JP4358715B2 - Molded product cooling system and cooling method, cooling pin - Google Patents

Description

  The present invention relates to a method and apparatus for molding and cooling plastic molded products, such as preforms (preforms) made of one or more materials such as plastic resins. In particular, the present invention relates to a rapid or fast injection molding process in which a molded product, such as a PET preform, is removed from the mold or mold before completing the cooling step. This is possible as a result of utilizing a new post-molding cooling process and apparatus that is cooled from the inside by convective heat transfer after the preform is removed from the mold and held out of the mold area. The present invention further discloses additional external cooling performed through convection or conduction heat transfer that occurs at least partially simultaneously with internal cooling.

  Proper cooling of the molded product is a very important aspect of the injection molding process because it affects product quality and also affects the injection cycle time. Cooling becomes even more important in applications where semi-crystalline or semi-crystalline resins are used, such as PET preform injection molding. After injection, the PET resin is held in the mold cavity or mold cavity space for a sufficient period of time to prevent the formation of crystalline parts and allow it to solidify before the preform is removed. The

  If the preform is suddenly removed from the mold to shorten the cycle time of the injection process, two things are likely to happen. First, the preform is not cooled uniformly. In many cases, the bottom portion facing the mold gate is crystallized. The amount of heat that accumulates on the walls of the preform during the injection process will remain high, particularly in the gate region of the preform, causing crystallization after molding. The gate region becomes a very important part because the mold cooling in this part is not efficient enough and the resin remains in contact with the hot stem of the hot runner injection nozzle in the cavity space of the mold. . If this region of the preform remains crystalline beyond a certain size and depth, the quality of the blow molded product will be weakened. The second problem is that the preform becomes too soft and may deform during the next processing step. The neck finish portion, which in many cases is thicker than the other, and therefore accumulates more heat, is also an important area of the preform. The neck needs to be actively cooled after molding so as not to crystallize. In addition, aggressive cooling strengthens the neck so that it can handle further processing.

  In the past, many attempts have been made to increase the cooling efficiency of PET injection molding systems, but the quality of molded preforms has not been significantly improved or cycle times have not been substantially reduced. In this regard, reference is made to US Pat. No. 4,382,905 issued to Valyl. In this patent, the molded preform is transferred to a first tempering mold for the first cooling step and then transferred to a second tempering mold for final cooling. An injection molding method for performing the steps is disclosed. All tempering molds are similar to injection molds and have internal means for cooling the walls that are in contact with the preform during the cooling process. The Valyl '905 patent does not disclose the provision of a cooling device located on the means for transporting the preform from the molding region or an additional cooling device for circulating the fluid refrigerant in the molded parison.

  U.S. Pat. No. 4,592,719 issued to Ballehache describes a first movable device which is constituted by a vacuum suction device for holding a preform and constituted by intake (convection) cooling means on the outer surface of the preform. Discloses an injection molding method for producing a PET preform in which a molded preform is taken out from an injection core. In the Bellehache '719 patent, a second cooling device is utilized along with a second movable device to further cool the interior of the preform by intake air as well. See FIG. 22 herein. The Bellehache '719 patent does not disclose cold air blowing into a preform that has a much higher cooling effect with respect to inhalation or absorption of ambient air, and conductive heat transfer located in close proximity to the preform wall. Neither cooling means nor air blowing means directed to the dome-shaped part of the preform are disclosed. The Bellehache patent has several deficiencies, including reduced cooling efficiency, reduced uniformity, extended cooling time, increased possibility of preform deformation, and the like.

  U.S. Pat. Nos. 5,176,871 and 5,232,715 show preform cooling methods and apparatus. The molded preform is held by an injection molded core outside the mold area. The mold core is cooled by a coolant that does not contact the molded preform. A cooling pipe larger than the preform is arranged around the preform and blows cooling air around the preform. A major problem with the devices and methods shown in these patents is that the cycle time is significantly increased because the preform is held in the mold core. Further, internal cooling by direct contact between the refrigerant and the preform is not performed.

  Further reference is made to US Pat. Nos. 5,114,327, 5,232,641, 5,338,172 and 5,514,309 which disclose a preform internal cooling method utilizing a liquid refrigerant. . The preform removed from the mold is transferred to a preform carrier having vacuum means for holding the preform in place without contacting the outer wall of the preform. However, the preform carrier does not have a cooling device. A cooling core is further introduced inside the preform held in the carrier, and cooling fluid is blown into the preform to cool the preform. The refrigerant is further removed from the chamber surrounding the preform by the same vacuum means that holds the preform. These patents do not disclose a method in which cold air is blown into the preform and the air is free to exit the preform after cooling. These patents do not disclose a method of simultaneously cooling the preform from the inside and outside, nor a preform carrier having a cooling means. See FIG. 21 herein.

  Reference is also made to Japanese Patent Publication No. 7-171888 which discloses a preform cooling apparatus and method. A molded preform robotic carrier is used to transfer the preform to the cooling station. . The robot includes external cooling of the preform wall by conduction heat transfer using water refrigerant. The cooling station is constituted by a first movable transfer robot having a rotating hand portion having a vacuum means for holding the preform and external cooling of the preform wall by conduction heat transfer. The molded preform is transferred from the robot carrier to the hand unit. The hand part is moved from position A to position B rotated 90 degrees to transfer the preform (only the outer surface is cooled) to the cooling tool. The cooling tool has means for holding the preform, a device for cooling the inside of the preform by air blowing, and a device for cooling the outside of the preform by air blowing or water cooling. The internal cooling employed is shown in FIGS. 19 and 20 herein. This patent does not disclose a cooling method that provides internal and external cooling as soon as possible from the moment the preform is removed from the mold and placed in the carrier plate. Also, a method for simultaneously cooling the inside and outside of the preform while being held by the movable robot carrier is not disclosed. Therefore, this cooling method does not have sufficient speed and cannot prevent crystal formation outside the mold.

