JPH09155921A - Molding method and molding die for molded product having joint - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: Even if the abutting portion is slightly deformed, it is possible to closely abut the abutting portion at the time of secondary molding.
Provided is a molding method in which a resin for the next molding does not leak. SOLUTION: Molten resin is injected into a cavity (C1, C2) formed by a fixed mold (20) and a movable mold (40) to butt a pair of primary semi-molded products (A, B). Guide parts (G, G, ...) Are integrally formed inside the abutting part (TA) of one of the primary semi-molded products (A) during the primary molding in which the parts (TA, TB) are formed. To do. For the secondary molding, the butting part (TB) of the other primary semi-molded product (B)
When fitting to the abutting part (TA) of one primary semi-molded product (A), the abutment part (TB) of the other primary semi-molded product (B) is fitted to the one primary semi-molded product (A). Guide by the guide part (G, G, ...) Of the abutting part (TA).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pair of primary semi-molded products obtained by injecting a molten resin into a cavity formed by a fixed mold and a movable mold, and one of the primary semi-molded products. Forming step so that the abutment part of the other has a butting part that fits into the abutting part of the other primary semi-molded product, and after this primary forming process, move the movable die to the fixed die. And abutting portions of the pair of primary semi-molded products are abutted against each other, and molten resin is injected into the abutted portions so that the pair of primary semi-molded products are integrated into a secondary molding process. The present invention relates to a molding method for molding a molded article having a portion and a molding die used for carrying out this method.

[0002]

2. Description of the Related Art As a method for manufacturing a hollow molded article made of synthetic resin, a manufacturing method using an injection molding machine is known. The mold used for carrying out this injection molding method is roughly composed of a fixed mold and a slide mold as filed by the present applicant in, for example, JP-A-6-23789 and JP-A-6-23790. It is configured. One primary semi-hollow molded product is molded by the fixed mold, and the other primary semi-hollow molded product is molded by the slide mold. Therefore, 1
In the next molding, the slide mold is set to the first position, a pair of primary semi-hollow molded products are molded so as to have an abutting part around the opening, and after the solidification, the slide mold is slid to the second position. Then, the pair of primary semi-hollow molded products come to abut at the abutting portion. Therefore, when the molten resin is injected into the abutting portion in the secondary molding, a pair of 1
The next semi-hollow molded product is joined at the abutting portion to form a hollow molded product.

[0003]

According to the above-mentioned injection molding method, a pair of primary semi-hollow molded articles formed by primary molding are butted, and then the butted portion is injection-filled with molten resin by secondary molding. Since a hollow molded product can be obtained, there is an advantage that each step can be automated and the hollow molded product can be mass-produced. Further, since the pair of primary semi-hollow molded products are molded by injection molding, there is a feature that a hollow molded product having a complicated shape can be manufactured. However, there are some problems to be improved. That is, in order to increase the strength of the joint portion of the pair of primary semi-hollow molded products, the primary molding is performed so that the abutment portion has a filling space portion that is filled with the joining resin when they are abutted. After the subsequent molding, when the abutting part of one primary semi-hollow molded product is abutted against the abutting part of the other primary semi-hollow molded product, deformation due to contraction of the abutting part, and releasing the abutting part for abutting Due to the deformation and the like generated at the time, a gap is created in the filling space when the two are butted.
At the time of the next molding, the resin for joining may leak from this gap. Also, if the mold is clamped for secondary molding while it is deformed, it will be clamped with the butting part partially collapsed.
Similarly, the resin leaks from the filling space. Even if it does not leak, the bonding strength will be weak. It is considered that the above problems can be solved to some extent by increasing the rigidity of the abutting portion, but in order to increase the rigidity, the cooling and solidifying time after the primary molding is lengthened, or Although the wall thickness must be increased, another problem arises in that a longer cooling time lengthens the molding cycle, and a larger wall thickness increases the weight of the molded product. The present invention is intended to provide a method for molding a molded article having a joint and a molding die, which solves the above-mentioned problems. Specifically, a pair of primary semi-molding is performed by primary molding. Even if the butt portion is slightly deformed after the product is molded to have the butt portion, the butt portions can be closely butted or fitted to each other at the time of the secondary molding. It is an object of the present invention to provide a method for molding a molded article having a joint, in which a molding resin does not leak, and a molding die used directly for carrying out this method.

