JP7011819B2 - Blow molding method and molded product manufacturing equipment - Google Patents

Description

The present invention relates to a blow molding method and a molded product manufacturing apparatus. More specifically, the present invention relates to a blow molding method and a molded product manufacturing apparatus for producing a molded product including a hollow skin portion having a cavity inside and a non-hollow solid portion by blow molding.

Conventionally, it is conceivable to manufacture a molded product including a hollow skin portion having a cavity inside and a non-hollow solid portion by using a blow molding technique. A method for forming such a molded product is disclosed in, for example, Patent Document 1. In Patent Document 1, conventionally, when a molded product having a hollow skin portion (thin wall portion) and a solid portion (bonded portion) as described above is manufactured by blow molding, a recess or a recess is formed on the surface of the solid portion. It is disclosed that there was a problem that a sink mark consisting of waviness appeared and the appearance of the molded product was spoiled.

In Patent Document 1, the reason for the occurrence of sink marks as described above is that the thickness of the solid portion is, for example, approximately twice the thickness of the hollow skin portion, and is often larger than the thickness of the hollow skin portion. The amount of heat accumulated in the solid part during blow molding becomes much larger than the amount of heat in the hollow skin part, and the degree of shrinkage caused by the subsequent cooling becomes remarkable in the solid part, and the surface of the solid part has recesses and waviness. It is supposed to occur.

Then, in Patent Document 1, as a means for solving problems such as the occurrence of sink marks, a bonded portion (corresponding to a "solid portion") in which the inner surface of a predetermined portion of the parison is in close contact is used as a product portion. When blow molding a hollow plastic molded product, there is a molding method in which air is blown into the parison to inflate and shape the parison, and then the inner surface of the predetermined part of the parison to be the bonding portion is brought into close contact with each other for bonding. , Is presented.

According to the molding method of Patent Document 1, when air is blown into the parison and shaped, the bonded portion becomes hollow, and therefore the parison of the bonded portion is cooled from the inside by blowing air into the hollow portion. Will be done. As a result, the parison is cooled by the blown air at the time of shaping the coupling portion, and the amount of heat possessed by the parison is smaller than that at the time of shaping by air blowing. Patent Document 1 states that such a molding method reduces the amount of shrinkage due to a change in the amount of heat between the time of forming the bonded portion and the subsequent molded product, and makes it difficult for sink marks to occur on the surface of the bonded portion.

Japanese Unexamined Patent Publication No. 11-34158

However, when the molding method described in Patent Document 1 is adopted, it is considered that it takes time to slowly cool the bonded portion so that the change in the amount of heat does not become abrupt. Further, since the portion to be the joining portion is once shaped into a hollow shape and then joined in the subsequent process, it is considered that the number of man-hours increases and it takes time and effort. The molding method described in Patent Document 1 has room for improvement in these respects.

The present invention has been made in view of the above circumstances, and its potential purpose is to improve the transferability of the solid part without spending a lot of time and effort, and by extension, sink marks and the like. It is an object of the present invention to provide a blow molding method and a molded product manufacturing apparatus capable of preventing the occurrence.

The problem to be solved by the present invention is as described above, and next, the means for solving this problem will be described.

From the first aspect of the present application, there is provided a blow molding method for producing a molded product including a hollow skin portion having a cavity inside and a non-hollow solid portion by blow molding. This blow molding method includes the following steps a) to g). In a), the parison is inserted between the first mold and the second mold, which are a pair of molds. In b), the first mold and the second mold are molded. In c), gas is blown into the parison to cause the parison to bulge toward the molding surface side of the first mold and the second mold. In d), in the portion corresponding to the solid portion, the inner surface of the parison on the first mold side and the inner surface of the parison on the second mold side are in contact with each other and there is no gap. Of the molding surface, the working surface which is a part of the molding surface on the first mold side corresponding to the solid part is one of the molding surfaces on the second mold side corresponding to the solid part. Bring it closer to the facing surface, which is a part. In e), the parison is brought into close contact with the molding surface. In f), the blowing of gas into the parison is stopped. In g), the first mold and the second mold are opened, and the molded product is taken out.

In the second aspect of the present application, in the blow molding method according to the first aspect, in the d), the slide member that slides in the thickness direction of the solid portion is brought closer to the facing surface side.

