JPH06246781A - Method and apparatus for molding hollow product - Google Patents

Abstract

PURPOSE:To mold a hollow product required in the strength of its joining area such as a large-sized or medium-sized tank or intake manifold. CONSTITUTION:A pair of half hollow objects having joining areas are molded by primary molding and joined at the joining areas by secondary molding to mold a hollow product. In this molding method, a plurality of filling grooves opened on the side of the joining end parts of the half hollow objects and a plurality of the communication holes communicating with the filling grooves from the outside are formed to the joining areas 10A, 10B of a pair of the half hollow objects A, B in primary molding. A molten resin J is injected into the communication holes and the filling grooves in such a state that the joining end parts of the joining areas 10A, 10B of the half hollow objects A, B are brought into contact with each other to obtain the hollow product. At this time, protruding parts RA, RB... each developing the action of the head of a rivet are formed on the outsides of the joining areas 10A, 10B.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used for carrying out a molding method and a molding method for molding a hollow body product by molding a pair of semi-hollow bodies by primary molding and joining the joints by secondary molding. The present invention relates to a molding device.

[0002]

2. Description of the Related Art As a method for producing a synthetic resin hollow body product, a production method using a blow molding machine and a production method using an injection molding machine are known. When a hollow body product is manufactured by an injection molding machine, the hollow body product is formed as a half-hollow body or a divided body in the primary formation, the divided surfaces are abutted in the secondary formation, and the abutted portions are One hollow body product is manufactured by heating or welding. According to the manufacturing method using this injection molding machine, it is possible to make a completely sealed hollow body product, a hollow body product having a uniform wall thickness, and to deal with a complicated shape. However, the present applicant has disclosed that
No. 87315 provides a method for producing a hollow body product suitable for mass production by further improving the above production method. A set of molds is used to carry out the method. One die is provided with a male die and a female die for forming one of the divided bodies, and the other die has a female die and a male die for forming the other of the divided bodies. It is provided. A pair of divided bodies is formed by using this one set of molds, and after joining surfaces of these divided bodies are abutted with each other, a molten resin is injected to the periphery of the abutted surfaces to be integrated to obtain a hollow body product. It is like this.

By the way, in recent years, applications of plastics have been expanded, and taking advantage of the characteristics, for example, a part of an intake manifold of an internal combustion engine is also molded from plastic. To explain in detail, the intake manifold of an automobile is used to introduce a mixture for combustion from the carburetor to the cylinder of the engine.Because the pipe is branched like a branch, it is also called an intake manifold. Was integrally formed from a casting. However, castings are heavy and increase the weight of the vehicle body, resulting in poor fuel economy, so they have come to be formed from aluminum or its alloys, and recently the main body part is formed from aluminum and the cover is formed from a lighter weight plastic. Is becoming popular. In this way, the intake manifold formed by dividing the main body part made of aluminum or its alloy and the plastic cover part into a divided body,
At its peripheral edge, bolts and nuts are tightened and integrated with an O-ring interposed.

[0004]

According to the above method, one die is slid or rotated with respect to the other die to abut a pair of divided bodies, and a molten resin is injected to produce a hollow body product. So you can get
There is an advantage that each process can be automated and a hollow body product can be mass-produced. Further, since the pair of divided bodies are molded by injection molding, it has a feature that a hollow body product having a complicated shape can be manufactured. Thus, although there are many advantages, points to be improved have been found. That is, according to the above method, the pair of split bodies are joined by joining the joints, and by injecting the molten resin into the joined portions, the strength of the joint of the obtained hollow body product is improved. There is a problem of weakness. The strength of the joint is increased to some extent by increasing the injection pressure when injecting the molten resin during the secondary molding to improve the adhesion between the joint of the divided body and the resin injected during the secondary molding. You can In addition, the fusion property can be increased by injecting the same resin as that of the divided body during the secondary molding. However, in order to increase the injection pressure, it is necessary to make a secondary molding die or the like strong, and if the injection pressure is increased, the divided body may be deformed. If the same resin is injected, the choice of resin becomes inflexible. Based on the above, the conventional method for molding a hollow body product cannot be said to be suitable as a method for manufacturing a large-medium tank such as a kerosene tank in which the strength of the joint is relatively required.