  19 and 20 show a known preform internal cooling method that is used to blow cool air into the preform when the cooling device is located outside the preform. Since the air nozzle is located outside the preform, the incoming cold air flow will always interfere with the warm flow going out and will at least partially mix. This greatly reduces the cooling efficiency. If the cooling device is on the same axis as the preform, the method of FIG. 19 becomes inefficient because there is no air circulation in the preform. When the cooling device is moved in the lateral direction as shown in FIG. 20, the internal air circulation is performed, but the efficiency still deteriorates because one side of the preform is cooled better and faster than the other side. The refrigerant has a quasi-divergent flow profile with an asymmetric profile. This profile is very inefficient and does not concentrate the cooling fluid / gas towards the sprue gate or dome portion.

The main object of the present invention is to provide a preform manufacturing method and apparatus with improved cooling efficiency.
Another object of the present invention is to provide the above method and apparatus for producing preforms with improved quality.
Yet another object of the present invention is to provide such a method and apparatus which reduces the overall cycle time.
The above objective is accomplished by an apparatus and method according to the present invention.

  In one embodiment, the innovative molding and cooling method of the present invention allows the preform to be completely cooled within the mold, i.e., the preform is a sprue gate, neck finish or entire preform. Removing the preform from the mold while maintaining a certain amount of heat that can crystallize; holding the preform outside the molding region; and cooling the preform internally by convective heat transfer A step of preventing crystallization from occurring in these regions.

  In another embodiment, the innovative molding and cooling method of the present invention allows the preform to be completely cooled within the mold, i.e., the preform is a sprue gate, neck finish or entire preform. Removing the preform from the mold while still holding a certain amount of heat that may cause crystallization; holding the preform outside the molding area; cooling the preform internally by convective heat transfer The step of preventing crystallization from occurring in any of the above regions, the step of placing the refrigerant in direct contact with the preform; and the external cooling of the preform by convective heat transfer to The step of preventing the crystallization from occurring in the process is also provided. The external cooling step can be performed simultaneously, at least partially simultaneously or sequentially with respect to the internal cooling step.

  In yet another embodiment, the innovative mold cooling method of the present invention may be used before the preform is completely cooled within the mold, i.e., the preform is a sprue gate, neck finish or entire preform. Removing the preform from the mold while still holding a certain amount of heat that may cause crystallization; holding the preform outside the molding area; cooling the preform internally by convective heat transfer A step of preventing crystallization from occurring in any of the above regions, the step of placing the refrigerant in direct contact with the preform; and the external cooling of the preform by conduction heat transfer to The step of preventing the crystallization from occurring in the process is also provided. The external cooling step can be performed simultaneously, at least partially simultaneously or sequentially with respect to the internal cooling step.

  In each of these embodiments, the preform is ejected from the mold and held outside the mold by means independent of the mold, such as a movable take-off plate. This kind of independent holding means can hold one batch of preforms or several lots of preforms simultaneously. If the independent means holds several lots, these lots are formed at different times and therefore have different temperatures. In accordance with the present invention, the molded preform is cooled in different sequences from the inside and outside using the cooling method of the present invention. In each embodiment of the present invention, internal cooling is performed using means such as cooling pins that at least partially enter the interior of the preform and circulate the refrigerant therein. Cooling is performed preferentially by sending a quasi-symmetric flow of refrigerant inside the preform that can be directed to parts of the preform that require more cooling than other parts, such as the sprue gate and neck finish. Is done. In a preferred embodiment of the present invention, the refrigerant is directed to the bottom or dome of the preform to form an annular flow of refrigerant.

  In certain embodiments of the invention, the innovative internal cooling of the preform is supplemented by external cooling that can be done in several ways. For example, external cooling can be performed on extraction plates (single or multiple locations) having cooling means that operate using either conduction (cold water) or convection (air / gas) heat transfer. It can also be carried out on a take-out plate (single or multiple positions) where there is no cooling means and the preform only partially contacts the holder. In this way, the cooling gas / air can be delivered by an independent cooling device and brought into direct contact with the outer surface of the preform.

  In yet another embodiment, the preform is held by a take-out plate without cooling means and cooled only from the inside by the novel cooling pins of the present invention.

  In one embodiment, the innovative cooling method of the present invention comprises the steps of removing a preform or molded product from a mold, a robot take-off plate having a system for cooling the outer surface of the preform or molded product. plate) in the preform or molded product, followed by a cooling means engaging the interior of the preform or molded product to cool the outer and inner surfaces simultaneously. According to the present invention, an additional cooling step is introduced, whereby the temperature of the preform is lowered using heat transfer by convection, such as by circulating cooling gas inside the preform.

  The method and apparatus according to the present invention can be advantageously used to prevent crystallization in the most important parts of the preform, ie the bottom or dome where the sprue gate is located, and the neck, as described above. Furthermore, the cooling method and apparatus of the present invention may be integrated or integrated with an injection blow molding machine to further control the temperature of a cooled preform that has not been crystallized and blow molded into a bottle.

  In one aspect of the present invention, a method for preventing crystallization in an injection-molded preform by enhancing cooling outside the mold is performed at the position where the mold is open, that is, the mold open position. Injecting molten material into a mold formed by two mold halves or plates spaced apart to define a molding area; a mold in which the molten material is formed by a half mold Cooling the molten material to a temperature substantially close to its crystalline glass transition temperature while in the cavity space to allow the molded product to be mechanically processed outside the mold without causing geometric deformation; Opening each mold half so that the carrier of the molded product can move between the two molds; discharging the molded product from the mold and transferring it to the movable carrier; Cooling the molded product by heat transfer conduction while in the carrier to reduce crystallization, wherein the air is blown with refrigerant; and each molded product is substantially free of crystallized portions. Cooling the molded product from the inside by convective heat transfer (until the occurrence of crystallized parts can be avoided). The same method can also be realized using a movable carrier with convective heat transfer means for external cooling.