In the third aspect of the present application, in the blow molding method according to the second aspect, in the d), the slide member is slid and moved to approach the facing surface side by driving the hydraulic cylinder.

In the fourth aspect of the present application, in the blow molding method according to any one of the first aspect to the third aspect, a so-called H & C molding technique including a step of heating and cooling the molded surface is used.

From the fifth aspect of the present application, in the blow molding method according to the fourth aspect, the molded surface is heated in the e) and the molded surface is cooled in the f).

From the sixth aspect of the present application, in the blow molding method according to any one of the first aspect to the fifth aspect, the molded article has a designed surface and a non-designed surface. Further, the first mold corresponds to the non-designed surface of the molded product.

From the seventh aspect of the present application, in the blow molding method according to any one of the first aspect to the sixth aspect, before the a), a-0) the solid of the molded surface. The working surface on the first mold side corresponding to the portion is kept away from the facing surface on the second mold side corresponding to the solid portion.

From the eighth aspect of the present application, in the blow molding method according to any one of the first aspect to the seventh aspect, the d) is at the same time as the start of the e) or immediately before the e). Will be done.

In the ninth aspect of the present application, there is a molded product manufacturing apparatus for manufacturing a molded product including a hollow skin portion having a cavity inside and a non-hollow solid portion by blow molding accompanied by heating and cooling. Provided. This molded product manufacturing apparatus includes a first mold and a second mold, a gas supply device, a working surface, and a control device. The first mold and the second mold are a pair of molds for sandwiching the parison. The gas supply device blows gas into the parison. The heating / cooling device heats and cools the molding surface of the first mold and the second mold. The working surface is locally provided on the molding surface of the first mold corresponding to the solid portion of the molding surface, and is provided with respect to the facing surface of the second mold corresponding to the solid portion. Approach and separate. The control device controls the blowing of gas by the gas supply device and the proximity and distance of the working surface to the facing surface. In the control device, in the portion corresponding to the solid portion, the inner surface of the parison on the first mold side and the inner surface of the parison on the second mold side are in contact with each other and there is no gap. At the same time as or just before the parison begins to be transferred to the molded surface, the working surface is brought closer to the facing surface.

According to the first to ninth viewpoints of the present application, it is possible to improve the transferability of the solid portion without spending a lot of time and effort, and it is possible to prevent the occurrence of sink marks and the like.

In particular, according to the first aspect of the present application, in the step d), the working surface is brought close to the facing surface to apply pressure in the thickness direction, and the parison of the portion is brought into the working surface in a solid state. And can be pressed against the facing surface (molding surface). As a result, the transferability of the solid portion can be improved, and eventually the occurrence of sink marks and the like can be prevented.

In particular, according to the second aspect of the present application, the parison corresponding to the solid part can be pressed against the molded surface with a simple configuration.

In particular, according to the third aspect of the present application, the parison corresponding to the solid portion is pressed against the molded surface by the strong force of the hydraulic cylinder. Therefore, for example, even when the solid portion is long in the direction perpendicular to the opening direction of the pair of molds, it is possible to effectively prevent the occurrence of sink marks and the like over the entire length of the solid portion.

In particular, according to the fourth aspect of the present application, the transferability of the solid portion can be further improved by using the so-called H & C molding technique.

In particular, according to the fifth aspect of the present application, efficient blow molding is realized by heating the molded surface when transferring the parison to the molded surface and cooling the molded surface when solidifying the parison. can do.

Here, in general, the mold corresponding to the design surface of the molded product is often provided with a large-scale structure for heating and cooling the molded surface in order to finish the design surface neatly. .. In this regard, according to the sixth aspect of the present application, since the slide member and the hydraulic cylinder are arranged on the non-design surface side, a rational layout is realized without impairing the appearance quality of the design surface.

In particular, according to the seventh aspect of the present application, for example, even when the solid part is arranged at the flow end of the parison, the parison starts to solidify in the middle and sufficiently fills the part corresponding to the solid part. It is possible to prevent the situation where it is not done.

In particular, according to the eighth aspect of the present application, the parison in the solid portion can be pressurized at the timing when the surface of the parison in the solid portion is slightly solidified. Therefore, the occurrence of sink marks and the like can be prevented more effectively.