[0004]

DISCLOSURE OF THE INVENTION According to the present invention, the abutment portion of one of the pair of primary semi-molded products is joined to the abutment portion of the other primary semi-molded product at the time of abutment. It is intended to achieve the above object by integrally forming a guide portion for guiding. That is, in order to achieve the above-mentioned object, the present invention injects a molten resin into a cavity formed by a fixed mold and a moving mold to form a pair of primary semi-molded products, one of which is a primary semi-molded product. A primary molding step in which the butted portion of the molded product is formed to have a butted portion that fits into the butted portion of the other primary semi-molded product; and after the primary molding step, the movable die is fixed Move it to the mold,
When a molded product is obtained from the secondary molding step in which the abutting portions of the pair of primary semi-molded products are butted against each other, and molten resin is injected into the butted parts to integrate the pair of primary semi-molded products, At the time of the primary molding step, a guide portion that guides the abutting portion on the side to be fitted at the time of butting is integrally formed with the abutting portion on the side to be fitted. The invention according to claim 2 is configured to mold a pair of primary semi-hollow molded articles during the primary molding step according to claim 1. The invention according to claim 3 comprises a fixed mold and a movable mold movably provided with respect to the fixed mold, and these molds are molded with at least a pair of primary molded products. Cavities are provided for the purpose of molding, and the abutting portions, one of which is fitted into the other when the pair of primary molded products are butted, are integrally molded by these cavities. In the mold, the core of the cavity for molding the abutting portion on the fitted side is provided with a taper portion for molding a guide portion for guiding the abutting portion on the mating side at the time of butting. ing.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to a mold for molding a hollow molded article and a molding method using this mold. As shown in FIG. 1, the mold according to the present embodiment includes a fixed plate 1 located on the left side of the drawing, a fixed mold 20 fixedly attached to the fixed plate 1, and The slide mold 40 and the like are configured to be slidably driven in the vertical direction and to be able to open the mold. A drive device for driving the slide mold 40 in the vertical direction in the figure, a movable plate for driving the slide mold 40 in the mold opening direction, an ejector device provided in the slide mold 40, and the like are not shown in the figure.

A substantially central shaft portion of the fixed platen 1
A sprue 2 is provided so as to traverse. Also,
As shown in FIG. 2B, the fixed platen 1 is
The primary molding runners 3 and 3 extending symmetrically in the vertical direction with respect to the sprue 2 in the vertical direction and the secondary molding runner 4 extending upward are formed. These runners 3, 3 and 4 are runner switching devices 5 described below.
I am contacting you at. The runner switching device 5 is a cylindrical bore 6 having a semicircular cross section, which is formed on the fixed platen 1 in a direction perpendicular to the paper surface in FIGS. 1 and 2C, and is slidably guided to the bore 6. The valve body 7 includes a piston cylinder device 8 that drives the valve body 7, and the like.

As shown in FIG. 2A, the valve body 7 has a shape in which a cylindrical body is divided into two parts, and the lower surface 7'contacts the parting surface of the fixed mold 20. It is adapted to be driven in the bore 6. On the lower surface 7 ′ of the valve body 7, there is formed a first resin passage 9 which is opened to the lower surface 7 ′ so as to cross the valve body 7, and an axial groove for resin passage which is similarly opened to the lower surface 7 ′. 11, a lower surface 7 ′ of the valve body 7 and a side resin passage 12 that is open to the side are formed. A first through hole 9'is formed in the first resin passage 9 perpendicularly to the paper surface of Fig. 2B. Similarly, a second through hole 10 'is also formed at the end of the groove 11 perpendicularly to the paper surface. The distance between the first through hole 9 ′ and the second through hole 10 ′ is equal to the distance between the runners 3 and 3 for primary molding and the runner 4 for secondary molding. .

Therefore, the valve body 7 is shown in FIG.
When the first position shown in (c) is taken, the sprue 2 of the stationary platen 1 is aligned with the first through hole 9 ′, and the sprue 2 passes through the first resin passage 9 for primary molding. Communicates with runners 3 and 3. When the piston cylinder device 8 drives the valve body 7 in the direction of the arrow to bring the sprue 2 to the second position in which the sprue 2 is aligned with the second through hole 10 ′, the sprue 2 moves to the second through hole 10 ′, the groove 11 and the side. Runner 4 for secondary molding via resin passage 12
Will be in communication with. This makes it possible to easily switch the runners 3, 3 and 4 for primary and secondary molding. Runners 3 and 3 for primary and secondary molding according to the present embodiment
Is provided on the parting surface of the stationary platen 1, and the first resin passage 9, the concave groove 11 and the like of the valve body 7 are open downward, that is, on the parting line P side.
When opened, the sprue, runner, etc. can be easily taken out. If the hot runner is used, the runner switching device 5 that switches the runners 3, 3 and 4 for the primary and secondary moldings can be easily configured.

