JP2010064267A - Molding method and molding apparatus for molding hollow molded article - Google Patents

Abstract

[PROBLEMS] To form a hollow molded article having an accessory such as a rib and a partition wall, which is freed from the problem of the insert of the semi-hollow molded article, the problem of the dimensional accuracy of the hollow molded article, the problem of the strength of the joint, and the like. Provide a method.
A fixed mold (2) and a movable mold (20) are used to form a pair of semi-hollow molded products (T1, T2) for injection molding at the opening of the main body (H, H). The joints (S, S) are injection-molded (primary molding) so as to have fusion-bonded joints (M, M) at the abutting parts of the appendages (W). A pair of semi-hollow molded products are aligned in a state where they remain in the respective molds, and a heating body (31) is inserted between the joint portions of the appendages (W, W) to be melted. The heated body (31) is retracted, the mold is clamped to join the joints of the appendages (W, W), and the molten resin is injected and joined to the joints of the main body (H, H) ( Secondary molding).
[Selection] Figure 1

Description

  The present invention joins the openings of the body portions of a pair of semi-hollow molded products, and joins the mating portions of a pair of accessories such as ribs, protrusions, and partition walls that are integrally molded with the body portions. The present invention also relates to a molding method and a molding apparatus for molding a hollow molded article having the accessory therein.

  A molding method using an injection molding machine is known as one of molding methods for a hollow molded product made of synthetic resin. The mold used for carrying out this injection molding method is composed of a fixed mold and a slide mold or a movable mold, as proposed by the present applicant, for example, in Patent Documents 1-3. . One primary semi-hollow body is formed in the fixed mold, and the other primary semi-hollow body is formed in the slide mold. Therefore, in the primary molding, after the slide mold is driven to the primary molding position, the pair of primary semi-hollow bodies are molded so as to have a butt portion or a joint portion around the opening, and solidified to some extent. When the slide mold is slid to the secondary molding position, the pair of primary semi-hollow bodies are abutted at the abutting portion. Therefore, when the mold is clamped and the molten resin for secondary molding is injected into the joint portion, the pair of primary semi-hollow bodies are joined at the abutting portion, and a synthetic resin hollow molded product is molded.

Japanese Examined Patent Publication No. 2-38377 Japanese Patent Laid-Open No. 6-23789 JP-A-6-246781

  According to the injection molding method as described above, a pair of primary semi-hollow molded products molded by the primary molding are butted, and the molten resin is injected and filled into the butt portion or the joint by the secondary molding. Since a product can be obtained, each process can be automated, and there is an advantage that a hollow molded product can be mass-produced. In addition, since the pair of primary semi-hollow bodies are formed by injection molding, it has a feature that a hollow molded article having a complicated shape can be manufactured, and is currently being effectively implemented. However, a hollow molded article having accessories such as ribs, protrusions, and partition walls inside cannot be molded by the injection molding method as described above. This is because molten resin for secondary molding can be filled relatively easily into the joints of the openings of a pair of semi-hollow molded products, but up to abutting parts such as ribs, protrusions, partition walls, etc. This is because it cannot be filled for geometrical or structural reasons.

  Therefore, a hollow molded product having ribs, partition walls, and the like which are obstructive in the secondary molding is molded by the following procedure. That is, when a pair of semi-hollow molded products are formed by injection molding, a fusion bonding portion is formed in the opening of the main body portion, and a fusion bonding portion is also integrally formed in the rib, partition wall, etc. And store. Then, a pair of semi-hollow molded products are inserted into respective fusion molds separately prepared. Hold the joint part of the inserted semi-hollow molded product opening and the joint part such as ribs at a predetermined interval, insert a heating element between these joint parts, and melt the joint part. To do. And a heating body is evacuated, a pair of metal mold | die for fusion is clamped, and a junction part is pressure-welded. As a result, the main body portions of the pair of semi-hollow molded products are integrated with each other, the pair of ribs, partition walls, and the like are also integrated, and a hollow molded product having accessories such as ribs, partition walls, etc. inside is obtained. It is done.