Further, according to the ninth aspect of the present application, the molded product can be molded while pressurizing the parison in the solid portion at the timing when the surface of the parison in the solid portion is slightly solidified. Therefore, it is possible to obtain a molded product having good appearance quality with less sink marks and the like.

It is a figure which showed the outline of the blow molding method which concerns on this embodiment. It is a figure which showed the structure of the molded article manufacturing apparatus used in the blow molding method which concerns on this embodiment. It is a block diagram which conceptually showed the structure of the control system of the molded article manufacturing apparatus which concerns on this embodiment. It is a flowchart which showed each process of the blow molding method which concerns on this embodiment.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

<1. Outline of blow molding method>
First, the outline of the blow molding method according to the present embodiment will be described with reference to FIG. FIG. 1 schematically shows the flow of the blow molding method according to the present embodiment. In the blow molding method according to the present embodiment, the parison supply device 10 and the molded product manufacturing device 90 are mainly used. The blow molding of the present embodiment can be used to produce various molded products having a hollow portion in a part.

The parison supply device 10 is for supplying the parison P, which is a cylindrical (tube-shaped) material, to the molded product manufacturing device 90 in the subsequent stage. The parison feeder 10 includes a hopper 11, an extruder 12, and a die head 18.

The hopper 11 is a conical portion whose diameter decreases downward. The upper end of the hopper 11 is open, and the lower end of the hopper 11 is connected to the upstream end of the extruder 12. A pellet-shaped thermoplastic resin material is supplied to the hopper 11 from the upper end.

The extruder 12 has a cylindrical case 13, a screw shaft 14, and a heater 15. The case 13 extends in the horizontal direction along the axis. The screw shaft 14 is rotatably mounted inside the case 13. The heater 15 is provided in the middle of the case 13 in the longitudinal direction along the circumferential direction. The thermoplastic resin material supplied from the hopper 11 is conveyed toward the downstream end of the extruder 12 by the rotation of the screw shaft 14. During the transportation, the thermoplastic resin material is heated by the heater 15 and melts.

The die head 18 is a cylindrical portion extending in the vertical direction. The die head 18 puts the thermoplastic resin extruded from the extruder 12 into a cylindrical parison P, and makes the first mold 30 and the second mold 40, which are a pair of molds of the molded product manufacturing apparatus 90. Insert (derive) between.

The molded product manufacturing apparatus 90 includes a pair of molds, a first mold 30 and a second mold 40, as a main configuration. The operation of the first mold 30 and the second mold 40 will be briefly described with reference to FIG. 1. First, the parison P derived from the die head 18 is subjected to the first mold 30 and the second mold 40. , It is sandwiched from both sides in the direction perpendicular to the insertion direction of the parison P. That is, the first mold 30 and the second mold 40 are molded.

Subsequently, gas is blown into the parison P through the gas flow passage 31 formed in the first mold 30. More specifically, a blowing needle 32 for blowing gas is inserted into the gas flow passage 31, and the blowing needle 32 is pierced on the surface of the parison P. Gas is blown into the parison P through the passage in the blowing needle 32. As a result, the parison P is bulged according to the shape of the molding surface (shape of the cavity) of the first mold 30 and the second mold 40.

Then, when the parison P is in contact with substantially the entire area of the molded surface and is cooled from the inside by the blown gas and the surface of the parison P begins to solidify a little, the molded surface is heated and cooled, which will be described later. It is heated by the device 60. As a result, the parison P is heated to a temperature suitable for transfer, and the parison P is pressed against the molding surface and is brought into close contact with the molding surface.

After the time required for transfer has elapsed, the molded surface is cooled by the heating / cooling device 60. In addition, the blowing of gas into the parison P is stopped. Specifically, the blowing needle 32 passes through the gas flow passage 31 and is retracted from the surface of the parison P. As a result, the parison P is cooled and solidified.

Then, the first mold 30 and the second mold 40 are opened, and the molded product is taken out.

Finally, unnecessary parts such as burrs in the molded product are cut and finished by a known cutting device.

