JP2012025090A - Molding method of molding section in weather strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method of a molding section by which molding accuracy and the product quality are improved.SOLUTION: A so-called gas assist molding method is adopted in the molding of a hollow molding section 7 using the mold 8. A terminal part of an extrusion molding parts 5, 6 is inserted into a molding part cavity 9, a cavity 11 for a non-product shaped portion, which is branched from a position close to the terminal part of the extrusion molding parts 5, 6 is formed. A core 10 extended to range over both sides of the extrusion molding parts 5, 6 and the molding part cavity 9 is set to the mold 8. The resin material is injected to the molding part cavity 9 while injecting the assist gas in succession and the molding part 7 which uses the gas channel formed by the injection of the assist gas as an independent hollow part 15 is molded to be continuous with the extrusion molding parts 5, 6.

Description

  The present invention relates to a molding method of a molded part in a weather strip for automobiles, and more particularly to a method of molding a hollow mold part continuously with a hollow extruded part with a mold. is there.

  A method described in Patent Document 1 has been proposed as a method of forming a mold forming portion in this type of weather strip. In this conventional technology, when the hollow mold part is continuously formed after the hollow extrusion part, the so-called blow molding principle is applied. If the rubber material hangs down in a cylindrical shape, the cylindrical tip is closed, and the volume of the unvulcanized rubber material is increased in the mold, and at the same time, gas is blown into the interior, thereby removing the unvulcanized rubber material from the metal. While being pressed against the inner wall surface of the mold, it is molded as a hollow mold forming portion.

JP-A-5-237855

  The technique described in Patent Document 1 has the advantage that the core can be made small, and the shape of the core punched hole inevitably generated in the molded part after molding can be reduced. The next failure is forced to occur.

  (A) Since the unvulcanized rubber material is stretched locally before the unvulcanized rubber material reaches the inner wall surface of the mold in the details of the molded part, gas easily leaks from the unvulcanized rubber material. Not only can complicated shapes be molded.

  (B) It is necessary to close the cylindrical tip of the unvulcanized rubber material that hangs down in a cylindrical shape, and the mechanism for that is complicated. There is a risk of inviting.

  (C) Since the gas pressure cannot be increased, the thickness of each part of the molded part cannot be positively controlled.

  The present invention has been made paying attention to the above problems, and has the advantage that the shape of the core punch hole inevitably generated in the molded part after molding can be reduced in addition to the shape of the core. The present invention provides a molding method of a molded part that eliminates the secondary problems as described above and improves molding accuracy and molding quality while making full use.

  In the present invention, it can be understood that a so-called gas assist molding method is applied in forming a hollow mold-molded portion continuously with a hollow extrusion-molded portion in a weather strip with a mold.

  That is, the present invention is for a discarded dough that branches from a position close to the end of the extrusion molding part of the mold molding part cavity by inserting the end of the extrusion molding part into the mold molding part cavity of the mold. A cavity is formed. Furthermore, it is inserted into the inner periphery of the end of the extrusion molding part, so that it extends across both the extrusion molding part and the mold molding part cavity, and a part of which protrudes outside the mold molding part cavity. Set the core in the mold.

  Then, a plasticizing material is injected into the mold forming portion cavity, and subsequently, an assist gas is injected, and a mold forming portion having a gas channel formed by the injection of the assist gas as an independent hollow portion is provided. It shall be formed continuously in the extrusion part.

  According to the present invention, a so-called gas-assisted molding method is adopted, and a gas channel formed by gas injection is used as it is as a hollow part of the mold part, so that the core to be used has a minimum necessary size. In addition, the shape of the core punch hole inevitably generated in the molded part after molding can be reduced.

  In addition, since the waste dough cavity is formed separately from the mold molding part cavity, the pressure of the assist gas acts on every corner of the mold molding part, so that the thickness of the mold molding part can be made uniform. In addition, even thin portions can be accurately molded by being closely adhered to the mold. Furthermore, since the molded mold part can be sufficiently pressed against the end part of the extrusion part by the pressure of the assist gas, the bonding strength with the extrusion part is also improved.

  In addition, since the process of closing the tip of the cylindrical body is not required as in the prior art exemplified above, the mold structure can be simplified without causing molding defects.