As shown in FIG. 1, a fixed-side concave portion 21 having a rectangular side surface and having a predetermined depth is formed on the parting line P side above the fixed mold 20. The fixed-side concave portion 21 further extends from the bottom wall 22, a peripheral wall 22 ′ standing up from the bottom wall 22, a step portion 23 spreading outward from a predetermined height position of the peripheral wall 22 ′, and a step portion 23. It is composed of two peripheral walls 24 and the like. The fixed-side recessed portion 21 constitutes a first cavity C1 for forming a first primary semi-hollow molded product in cooperation with a slide-side core of a slide mold 40 described later. The second peripheral wall 24 is a portion for integrally forming a butt portion on a first primary semi-hollow molded product, which will be described later, and an annular sub runner 35 is provided on the parting line P side of the second peripheral wall 24. A plurality of secondary molding gates 36, 36, ... Provided from the sub-runner 35 with respect to the filling space for secondary molding have a gate angle smaller than 90 °.
6, the surface of the filling space and the gates 36, 3 leading to
6 and so on are opened so that they do not intersect vertically.

Further, in the lower position of the fixed mold 20, as shown in FIG.
As shown in FIG. 4, a hemispherical fixed-side core 26 of a predetermined size is formed protruding rightward from the parting line P. The fixed core 26 cooperates with a slide recess of the slide mold 40, which will be described later, to form a second cavity for molding a second primary semi-hollow molded product. An annular recess 27 is formed around the fixed core 26 so as to surround the fixed core 26 at a predetermined interval. Due to this annular recess 27, a butt portion described later is integrally molded with the second primary semi-hollow molded product.

At the upper position of the slide mold 40, a slide-side core 41 having a substantially columnar shape and protruding leftward in FIG. 1 from the parting line P is formed. The slide-side core 41 constitutes the first cavity C1 in cooperation with the fixed-side recess 21 of the fixed mold 20, and is smaller than the fixed-side recess 21 by the wall thickness of the hollow molded product. Then, at the base of the slide-side core 41, a first expanded diameter for cooperating with the second peripheral wall 24 of the fixed mold 20 to integrally form the abutment portion on the first primary semi-hollow molded product. Portion 43 and second expanded portion 4
5 are formed.

Between the first expanded diameter portion 43 and the second expanded diameter portion 45, a taper portion 46 for integrally forming a guide portion on the first primary semi-hollow molded product at the time of primary molding, 46, ... Are provided. The tapered portions 46, 46, ... Are provided so as to connect the distal end portion of the first expanded diameter portion 43 and the distal end portion of the second expanded diameter portion 45. Although only one taper portion 46, 46 is shown in FIG. 1, a plurality of taper portions 46, 46, ... Are formed at substantially equal intervals over the entire circumference in the present embodiment. In addition,
If the taper portion 46 is provided, the filling space portion described later becomes small, but it can be formed over the entire circumference.

A slide-side recess 47 having a hemispherical side surface opening to the parting line P is formed below the slide mold 40. This slide side recess 4
By means of 7, the second cavity C2 for forming the second primary semi-hollow molded product in cooperation with the fixed core 26 of the fixed mold 20 is configured. An annular core 48 that rises in a tapered shape is formed around the slide-side recess 47. The outer peripheral surface of the annular core 48, the inner peripheral surface of the annular recess 27 of the fixed mold 20, and the like form an abutment portion integrally with the second primary semi-hollow molded product.

As shown in FIGS. 1 and 2B, the fixed mold 20 has first and second sub-sprues 31 and 32 for primary molding and a sub-sprue 33 for secondary molding.
Are provided. One of the first and second sub-sprues 31 and 32 for primary molding communicates with the runners 3 and 3 for primary molding described above. Then, the first sub-sprue 31
The other of the second sub-sprues 32 opens to the bottom wall 22 of the fixed-side recess 21, that is, the first cavity C1 through a gate not shown in the figure, and the other of the second sub-sprues 32 to the top of the fixed-side core 26, that is, the second. Each of the cavities C2 is opened through a gate. One of the sub-sprues 33 for secondary molding communicates with the runner 4 for secondary molding, and the other communicates with an annular sub-runner 35 provided on the parting line P side.