It is assumed that a molded product including a hollow skin portion having a cavity inside and a non-hollow solid portion is manufactured by using the above-mentioned schematic blow molding method. In such a case, when this molded product is manufactured by a conventional general blow molding method, there is a problem that sink marks formed of recesses and waviness appear on the surface of the solid portion, and the appearance of the molded product is impaired. Conventionally, the reason for the occurrence of such sink marks is that the thickness of the solid portion is often larger than the thickness of the hollow skin portion, so that the amount of heat accumulated in the solid portion during blow molding is compared with the calorific value of the hollow skin portion. It was thought that the degree of shrinkage caused by the subsequent cooling became remarkable in the solid part. That is, conventionally, it has been considered that the occurrence of sink marks in the solid part is due to the change in the amount of heat in the solid part being significantly larger than the change in the amount of heat in the hollow skin portion.

In this regard, the inventors of the present application have found that, as another factor that causes sink marks in the solid part, the pressure due to the blowing of gas is not applied to the solid part, and the pressure to be pressed against the molded surface is insufficient. rice field. That is, the inventors of the present application have stated that the insufficient pressure applied to the molded surface in the solid portion results in poor transferability of the solid portion, which in turn causes sink marks in the solid portion. I considered it. In view of this viewpoint, the blow molding method and the molded product manufacturing apparatus according to the present embodiment include a unique process and configuration for suppressing the occurrence of sink marks in the solid portion.

<2. Configuration of molded product manufacturing equipment>
Hereinafter, the molded product manufacturing apparatus 90 according to the present embodiment will be described more specifically with reference to FIGS. 2 and 3. FIG. 2 shows a cross-sectional view of the first mold 30 and the second mold 40. FIG. 3 conceptually shows the configuration of the control system of the molded product manufacturing apparatus 90. In addition to the above-mentioned pair of molds, the first mold 30 and the second mold 40, the molded product manufacturing apparatus 90 includes a gas supply device 50, a heating / cooling device 60, a slide member 71, and a hydraulic pressure. It mainly has a cylinder 74 and a control device 80.

In the following, a case where a rear spoiler, which is an automobile part, is manufactured as a molded product S will be described as an example. The rear spoiler is attached to the rear part of the vehicle body (automobile) in order to reduce the lift applied to the vehicle body during traveling. The rear spoiler as the molded product S has a design surface s11 exposed to the outside when attached to the vehicle body, and a non-design surface s12 that cannot be seen from the outside. Further, the rear spoiler includes a hollow skin portion s13 having a cavity inside, and a non-hollow solid portion s14 having a material thickness larger than that of the hollow skin portion s13.

However, the products manufactured by using the molded product manufacturing apparatus 90 are not limited to this, for example, instead of the rear spoiler, other parts such as automobiles, agricultural / construction work vehicles, motorcycles, or home appliances. It may be a frame or the like included in a product or the like.

The first mold 30 shown in FIG. 2 corresponds to the non-designed surface s12 of the rear spoiler. The first mold 30 has a molding surface 33 for molding (transferring) the non-designed surface s12 of the rear spoiler. The first mold 30 is formed with a gas flow passage 31 that communicates the molding surface 33 with the outside. As described above, the gas flow passage 31 is used to advance and retreat the blowing needle 32 (see FIG. 1).

The second mold 40 is a mold paired with the first mold 30. The second mold 40 corresponds to the design surface s11 of the rear spoiler. The second mold 40 has a molding surface 41 for molding (transferring) the design surface s11 of the rear spoiler. The combination of the molding surface 33 and the molding surface 41 corresponds to the entire outer surface of the rear spoiler.

The gas supply device 50 is a device for supplying gas into the parison P sandwiched between the first mold 30 and the second mold 40. The gas supply device 50 includes a blowing needle 32, a compressed gas source 51 for supplying gas to the blowing needle 32, and an electromagnetic valve 52 for switching between supplying and stopping the gas. The gas supplied into the parison P by the gas supply device 50 may be, for example, compressed air, but is not limited to this, and may be another gas such as helium.

The heating / cooling device 60 is a device for heating / cooling the molding surface 33 and the molding surface 41. In this embodiment, a so-called H & C blow molding technique is realized by heating and cooling the molding surface 33 and the molding surface 41. As the heating / cooling device 60, various known methods can be adopted, but in the present embodiment, a steam heating method, which is a method of switching between steam and cold water, is adopted. Specifically, a space or a flow path for flowing steam and cold water is formed inside the first mold 30 and the second mold 40. In FIG. 2, the region where this space or flow path is formed is shown by a two-dot chain line. In particular, in the second mold 40, the above space or flow path is formed along the entire surface of the molding surface 41 in order to finish the design surface neatly.