Further, as described above, if the aluminum main body portion and the plastic cover portion are tightened with bolts and nuts with the O-ring interposed, there is a drawback that the manufacturing cost, the assembly cost, etc. increase. If a conventional hollow body product molding method is applied instead of tightening with bolts and nuts and joining is performed, an O-ring is not required and assembly is easy and cost can be reduced, but insufficiency of strength of the joining portion cannot be avoided. The present invention has been proposed in order to improve the above-mentioned problems. Specifically, the strength of the joining portion is large, and the present invention is not limited thereto. For example, large and medium-sized tanks, intake manifolds, etc. An object of the present invention is to provide a molding method and a molding apparatus suitable for manufacturing a hollow body product in which the strength of a joint is required.

[0006]

In order to achieve the above object, the present invention according to claim 1 is characterized in that a pair of semi-hollow bodies are molded by a primary molding so as to have a joint portion, and the joint portions are joined together. In a method for forming a hollow body product by joining parts by secondary molding, a filling groove opened to the joint end side is formed in the joining portion of a pair of semi-hollow bodies in the first forming and the filling groove is communicated from the outside. And a plurality of communicating holes are formed, and in the secondary molding, molten resin is injected into the plurality of communicating holes and the filling groove in a state where the ends of the joints are in contact with each other. Configured to get the product. According to a second aspect of the present invention, in the secondary molding according to the first aspect, when the molten resin is injected into the plurality of communication holes and the filling groove, one of the pair of semi-hollow bodies communicates with each other. The injection port is configured to be injected corresponding to the hole, and the invention according to claim 3 is the secondary molding according to claim 1 or 2, wherein the molten resin is injected into the plurality of communication holes and the filling groove. At this time, a protrusion or a ridge larger than the diameter of the communication hole is formed outside the communication hole. The molding apparatus according to claim 4, wherein a filling groove is formed over the entire circumference of the joint, and a plurality of communication holes are formed that communicate with the filling groove from the outside of the joint. A molding apparatus for joining hollow bodies, comprising a first holder for holding one semi-hollow body A and a second holder for holding the other semi-hollow body. The two holders hold the joint portion of the semi-hollow body, and at least one of the holders is provided with a resin supply port for injecting molten resin into the communication hole and the filling groove. The invention according to claim 5 is such that the resin supply port according to claim 4 corresponds to the number and position of the communication holes, and the invention according to claim 6 is
Alternatively, the resin supply port formed in one holder described in 5 corresponds to the number and position of the communication holes in a bowl shape, and the holding portion of the other holder also has a bowl shape in the number of communication holes. And the position.

[0007]

The invention according to claim 4 operates as follows.
That is, a pair of semi-hollow bodies is prepared in which a filling groove is formed over the entire circumference of the joint portion and a plurality of communication holes communicating with the filling groove from the outside of the joint portion are formed. Then, the joint portion of one semi-hollow body is held by the first holder, the joint portion of the other semi-hollow body is held by the second holder, and the ends of the joint portions are kept in contact with each other. Since the resin supply port is formed in at least one of the first and second holders, the molten resin is injected from the resin supply port into the plurality of communication holes and the filling groove to integrate the semi-hollow body. To do. After the cooling and solidification of the molten resin, the integrated hollow body product is taken out.
In the invention according to claim 5, since the resin supply port corresponds to the number and position of the communication holes of the semi-hollow body, when the joint portion of the pair of semi-hollow bodies is held by the first and second holders, the resin supply is performed. Hold the mouth so that it matches the number and position of the communication holes of the semi-hollow body. Then, the molten resin is injected from the resin supply port. Then, the molten resin is filled in the plurality of communication holes and the filling groove formed in the pair of semi-hollow bodies. Wait for solidification of the molten resin, and take out the integrated hollow body product. The invention according to claim 6 acts like the inventions according to claims 4 and 5, and the resin supply port formed in one of the holders corresponds to the number and position of the communication holes in the shape of a bowl. At the same time, the holding portion of the other holder also has a bowl-shaped depression corresponding to the number and position of the communication holes, and therefore the resin is injected so that these depressions are also filled.

[0008]

EXAMPLES Examples of the present invention will be described below. In the present embodiment, the hollow body product is manufactured from synthetic resin by primary molding and secondary molding. That is, in this example, a primary molding method of molding a pair of half-hollow bodies or split bodies in half with respective molds, and molten resin at the joints of the split bodies obtained by this primary molding method. It is composed of a secondary molding method for injecting a hollow body product and a molding apparatus used for the secondary molding. The primary molding method for forming the pair of divided bodies and the mold used for carrying out the method are not shown in the drawings and are not explained because conventionally known or known methods and molds can be applied. Absent. Although the pair of divided bodies obtained by the primary molding, that is, the semi-hollow body does not need to be formed symmetrically, an example in which they are formed symmetrically will be described with reference to FIGS. 1, 2, 5 and 6.