Next, using the fixed mold 20 and the slide mold 40, first and second primary semi-hollow molded products are molded by primary molding, and molten resin is applied to the abutting portions of the peripheral edges thereof. A molding method for molding a hollow molded article by a secondary molding method for injection will be described. The slide mold 40 is slid to the first position shown in FIG. 1 and clamped. Also,
The valve element 7 of the runner switching device 5 is also switched to the first position shown in (b) and (c) of FIG. Then, the fixed board 1
The molten resin for primary molding is injected from the sprue 2 in the conventional manner. The molten resin flows from the sprue 2 of the stationary platen 1 to the first through hole 9 ′ of the valve body 7 of the runner switching device 5, the first resin passage 9, the primary molding runners 3, 3 and the primary molding. First and second through the first and second sub-sprues 31 and 32
The cavities C1 and C2 are injected and filled. The state in which the injection filling is completed and the first and second primary semi-hollow molded products A and B are molded is shown by dots in FIG.

By this primary molding, when the first primary semi-hollow molded article A is molded, it is shown in the opening of the first primary semi-hollow molded article A, as shown in FIGS. As described above, an abutting portion T including an annular step portion D, a bottom surface S, a peripheral surface M, and the like.
A is integrally molded. A plurality of guide portions G, G, ... Are integrally formed between the bottom surface S and the peripheral surface M. At the opening of the second primary semi-hollow molded product B, similarly, the abutting portion TB including the annular contact end D ′, the outer peripheral surface portion M ′, etc. is integrally molded.

After waiting for a certain degree of cooling and solidification, the slide mold 40 is opened by a predetermined interval. Then slide mold 4
0 is slid upward with the second primary semi-hollow molded product B attached to the mold, and the second semi-hollow molded product B is inserted into the opening of the first semi-hollow molded product A, that is, the abutment portion TA. To the second position where the abutting portion TB of is aligned. Then match the molds to tighten the molds. At this time, when the butting portion TB of the second semi-hollow molded product B is deformed, etc., as shown in FIG. The outer peripheral surface portion M ′ of the semi-hollow molded product B is forcibly guided to a normal position by the guide portions G, G, ... The contact end D ′ of the next semi-hollow molded product B surely contacts the step D of the first primary semi-hollow molded product A. Thus, the peripheral surface M and the bottom surface S of the first primary semi-hollow molded product A and the outer peripheral surface portion M ′ of the second primary semi-hollow molded product B form a leak-free filling space K. It

The valve element 7 of the runner switching device 5 is driven by the piston cylinder device 8 in the direction of the arrow in FIG. 2B to switch to the second position. A molten resin for secondary molding is injected from an injection machine. The molten resin is the sprue 2 of the fixed plate 1,
The second through hole 10 ′ of the valve body 7 of the runner switching device 5 and the concave groove 1
1, through the side resin passage 12, the second runner 4, the secondary sprue 33 for secondary molding, etc., to reach the annular subrunner 35 for secondary molding, and a plurality of gates 36, 36,
The filling space K is filled from. By this secondary molding, the first and second primary semi-hollow molded products A and B are integrated. Waiting for cooling and solidification, the slide mold 40 is opened. Although the surface areas of the primary semi-hollow molded products A and B are not accurately shown in the figure, there is a difference, and when the slide mold 40 is opened, the integrated molded product is the one of the slide mold 40. Be opened with. The molded product is ejected by the ejector pin. The integrated hollow molded product is shown in FIG.
The above operation is repeated to mold.

According to the present embodiment, at the time of the secondary molding, even if the outer peripheral surface portion M ′ of the second primary semi-hollow molded product B forming the filling space portion K is deformed, the filling space is filled. Part K
Since they are densely packed, the resin for secondary molding does not leak. Therefore, it is possible to obtain a hollow molded product having a high bonding strength and high quality. Further, according to the present embodiment, the gate angle is set to be smaller than 90 ° during the secondary molding so that the surface of the filling space communicating with the gates 36, 36, ... And the gates 36, 36 ,. Since injection filling is performed so as not to intersect with each other, even if the injection pressure for the secondary molding is increased, the molten resin for the secondary molding is abutted at the abutting portions TA, TB.
There is little danger of breaking through and leaking inside.