The method of the heating / cooling device 60 may be, for example, a method of switching between pressurized hot water and cold water for heating / cooling, or a method of switching between hot oil and cooling oil, instead of the steam heating method described above. Alternatively, a method of energizing the conductive layer provided along the molding surfaces 33 and 41 to raise the temperature may be used.

The slide member 71 is a member that slides and moves in the thickness direction of the solid portion s14. The working surface 71a, which is one surface of the slide member 71 in the sliding direction (see the double-headed arrow in FIG. 2), is the first mold 30 side of the molded surfaces 33 and 41 corresponding to the solid portion s14. It forms a part of the molding surface 33 of. The working surface 71a can be brought close to and separated from the facing surface 41a which is a part of the molding surface 41 on the second mold 40 side corresponding to the solid portion s14 by sliding the slide member 71. It is possible. The facing surface 41a is arranged so as to face the working surface 71a with the solid portion s14 interposed therebetween.

The hydraulic cylinder 74 is driven to slide and move the above-mentioned slide member 71. The tip of the cylinder rod 74a of the hydraulic cylinder 74 is connected to the other surface of the slide member 71 in the slide direction. The hydraulic cylinder 74 is mounted on the first mold 30. More specifically, the hydraulic cylinder 74 is arranged in the above-mentioned heating / cooling device 60 in a region where a space or a flow path for flowing steam and cold water is not formed.

The control device 80 shown in FIG. 3 is a means for controlling the operation of each part in the molded product manufacturing device 90. The control device 80 of this embodiment is composed of a computer having a processor 81 such as a CPU, a memory 82 such as a RAM, and a storage unit 83 such as a hard disk drive. The control device 80 is electrically connected to a mold opening / closing device 49 for opening / closing a pair of molds 30 and 40, a gas supply device 50 described above, a heating / cooling device 60, and a hydraulic cylinder 74, respectively. There is. The control device 80 temporarily reads the computer program CP stored in the storage unit 83 into the memory 82, and the processor 81 performs arithmetic processing based on the computer program CP to control the operation of each of the above units. As a result, by the cooperation of the above hardware and software, opening and closing of the molds 30 and 40 in the molded product manufacturing apparatus 90, blowing of gas, heating / cooling processing, advancing / retreating processing of the slide member 71, etc. are integrated. It progresses while being controlled in a positive manner.

<3. Details of blow molding method>
Subsequently, the blow molding method of the present embodiment will be described in more detail. In particular, the steps specific to this embodiment will be described in detail.

First, the distance T in the thickness direction after molding between the working surface 71a of the slide member 71 and the facing surface 41a is 6.5 mm, which is larger than the specified thickness (5.5 mm in this embodiment). The slide member 71 is retracted so as to be (step S1). That is, in the present embodiment, the separation distance (thickness) T formed between the working surface 71a and the facing surface 41a is 105% or more and less than 130%, more preferably 115% or more and 120 with respect to the specified thickness. It is tried to be less than%. The "specified thickness" here refers to the thickness (product thickness) of the solid portion s14 when the molded product is finished to become a finished product (rear spoiler in this embodiment).

Then, the parison P made of the thermoplastic resin material is inserted between the first mold 30 and the second mold 40 in the mold open state (step S2).

Subsequently, the mold opening / closing device 49 is driven by the control device 80 before the parison P is solidified, so that the first mold 30 and the second mold 40 are molded (step S3).

Subsequently, gas is blown into the parison P to cause the parison P to bulge toward the molding surfaces 33 and 41 of the first mold 30 and the second mold 40 (step S4). In other words, the parison P is roughly shaped with respect to the molded surfaces 33 and 41. Specifically, by piercing the surface of the parison P with the blowing needle 32 and opening the above-mentioned solenoid valve 52, gas is supplied from the tip of the blowing needle 32 to the inside of the parison P. As a result, the high-pressure gas from the compressed gas source 51 is blown into the parison P.