  As described above, when a pair of fusion molds and a heating body are used, a hollow molded product having an accessory therein can be molded, but there are various problems. For example, since a semi-hollow molded product is injection molded and stored in advance, it changes over time due to temperature and the like. Therefore, it is difficult to insert directly into the fusion mold. Therefore, it is necessary to mold a semi-hollow molded product in anticipation of a shape change, that is, a shrinkage change, and it costs a lot to design a molding die. Alternatively, in order to insert a semi-hollow molded product having a shape change, it is necessary to adjust the size of the fusion mold. When the dimensions of the injection mold or the fusion mold are adjusted in this way, the shape accuracy of the hollow molded product is lowered. Moreover, even if it can insert by adjusting a metal mold dimension, there is no guarantee that it will be inserted so that the surface of a junction part may become a uniform plane. If the flatness or parallelism of the joint surfaces is not maintained, the pressing pressure is unbalanced when the joints are pressed together, resulting in a fatal defect for hollow molded products, such as “fusing strength variation”. Furthermore, since the semi-hollow molded product that has been cooled to room temperature must be heated to the fusion temperature, although only in the vicinity of the joint, there is also a problem of increased energy consumption.

  The present invention has been made in view of the conventional problems as described above, and provides a molding method and molding apparatus for a synthetic resin hollow molded product that can form a highly accurate hollow molded product at low cost. It is intended to provide. In more detail, the hollow resin molded plastic product that has been freed from various problems such as the problem of the insert of the semi-hollow molded product, the problem of the dimensional accuracy of the hollow molded product, the problem of the strength of the joint, the problem of the energy cost, etc. It aims at providing the shaping | molding method and the shaping | molding apparatus used for implementation of this method.

  According to the molding method or molding apparatus described in Patent Documents 1 to 3, various effects as described above are obtained, and the above-described disadvantages of the conventional molding method using a heating body are particularly in the molding method. Absent. Then, this invention tries to achieve the said objective by combining the shaping | molding method or shaping | molding apparatus using a fixed mold | type and a movable mold | type as described in patent documents 1-3, and the shaping | molding method using a heating body. To do. That is, in order to achieve the above-mentioned object, the invention according to claim 1 joins the openings of the body portions of a pair of semi-hollow molded products, and ribs and protrusions that are integrally molded with the body portions. A molding method for joining a pair of appendages such as an object and a partition wall to form a hollow molded product having the accessory therein, the molding method comprising a fixed mold and a movable mold The cavity is injected and filled with molten resin, a pair of semi-hollow molded products, a joint for injection molding at the opening of the main body, and a joint for fusion at the butt of the accessory Primary molding step of injection molding in this way, and the other semi-hollow molded product remaining in the other mold in a state where one half-hollow molded product molded in the primary molding step remains in the mold Insert a heating element between the joints of the appendages, facing each other at a predetermined interval. A heating and melting step of melting the joint, and retracting the heating body after the heating and melting step, and clamping the movable mold to the fixed mold and fusing the joint of the accessory, And a secondary molding step of injecting molten resin to the joint portion of the main body portion and joining the joint portion. According to a second aspect of the present invention, in the molding method according to the first aspect, in the primary molding step, the joint portion for fusion bonding of the attachment is located more than the joint portion for injection molding of the main body portion. The invention according to claim 3 is configured to use a heating element made of a halogen lamp or a carbon heater in the heating and melting step in the molding method according to claim 1 or 2 so as to increase only by a fixed amount. Is done.

  The invention according to claim 4 is a molding apparatus for a hollow molded product comprising a combination of a mold device composed of a fixed mold and a movable mold and a heating element, wherein the movable mold is a mold relative to the fixed mold. It is configured to be opened and closed and slidably driven. A pair of semi-hollow molded products are provided between the parting lines of these molds, and an injection molding joint is provided at the opening of the main body. Is formed in the abutting portion of an accessory such as a rib, a projection, and a partition wall so as to have a fusion bonded portion, and a molten resin for primary molding is formed in the cavity, The joining portion of the opening of the main body is configured to be injected and filled with a molten resin for secondary molding, and the heating body has a predetermined position with respect to the fixed die. When inserted between the solid mold and movable mold, the attachment Of heating the bonding portion of the fusing of the butting portion, and configured to retract from between the fixed mold and the movable mold.