The present invention can be implemented in various forms without being limited to the above embodiment. For example, it is obvious that the shapes of the abutting portions TA and TB of the first and second primary semi-hollow molded products A and B are not limited to the above-mentioned embodiment, and can be implemented with other shapes. Further, in the above embodiment, the guide portions G, G, ... Are molded into the first primary semi-hollow molded product A, but the shape of the abutting portions TA, TB is changed to the second primary semi-hollow molding. It can also be provided on the molded product B. Moreover,
Although a hollow molded product is molded in this embodiment, it is obvious that molded products other than the hollow product can be molded in the same manner.
That is, in the primary molding, a pair of primary molded products are molded so as to have the abutting portion, the abutting portions are abutted as described above, and the resin is injected into the abutting portion in the secondary molding to obtain a complicated shape. It is also possible to mold a real molded product. Further, it is also possible to increase the number of cavities and simultaneously mold a plurality of hollow molded products with a mold having one surface. Further, it is apparent that the rotating die which takes the first position and the second position by rotating, instead of the slide die 40, can be similarly implemented.

[0021]

As described above, according to the present invention, the molten resin is injected into the cavity formed by the fixed mold and the moving mold to form a pair of primary semi-molded products, one of which is one of In the primary molding process, the abutting portion of the next semi-molded product is formed so as to have the abutment portion that fits into the abutment portion of the other primary semi-molded product Sometimes the guide part that guides the abutting part on the mating side is integrally molded, so even if the abutting part is slightly deformed and the position is misaligned, the abutting part should be closely abutted during secondary molding. Can be fitted or fitted. Therefore,
According to the present invention, it is possible to obtain a molded product having a high-quality bonded portion with a high bonding strength without the secondary molding resin leaking. Even if the rigidity of the abutting portion is low, the abutting portion can be closely abutted by the guide portion, so that the cooling and solidifying time after the primary molding can be shortened. Alternatively, the abutting portion can be made thin. Therefore, according to the present invention, the effect that the molding cycle can be shortened and the joint portion can be made thin is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an embodiment of a mold of the present invention with a slide mold opened.

FIG. 2 is a diagram schematically showing an example of an embodiment of a runner switching device, in which (a) is a perspective view of a valve body, and (b) is a runner when the valve body moves to a first position. The top view of a switching device and the (C) are sectional drawings.

FIG. 3 is a cross-sectional view showing a state in which primary molding has been completed using the mold shown in FIG.

FIG. 4A is a cross-sectional view showing a state before secondary molding in which a slide mold is slid to a second position, and FIG. 4B is a hollow molded product molded by secondary molding. FIG.

[Explanation of symbols]

1 fixed plate 20
Fixed mold 21 Fixed side recess 26
Fixed core 40 Slide mold 41
Sliding side core 46 Tapered part 47
Sliding side recess C1, C2 First and second cavities K Filling space TA, TB Butt

Claims (3)

[Claims] 1. A pair of primary semi-molded products (A, B) are obtained by injecting a molten resin into a cavity (C1, C2) constituted by a fixed mold (20) and a movable mold (40). , A butting portion (TA, TB) such that the butting portion (TB) of one of the primary semi-molded products (B) is fitted to the butting portion (TA) of the other primary semi-molded product (A). A primary molding step of molding so as to have, and after the primary molding step, the movable mold (40) is moved with respect to the fixed mold (20) to form a pair of primary semi-molded products (A, Butt parts (TA, TB) of B) are butted against each other,
Then, the molten resin is injected into the butted part (K),
When a molded product is obtained from a secondary molding process in which a pair of primary semi-molded products (A, B) are integrated, a butt part (TA) on the side to be fitted during the primary molding process.
, A guide part (G, G, ...) Which guides the abutting part (TB) on the mating side at the time of butting is integrally formed.
A method for molding a molded article having a joint, characterized in that 2. A method of molding a molded article having a joint, wherein a pair of primary semi-hollow molded articles (A, B) are molded during the primary molding step according to claim 1. 3. A fixed mold (20) and the fixed mold (2)
0) movable mold (4
0) and these dies (20, 40) are provided with cavities (C1, C2) for molding at least a pair of primary molded products (A, B), and these cavities (C1 , C2), a pair of primary molded products (A, B)
Is a mold in which the abutting portions (TA, TB), one of which is fitted to the other of the two when they are butted, are integrally molded, and the fitting of the cavity (C1) Butt part (T
The core (41) for molding A) is provided with a guide portion (G,
Tapered portions (46, 46, ...) For molding G, ...
A mold for molding a molded article having a joint portion characterized by being provided with.