  In one aspect of the invention, an apparatus for forming an injection molded product that does not cause crystallization includes a mold having two half molds movable between a mold closed position and a mold open position. Having means for injecting molten material into the mold while the half mold is in the mold closed position; so that the molded product can be mechanically processed outside the mold without causing shape deformation Means for cooling the molten material within the cavity space formed by each half mold to a temperature substantially close to the crystalline glass transition temperature of the molten material; the carrier of the molded product is movable between the two half molds Means for opening the mold by a certain distance; means for discharging the molded product from the mold; means for transferring the molded product to a movable carrier; the carrier holds the preform and transfers heat Cooling the molded product by conduction to reduce crystallization Means; and each molded product preferably comprises means for further internal cooling of the molded product by convective heat transfer until the entire product is substantially free of crystallization parts, particularly in the gate region of the mold. Is done. The same method can also be realized using a movable carrier with convective heat transfer means for external cooling.

  As used herein, “take-off plate”, “take-out plate” and “end of arm tool” are used interchangeably and are the same Refers to the structure.

  Other details of the method and apparatus of the present invention as well as other objects and advantages attendant thereto are set forth in the following detailed description and the accompanying drawings. In the drawings, like reference numbers indicate like elements.

  Referring to the drawings, FIG. 1 is a graph showing the evolution of preform temperature over time during and after the injection step. FIG. 2 is a schematic view when the preform is in the mold. As can be seen from the figure, the cooling in the mold is usually affected by the cooling pipes 12 and 14 and the mold core portion 18 located in the mold cavity 16, respectively. As a result, cooling is performed from both sides of the preform 11. In addition, as shown in FIG. 2, the mold cavity plate 16 typically has a gate region 20 in which the bottom or dome portion 22 of the preform 11 is formed. Preforms often have a neck finish 13 with thick walls that are difficult to cool to prevent crystallization.

  FIG. 3 (a) and FIG. 3 (b) show the temperature gradient across the walls of the molded preform (molded preform) during cooling. FIG. 3A shows the temperature gradient inside the mold, and FIG. 3B shows the temperature gradient outside the mold. FIG. 3 (c) shows the temperature profile along the preform wall. The temperature spike portion represents the temperature within the dome or sprue gate portion of the preform.

  Referring to FIG. 4, an injection mold is provided comprising a stationary half mold or plate 32 having an array of mold cavities 34 and a movable half mold or plate 36 having an array of mold cores 38. The mold cavity plate 32 is in fluid communication with a manifold plate (not shown) that receives molten material from an injection unit (not shown) of the injection molding apparatus. Mold cavity 34 receives molten material via mold cavity gate 40 from a hot runner nozzle (not shown), such as a valve gate nozzle (not shown). The mold cavities are each surrounded by cooling means 42 for cooling the molten material in the cavity space formed by the mold core 38 and the mold cavity 34 when the mold plates 32, 36 are in the mold closed position. It is. The cooling means 42 is preferably formed by a cooling path embedded in the mold plate 32 that transmits the cooling fluid. As described above, the mold core 38 and the mold cavity 34 form a plurality of mold cavity spaces (not shown) in the mold closed position, and these spaces melt through the mold gate 40 during the injection step. Filled with material. The mold core 38 also includes means 44 for cooling the molten material in the cavity space. The cooling means 44 is preferably constituted by a cooling pipe in each mold core. The mold core plate 36 further includes an ejector plate 46 used to take out the molding preform 48 from the mold core 38. The operation of the ejector plate 46 is well known in the prior art and does not form part of the present invention. In practice, the ejector plate 46 is constituted by a suitable ejector plate known in the art.

  According to the present invention, any molten plastic, metal or ceramic material can be injected into the mold cavity space and cooled to the desired product using the mold system of FIG. In a preferred embodiment of the invention, the molten material is PET and the molded product is a preform. However, according to the present invention, the molded product can be a preform made of two or more materials such as virgin PET, recycled PET, and EVOH, for example, any suitable barrier.

  As is well known in the art, the preform closes the mold, injects molten material into the cavity space, initiates cooling of the cavity space, fills the cavity space, holds the molten material under pressure, and finally Molding is performed by performing typical in-mold cooling, opening the mold, discharging the solidified product or preform from the core and transferring the product or preform to a take-off plate. In accordance with the present invention, in order to shorten the overall cycle time, the time for the preform to stay in the mold must be minimized so that the mold can produce a preform lot or batch as soon as possible. I must. The problem with reducing the residence time in the mold is that the molded product or preform must be strong enough to withstand all of the subsequent processing steps without deformation, while reducing the cooling time. It is not to be. Reducing the cooling time is a problematic option because the product or preform is not cooled sufficiently and uniformly by the cooling means 42,44. The amount of heat that is maintained in the product or preform after cooling in the mold for a reduced amount of time and immediately after opening from the mold is critical and depends on the thickness of the molded product or preform . This internal heat can cause crystallized portions in the sprue gate region or dome portion of the molded product or preform, or in the neck finish portion or the entire preform of the molded product or preform. In order to prevent crystallization of the molded product or preform, a very aggressive cooling method must be used. During cooling, care must be taken to control the shrinkage of the molded product that can adversely affect the final dimensions.

  FIG. 5 shows one embodiment of a robot take-off plate 60 that can be used in the cooling method of the present invention. The take-off plate 60 comprises a plurality of hollow holders or receptacles 62, which can be water-cooled tubes. Typical takeoff plates that can be used as the takeoff plate 60 are shown in US Pat. No. 5,447,426 to Gessner et al. And US Reissue Patent RE33,237 to Delfer, III. . All of these patents are incorporated herein by reference. During operation, the mouths of the plurality of holders 62 are aligned with the mold core 38 of the mold plate 36. The molded product 48 is transferred to the holder 62 by the operation of the ejector plate 46. According to the present invention, the take-up plate 60 can be provided with as many holders 62 as the number of mold cores 38 or a multiple of the number of mold cores, for example three or four times the number of mold cores. By providing more holders 62 than the number of cores 38, it becomes possible to hold some molded products for longer than one molding cycle, thereby cooling time while maintaining high output of the molded products. Can be lengthened. The method of the present invention can be performed regardless of the relative number of molded products held by the holder 62. However, in the preferred embodiment of the present invention, the robot take-off plate 60 has as many holders 62 as the number of cores 38. This means that the take-off plate 60 does not always carry the same number of preforms or molded products as the holder 62. It also shows that one lot or batch of preform can be returned between the mold core and cavity plate more than once in the mold area to carry other batches or lots of molded products. In this case, the molded product is due to the intimate contact between the hollow tube 64 in the take-off plate that conveys a coolant such as water and the outer wall of the preform shown in more detail in the aforementioned US Pat. No. 5,447,426. Carried while cooling. Heat transfer between the tube 64 and the released hot molded product is conducted by conduction. More specifically, a solid material with cooling means can be used, which cools the molded product in intimate contact with the outer wall of the molded product. By utilizing a cooling system based on heat transfer by conduction realized through intimate contact between the molded product or preform and the cooling means, the shape of the product or preform can be obtained without any deformation or scratches caused by processing. Maintained.