Subsequently, by blowing gas into the inside of the parison P in step S4, the parison P is gradually cooled from the inside, and at the timing when the surface of the parison P is slightly solidified, the working surface 71a of the slide member 71 is pressed. It approaches the facing surface 41a (step S5). Specifically, the drive state of the hydraulic cylinder 74 is controlled by the control device 80 so that the thickness of the solid portion s14 after solidifying the parison P becomes a specified thickness (5.5 mm in this embodiment). .. That is, in the present embodiment, the hydraulic cylinder 74 is driven so that the distance in the thickness direction between the working surface 71a and the facing surface 41a is the same as the specified thickness. As a result, the thickness of the solid portion s14 is reduced by the difference between the thickness T (6.5 mm in the present embodiment) set in step S1 and the specified thickness (5.5 mm in the present embodiment). It is compressed.

Further, at the same time as step S5 or immediately after step S5, the molding surfaces 33 and 41 are heated by the heating / cooling device 60, and the temperature of the surface of the parison P is raised to a temperature suitable for transfer. (Step S6). More specifically, when steam is supplied to the space or flow path of the heating / cooling device 60, the temperature of the parison P in contact with the molding surfaces 33 and 41 is the temperature at which the parison P is completely solidified and the parison. The temperature is adjusted to be near the middle of the temperature at which P is completely melted. Even in this step S5, the blowing of air into the inside of the parison P is continued. As a result, the parison P is brought into close contact with the molding surfaces 33 and 41. Strictly speaking, the portion of the parison P corresponding to the hollow skin portion s13 is shaped to the molding surfaces 33 and 41 with the cavity. On the other hand, the portion of the parison P corresponding to the solid portion s14 is brought into close contact with the molded surfaces 33 and 41 in a state where no cavity (hollow portion) is formed. At this time, since the working surface 71a of the slide member 71 is close to the facing surface 41a, both sides of the solid portion s14 of the parison P in the thickness direction are pressed against the molding surfaces 33 and 41 with a strong force. As a result, the transferability of the solid portion s14, which was conventionally insufficient in transferability, is improved.

In step S6, after the time required for transfer has elapsed, the molded surfaces 33 and 41 are subsequently cooled by the heating / cooling device 60, and the temperature of the parison P is set to a temperature suitable for solidification. At the same time, by retracting the blowing needle 32 from the parison P and stopping the supply of the compressed gas to the tip portion, the blowing of the gas into the parison P is stopped (step S7).

After the parison P is sufficiently cooled and solidified, the mold opening / closing device 49 is driven by the control device 80 to open the first mold 30 and the second mold 40, and the molded product is taken out (the molded product is taken out). Step S8). After that, although not shown in the flow of FIG. 4, burrs and the like are cut off from the molded product and finished (see FIG. 1).

As shown above, the blow molding method according to the present embodiment includes the step of step S5. Therefore, by bringing the working surface 71a close to the facing surface 41a, pressure in the thickness direction can be applied to strongly press the parison P of the portion against the working surface 71a and the facing surface 41a. As a result, the transferability of the solid part s14 can be improved without spending a lot of time and effort, and as a result, sink marks on the solid part s14 due to insufficient pressing force against the molded surfaces 33 and 41, etc. Can be prevented.

Further, in the blow molding method according to the present embodiment, the pressing force in the solid portion s14 is improved by sliding the slide member 71 toward the facing surface 41a in step S5. As a result, the surface of the parison P corresponding to the solid portion s14 can be pressed against the molding surfaces 33 and 41 with a simple configuration.

Further, in the blow molding method according to the present embodiment, a so-called H & C molding technique including a step of heating and cooling the molding surfaces 33 and 41 is used. Specifically, when the molded surfaces 33 and 41 are transferred to the parison P, the molded surfaces 33 and 41 are heated to a temperature suitable for transfer (step S6), and when the parison P is solidified, the molded surfaces 33, 41 is cooled (step S7). This makes it possible to realize efficient blow molding.

Further, in the blow molding method according to the present embodiment, in step S5, the hydraulic cylinder 74 is driven to slide the slide member 71 so that the working surface 71a approaches the facing surface 41a side. As a result, the parison P corresponding to the solid portion s14 is pressed against the molding surfaces 33 and 41 by the strong force of the hydraulic cylinder 74. Therefore, for example, even when the solid portion s14 is long in the direction perpendicular to the opening direction of the pair of molds 30 and 40, it is effective to generate sink marks over the entire length of the solid portion s14 in the longitudinal direction. Can be prevented.