  As described above, according to the present invention, one semi-hollow molded product molded by the primary molding process remains in the mold while the other semi-hollow molded product remaining in the other mold has a predetermined shape. A heating and melting step in which a heating body is inserted between the joint portions of the attachment so as to face each other at an interval to melt the joint portion, and the heating body is retracted after the heating and melting step, and the movable mold is Since it is composed of a secondary molding step in which the mold is clamped to the fixed mold and the joint portion of the accessory is fused, and the molten resin is injected and joined to the joint portion of the main body portion, that is, Since a hollow molded product having an accessory therein is also subjected to secondary molding in the same primary mold, no dedicated welding mold is required. Therefore, according to the present invention, there is no problem of the insert of the semi-hollow molded product, the problem of the dimensional accuracy of the hollow molded product, and further the problem of the strength of the joint portion, and the hollow molding having the accessory inside with high quality. The effect peculiar to the present invention that the product can be molded at low cost is obtained. Moreover, since the main body part is joined by secondary injection molding, a hollow molded product excellent in appearance shape as well as joint strength can be obtained. According to another invention, the joint part for attachment of the accessory is molded so as to be higher by a predetermined amount than the joint part for injection molding of the main body part. If the movable mold is clamped with respect to the fixed mold later, the effect of reliably fusing can be obtained. According to the invention using a heating element composed of a halogen lamp or a carbon heater, these heaters are excellent in thermal response, so that the molding cycle can be shortened and inserted between the fixed mold and the movable mold. The energization can also be started from. That is, it is turned off while being saved, and even if energization is started at the same time as insertion, it can be melted instantaneously, and energy-saving molding can be performed without increasing the molding cycle.

  Hereinafter, in order to simplify the description of the embodiment of the present invention, a molding example of a hollow molded product having a partition wall as an accessory inside from a pair of semi-hollow molded products having the same shape and the same size. explain. As shown in FIG. 1A, the molding apparatus 1 according to the present embodiment is opened and closed with respect to the fixed mold 2 and the fixed mold 2 and is slidably driven in the vertical direction. The movable mold 20 and the heating device 30 shown in FIG. In the upper position of the fixed mold 2 on the parting line P side, a fixed-side concave portion 3 having a predetermined size for forming one semi-hollow molded product is formed. A fixed core 5 for forming the other semi-hollow molded product is formed on the parting line P side below the fixed recess 3.

  The fixed core 5 includes two relatively large first and second cores 6 and 7 protruding toward the movable mold 20 and a small small core 8. In the primary molding position, the first and second cores 6 and 7 are positioned at the center of a movable recess having a predetermined size, which will be described later, and the first and second cores 6 and 7 and the movable recess are shared. Thus, a semi-hollow molded product having two recesses is formed. The first and second cores 6 and 7 are separated by a predetermined interval. Thereby, the partition wall of predetermined thickness is shape | molded integrally with a main-body part. The small core 8 is formed outside the first and second cores 6 and 7 at a predetermined interval. The small core 8 forms a filling space portion in which the joint portion of the main body portion is filled with a molten resin for secondary molding.

  FIG. 1A is a cross-sectional view showing a state in which the movable mold 20 is closed with respect to the fixed mold 2 in the primary molding position. As shown in FIG. On the parting line P side, a movable core 25 corresponding to the fixed recess 3 is provided. The movable side core 25 is formed in the same shape and the same size only in the direction opposite to that of the fixed side core 5 described above. That is, it consists of two relatively large first and second cores 26 and 27 and a small small core 28. The first and second cores 26, 27 are located in the center of the fixed-side recess 3, and the outer peripheral surfaces of these cores 26, 27 are larger than the inner peripheral surface of the fixed-side recess 3 by the thickness of the hollow molded product. Only getting smaller. One semi-hollow molded product having two concave portions is formed by the first and second cores 26 and 27 and the concave portion 3 on the fixed side. The first and second cores 26 and 27 are separated by a predetermined interval. Thereby, the partition wall of predetermined thickness is shape | molded. The small core 28 is formed outside the first and second cores 26 and 27 at a predetermined interval, and the outer peripheral surface of the small core 28 is in close contact with the inner peripheral surface of the fixed recess 3. By this small core 28, a filling space portion in which the joint portion of the main body portion is filled with molten resin for secondary molding is formed.

