WO2024048318A1

WO2024048318A1 - Method for molding extension member

Info

Publication number: WO2024048318A1
Application number: PCT/JP2023/029788
Authority: WO
Inventors: 賢一松永
Original assignee: 株式会社小糸製作所
Priority date: 2022-08-31
Filing date: 2023-08-18
Publication date: 2024-03-07
Also published as: JP2024033782A

Abstract

The present invention relates to a method for injection molding an extension member provided in a vehicle lamp, in particular to a method for injection molding an extension member including a bridge footing portion. Provided is a method for injection molding an extension member, the extension member being provided in a vehicle lamp which accommodates a plurality of light-emitting optical units, having an opening formed inside, including a bridge footing portion dividing the opening into multiple parts, and shielding at least some of the optical units from the outside. A die for molding the extension member is provided with at least a pair of gates in a position facing a cavity for forming the bridge footing portion. An adjustment is made to guide the position of a weld line formed on the bridge footing portion to a desired area by setting different gate open start times for the pair of gates. In this way, development of a weld line is inhibited.

Description

Extension member molding method

The present invention relates to a method of molding an extension member included in a vehicle lamp, and particularly relates to a method of molding an extension member having a pier portion.

In vehicle lighting, the shape of the extension member that hides the internal structure is becoming more complex due to design needs. For example, Patent Document 1 discloses a vehicle lamp equipped with a plurality of optical units, but such a combination lamp has a plurality of openings through which the irradiated light from each optical unit passes. Large extension members are used. An extension member having a plurality of openings is mainly composed of a frame portion having a large opening in the center and forming an outer shell, and a pier portion provided so as to partition the openings of the frame portion.

When a large extension member with multiple openings is injection molded, weld lines will occur in the molded product due to the wraparound and merging of molten resin. For this reason, measures are taken to minimize the impact on the design by making the weld line as inconspicuous as possible, and by providing a degassing nest in the mold to make the weld line thinner. In recent years, the position of weld line occurrence has been predicted to some extent through simulation, and molds have been created by providing degassing nests in accordance with the predicted position of weld line occurrence.

JP2010-123292

However, in extension members that have piers, the piers are thinner and thinner than the frame, so it is difficult to accurately predict the position of weld lines that occur on the piers. There is a problem in that there is often a large difference between the predicted position by simulation and the actual position of occurrence. The mold for the extension member is pre-installed with a degassing insert at the predicted position of the weld line, so if there is a discrepancy between the predicted position and the actual position, the wall thickness must be changed or the degassing insert must be replaced. It is necessary to take measures such as changing the position of the mold that involve mold processing, which takes time and costs.

The present invention was made in view of such problems, and provides a resin molding method for extension members that includes measures against weld lines of bridge piers.

In order to solve the above problem, a resin molding method for an extension member according to an aspect of the present disclosure is provided in a vehicle lamp that houses a plurality of optical units that emit light, an opening is formed inside, and the opening is A method for injection molding an extension member that has a pier that divides the optical unit into a plurality of parts and that shields at least a portion of the optical unit from the outside, the mold for molding the extension member having at least a pair of gates. , is provided at a position opposite to the cavity forming the pier, and by making the gate opening start times of the pair of gates different, the position of the weld line formed on the pier can be set at a desired location. Adjustments were made to guide the

According to this aspect, in order to make the gate opening start times of the pair of gates different, if the gate opening start time of one of the pair of gates is delayed (hereinafter referred to as adjusting the gate opening start time of the pair of gates). (In particular, control that delays the opening start time of one gate is called "delay control.") Compared to a case where the opening start time of a pair of gates is set at the same time, the weld line that occurs on the bridge pier is less likely to occur when the gate opens. Occurs near one gate where the start time is delayed. Piers are thinner, thinner, and smaller in volume than other parts, making them difficult to predict and susceptible to delay control. By delay control, the weld line generation position can be guided to a desired location such as the installation position of the degassing insert without machining the mold.