Further, in the blow molding method according to the present embodiment, the molded product S has a design surface s11 and a non-design surface s12. The first mold 30 corresponds to the non-designed surface s12 of the molded product S. Here, in general, when the mold corresponding to the design surface of the molded product is provided with a large-scale structure for uniformly heating and cooling the molded surface in order to finish the design surface neatly. There are many. Also in this embodiment, as shown in FIG. 2, the heating / cooling device 60 corresponding to the entire area of the molding surface 41 is arranged in the second mold 40 corresponding to the design surface s11. In this respect, according to this configuration, since the slide member 71 and the hydraulic cylinder 74 are arranged on the non-design surface s12 side where there is a lot of empty space, a rational layout is realized without impairing the appearance quality of the design surface s11. .. Furthermore, in the blow molding method according to the present embodiment, there is no step on the design surface s11 side due to the slide member 71.

Further, in the blow molding method according to the present embodiment, the step of step S1 is executed before the pair of molds 30 and 40 are molded. In step S1, of the molded surfaces 33 and 41, the working surface 71a on the first mold 30 side corresponding to the solid portion s14 is the facing surface 41a on the second mold 40 side corresponding to the solid portion s14. Keep away from.

Thereby, for example, even when the solid portion s14 is arranged at the flow end of the parison P (typically toward the corner of the molded product S), the area of the flow path through which the parison P flows can be increased. It can be secured to a large extent. Therefore, the parison P begins to solidify in the middle, or the flow path of the parison P is too small and the supply is interrupted in the middle, so that the portion corresponding to the solid portion s14 is not sufficiently filled with the parison P. Can be prevented in advance.

Further, in the blow molding method according to the present embodiment, step S5 is performed at the same time as step S6 or immediately before step S6. As a result, the parison P in the solid portion s14 can be pressurized at the timing when the surface of the parison P is slightly solidified. Therefore, the parison P in the portion corresponding to the solid portion s14 can be pressurized at a suitable timing for promoting the transfer, and the transferability of the solid portion s14 can be significantly improved. As a result, the occurrence of sink marks and the like in the solid portion s14 is suppressed.

Further, in the blow molding method according to the present embodiment, the amount (distance) of moving the working surface 71a away from the facing surface 41a in step S1 and the amount (distance) of bringing the working surface 71a closer to the facing surface 41a in step S5. It can be changed by software. Therefore, the magnitude of the force for pressing the solid portion s14 against the molding surfaces 33 and 41 can be fluidly changed according to the fluctuation of the molding conditions and the like.

Further, the molded product manufacturing apparatus 90 disclosed in the present embodiment includes a first mold 30, a second mold 40, a gas supply device 50, a heating / cooling device 60, a working surface 71a, and a control device 80. To prepare for. The first mold 30 and the second mold 40 are a pair of molds for sandwiching the parison P. The gas supply device 50 blows gas into the parison P. The heating / cooling device 60 heats and cools the molding surfaces 33 and 41 of the first mold 30 and the second mold 40. The working surface 71a is locally provided on the molding surface 33 of the first mold 30 corresponding to the solid portion s14 among the molding surfaces 33 and 41. The working surface 71a approaches and separates from the facing surface 41a of the second mold 40 corresponding to the solid portion s14. The control device 80 controls the blowing of gas by the gas supply device 50, the heating and cooling by the heating / cooling device 60, and the proximity and separation of the working surface 71a with respect to the facing surface 41a. The control device 80 brings the working surface 71a closer to the facing surface 41a at the same time as or immediately before the molding surfaces 33 and 41 are started to be heated by the heating / cooling device 60.

Thereby, at the timing when the surface of the parison P is slightly solidified, the H & C treatment can be performed while pressurizing the parison P in the portion corresponding to the solid portion s14. Therefore, it is possible to obtain a molded product having good appearance quality with less sink marks and the like.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made to the above-mentioned one without departing from the spirit of the present invention. It is possible.