The kind of resin of the pair of semi-hollow bodies and the kind of resin injected in the secondary molding are not particularly limited. For example, a pair of semi-hollow bodies are made of polyphenylene sulphate PP.
Molded with S, polyamide PA, nylon PA for secondary molding
6, polyphenylene sulphite PPS, polycarbonate PC, polybutylene terephthalate PBT and the like can be applied. When the same type of resin is applied to the primary molding and the secondary molding, the pair of semi-hollow bodies and the resin injected during the secondary molding are well compatible with each other, and the fusion property of the joint is improved even if the resin is injected at low temperature and low pressure. . Further, since the types of resin are the same, there is an advantage that the resin can be directly melted and recycled.

One of the semi-hollow bodies A is (a) in FIG.
As shown in (b), it has a semi-hollow or bowl-shaped main body 1A. The main body portion 1A is composed of a circular bottom portion 2A and a tubular body portion 3A, and a ring-shaped connecting portion 10A is integrally formed on the outer peripheral portion of the open end portion 4A of the body portion 3A. The connecting portion 10A has a predetermined thickness in the same axial direction as the body portion 3A. A groove 11A having a predetermined depth is formed in the connecting portion 10A from the open end 4A to the bottom 2A over the entire circumference. As a result of forming the groove 11A in this way, the contact portion 12 is formed on the inner diameter side and the outer diameter side of the groove 11A.
A and 13A are formed concentrically. Further, in the connecting portion 10A, a plurality of through holes 14A, 14A, ... Communicating from the outside to the groove 11A are opened in parallel with the body portion 3A. According to this embodiment, the other semi-hollow body B
However, since it is formed in the same shape as the above-mentioned semi-hollow body A, the same reference numeral as in FIG.

The molding apparatus 20 used for the secondary molding is composed of a first holder 21 and a second holder 30, as shown in FIG. The first holder 21 holds the joint 10B of the semi-hollow body B shown in FIG. 2 described above during the secondary molding, and the second holder 30 holds the joint 10A of the semi-hollow body A. Has become. First holder 2
1 includes a cylindrical portion 22 having substantially the same diameter as the joint portion 10B of the semi-hollow body B. The receiving portion 23 at the tip of the tubular portion 22
In addition, as shown in FIG. 4B, a plurality of concave portions 28, 28, ... The diameter of the open ends of these recesses 28, 28, ...
It is larger than the diameter of 4B, 14B, .... And the recesses 28, 2
The ejection ports 24, 24, ... In this way, the injection ports 24, 2 are provided at the bottoms of the recesses 28, 28 ,.
.. face each other. Therefore, when the molten resin is injected from these injection ports 24, 24 ,.
A convex portion having the shape of a rivet head is formed outside 0B. Recesses 28, 28, ...
4, 24, ... accord with the number and position of the through holes 14B, 14B, ... Opened in the joint portion 10B of the semi-hollow body B, and the resin supply passage 2 through the resin branch passages 25, 25.
It communicates with 6. Reference numeral 27 in FIG. 3 indicates a nozzle of the injection machine.

Similarly to the first holder 21, the second holder 30 also has a cylindrical portion 31 having a diameter substantially the same as that of the joint portion 10A of the semi-hollow body A. Then, in the pressing portion 32 at the tip of the tubular portion 31,
A plurality of concave portions 33, 33, ... And these recesses 33, 33, ... Are also semi-hollow bodies A
Through holes 14A, 14A formed in the joint portion 10A of
Matches the number and position of. Recesses 33, 33, ...
The arrangement state of is shown in FIG. A mechanism for tightening the first and second holders 21 and 30 during the secondary molding, for example, a hydraulic piston cylinder is not shown in the figure.

