher than the atmospheric pressure supplied from the constant pressure source 45 to the hollow portion 41a1. For this reason, the external pressure of the plug 40 becomes higher than the internal pressure, and the sub plug 42 is pushed. FIG. 7 schematically shows the moving direction of the thermoplastic resin plate and the moving direction of the sub plug 42 at this time. In this state, the upper end of the sub-plug 42 is retracted toward the main cavity 21 side.
  The sub-plug 42 is moved in this way for adjusting the thickness. In the case of a conventional plug, as shown in FIG. Then, even if it is going to form a thread | yarn bottom in the position deeper from the heel bottom part of the main cavity 21 like this female mold 20 for thermoforming this time, a thermoplastic resin board must be extended further far, inevitably The thickness will be thin. Since the yarn bottom is a part that supports the entire load, it is desired to increase the wall thickness. In this respect, the conventional thermoforming plug would cause problems.
[0035]
  In this state, although the outer shape of the yarn bottom formed on the bottom of the heel is formed, the original shape of the heel is formed in an intermediate shape formed at a position deeper than the yarn bottom. However, at timing T51 slightly behind timing T50, as shown in FIG. 8, the bottom mold base 14 is lowered by the actuator, and the bottom mold 22 is lowered in the through hole 21a. As the bottom mold 22 descends in the through hole 21a, the original reed bottom is moved to the open end side of the through hole 21a, and from the end of the yarn bottom to the reed bottom along the inner peripheral surface of the through hole 21a. The part that was continuous and rolled up to form a new inner wall surface of the yarn bottom. Further, since the bottom mold 22 is lowered with a slight delay, the thermoplastic resin plate itself is still in a softened state, and as described above, the lower end of the bottom mold 22 is slightly larger than the opening end diameter of the through hole 21a. Since it has a diameter, the peripheral edge of the heel bottom and the starting end portion of the yarn bottom, which are in a softened state, are pressed and welded, eliminating the gap. This state is shown in FIG.
[0036]
  Even in this state, compressed air is supplied, and the sub-plug 42 remains accommodated in the plug body 41 and does not interfere with the thermoformed product.
  The supply of compressed air from the compressed air box is stopped at timing T6 after a predetermined curing time, and the exhausted air is communicated with the outside air. At the same time, the plug AD is switched to the silencer 44 side to open the hollow portion 41a1 of the plug 40 to the atmosphere. As a result, both the outside of the plug 40 and the inside of the hollow portion 41a1 become atmospheric pressure to eliminate the pressure difference, and the sub-plug 42 is held in the storage state immediately before that.
  Further, the supply of the negative pressure to the vacuum / release hole 23 is stopped and the bottom mold 22 is raised. FIG. 10 shows a cross section of the molded body immediately after raising the bottom mold 22. Since the diameter of the through hole 21a is expanded in a divergent shape, the bottom of the yarn is surely undercut, and even if knockout is performed as it is, it is not always possible to release the yarn reliably. If there is one that cannot be released from the mold, the other formed bodies and all of them will be damaged in the next feeding step.
[0037]
  In this embodiment, prior to separating the upper table and the lower table, first, compressed air is supplied from the vacuum / release hole 23 at timing T8. Since it is before mold release, the molded object in the shape of the heel is pressed at the open end, and in this state, the compressed air is sent to the bottom of the heel, so the heel bottom naturally tends to bend inward. Then, the lower table starts to be lowered at timing T9 slightly delayed. FIG. 11 shows a state where the heel bottom is about to be bent inward, and even if the yarn bottom is in an undercut shape, if the center of the heel bottom is pushed down, the periphery is slightly pulled inward. When pulled in this way, the end portion of the yarn bottom is also drawn inward, so that it can be slipped out of the undercut formation site. In this state, when the lower table is lowered, the seal plate 34 is lowered and the lower end of the molded body becomes free. In most cases, the yarn bottom comes off at this point, but the knockout plate 15 is also pushed down at the timing T10 later than this, so that the mold release is surely completed.