The perspective view which shows the outline of the door of the motor vehicle with which the door weather strip was mounted | worn. (A) is the A section enlarged view of the door weather strip in FIG. 1, (B) is an expanded sectional view which follows the aa line | wire of the same figure (A). The figure which shows the 1st Embodiment of this invention, and is plane | planar explanatory drawing of the metal mold | die for shape | molding the shaping | molding part shown in FIG. The expanded sectional view which follows the BB line of FIG. Cross-sectional explanatory drawing which follows the CC line | wire of FIG. Cross-sectional explanatory drawing which follows the DD line | wire of FIG. FIG. 5 is a perspective view of the core shown in FIG. 4 alone. (A) is front explanatory drawing of the core shown in FIG. 7, (B) is sectional drawing which follows the EE line | wire of the same figure (A). FIG. 2 is an explanatory view when assist gas is injected following a resin material in the mold structure shown in FIG. 1. The expanded sectional view which follows the FF line of FIG. The expanded sectional view which follows the GG line of FIG. The expanded sectional view which follows the HH line of FIG. (A) is explanatory drawing at the time of shaping | molding in case the protrusion part is not formed in the core of FIG. 10, (B) is explanatory drawing which shows the state which extracted the core from the state of the same figure (A). Cross-sectional explanatory drawing of the molding part shape | molded with the metal mold | die structure of FIG. FIG. 10 is a diagram of a molding part molded with the mold structure of FIG. It is a figure which shows the 2nd Embodiment of this invention, and is process explanatory drawing at the time of resin material injection | pouring. Process explanatory drawing when assist gas is inject | poured following FIG.

  FIG. 1 shows an outline of a door (front door) 1 of an automobile to which a door weather strip 4 is mounted. As is well known, it is a peripheral portion of a door 1 including a door body 2 and a door sash 3 and the vehicle. A long string-like and hollow door weather strip 4 is mounted in a closed loop shape on the indoor side. The door weather strip 4 is formed of a thermoplastic resin material such as an elastomer (TPE = thermo-plastic / elastomer) generally defined as “a thermoplastic plastic having low hardness and rubber elasticity”, for example. .

  FIG. 2 shows an example of a molded part (corner molded part) of the door weather strip 4 at a part corresponding to the corner part of the door sash 3 as an enlarged view of the A part of FIG. The end portions of the hollow extruded portions 5 and 6 that are extruded as general portions are connected to and integrated with the molding portion 7 with joint lines P1 and P2. As shown in FIG. 2B, the cross-sectional shape of the molded part 7 is substantially the same as that of the extruded parts 5 and 6, the bottom side is the mounting surface 7a to the door sash 3, and the top side is the counterpart side The elastic contact seal surface 7b to the panel is so-called crushed and deformed by the elastic contact of the elastic contact seal surface 7b.

  FIG. 3 is an explanatory plan view of a mold for forming the mold forming portion 7, and FIG. 4 is an enlarged cross-sectional view taken along line BB of FIG. 5 and 6 are sectional views taken along lines CC and DD in FIG. 4, respectively.

  The mold 8 shown in FIG. 3 is engraved with a mold forming portion cavity 9 as a product shape portion space for controlling the forming of the mold forming portion 7. Note that the mold 8 includes an upper mold 8A and a lower mold 8B as main elements as shown in FIGS. As shown in FIGS. 3 and 4, the end portions of the hollow extruded portions 5 and 6 extruded in a separate process are inserted into both ends of the cavity 9 for the molded portion so as to be inserted. The molding part cavity 9 is a sealed space. In addition, a material injection port 13 that also serves as a gas injection port is formed in the mold 8 so as to communicate with the mold molding portion cavity 9, and a resin material that is to become the molding unit 7 from the material injection port 13, That is, the same plastic material as the material of the extrusion molding parts 5 and 6 or a plasticized resin material having good affinity is injected (filled) toward the mold molding part cavity 9.

  A substantially elbow-shaped core 10 is set in the mold 8 in advance as shown in FIGS. The core 10 is for preventing the rubber material from entering the hollow portions of the respective extrusion molding parts 5 and 6, and is one of the main body parts 10a inserted into the terminal parts of the extrusion molding parts 5 and 6. A leg portion 10b for positioning is formed on the portion, and is bent in a substantially elbow shape as a whole. The end of the main body 10a of the core 10 is inserted into the inner periphery of the end of the extrusion parts 5 and 6 so as to extend over both the extrusion parts 5 and 6 and the mold part cavity 9. The legs 10b are pre-fitted to the mold 8 and positioned so that the legs 10b protrude to the outside of the mold forming cavity 9. The detailed shape of the core 10 alone is shown in FIGS.