  If necessary, the conductive cooling means 64 used for the take-off plate can be replaced with a convective heat transfer means. Any suitable convective heat transfer means known in the art can be used with the takeoff plate 60 to cool the outer surface of the molded product or preform carried by the takeoff plate 60.

  Referring now to FIGS. 6 (a) and 6 (b), an additional or additional cooling device 70 is used with the robot take-off plate 60 so that the molded product or preform can be transferred by convective heat transfer. By allowing the inner and outer surfaces to be cooled simultaneously, post-molding cooling efficiency is increased, thereby reducing cycle time and improving preform quality. The additional cooling device 70 comprises an array of elongate cooling pins 74, whose role is to deliver cooling fluid inside the molded product held by the take-off plate 60. In the preferred embodiment of the present invention, the cooling fluid is directed directly toward the dome (sprue gate) portion 22 of the molded product or preform. This part has the greatest chance of crystallization because the cooling time in the mold is shortened. A cooling fluid is introduced to form an annular flow pattern. According to the present invention, the cooling fluid can be a suitable refrigerant, such as a liquid or a gas. In the preferred embodiment of the present invention, the cooling fluid is pressurized air disposed through a passage 90 located within the cooling pin 74. This aspect of the invention is illustrated in more detail in FIG.

  FIG. 9 (a) shows a cooling pin 74 according to the present invention placed in a preform or molded product 48 to be cooled. In order to generate an optimal flow of coolant, the cooling pins 74 are introduced deep inside the preform 48 to allow the refrigerant to reach the dome or sprue gate portion 22. In addition, the cooling pin 74 serves as a further cooling core. The cooling pins 74 help to form an annular flow pattern that has a higher cooling capacity than other cooling flow patterns. In addition, by using the new cooling pin 74, the blown-in cold air entering and the hot air coming out are completely separated, and the two are prevented from being mixed.

  As shown in FIG. 9 (a), the cooling pin 74 is centered within the preform or molded product, and preferably the central axis 220 of the cooling pin 74 is aligned with the central axis 222 of the preform. The As can be seen from the figure, the outer wall 224 of the cooling pin 74 in the upper region UP is separated from the inner wall 226 of the preform by a distance D. Further, the outlet nozzle 92 of the cooling pin 74 is separated from the inner wall 228 of the dome portion 22 by a distance d. In order to form the desired annular flow pattern of the cooling fluid, the d: D ratio is preferably in the range of about 1: 1 to 10: 1. Also, it is highly desirable that the cooling pin outlet nozzle 92 be formed by a diffusion nozzle structure. Although it is preferred to use a diffusing nozzle for the outlet 92, it is also possible to form the outlet 92 from a straight wall nozzle structure.

  Since the cooling pin 74 penetrates deeply into the preform and functions as a cooling core, the pattern of warm air, that is, warm air, that freely escapes from the preform and exits, becomes an annular shape.

The preferred structure of the cooling pin is shown in FIG. 9A. As shown in FIGS. 8A to 8G, 17 and 18, the cooling pin 74 has various cooling effects. In addition, it can have various dimensions and shapes. For example, as shown in FIG. 8 (a), the lower portion LP of the cooling pin may have a different diameter D ₂ is the diameter D ₁ of the upper portion UP of the pin. As shown in FIGS. 8A to 8C, the upper portion UP of the pin may have a different shape. Referring to FIG. 8 (d), the cooling pin 74 may have a side outlet 82 that discharges cooling fluid onto the side wall of the molded product where crystallization may occur. As shown in FIG. 8E, the cooling pin 74 may have a spiral groove 84 for obtaining a special cooling effect. Similarly, as shown in FIGS. 8 (f) and 8 (g), the cooling pin 74 may have a plurality of ribs 86 or a plurality of contact elements 88 around it.

  18 (a) and 18 (b), a cooling pin having a plurality of radial or radial conduits 230 for injecting coolant onto a region of the preform other than the dome 22 such as a neck finish or body portion. 74. The radial conduits 230 are spaced along the length of the cooling pin to route the refrigerant toward a specific area of the preform 48.

  The cooling pin 74 can be made from any material having suitable thermal conductivity or thermal insulation. If desired, the cooling pins 74 can be made from a porous material 232 as shown in FIG. 17 so that additional coolant can diffuse very evenly over areas of the preform other than the dome or sprue gate portion 22.

  In the preferred embodiment of the present invention, the cooling pins 74 are intended to concentrate the maximum cooling on the sprue gate or dome portion 22 of the molded product 48 and to concentrate the cooling fluid strongly to cool this region. Designed as Thereby, a molded product such as a preform having no crystallized region in the sprue gate or the dome portion 22 can be formed.

  An alternative pin structure with a cold air blowing system that can be used in the apparatus of the present invention is shown in FIG. 9 (b). As shown in the figure, the pin 74 has a cold air outlet passage 90 with an outlet 92 for directing cold air or cold air to the inner surface of the molded product 48, preferably the dome or sprue gate portion 22 of the molded product. . The passage 90 communicates with a cold air source (not shown) through the inlet 94. The cooling pin 74 is further provided with a vacuum passage 96 for removing cold air from the inside of the molded product 48. The vacuum passage 96 is connected to any desired vacuum source (not shown). As shown in FIG. 9B, the cooling pin 74 is placed on a portion of the frame 98 by a sliding pad 100 used for pin self-alignment and a fastening means such as a nut 102. The nut 102 can be secured to an element 104 having a male thread portion (not shown).