Next, an example of secondary molding will be described. As shown in FIG. 2, the contact portions 12 of the semi-hollow bodies A and B are
A, 13A, 12B, 13B are brought into contact with each other so that the outside of the connecting portion 10B of the semi-hollow body B is placed in the first holder 21.
It is received by the receiving portion 23 of. And the connecting portion 10 of the semi-hollow body A
The outside of A is pressed by the pressing portion 32 of the second holder 30 using a hydraulic piston cylinder or the like. Then, the mold is clamped. At this time, the ejection openings 24, 2 of the first holder 21
4, ..., Through holes 14B, 14B, ... 14 of semi-hollow bodies B, A
The recesses 33, 33, ... Of the pressing portion 32 of the second holder 30 are aligned with each other. Then
Molten resin is injected from the nozzle 27 of the injection machine. Then, the molten resin flows from the resin supply passage 26 to the resin branch passage 25,
25, ..., From the injection ports 24, 24 ,.
Through holes 14B, 14B, ..., Grooves 11 of semi-hollow bodies B, A
The spaces formed by B and 11A and the through holes 14A, 14A, ... Of the semi-hollow body A are filled. At this time, the recess 2
8, 28, ..., 33, 33 ,. The state after the injection filling is indicated by J, J, and J in FIG. After cooling and solidification, the second holder 30 is moved in the direction of the arrow in FIG. 6 to take out the product.

According to this embodiment, various effects can be obtained. For example, the plurality of ejection openings 24, 24, ... Provided in the receiving portion 23 are concave portions 28, 2 that are depressed like a bowl.
8 ..., so that the through holes 14B of the semi-hollow body B, 1
Outside the 4B, ..., Protrusions RB, RB, ... In the shape of the head of the rivet as shown in FIG. 6 are formed.
Similarly, convex portions RA, RA, ... In the shape of the rivet head are also formed outside the through holes 14A, 14A, ... Of the semi-hollow body A. Therefore, even if a large force that separates the semi-hollow bodies A and B in the axial direction acts, the force is the same as the convex portions RA, RA, ...
The semi-hollow bodies A and B are not separated by being received by RB, RB, .... Although not shown in the drawing, the convex portions RA, RA, ..., RB, RB ,. That is, the recesses 28, 3
When using the first and second holders 21 and 30 without 3, ...
The convex portions RA, RA, ..., RB, RB, ... Are not molded.
Even without these protrusions, the through holes 14B, 14B, ..., 1
Since 4A, 14A, ... Are filled with resin, the fusion distance or area is larger than that of the conventional one. Therefore, it is possible to obtain a hollow body product having a large bonding force. Further, according to the present embodiment, the injection port 24 of the first holder 21,
24, ..., Through holes 14A, 14A, ...
.. and the recesses 33, 33, ... Of the pressing portion 32 of the second holder 30 are aligned with each other, so that injection can be performed with a relatively low injection pressure. Furthermore, the first and second holders 21 and 30 are connected to the connecting portion 1 of the semi-hollow bodies A and B.
Since only 0A and 10B are held, there is also an effect that the structure of the molding apparatus is simpler than that of the conventional mold.

Next, another embodiment of the molding apparatus 20 'will be described with reference to FIGS. It should be noted that members similar to those in the embodiment shown in FIGS. 3 and 4 are denoted by the same reference numerals with a dash “′” and will not be repeatedly described. According to this embodiment, as shown in FIGS. 7A and 7B, the first holder 2
A ring-shaped groove 40 having a bowl-shaped cross section is provided on the receiving portion 23 'at the tip of the tubular portion 22' of 1 ', over the entire circumference. A plurality of injection ports 41 are provided in the groove 40,
41 is open. The injection ports 41, 41 are provided at arbitrary positions, and the through holes 14A, 14A of the semi-hollow bodies A, B, ...
It is not matched with 14B, 14B, ... Second holder 3
As shown in FIGS. 8A and 8B, a ring-shaped groove 50 recessed in a bowl shape is formed in the pressing portion 32 ′ at the tip of the cylindrical portion 31 ′ of 0 ′. .

Therefore, the outside of the connecting portion 10B of the semi-hollow body B is received by the receiving portion 23 'of the first holder 21', the pressing portion 32 of the second holder 30 'pushes the connecting portion 10A of the semi-hollow body A, and When the molten resin is injected from the injection ports 41, 41, the molten resin passes through the through holes 14B, 14B, ... Of the semi-hollow body B from the ring-shaped groove 40 and the groove 11 of the semi-hollow bodies A, B.
The spaces formed by A and 11B and the through holes 14A, 14A, ... Of the semi-hollow body A are filled. And the pressing portion 3
The 2 ′ ring-shaped groove 50 is also filled. Therefore,
A ridge is formed around the entire circumference of the through holes 14B, 14B, ... Of the semi-hollow body B and the outside of the through holes 14A, 14A ,. Similar effects are obtained.