  Further, as shown in FIG. 5, the mold 8 is not positioned at a position close to the end portions of the extrusion molding portions 5 and 6 in a plan view, that is, on both side positions overlapping with the positions of the respective cores 8 as shown in FIG. Disposable dough cavities 11 as product shape space are formed symmetrically in advance. These waste dough cavities 11 are branched via a runner portion 12 from a position in the mold forming portion cavity 9 that overlaps the core 10 in the longitudinal direction. As shown in FIGS. 7 and 8 in addition to FIGS. 4 and 5, a concave groove 10 c is formed in a portion of the both side surfaces of the main body portion 10 a of the core 10 facing the runner portion 12. The concave groove 10c gradually changes so that the groove width gradually decreases toward the end face 10d.

  Here, in the main body portion 10a of the core 10, the portion opposite to the portion inserted into the end portions of the extruded portions 5 and 6, that is, the other end portion on the opposite side to the end surface 10d side is used as one end portion. The shape of 10e is an important element in controlling the flow of the resin material and assist gas filled from the direction of arrow Q in FIG. For this reason, as shown in FIG. 7, the shape of the other end 10e of the main body 10a in the core 10 is a smooth cylindrical surface in plan view, and the leg 10b among the other ends 10e. A projecting portion 10f is formed by projecting a portion far from the projection.

  Since the waste dough cavity 11 is set to prevent short shots (insufficient filling) of the resin material, the waste dough cavity 11 is filled with a predetermined resin material in the same manner as the mold forming portion cavity 9. However, the waste dough cavity 11 does not function as a product part shape space like the mold forming part cavity 9, but only functions as a non-product shape part space.

  Therefore, the molding of the molding part 7 under the structure of the mold 8 including the core 10 is performed in the following procedure.

  As shown in FIGS. 5 and 6 in addition to FIGS. 3 and 4, the end portions of the extrusion molded portions 5 and 6 are inserted into both end portions of the cavity 9 for the molded portion, and the end portions of the extrusion molded portions 5 and 6 are inserted. When the core 10 is set so as to insert the main body portion 10a, the mold is clamped, and a resin material is injected (filled) from the material injection port 13, followed by an assist gas (for example, nitrogen) from the material injection port 13 similarly. ).

  Here, FIG. 9 shows a state of the mold 8 when the assist gas is injected following the resin material, and FIG. 10 shows an enlarged sectional view taken along the line FF of FIG. Moreover, sectional views taken along lines GG and HH in FIG. 10 are shown in FIGS. 11 and 12, respectively.

  As is apparent from FIGS. 9, 10 and 11, 12, when the assist gas is injected after the resin material, the gas proceeds while pushing out the resin material from the material injection port 13 toward the distant dough cavity 11. In response to the gas pressure, the resin material is spread to every corner of the mold forming part cavity 9 as well as the waste dough cavity 11. The mold forming part 7 is formed so as to be connected. At the same time, the discarded dough forming portion 14 is formed in the discarded dough cavity 11. In the passage portion formed by the passage of gas, the resin material is pressed against the mold 8 at a uniform pressure and shaped, so that the mold surface has good transferability, and particularly a thin portion is faithfully molded. Moreover, since the waste dough cavity 11 is formed symmetrically, the fluidity of the resin material and the assist gas is extremely stabilized.

  On the other hand, since the gas passage is extended not only to the mold forming portion cavity 9 but also to the discarded dough cavity 11, the gas channel 15 as the gas passage is left inside as a hollow portion. In particular, in the molded part 7 after molding, the gas channel 15 remains as it is while being connected to both the hollow extruded parts 5 and 6, and the hollow part is independent from the extruded parts 5 and 6. Will function as.

  In this case, the waste dough cavity 11 is formed so as to branch from the position farthest from the material injection port 13 in the mold forming portion cavity 9, and the gas channel 15 extends to the waste dough cavity 11. Therefore, as a result, the resin material is surely injected into every corner of the cavity 9 for the molded part, and so-called short shot (underfilling) is prevented from occurring.

  More specifically, as apparent from FIG. 10, since the shape of the other end 10e of the main body 10a of the core 10 is cylindrical in plan view (see FIG. 7), the resin material is injected following the resin material. The abutted assist gas abuts against the other end portion 10e of the main body portion 10a, splits into two forks and flows into both side surfaces of the core 10 (main body portion 10a). The end of the gas channel 15 is formed from the concave groove 10c (see FIGS. 7 and 8) through the runner portion 12 to the waste dough cavity 11.