  Referring to FIGS. 6 and 7, an array of cooling pins 74 is mounted on a cooling frame 98 that can be made of a lightweight material such as aluminum. According to the present invention, the cooling frame 98 can operate in either a vertical position or a horizontal position. In any case, the frame 98 can move toward the take-up plate 60 when the take-up plate 60 reaches a position outside its final mold. Any means known in the art can be used to move the frame 98 and advance it at high speed so that the cooling pins 74 can be immediately introduced into the molded product. In the preferred embodiment of the present invention, the frame 98 is moved using a hydraulic cylinder 110. According to the present invention, the number of cooling pins 74 may be the same as or less than the number of receptacles in the take-off plate 60. According to the present invention, the take-up plate 60 is provided with means such as suction means (not shown) for holding the molded product or preform 48 in the receptacle 62 and means for discharging the preform from the take-up plate. . The holding means and the discharging means may be those disclosed in the above-mentioned US Pat. No. 5,447,426, which is incorporated herein by reference. As shown in FIGS. 6C and 6D, the cooling frame 98 is provided with a plurality of spaces 112. By this space 112, the molded product or preform that has been discharged from the take-off plate 60 and finally cooled is dropped onto the conveyor 114 and carried away from the system. In the preferred embodiment of the present invention, the fully cooled preform 48 is moved into space by moving the cooling pins 74 laterally relative to the receptacle 62 that holds the preform to be ejected from the take-off plate 60. 112 is dropped onto the conveyor 114. This is the case when the cooling frame is in a horizontal position. When the cooling frame is in the vertical position, it does not interfere with the preform dropped by the take-off plate.

  Referring to FIGS. 7A and 7B, the cooling pins 74 of the first array are illustrated. As shown in FIG. 7B, each cooling pin 74 has a cooling air passage 90 that communicates with a cooling air source (not shown) via a passage 122. The passage 122 incorporates a plurality of air valves 124 that can be used to regulate the flow of cooling air. In this way, a variable amount of cooling air can be supplied to the cooling pin 74.

  Referring now to FIG. 7 (c), it is also possible to supply each cooling pin 74 directly with air from a cooling fluid source (not shown) via a simple passage 126. Further, as shown in FIG. 7 (d), if desired, the passage 126 can be connected to the fluid conduit 120 within each of the cooling pins via a flexible conduit 128.

  In one embodiment of the present invention, the cooling pins 74 enter the preform held by the take-off plate 60 in several steps, and in each step, the preforms molded at different times are at different temperatures. In order to optimize the entire cooling step and to avoid waste of refrigerant, during the first step of cooling, the preform is very hot, so the maximum amount of cooling air is fed by the pins. From the second step onward, the amount of cooling air directed by the pins engaging the first molded preform is substantially less than the amount directed to the newly molded, hotter preform. To further optimize the cooling process, use any of the known suitable temperature sensors such as thermocouples to measure the temperature before and after cooling the preform and interrupt the molding cycle to adjust the cooling rate Be able to run without having to. In the preferred embodiment, a thermocouple (not shown) connected to some cooling control means (not shown) is placed in the take-off plate 60 adjacent to each preform. By monitoring the temperature of each preform, some adjustment can be made to the amount of cooling air sent to all or some of the cooling pins 74. Thereby, the inefficiency or non-uniformity of the cooling of the conductive cooling means placed on the take-off plate is also corrected.

  Referring to FIGS. 10 (a) and 10 (b), FIG. 10 (a) shows in cross section a preform 48 formed by a system according to the prior art. As shown in this figure, the preform 48 has crystalline regions in four different portions including the dome portion 22 and the neck 13. On the other hand, FIG. 10B shows a preform 48 manufactured using the system of the present invention in a sectional view. As shown, there are no crystalline regions.

  Another embodiment of the present invention is shown in FIGS. 11 (a) to 11 (l). In these figures, the take-off plate 60 'is always maintained in a vertical position throughout the molding cycle. Thereby, a complicated motor can be eliminated, and it is lighter and can move quickly inside and outside the molding space formed between the half molds or the mold plates 32 and 36. The cooling frame 98 'utilized in this system has additional functionality and additional movement. First, the pin 74 ′ uses blown air to cool the molded product or preform and uses adsorbed air to remove the molded product or preform from the take-up plate 60 ′. The preform is held on the pin 74 'by vacuum and is separated from the tube 62' in the take-off plate 60 'during the return operation. The cooling frame 98 'moves toward and away from the take-up plate 60', and further rotates to move from a vertical position to a horizontal position parallel to the conveyor 114 'to stop the vacuum and pin 74 'Can be discharged from. In accordance with the present invention, the cooling frame 98 'can be rotated with the pin 74' using any suitable means known in the art. In accordance with the preferred embodiment of the present invention shown in FIGS. 11 (a) to 11 (l), the frame transition is converted to rotation using the stationary cam 130 as a very simple means, so that the cooling frame is The preform to be held can be dropped onto the conveyor 114 '. As shown in FIG. 11 (h), the cooling pins 74 'can be engaged with the preform by vacuum to separate them from the take-up plate 60'. Next, the preform is dropped from the pin 74 'onto the conveyor.

  The operation of the innovative cooling device of the present invention can be understood from FIGS. 6 (a) to 6 (d). After the in-mold cooling process, where the product or preform is shortened to a point where it reaches a solidified state that prevents deformation of the product or preform, the mold is opened or opened, and the take-up plate 60 is moved between the mold core plate 60 and the mold. It is moved into the molding area between the mold cavity plate 32. The relative movement between the mold core and the mold cavity plate is performed in a manner known in the art using any suitable means known in the art (not shown). When the take-off plate 60 reaches the out-of-mold position, the cooling pins 74 engage the molded product and cool, particularly in the dome region 22 of each product or preform.

  Although the take-off plate 60 is described as a water cooling means for conducting and cooling the outer surface of the preform within the holder 62, it may not be desired to initiate cooling of the outer surface when the preform is first placed in the take-off plate. Let's go. For this purpose, means may be provided for controlling the cooling in the take-off plate so that the internal cooling of the preform is started or not started until completion. For example, suitable valve means (not shown) can be incorporated into the take-off plate to prevent cooling fluid flow to a desired point in time. In this way, the internal and external cooling of the preform can be performed simultaneously, at least partially simultaneously, or sequentially.