According to the present embodiment, the area around the molten resin is not good, but the resin branch passages 25 ', 2'of the first holder 21',
The structure such as 5'is simplified, and the first and second holders 2 are
Positioning of the 1'and 30 'and the semi-hollow bodies A and B becomes easy. As is clear from the above description, the first holder 21 shown in FIG. 3 and the second holder 3 shown in FIG.
0'can be used in combination, or conversely, the second holder 30 shown in FIG. 3 and the first holder 21 'shown in FIG. 7 can be used in combination. it can.

The semi-hollow bodies A and B molded by the primary molding can also be carried out in various shapes, and other typical examples thereof are shown in FIG. In this embodiment as well, members similar to those in the above-mentioned example are designated by the same reference numerals with a dash "'" to avoid duplicate description, but in the example shown in FIG.
1A 'and 11B' are formed in a dovetail shape in side cross section. Therefore, even if the semi-hollow bodies A ′ and B ′ are poorly adhered to the resin injected in the secondary molding, and even if a large pulling force acts in the direction of separating the joints, the semi-hollow bodies A ′ and B ′.
And the semi-hollow bodies A'and B'will not separate unless the resin injected in the secondary molding is compressed or expanded and deformed. In the example shown in (b), the grooves 11A ′, 1
The outer peripheral side of 1B 'is cut off. Therefore, at least one of the first holder 21 and the second holder 30 cannot be the holder shown in FIGS. 3, 4, 7 and 8, but can be ejected from the circumferential direction by using an appropriate holder. The effect is obtained. In the example shown in FIG. 9C, the groove 11B ′ is formed only in the semi-hollow body B. This embodiment is convenient when the shapes of the semi-hollow bodies A ′ and B ′ are different and the semi-hollow bodies A ′ and B ′ cannot be molded with the same mold. In the example shown in (d), the through hole 1
4A ′, 14A ′, ..., 14B ′, 14B ′, ... Spread obliquely when viewed from the side, and the open ends thereof are the body portions 3A ′, 3
It is separated from B '. Therefore, according to this embodiment, the effect that the receiving portion 23 and the pressing portion 32 of the first and second holders 21 and 30 can be secondarily molded without being interfered by the body portions 3A ′ and 3B ′ is obtained. In the embodiment shown in (e), the grooves 11A ', 11B' are formed in a dovetail shape in side cross section, and the through holes 14A ', 14B', ... are reduced in diameter toward the joint. There is. Therefore, as in the example shown in (a), unless the semi-hollow bodies A ′ and B ′ and the resin injected in the secondary molding are compressed or stretch-deformed, the semi-hollow bodies A ′ and B ′ are There is no separation.

Various combinations can be made in this embodiment as well.
For example, a semi-hollow body A ′ shown in FIG.
It can also be combined with the semi-hollow body B ′ shown in (e). Similarly, various combinations are possible. Also, the molding apparatus 20 can be applied to the holders 21, 30, 21 'and 30' shown in FIGS. 3, 4 or 7 and 8 as they are or with some modifications, or can be used in combination.

[0020]

As described above, according to the first aspect of the present invention, in the primary molding, at the joint portion of the pair of semi-hollow bodies, the filling groove opened to the joint end side and the filling groove from the outside are formed. A plurality of communicating holes that communicate with each other are molded, and molten resin is injected into the plurality of communicating holes and the filling groove in a state where the end portions of the joints are brought into contact with each other in the secondary molding to obtain a hollow body product. Therefore, since the plurality of communication holes are also filled with the resin, it is possible to obtain a hollow body product having a strong joint portion. Therefore, the present invention makes it possible to manufacture hollow body products, such as large and medium-sized tanks and intake manifolds, which require relatively high joint strength.
According to the second aspect of the invention, the effect of the first aspect is obtained, and in the secondary molding, the injection hole is made to correspond to the communication hole of one of the semi-hollow bodies of the pair of semi-hollow bodies. , The injection pressure can be lowered. According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, when the molten resin is injected into the plurality of communication holes and the filling groove, the communication holes are formed outside the communication holes. Since the protrusions or ridges having a larger diameter are formed, the protrusions or ridges can provide a hollow body product having even greater bonding strength. The molding apparatus according to claim 4 comprises a first holder that holds one semi-hollow body and a second holder that holds the other semi-hollow body, and these first and second holders are semi-hollow bodies. Since it is configured to hold the joint portion, it has a simpler structure and is less expensive than a conventional die for secondary molding. At least one of these holders is provided with a communication hole and a resin supply port for injecting molten resin into the filling groove. Body products can be molded. According to the invention of claim 5, in addition to the effect of claim 4, since the resin supply port corresponds to the number and position of the communication holes, it is possible to mold the hollow body product with a low secondary injection pressure. According to the invention of claim 6, claim 4
Alternatively, the effect of the invention described in 5 is obtained, and the resin supply port formed in one holder is recessed in a bowl shape corresponding to the number and position of the communication holes, and the holding portion of the other holder is also bowl-shaped. Since the depressions correspond to the number and positions of the communication holes, it is possible to form a convex portion or a convex strip on the outer side of the joint portion.