  A movable side recess 23 is provided at a lower position of the movable mold 20 on the parting line P side corresponding to the fixed core 5. The relationship between the movable side recess 23 and the fixed side core 5 such as the size and shape is the same as the relationship between the fixed side recess 3 and the movable side core 25, and therefore will not be described repeatedly. A relatively large escape recess 24 is formed in the lower position of the movable mold 20 on the parting line P side to allow the stationary core 5 to escape during secondary molding.

  The fixed mold 2 configured as described above is provided with a runner 10 for primary molding parallel to the mold 2, and the first sprue 11 extending from the runner 10 so as to cross the fixed mold 2 is The fixed side recess 3 is opened through the gate, and the second sprue 12 is also opened at the top of the first core 6 through the gate. Further, the fixed mold 2 is provided with a secondary forming sprue 13, and this sprue 13 is open to the side of the fixed recess 3 through a runner 14 formed on the parting line P and a gate. .

  FIG. 2 shows an embodiment of the heating device 30. The heating device 30 according to the present embodiment includes a heating body 31 made of a carbon heater, a halogen heater, or the like that has excellent thermal responsiveness. The heat source 32 made of a carbon heater or a halogen heater constituting the heating body 31 is arranged in a shape that matches the shape of the fusion part of the partition wall, and is configured in a flat plate shape as a whole. Therefore, even if the space | interval of the fixed mold | type 2 and the movable mold | type 20 is narrow, it can insert and can heat-melt the fusion | melting part of a partition wall efficiently. The heating body 31 configured as described above is connected to the heating control device 34 by the power supply lines 33 and 33 so that controlled electric power is supplied. For example, when the heating body 31 is inserted between the fixed mold 2 and the movable mold 20, predetermined power is supplied, and the heater 31 is controlled to be turned off when it is saved or to reduce the supplied power. In order to insert and retract the heating body 31 between the fixed mold 2 and the movable mold 20, a heating body driving device is provided. The heating element driving device is composed of a piston cylinder unit 35, a hydraulic device 36 that supplies and discharges hydraulic oil to and from the piston cylinder unit 35, and a piston rod 37 that protrudes from the piston cylinder unit 35. A heating body 31 is attached to a support body 38 that is dynamically driven. The hydraulic device 36 includes a hydraulic pump, a valve, and the like, and hydraulic oil is supplied to and discharged from the piston cylinder unit 35 in response to a signal from a control device (not shown) so that the heater 31 is driven reciprocally.

  Next, the operation of the above embodiment will be described. As shown in FIG. 1A, the movable mold 20 is slidably driven to the lower primary molding position to clamp the fixed mold 2. A state where the mold is clamped at the primary molding position is shown in FIG. When the mold is clamped in this way, the fixed recess 3 and the movable core 25 form a cavity Ch for molding one main body and a cavity Cs for molding the partition wall. These cavities Ch and Cs constitute a communicating cavity. The outer periphery of the cavity Ch in the vicinity of the opening of the main body is partly cut away by the small core 28. Similarly, the fixed core 5 and the movable recess 23 constitute a cavity Ch for molding the other main body and a cavity Cs for molding the partition wall. The outer periphery of the cavity Ch near the opening of the main body is partially cut away by the small core 8.

  The molten resin for primary molding is injected and filled from the runner 10 into the cavities Ch and Cs via the first and second sprues 11 and 12. As shown in FIG. 1A, a pair of semi-hollow molded products T1 and T2 including a main body H and a partition wall W are formed substantially simultaneously. When molded in this way, the opening of the semi-hollow molded product H is the joint S, but according to the present embodiment, a part of the outer periphery of the joint is cut off. The top of the partition wall W or the parting line P side is a fusion part M. After waiting for solidification to some extent, the movable mold 20 is opened and driven to the secondary molding position shown in FIG. The secondary molding position is matched between the pair of semi-hollow molded products T1 and T2. The distance between the fixed mold 2 and the movable mold 20 is kept at a predetermined distance, and the heating body 31 is inserted between the fusion parts M, M of the partition walls W, W to melt the fusion parts M, M. The heating element 31 is retracted. Then, the mold is clamped as shown in FIG. Then, the pair of partition walls W and W are fused at the fusion portions M and M.