  FIG. 16 shows another embodiment in which a molded preform is taken out of the molding area using a take-off plate 60 ″ having no cooling means. The take-up plate 60 ″ can be either one batch or multiple batches of preform. There is a sufficient number of preform holders 62 ″ to accommodate the preform. The preform is held by vacuum means (not shown), which vacuum means through the opening 240 and the sprue gate of the preform 48. Or it adsorbs to the dome portion 22. The preform is held by a holder 62 "that can have a desired structure that allows the preform to be directly cooled using cooling gas / air. Holder 62 "is preferably strong enough to hold the preform and has perforations or other openings 242, 244 at which the holder does not make direct contact with the preform. By providing such a holder that only partially covers the outer surface of the preform, the preform can be cooled at the outer surface and further cooled from the inside by cooling pins 74. In this case, cooling The steps comprise a step of transferring the preform from the mold to the take-up plate 60 "and a step of moving the take-up plate 60" to the outside of the forming region and moving it to a cooling region adjacent to the forming region. In the region, the preform 48 is removed from the interior using a frame 98 and cooling pins 74 that at least partially enter the interior of the preform. Is retirement. At the same time, the preforms 48 held in the take-up plate 60 "has its outer surface, it is convection cooled by another cooling station 250 that blows a coolant fluid to the preform holder. As shown in FIG. 16, the additional cooling station 250 has a plurality of nozzles 252, 254, 256 that spray coolant onto the outer surface of the preform. The nozzles 252, 254, 256 spray cooling fluid through the windows 258 of the take-off plate 60 ″ to the outer surface of the preform through the windows or openings 242, 244 in the preform holder. 252, 254 and 256 spray cooling fluid to the outer surface of the preform through openings 242 and 244 in the preform holder 62 ″. Although the additional cooling station 250 is illustrated with a nozzle that cools the two preforms, in practice the cooling station 250 is required to cool the outer surface of any desired number of preforms. Of course, it is possible to have as many nozzles as possible.

  With the additional cooling station 250, the preform 48 can be cooled simultaneously in and out using cooling means independent of the take-up plate 60 ". Using this method, the take-up plate 60" Lightweight, quick and easy to use. If desired, the preform holder 62 "grips the preform only around the neck, leaving a wider open window, and the sprayed cooling fluid can cool the outer portion of the preform. .

  According to another embodiment of the present invention, the take-off plate may be provided with external cooling means using blowing air or may not be provided with cooling means. In either case, internal cooling is achieved using the novel cooling method and apparatus of the present invention.

  The innovative cooling method and apparatus of the present invention is extremely advantageous for cooling preforms molded in high cavity molds. The temperature of the molten resin flowing through the mold is known to vary considerably for various reasons: (a) the hot runner manifold is not heated uniformly; (b) inside the manifold melt path A boundary layer is formed; (c) the mold cavity is not cooled uniformly; and (d) the cooling in the gate region of the mold may be insufficient. As a result of the temperature fluctuations at both ends of the mold, it occurs that the cooling time must be adjusted to a local level to cool the hottest preform before crystallization occurs in the final preform. In order to prevent the formation of crystallized portions, the cooling system of the present invention can provide different cooling patterns that can be adjusted to the temperature characteristics of each mold. The amount of cooling from each cooling pin 74 can be adjusted by providing a sensor in the take-off plate 60. In addition, the non-uniform temperature within the mold often further results in the gate sprue region located in the preform dome portion 22 being the hottest portion of the molded preform. This sprue gate part cools more slowly in the mold closed position, so if the in-mold cooling is too long or no additional cooling is performed outside the mold, this part May crystallize. In accordance with the present invention, the cooling pin 74 that blows cool air into the preform directly adjacent to the sprue gate region is a novel operation that effectively prevents the formation of a crystallization region within the preform.

  The innovative cooling method and apparatus of the present invention is also very advantageous for correcting the inefficiency of cooling of the take-off plate. Due to incomplete contact between the hot molded product and the cooling tube, the temperature of the molded product held on the take-up plate may change at both ends of the take-up plate. In accordance with the present invention, information can be provided to a cooling control unit that varies the amount of cooling fluid directed to each preform using a temperature sensor disposed within a take-off plate or cooling frame.

  The adaptive cooling method described above further provides a valve stem in the hot preform runner nozzle, where the temperature pattern of the molded preform is one day, depending on the function of the particular resin used, or by machine settings. This is extremely advantageous because it can take into account the possibility of fluctuations due to local variations in the thickness of the preform caused by improper operation of the mold, or uneven displacement of the core within the mold cavity. . This situation is unpredictable and cannot be easily repaired. However, the present invention provides a mechanism for adjusting the post-molding cooling step for each cavity based on the temperature of each molded product or preform.

  By simplifying the design and operation of the take-off plate and cooling frame, the cycle time can be significantly reduced to increase the post-molding cooling time. This must take into account critical assembly, maintenance and operational constraints such as stiffness, accuracy of motion, alignment and variation of cooling pins and molded products or preforms on the take-off plate. Further, the position of the cooling frame including the pins must be determined so as to reduce the “installation area” of the entire apparatus.

  In this regard, reference is made to FIGS. 13 (a) and 13 (b). In these figures, the take-up plate 60 is in a vertical position, ie parallel to the mold plates 32, 26, during an additional air cooling step. The cooling frame 98 is moved toward the take-off plate 60 and the cooling pins 74 enter the molded product or preform 48. When all the preforms are cooled, the cooling frame 98 is withdrawn, and the take-up plate 60 is rotated 90 degrees and taken out from the take-up plate 60. This method does not require rotating means and means for preventing interference between the preform discharged from the take-up plate and simplifies the design of the cooling frame.

  Reference is made to FIG. 14 showing another embodiment of the present invention. In this embodiment, the robot take-off plate 60 is constituted by additional moving means 150 for moving the preform 48 along an axis parallel to its rotational axis. This further movement of the preform 48 simplifies the cooling frame 98 that is substantially stationary during the cooling process. As shown in FIG. 14, the take-off plate 60 or other means for holding the preform is moved along the axis X toward the stationary cooling frame 98. After the cooling step, the take-off plate 60 is rotated 90 degrees and the cooled preform is discharged against the conveyor 114.