In the blow molding method of the above embodiment, in addition to pressurizing both sides of the solid portion s14 in the thickness direction at the time of transfer, a so-called H & C molding technique is used. In the above embodiment, there is an advantage that the transferability of the solid portion can be significantly improved by combining with the H & C molding technique. However, it is not essential to use the H & C molding technique, and the above heating / cooling step may be omitted.

Further, even when the H & C molding technique is used as described above, the timing at which the heating / cooling of the molded surfaces 33 and 41 is started is not limited to that described above. For example, heating of the molded surfaces 33 and 41 may be started from the time when the pair of molds 30 and 40 are molded.

In the above embodiment, the slide member 71 is moved forward and backward by driving the hydraulic cylinder 74, but the drive source is not limited to this. For example, instead of this, the slide member 71 may be moved back and forth by driving an electric motor or an air cylinder.

30 1st mold 33 Molding surface 40 2nd mold 41 Molding surface 41a Facing surface 50 Gas supply device 60 Heating / cooling device 71 Slide member 71a Working surface 74 Hydraulic cylinder 80 Control device 90 Molded product manufacturing equipment S Molded product (rear) Spoiler)
s11 Design surface s12 Non-design surface s13 Hollow skin part s14 Solid part

Claims (9)

A blow molding method for producing a molded product including a hollow skin portion having a cavity inside and a non-hollow solid portion by blow molding.
a) Insert the parison between the first and second molds, which are a pair of molds.
b) The first mold and the second mold are molded and molded.
c) A gas is blown into the parison to cause the parison to swell toward the molding surface side of the first mold and the second mold.
d) In the portion corresponding to the solid portion, the inner surface of the parison on the first mold side and the inner surface of the parison on the second mold side are in contact with each other and there is no gap. Of the molding surfaces, the working surface that is a part of the molding surface on the first mold side corresponding to the solid part is a part of the molding surface on the second mold side corresponding to the solid part. Close to a certain facing surface,
e ) The parison is brought into close contact with the molding surface.
f) Stop the gas blowing into the parison and stop it.
g) A blow molding method in which the first mold and the second mold are opened and the molded product is taken out. The blow molding method according to claim 1, wherein the blow molding method is used.
In d), a blow molding method in which a slide member that slides and moves in the thickness direction of the solid portion is brought closer to the facing surface side. The blow molding method according to claim 2, wherein the blow molding method is used.
In d), a blow molding method in which the slide member is slid and moved to approach the facing surface side by driving a hydraulic cylinder. The blow molding method according to any one of claims 1 to 3.
A blow molding method using a so-called H & C molding technique including a step of heating and cooling the molding surface. The blow molding method according to claim 4, wherein the blow molding method is used.
In the e), the molded surface is heated and the molding surface is heated.
In f), a blow molding method for cooling the molding surface. The blow molding method according to any one of claims 1 to 5.
The molded product has a design surface and a non-design surface, and has a design surface and a non-design surface.
The first mold is a blow molding method corresponding to the non-designed surface of the molded product. The blow molding method according to any one of claims 1 to 6.
Before a) above
a-0) A blow that keeps the working surface of the first mold side corresponding to the solid portion of the molding surface away from the facing surface of the second mold side corresponding to the solid portion. Molding method. The blow molding method according to any one of claims 1 to 7.
The d) is a blow molding method performed at the same time as the start of the e) or immediately before the e). A molded product manufacturing apparatus for manufacturing a molded product including a hollow skin portion having a cavity inside and a non-hollow solid portion by blow molding accompanied by heating and cooling.
A pair of molds for sandwiching the parison, the first mold and the second mold,
A gas supply device for blowing gas into the parison, and
Of the molding surfaces, it is locally provided on the molding surface of the first mold corresponding to the solid portion, and approaches and separates from the facing surface of the second mold corresponding to the solid portion. In terms of action,
A control device that controls the blowing of gas by the gas supply device and the proximity and separation of the working surface from the facing surface.
Equipped with
In the control device, in the portion corresponding to the solid portion, the inner surface of the parison on the first mold side and the inner surface of the parison on the second mold side are in contact with each other and there is no gap. A molded article manufacturing apparatus that brings the working surface closer to the facing surface at the same time as or immediately before the molded surface starts to be transferred to the parison.

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