  In this case, in the present embodiment, as shown in FIG. 10, since the protrusion 10f is formed at the other end 10e of the main body 10a in the core 10, the resin material and the assist that is subsequently injected are formed. The partition 16 is formed of a resin material whose gas flow is positively controlled by the protrusion 10f and pressed against the other end 10e of the main body 10a by the pressure of the assist gas. The thickness near the top of the elastic contact seal surface 7b (see FIG. 2) is substantially uniform. As a result, it is possible to ensure appropriate elasticity (reaction force characteristics) on the elastic contact seal surface 7b side, which is functionally important as the hollow molded part 7.

  On the other hand, FIG. 13 shows an example in which the protruding portion 11 f is not formed on the other end portion 10 e of the main body portion 10 a of the core 10. 2A shows a cross-sectional view during gas injection, and FIG. 2B shows a state after molding and after the core 10 has been removed. In the case of these FIG. 13, the flow of the resin material and the assist gas injected subsequently is different from that of FIG. 10, and the elastic sealing surface 7b at the top of the partition wall 16 (see FIG. 2). ) Will be formed as the thick portion W. As a result, it is not possible to ensure an appropriate elasticity on the elastic contact seal surface 7b side, which is functionally important as the hollow molded part 7.

  When the extrusion molding parts 5 and 6 are connected together with the molding of the mold molding part 7, the mold is opened and the molded product is taken out from the mold 8 together with the core 10, and the core 10 is molded. The so-called forcible removal is performed using the elasticity of the portion 7. Finally, the discarded dough forming part 14 attached to the mold forming part 7 is cut and removed together with the runner part 12. FIG. 14 shows a cross-sectional shape of the molded part 7 including the extruded parts 5 and 6 thus formed, and FIG. 15 shows a cross-sectional view equivalent to FIG.

  As is apparent from FIGS. 14 and 15, the extrusion molded parts 5, 6 are connected to the mold molding part 7 with joint lines P 1, P 2, but the gas channel 15 is left as an independent hollow part in the mold molding part 7. In other words, the hollow portions of the extrusion moldings 5 and 6 are left as non-continuous hollow portions 15.

  And since only the oval or oval core punching hole R corresponding to the leg portion 10b of the core 10 is opened on the side of the mounting surface 7a (see FIG. 2) of the molded mold portion 7, For example, the closing process of the core punching hole R becomes unnecessary. This is because the partition wall 16 is formed adjacent to the core punching hole R. For example, when the mold forming portion 7 is so-called crushed and deformed, the partition wall 16 is necessary and sufficient without closing the core punching hole R. This is because a good reaction force characteristic can be maintained.

  As described above, according to the present embodiment, the so-called gas assist molding method is adopted, and the gas channel 15 formed by gas injection is used as it is as the hollow portion of the mold forming portion 7. As a result, the shape of the core punching hole inevitably generated in the molded part 7 after molding can be reduced.

  Further, since the waste dough cavity 11 is formed separately from the mold molding portion cavity 9, the pressure of the assist gas acts on every corner of the mold molding portion 7 to make the thickness of the mold molding portion 7 uniform. In addition to being molded as a product, even thin portions can be molded with high precision by being closely adhered to the mold 8. In addition, since the molded mold part 7 can be sufficiently pressed against the terminal parts of the extrusion molding parts 5 and 6 by the pressure of the assist gas, the bonding strength with the extrusion molding part 7 is also improved. Furthermore, since the process of closing the tip of the cylindrical body as in the prior art exemplified above is unnecessary, the molding 8 can be simplified without causing molding defects.

  16 and 17 show a second embodiment of the molding method according to the present invention, and the same reference numerals are given to the parts common to the first embodiment.

  In the second embodiment, when molding at least the molding part 7 using a thermoplastic resin material, a heater 17 is embedded in the other end part 10e of the main body part 10a of the core 10, and the other end part is provided. The temperature near 10e is positively controlled. That is, during molding, by maintaining the temperature in the vicinity of the other end 10e of the core 10 higher than that of other parts, the wall of the partition wall 16 (see FIG. 15) formed by contacting that part. It tries to make the thickness thinner.

  As shown in FIG. 16A, the temperature in the vicinity of the other end portion 10e of the main body portion 10a of the core 10 is maintained higher than the other portions by energizing the heater 17 as shown in FIG. As shown, a predetermined resin material is injected to mold the mold part 7. When the resin material is injected, the resin material M in the vicinity of the other end portion 10e of the main body portion 10a in the core 10 is relatively solidified by thermal influence from the other end portion 10e as shown in FIG. It becomes possible to maintain the molten state until late, with a delay in the time until.