  Furthermore, reference is made to FIG. 15 showing a novel air cooling means attached to the take-off plate 60. The method shown in this figure eliminates the need for a separate frame to hold the cooling pins, thereby reducing the size of the cooling system and the size of the injection molding apparatus. The new cooling pin 174 is generally U-shaped and can be moved together in parallel to the preform 48 so that the strip 176 that is actuated by the piston BB or any other known means can be used. Can be used to introduce into the preform and move out of the preform. The pin 174 can also rotate about an axis “A” parallel to the preform so that it is in axial alignment with the preform and can be removed therefrom. This simultaneous rotation of all pins 174 can be done by any suitable means known in the art. According to the present invention, the U-shaped cooling pin 174 has an arm “A” that enters the preform, an arm “C” that is used to move the arm “A” in parallel with the arm “A”, and an arm “A”. And an arm “B” connected to the arm “C”. Rotating the pin about axis “A” of arm “C” can be done in various ways. As shown in FIG. 15, this can be done with an elongate rack 178 that is actuated by a piston AA and engages a pinion 180 attached to each cooling pin arm “C”. When one is moving and the other is rotating, the same rotation can be performed using friction means. While moving the preform 48 from the core 38 to the cooling tube 62 of the take-off plate 60, the U-shaped cooling pin 174 "stops" at a dedicated position located adjacent to each cooling tube 62 and moves the preform. So that the space for opening the mold is small. Immediately after the preform 98 is held on the take-off plate 60, the cooling pin 174 attached to the take-off plate 60 is moved forward by the piston BB and the piece 176 so that the arm “A” can reach the top of the preform. When the pin reaches this height, it is rotated in an axially aligned state with the preform, and the piston BB is retracted and finally introduced into the preform. Permanent contact between the strip 176 and each arm “C” is made by a coil spring 182 that operates against the shoulder 181 or any other suitable means. This design of the cooling pin attached to the take-off plate provides the following advantages. Simplify and reduce the size of the cooling system, the cooling rate is improved because the inner cooling starts immediately after the preform enters the take-up plate, the preform is cooled by the take-up plate during the move of the take-up plate In practice, internal cooling can be performed continuously. While discharging the cooled preform, the cooling pin must be rotated again toward its initial position so that it does not align with the preform.

  Still referring to FIG. In the figure, an air cooling means constituted by a cooling path 210 incorporated in the half molds 32, 36 is shown, before and after the mold is opened, before the take-up plate enters the molding area. The preform held by the mold core can be cooled. This additional cooling step further solidifies the preform before the take-up plate enters the mold area and before it is transferred to the take-up plate.

  According to another embodiment of the present invention, which can be easily understood from the other drawings of this specification, the robot and the take-off plate hold only one batch of preform. After the injection step, the take-off plate stops outside the mold area and cooling air or chilled air is blown into each preform from the cooling pins. The cooled preform is discharged from the take-up plate, and the take-up plate is returned to the molding region without having the preform.

  FIG. 23 shows an alternative structure of the frame 98 that holds the cooling pins 74. As shown in this figure, the frame 98 has cooling pins 74 on two opposing surfaces. Further, the frame can rotate around a first axis 300 and a second axis 302 perpendicular to the first axis 300. Any suitable means known in the art (not shown) can be used to rotate the frame 98 about the axes 300,302.

  By providing this type of structure, it is possible to engage the first set of cooling pins 74 with the preform 48 in the take-off plate 60 and initiate internal cooling of the preform. The preform 48 is then transferred from the holder 62 onto the pins 74 within the take-off plate 60. The frame 98 can rotate around one or more of the shafts 300, 302, during which internal cooling of the preform 48 is performed by pins 74. When the first set of preforms reaches the left position shown in FIG. 23, the second set of cooling pins 74 engage with the second set of preforms 48 held in the take-off plate 60. If desired, the left set of preforms 48 can convectively cool the outer surface using a cooling station 304 having a plurality of nozzles (not shown) that blow cool air onto the outer surface. If desired, the frame 98 may include a preform retaining plate 308 attached thereto.

Fig. 6 is a graph showing preform temperature versus time during and after the injection step. It is explanatory drawing which shows schematically the preform in a metal mold | die. It is explanatory drawing which shows the temperature gradient thru | or inclination in the both ends of the wall of the shaping | molding preform during cooling. It is explanatory drawing which shows the temperature inclination thru | or inclination in the both ends of the wall of the shaping | molding preform in cooling. It is explanatory drawing which shows the temperature profile along a preform wall. It is sectional drawing which shows the injection mold by a prior art. FIG. 3 is a cross-sectional view showing a movable robot having an arm / tool end (ECAT) device placed in a molding region between a fixed mold plate and a movable mold plate. FIG. 3 is a side view of an embodiment of the present invention including a robot take-off plate (or arm tool end (EOAT)) and a frame holding cooling pins. FIG. 3 is a side view of an embodiment of the present invention including a robot take-off plate (or arm tool end (EOAT)) and a frame holding cooling pins. It is a front view of the Example of Fig.6 (a) and FIG.6 (b). It is a front view of the Example of Fig.6 (a) and FIG.6 (b). It is explanatory drawing which shows the flame | frame and cooling pin by 1st Example of this invention. It is explanatory drawing which shows the flame | frame and cooling pin by 1st Example of this invention. It is explanatory drawing which shows the flame | frame and cooling pin by 1st Example of this invention. It is explanatory drawing which shows the flame | frame and cooling pin by 1st Example of this invention. FIG. 6 is an illustration showing several designs of cooling pins according to the present invention. FIG. 6 is an illustration showing several designs of cooling pins according to the present invention. FIG. 6 is an illustration showing several designs of cooling pins according to the present invention. FIG. 6 is an illustration showing several designs of cooling pins according to the present invention. FIG. 6 is an illustration showing several designs of cooling pins according to the present invention. FIG. 6 is an illustration showing several designs of cooling pins according to the present invention. FIG. 6 is an illustration showing several designs of cooling pins according to the present invention. It is more detailed explanatory drawing of the cooling pin in two Example of this invention. It is more detailed explanatory drawing of the cooling pin in two Example of this invention. It is explanatory drawing which shows the preform which has a crystallization part produced | generated by the method by a prior art. It is explanatory drawing which shows the preform which does not have a crystallization part by the method of this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. It is explanatory drawing which shows another Example of the flame | frame and cooling pin by this invention. FIG. 2 is a cross-sectional view of a system in which an air cooling path is incorporated in a half mold. FIG. 6 is a side view of another embodiment of the cooling system of the present invention. FIG. 6 is a side view of another embodiment of the cooling system of the present invention. It is a top view of the injection molding system which has another Example of the cooling system of this invention. It is sectional drawing of another Example of the cooling system of this invention which shows the mechanism which cools the inside of the molded product attached to a take-off board. It is explanatory drawing which shows the Example of this invention which takes out a shaping | molding preform from a shaping | molding area | region using the take-out board which does not have a cooling means. It is explanatory drawing which shows the structure of the alternative cooling pin by this invention. It is explanatory drawing which shows the structure of another alternative cooling pin by this invention. It is explanatory drawing which shows the structure of another alternative cooling pin by this invention. It is explanatory drawing which shows the method by the prior art which cools the inside of a preform. It is explanatory drawing which shows the method by the prior art which cools the inside of a preform. It is explanatory drawing which shows another system by the prior art which cools the inside of a preform, and the exterior. It is explanatory drawing which shows the system by the prior art which sucks ambient air and cools a preform. FIG. 6 is an illustration showing an alternative frame structure having cooling pins on multiple surfaces of the frame.