[Brief description of drawings]

FIG. 1 is a view showing an example of a semi-hollow body used for carrying out the present invention, (a) is a sectional view thereof, and (b) is a side view thereof.

FIG. 2 is a cross-sectional view showing a combination of a pair of semi-hollow bodies used for implementing the present invention.

FIG. 3 is a view showing an embodiment of a molding apparatus, (a) is a sectional view showing an embodiment of a second holder thereof, and (b) is a sectional view showing an embodiment of a first holder.

4 is a plan view of the first and second holders shown in FIG. 3, in which (a) is a second holder and (b) is a first holder.

FIG. 5 shows a pair of semi-hollow bodies shown in FIG.
FIG. 6 is a cross-sectional view showing a state in which secondary molding has been completed using the first and second holders shown in FIG.

FIG. 6 is a cross-sectional view showing a state where the hollow body product is obtained and taken out after the secondary molding is completed.

7A and 7B are views showing another embodiment of the first holder, in which FIG. 7A is a plan view thereof, and FIG. 7B is a side view partially shown in section.

8A and 8B are views showing another embodiment of the second holder, FIG. 8A is a side view showing a partial cross section, and FIG. 8B is a plan view.

FIG. 9 is a diagram showing an example of a pair of semi-hollow bodies, in which (a)-
(E) is a side view partially showing different examples.

[Explanation of symbols]

A, B Semi-hollow body (divided body) 1A, 1
B body part 10A, 10B connection part 11A,
11B groove 14A, 14B through hole 20
Molding device 21 First holder 24 Injection port 30
Second holder 28, 33 Recess

Claims (6)

[Claims] 1. A method for molding a hollow body product by molding a pair of semi-hollow bodies so as to have a joint by primary molding, and joining the joint by means of secondary molding, wherein a pair of semi-hollow bodies are molded in the primary molding. Joint part 10 of semi-hollow bodies A and B
A and 10B, filling grooves 11A and 11B opened to the joining end portions 4A and 4B, and the filling grooves 11A and 11B from the outside.
, 14B, ..., and a plurality of communication holes 14A, ..., 14B, which are communicated with each other, and in the secondary molding, the joint ends 4A, 4B of the joints 10A, 10B are brought into contact with each other. , 14B, ... and the filling grooves 11A, 11B by injecting a molten resin to obtain a hollow body product. 2. The secondary molding according to claim 1, wherein a plurality of communication holes 14A, ..., 14B ,.
When the molten resin is injected into 1B and 1B, a pair of semi-hollow bodies A,
One of B semi-hollow bodies A, B communicating holes 14A,
, 14B, ..., Corresponding injection ports 24, 24 ,. 3. The secondary molding according to claim 1 or 2, wherein a plurality of communication holes 14A, ..., 14B ,.
When the molten resin is injected into 1A and 11B, the communication hole 14
, 14B, ..., A convex portion RA, ..., RB, ... 4. Filling grooves 11A, 11B are formed along the entire circumference of the joints 10A, 10B, and the filling grooves 11A, 11B are formed from the outside of the joints 10A, 10B.
11B, a plurality of communication holes 14A, ..., 14B,
A molding device 20 for joining a pair of semi-hollow bodies A and B, which are molded, wherein the device 20 includes a first holder 21 for holding one semi-hollow body A and another semi-hollow body. A second holder 30 for holding a body B, wherein the first and second holders 21, 30 are the semi-hollow bodies A, B
While holding the joint portions 10A and 10B, the holder 21 of at least one of the holders has a communication hole 14A,
, 14B, ... And filling grooves 11A, 11B are provided with resin supply ports 24, 24 for injecting molten resin. 5. The resin supply ports 24, 24 according to claim 4,
Are corresponding to the numbers and positions of the communication holes 14B, 14B ,. 6. The holder 2 according to claim 4 or 5.
The resin supply ports 24, 24 formed in 1 correspond to the number and positions of the communication holes 14B, 14B, ... In a bowl shape, and the holding portion of the other holder 30 also has a bowl shape. A molding apparatus for hollow products corresponding to the number and positions of the communication holes 14A, 14A ,.