Further, in one aspect, the opening speeds of the pair of gates are made different to adjust the weld line formed on the pier portion to be guided to a desired location. According to this aspect, when the opening speed of one gate is delayed, the weld line that occurs on the pier section is smaller than when the opening speed of the gate is delayed, compared to when a pair of gates are opened at the same speed at the same time. Occurs near the gate. Thereby, it is possible to guide the generation position of the weld line to the installation position of the degassing nest.

As is clear from the above description, it is possible to provide a method for molding an extension member that includes measures against weld lines of bridge piers.

FIG. 1 is a front view showing a schematic configuration of a vehicle lamp including an extension member according to a preferred embodiment. An extension member is shown. FIG. 2(A) is a front view of the extension member. FIG. 2(B) is an end view taken along line II(B)-II(B). It is a perspective view of an extension member. FIG. 3(A) is a front side perspective view. FIG. 3(B) is a perspective view of the back side. The extension members are colored with light ink. The position of the weld line that occurs on the extension member is shown. FIG. 4(A) shows predicted positions of weld lines generated by simulation. FIG. 4(B) shows the position where a weld line actually occurs (without delay control). The thick line rectangle in the figure indicates the position of the degassing insert provided in the mold of the extension member. 7 is a table showing an example of weld line movement amount by delay control. The position of the weld line that occurs on the extension member is shown. The thick line rectangle in the figure indicates the position of the degassing insert provided in the mold of the extension member. The mold for the extension member is shown. 7 is an end view cut at a position corresponding to line VII-VII in FIG. 6. FIG. The mold for the extension member is shown. 7 is an end view cut at a position corresponding to line VIII-VIII in FIG. 6. FIG. The flow of the molding method is shown.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The embodiments are illustrative rather than limiting the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. In addition, in the following description of the embodiment and modified examples, the same configurations are denoted by the same reference numerals, and overlapping description will be omitted as appropriate.

(vehicle lighting)
FIG. 1 is a front view of a vehicle lamp 1 including an extension member 10 according to an embodiment. The vehicle lamp 1 is a combination lamp consisting of a headlamp and a turn signal lamp, and is arranged in a pair on the left and right at the front end of the vehicle body.

As shown in FIG. 1, the vehicle lamp 1 includes a lamp body 2 and a lamp cover 4. The lamp body 2 is formed into a box shape with an open front. The lamp cover 4 is made of translucent resin, glass, or the like, and is attached to the front opening of the lamp body 2 to form a lamp chamber.

Inside the lamp chamber, a first optical unit LU1 forming a headlamp unit, a second optical unit LU2 forming a turn signal lamp unit, and an extension member 10 are arranged.

The first optical unit LU1 and the second optical unit LU2 include a light source that is a light emitting element, and emit light emitted from the light source to the front of the vehicle. The first optical unit LU1 is a variable light distribution unit that forms not only high beam light distribution and low beam light distribution, but also a light distribution pattern adapted to the driving situation of the vehicle and surrounding conditions, and irradiates the front of the vehicle. . The second optical unit LU2 emits amber light to the front of the vehicle. Hereinafter, the two optical units will be collectively referred to as an optical unit LU, unless a specific optical unit is specified.

The optical unit LU uses a known configuration such as a scanning mechanism device, a reflector type device, a projector type device, etc., and the type thereof does not matter. Further, the configuration of the present disclosure is not limited to the extension member used in the combination lamp. For various types of vehicle lighting where combination lamps with multiple optical units are used, such as tail lamps, turn signal lamps, stop lamps, clearance lamps, daytime running lamps, cornering lamps, hazard lamps, positioning lamps, back lamps, fog lamps, etc. , it can be widely applied as an extension member that hides the internal structure.

(Extension member)
2 and 3 show the extension member 10. FIG. FIG. 2(A) is a front view of the extension member 10. FIG. 2(B) is an end view taken along line II(A)-II(A) in FIG. 2(A). FIG. 3(A) is a front perspective view (front side perspective view) of the extension member 10. FIG. 3(B) is a rear perspective view (back perspective view) of the extension member 10. Note that in FIGS. 2, 3, and 4 and 6, which will be described later, the extension member 10 is colored with light black in order to clearly show the opening.