Claims (5)

Cooling pins (74, 174) for cooling the inner surface of the molded product;
A body portion (224) having an outer surface and in use, including an internal channel (90) having a first end connectable to a source of gaseous cooling fluid; The internal channel (90) has a second end that terminates at an outlet nozzle (92) through which gaseous cooling fluid is delivered in use, and is along the cooling pin and At the position away from the outlet nozzle (92), the outer shape of the outer surface is changed. Therefore, in use, the outer shape from the inner surface of the molded product into which the cooling pin (74, 174) is inserted. In the cooling pin where the distance between the outer surfaces changes during use,
The cooling pins (74, 174) are
The change in distance is realized by a plurality of ribs (86) or contact elements (88) projecting outward from the outer surface, the ribs (86) or contact elements (88) being radially around the outer surface. A cooling pin, characterized in that A system for cooling a molded product,
It comprises a carrier (60) for removing at least one molded product from the mold (16) and transporting said at least one molded product to a cooling position, said molded product having an inner surface (226,228). Have
A frame (98) having at least one cooling pin (74, 174) attached thereto, said cooling pin being connected to an outer surface and a source of gaseous cooling fluid in use. A body portion (224) with an internal channel (90) having one end, said internal channel (90) being an outlet nozzle through which gaseous cooling fluid is pumped in use A second end that terminates at (92), the frame moving relative to the carrier to the carrier, whereby the at least one cooling pin (74, 174) of the at least one molded product; In the system inserted inside,
The at least one cooling pin (74, 174) has a plurality of ribs (86) or contact elements (88) protruding outward from the outer surface, and the spaced apart ribs (86) or contact elements (88) Extends radially around the outer surface, and outwardly projecting ribs (86) or contact elements (88), in use, provide a measure of the distance distance to the inner surface of the molded product. system characterized in being arranged to limit, the. A method of cooling a molded product (48) having a relatively high temperature first region (22) and a relatively low temperature adjacent region, the molded product having an inner surface;
Removing the molded product (48) from the mold composed of each half mold (16, 18, 32, 36), while the molded product (48) retains a certain amount of heat. The molded product is moved into the holder (62) at the end (60) of the arm tool, the end of the arm tool being between the half molds (16, 18, 32, 36) and the holder (62) operates between a first position for receiving the molded product (48) and a second position outside the mold (16, 18, 32, 36);
Withdrawing the end of the arm tool from between each half mold (16, 18, 32, 36) to the second position;
Immediately after the arm tool (60) is retracted to the second position, the tip of the cooling pin (74, 174) is moved into the molded product (48) while holding the molded product in the holder. The cooling pin has a body portion (224) with an outer surface, and a plurality of ribs (86) or contact elements (88) along the body portion are located on the outer surface. The ribs (86) or contact elements (88) extend radially around the outer surface, so that when the cooling pin is inserted into the molded product, the reduced Ji is in accordance with the physical dimensions of the distance interval of the cooling pin relative to the inner surface of the molded product is said ribs (86) or contact elements (88),
Forming a release system for the cooling pin and the molded product, the release system having a passage that allows drainage of cooling fluid from the molded product (48) to an ambient environment. And the release system opens the cooling pin to the opening of the molded product (48) so as to define a space between the outer surface area of the cooling pin and the open end of the molded product (48) adjacent to the outer surface area. Formed by positioning with respect to the end, the passage is defined by the space,
Feeding a cooling fluid along the internal channel (90) of the cooling pin, the internal channel being inserted into the molded product (48) and the first region (22). Ends with a tip (92) spaced from the tip, and at least in order to enhance cooling in the first region (22), the cooling fluid is mainly directed from the tip (92) in the direction of the first region. Released, thereby allowing the cooling fluid to flow from within the molded product (48) and to be discharged into the ambient environment via the passageway and when placed in the molded product, An internal channel and the tip cooperate to concentrate the cooling fluid on the first region, and a plurality of ribs (86) or contact elements (88) project outward from the outer surface. ,this In more use, the cooling fluid is maintained in close proximity to the inner surface of the molded product as the cooling fluid flows along the body portion of the cooling pin. Method.   The method for cooling a molded product according to claim 3, wherein the tip portion is formed so as to generate a diffused flow of cooling fluid from the tip portion.   5. The molded product according to claim 3, wherein the tip of the cooling pin is introduced into the preform to a depth that allows the refrigerant to reach the inner dome of the preform and cool it. Cooling method.

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