  Therefore, as shown in FIG. 17A, when the assist gas is injected after the resin material, the gas proceeds to push out the resin material to form the gas channel 15.

  At that time, as described above, the temperature in the core 10 near the other end 10e of the main body 10a, that is, the portion of the core 10 opposite to the portion inserted into the end portions of the extrusion molded portions 5 and 6 is opposite. The temperature of the portion adjacent to the tip of the gas channel 15 formed by the assist gas injected into the mold forming portion 7 is set higher in advance than the temperature of the other portion of the core 10. Therefore, the resin material M near the other end 10e of the main body 10a in the core 10 is relatively delayed in solidification due to the thermal effect from the other end 10e. Therefore, as shown in FIG. 5B, the partition wall 16 formed by being pressed against the other end portion 10e of the main body portion 10a by gas pressure is further extended, and the partition wall 16 is made thinner. It will be. Thereafter, when a predetermined time has elapsed from the start of filling of the resin material and the assist gas, the heater 17 is turned off to promote solidification.

  According to the second embodiment, the thickness of the partition wall 16 that separates and forms the gas channel 15 as an independent hollow portion of the mold forming portion 7 is further reduced, so that the mold forming portion 7 The elasticity or flexibility of the elastic contact seal surface 7b (see FIG. 2), which is important in terms of function, is further improved.

  In each of the above embodiments, the case where the molding part 7 is molded together with the extrusion molding parts 5 and 6 using a thermoplastic resin material such as an elastomer is exemplified, but molding is performed using a rubber material such as EPDM. In this case, the present invention can be applied. However, in the case of a rubber material, vulcanization is required, so the heater 17 shown in FIGS. 16 and 17 is eliminated.

  Moreover, not only when the extrusion molding parts 5 and 6 are connected by shaping | molding of the shaping | molding part 7 as mentioned above, but a deformed and hollow terminal part is shape | molded at one terminal of a long weather strip, for example. The present invention can also be applied to cases.

DESCRIPTION OF SYMBOLS 4 ... Door weather strip 5,6 ... Extrusion part 7 ... Molding part 8 ... Mold 9 ... Mold forming part cavity 10 ... Core 10a ... Main-body part 10e ... Other end part 10f ... Protrusion part 11 ... For waste cloth Cavity 11c ... concave groove 13 ... material injection port 14 ... discarded dough forming part 15 ... gas channel (hollow part)
17 ... Heater

Claims (6)

A method of forming a hollow mold-molded part in a mold in succession to a hollow extruded part in a weather strip,
Insert the end of the extrusion part into the mold part cavity of the mold,
While forming a waste dough cavity branching from a position close to the end of the extrusion molding portion of the mold molding portion cavity,
Inserted into the inner periphery of the end of the extrusion part, it extends across both the extrusion part and the mold part cavity, and a part of it protrudes outside the mold part cavity. Set the child in the mold,
While injecting plasticizing material into the mold part cavity, and subsequently injecting assist gas,
A molding method for a molded part in a weather strip, characterized in that a molded part having a gas channel formed by injection of the assist gas as an independent hollow part is continuously molded in an extruded part.   2. The molding of a mold part in a weather strip according to claim 1, wherein a plasticizing material is injected into the mold part cavity including the waste dough cavity, and subsequently an assist gas is injected. Method.   3. The molding of the mold forming part in the weather strip according to claim 2, wherein a waste dough cavity branching from a position overlapping with the core in the longitudinal direction of the mold forming part cavity is formed. Method.   4. A method for forming a mold forming portion in a weather strip according to claim 3, wherein a dough cavity is formed on both sides of the core.   Of the above core, the shape of the portion opposite to the portion inserted into the end of the extrusion molding portion is such that the partition wall formed of a plasticizing material pressed against the portion by the pressure of the assist gas has a uniform thickness The method for forming a mold forming portion in a weather strip according to any one of claims 1 to 4, wherein the shape is a shape to be obtained.   The temperature of the portion of the core that is opposite to the portion that is inserted into the end of the extrusion molding portion and that is close to the tip of the gas channel formed by the assist gas injected into the mold forming portion. 6. The method for forming a molded part in a weather strip according to claim 5, wherein the temperature is set in advance higher than the temperature of the other part of the core.

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