[0038]
  When the knockout plate 15 starts to be pushed down, the upper table also starts to rise, but at the beginning, it begins to rise slowly, and then the speed increases from the time T11 when it is considered that the mold has been completely released. To do. In addition, the supply of pressurized air from the vacuum / release hole 23 is stopped at timing T12 with the completion of the release.
  When the lower table starts to descend as the knockout plate 15 descends, it is no longer necessary to connect the compressed air box to the atmosphere, and the exhaust is stopped at timing T10. When the upper table and the lower table completely stop, the knockout plate 15 is also pulled back to the original position close to the cabinet holder 13. FIG. 12 shows a state when the upper table and the lower table are completely stopped and the knockout plate 15 is not yet pulled back.
[0039]
  With the above as one thermoforming cycle, a bowl-shaped molded body is manufactured. In addition, when the yarn bottom spreading outward from the heel bottom portion can be formed in this way, the heel looks more gorgeous and the texture is improved. In addition, this thread bottom part is doubled while increasing the thickness of the thermoplastic resin plate, so that it has sufficient strength, and further, there is no gap communicating with the inside of the thread bottom on the inner peripheral surface of the heel, so hygiene Is also good.
  By the way, in embodiment mentioned above, although the thread bottom is formed in a heel bottom part, it is not necessarily restricted to such a structure, What is necessary is just to adjust a thickness partially. . FIG. 13 shows a modification for dealing with such a desire. In FIG. 1 (I), the peripheral wall of the ridge is thinned as a molded product, the lower corner is the middle, and the bottom of the ridge is thick. On the other hand, in FIG. 11 (II), the portion near the opening of the peripheral wall is the middle, the corner is thinned, and only the portion from the center of the bottom is thick. This is because, as a basic policy, the protrusion length is increased while reducing the diameter of the sub plug. Therefore, the thickness may be adjusted appropriately by applying such a viewpoint.
[0040]
  The plug 40 is only doubled, but is not limited to a double one. For example, when the thickness is thick at the bottom side of the ridge and gradually becomes thinner as it approaches the opening edge, the same configuration may be used in triplicate. This is because it becomes possible to adjust the amount of stretching for each stage.
  Further, the projecting direction is not limited to the bottom side, and the projecting direction may be projected so as to approach the inner peripheral surface of the thermoforming female mold 20 at a portion where the wall thickness is desired to be increased. Therefore, it is possible to increase the thickness at the side surface portion to form a pattern.
[0041]
  Furthermore, the reason why only the external pressure is adjusted when driving the sub plug 42 is to make the structure of the plug 40 as simple as possible and to facilitate the overall control. Therefore, it is also possible to control the advance / retreat timing by positively adjusting the air pressure of the hollow portion 41a1.
  As described above, the plug 40 is configured by the plug body 41 and the sub-plug 42, and the sub-plug 42 is configured to be able to advance and retract with respect to the plug body 41. Therefore, the thermoforming female mold 20 is formed at a portion where the thickness is to be increased. The thermoformed product can be formed without interference even when the thermoforming female mold 20 is operated.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a thermoforming plug according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a main part of a thermoforming apparatus to which the same thermoforming plug is applied.
FIG. 3 is a timing chart showing an operation sequence of the thermoforming apparatus.
FIG. 4 is an enlarged schematic cross-sectional view of a female mold of the thermoforming apparatus.
FIG. 5 is a cross-sectional view of a main part of the thermoforming apparatus in a mold clamping state.
FIG. 6 is a cross-sectional view of a principal part showing a positional relationship between a thermoplastic resin plate and a plug immediately after mold closing.
FIG. 7 is a schematic cross-sectional view of a molded body and a plug immediately after the start of molding.
FIG. 8 is a cross-sectional view of the main part of the thermoforming apparatus in a state where the bottom mold is lowered.