  When molding as described above, the heating body 31 is kept in a low temperature state or an off state by the heating control device 34 when it is retracted, but the fixed die 2 and the movable die 20 are separated by the piston cylinder unit 35. At the same time as being inserted, predetermined power is supplied. According to the present embodiment, since the heating element 31 is composed of a halogen lamp or a carbon heater, the temperature is instantaneously set to a predetermined temperature, and the fusion parts M and M are melted.

  When the mold clamping is performed as described above, the pair of partition walls W and W are fused at the fusion portions M and M. Almost simultaneously with the completion of mold clamping, a molten resin for secondary molding is injected from the sprue 13. The molten resin for secondary molding is filled in the main body portions H, the joint portions S of the H, and the filling space portion JK of the S. Thereby, the main-body parts H and H are joined by injection molding. When the movable mold 20 is opened after cooling and solidification, the internal partition walls W, W are heat-sealed, the main body portions H, H are joined by injection molding, and a hollow molded product having a partition wall inside is obtained.

  In the above embodiment, the abutting part of the partition walls W, W or the top part of the fusion part M, M is substantially the same height as the parting surface P, or is the same height as the joint part of this end part. However, it can be carried out so as to be fused in a compressed state with a predetermined amount higher. It is obvious that ribs, protrusions, and the like can be formed in the same manner as the partition wall. Furthermore, it is clear that a plurality of hollow molded products can be formed simultaneously by forming a plurality of compositions of a pair of semi-hollow molded products.

It is sectional drawing which shows the metal mold | die of the shaping | molding apparatus which concerns on embodiment of this invention, (a) is the state which closed the metal mold | die in the primary molding position, (a) is the metal which moved to the secondary molding position FIG. 2C is a cross-sectional view schematically showing a state in which the mold is opened and (c) in a state where the mold is closed at the secondary molding position. It is a perspective view of the heating device concerning an embodiment of the invention.

Explanation of symbols

2 Fixed type 3 Fixed side recessed part 5 Fixed side core 20 Movable type 23 Movable side recessed part 25 Movable side core
31 Heating body
Ch, Cs Cavity T1, T2 Semi-hollow molded product
H, H Main body W, W Semi-partition wall
M, M fusion part S, S joint part JK joint space part

Claims (4)

Joining the opening of the body part of a pair of semi-hollow molded products and joining the abutment part of a pair of appendages such as ribs, protrusions, partition walls, etc. integrally formed in the body part, A molding method for molding a hollow molded article having the accessory, wherein the molding method includes:
A cavity composed of a fixed mold and a movable mold is injected and filled with molten resin, a pair of semi-hollow molded products, a joint for injection molding at the opening of the main body, and an abutment of the accessory Is a primary molding step of injection molding so as to have a fusion bonded portion;
In a state where one half-hollow molded article molded by the primary molding step remains in the mold, the other half-hollow molded article remaining in the other mold is opposed to the other half-hollow molded article with a predetermined interval, A heating and melting step in which a heating element is inserted between the joints of the accessory to melt the joints;
After the heating and melting step, the heating body is retracted, the movable mold is clamped to the fixed mold, and the joint portion of the accessory is fused, and molten resin is injected into the joint portion of the main body portion. And a secondary molding step of joining together. A method for molding a hollow molded product. The molding method according to claim 1, wherein at the time of the primary molding step, the joint part for fusion bonding of the accessory is molded so as to be higher by a predetermined amount than the joint part for injection molding of the main body part. A method for forming a hollow molded product. The molding method according to claim 1 or 2, wherein a heating body comprising a halogen lamp or a carbon heater is used in the heating and melting step. A molding device for a hollow molded product composed of a combination of a mold device composed of a fixed mold and a movable mold and a heating element,
The movable mold is configured to be opened / closed with respect to the fixed mold and to be slidably driven, and a pair of semi-hollow molded products are interposed between the parting lines of these molds. A cavity for forming the joint part for injection molding in the opening part of the part, and a joint part for attachment such as ribs, projections, partition walls, etc. is formed to have a joint part for fusion,
The cavity is configured to be injected and filled with a molten resin for primary molding, and a joint for the opening of the main body portion with a molten resin for secondary molding.
The heating body is inserted between the solid mold and the movable mold when the movable mold assumes a predetermined position with respect to the fixed mold, and heats the joining portion of the abutting portion of the appendage. And a device for molding a hollow molded article that is retracted from between the fixed mold and the movable mold.

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