FIG. 9 is a schematic cross-sectional view of a molded body and a plug in the same state.
FIG. 10 is a schematic cross-sectional view of a molded body in a state where the bottom mold is raised again.
FIG. 11 is a schematic cross-sectional view of a molded body in a state in which pressurized air is supplied from a vacuum / release hole to bend the bottom of the ridge.
FIG. 12 is a cross-sectional view of a main part in a state where a knockout plate of the thermoforming apparatus is pushed down.
FIG. 13 is a cross-sectional view of an essential part showing a modification for adjusting the thickness.
[Explanation of symbols]
11 ... Upper substrate
12 ... Cabinet base
13 ... Cabinet holder
14 ... Bottom mold base
15 ... Knockout plate
20 ... Female mold for thermoforming
21 ... Main cavity
21a ... through hole
22 ... Bottom type
22a ... Step part
23 ... Vacuum / release hole
24 ... Air communication hole
31 ... Lower substrate
32 ... Plug base
32a ... Communication entrance
33 ... Spacer
34 ... Seal plate
40 ... Plug
41 ... Plug body
41a ... Upper plug body
41a1 ... hollow part
41b ... Lower plug body
41b1 ... convex portion
41b2 ... annular groove
41b3 ... O-ring
41b4 ... Reserve room

Claims (5)

A plug for thermoforming, comprising a plug body and a sub-plug that is housed in the plug body and advances and retracts into the female mold to assist in adjusting the wall thickness ,
The sub-plug is accommodated and supported by the plug body, communicates with an airtight chamber inside the plug body, and advances and retreats according to a pressure difference between the airtight chamber and the outside .   2. The thermoforming plug according to claim 1, wherein the plug body and the sub plug are formed in a substantially concentric circle shape. The thermoforming plug according to claim 1 or 2 , wherein the plug body and the sub plug are formed in a cylinder piston shape. A method for producing a thermoformed article, wherein a plug is advanced and retracted into a female mold for thermoforming to pre-stretch a softened thermoplastic resin plate to produce a thermoformed article,
The plug is composed of a plug main body and a sub-plug that is housed and supported by the plug main body and communicates with an airtight chamber inside the plug main body and can advance and retreat into the female mold in accordance with a pressure difference between the airtight chamber and the outside. configured with, together with the plug body as a state of being protruded to the Sabupuragu by performing pressure adjustment of the air-tight chamber and the outside is advanced to the heat molding resin female form in, followed by pressure between the hermetic chamber and the outside A method of manufacturing a thermoformed product, characterized in that the thickness adjustment is performed by retracting the sub-plug by adjusting. A thermoforming apparatus having a female mold for thermoforming and a plug that advances and retreats so as to push a softened thermoplastic resin plate into the female mold for thermoforming,
The female mold for thermoforming is
While being formed into a bowl-shaped concave shape,
A thread bottom outer shape concave portion that forms a thread bottom outer peripheral shape in a continuously spreading shape from the saddle-shaped concave bottom portion;
The thread bottom outer shape recessed portion is supported in such a manner as to be able to advance and retreat with respect to the saddle-shaped concave shape while being formed in a columnar shape that approximates the opening edge to the saddle-shaped concave portion, and is retracted slightly from the thread bottom outer shape concave portion A yarn bottom inner mold that is driven from a first stop position to a second stop position adjacent to the opening edge;
The above plug
A plug body capable of entering the saddle-shaped recess,
Being formed in the pillar shape that can enter into the opening of the recess for the Itozoko contour is movably supported with respect to the same opening from the bowl bottom of the plug body, the plug body inner being housed supported by said plug body The yarn bottom inner mold is reciprocated between the first stop position and the second stop position, and communicates with the airtight chamber of the same and moves forward and backward according to the pressure difference between the airtight chamber and the outside . And a sub-plug that is driven to reciprocate without abutting.

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