The extension member 10 is arranged in front of the optical unit LU, and covers the gap between the optical unit LU and the lamp body 2 and the gap between the adjacent optical units LU, so that the internal structure of the optical unit LU can be seen from the outside. It is a thin injection molded product made of PBT (polyrylene terephthalate) resin, polypropylene resin, polyester resin, etc.

In the present embodiment, the extension member 10 has a pentagonal outer shape when viewed from the front, and has a large opening formed inside to form the outer shell of the extension member 10, and a frame portion 20 that forms the outer periphery of the opening. , mainly consists of a pier section 12 that spans the opening of the frame section 20 and extends in the vertical direction.

When viewed from the front, the frame portion 20 is formed by connecting five sides of a predetermined width, including an upper side 21 which is the longest side, a lower side 22 that is approximately half the length of the upper side 21, and a lower side 22 that is parallel to the upper side 21, and an upper side 21. The right side 23 is the oblique side that connects the right end of the upper side 21 and the right end of the lower side 22, the left side 24 extends vertically downward from the left end of the upper side 21, and the lower left side is the oblique side that connects the lower end of the left side 24 and the left end of the lower side 22. The five sides of side 25 are connected.

The pier portion 12 is provided vertically above the opening of the frame portion 20, connecting the connection portion between the lower side 22 and the right side 23 and the upper side 21 in the vertical direction. The opening formed inside the frame 20 is largely divided into right and left sides by the pier 12 extending over the opening of the frame 20. Inside the frame 20, with the pier 12 as a boundary, a large rectangular first opening OP1 is formed on the left side, and a relatively small triangular second opening OP2 is formed on the right side.

The first opening OP1 and the second opening OP2 are formed at positions corresponding to the arrangement of the first optical unit LU1 and the second optical unit LU2, and are provided for passing the irradiated light of the optical unit LU, respectively. ing. The first optical unit LU1 constitutes a headlamp unit, and because it is necessary to form a light distribution in front of the vehicle to ensure the driver's visibility in the dark, it irradiates high-intensity light at a wide angle. A large optical device is used as the device, and the corresponding first opening OP1 also has a larger opening area than the second opening OP2.

As shown in FIG. 2(B), both the pier portion 12 and the frame portion 20 have an inverted U-shape in cross section. In this inverted U-shaped cross-sectional shape, the pier portion 12 and the frame portion 20 have the same height but different widths and wall thicknesses. The width of the frame portion 20 is wider than the width of the pier portion 12, and the wall thickness of the frame portion 20 is configured to be thicker than the wall thickness of the pier portion 12. Therefore, the cross-sectional area of the frame portion 20 is wider than the cross-sectional area of the pier portion 12. The sides forming the frame portion 20 and the pier portion 12 have the same elongated cross-sectional shape no matter where they are cut in the longitudinal direction. If the same length is cut, the volume of the frame portion 20 will be larger than the volume of the pier portion 12.

(Position of weld line occurrence)
A method of molding the extension member 10 configured as described above will be explained.

Weld lines are likely to occur not only in the extension member 10 but also in resin molded products in which multiple large openings are formed. A weld line is a molding defect that occurs during injection molding when gas remains at the point where the molten resin flowing inside the mold cavity joins or at the blind alley, and the residual gas causes gas burns on the surface of the molded product. It is. Two large openings, a first opening OP1 and a second opening OP2, are formed in the extension member 10, and the cavity of the mold is formed into two large rings that share a part. Sometimes the melted resin goes around the ring-shaped cavity and merges at some point, creating a weld line at the merged point.

To deal with weld lines, first create the weld line in an inconspicuous location, then install a gas vent in the mold at the location where the weld line occurs to suppress the weld line, or make the weld line thinner. A method is taken to make the weld line less noticeable and to minimize the influence of the weld line on the design of the resin molded product.

Based on the above, first, before forming a mold for the extension member 10, the position where the weld line will occur in the extension member 10 is predicted by simulation. Then, based on the simulation prediction, a mold is created in which a degassing nest is provided in accordance with the predicted position of the weld line. As for the simulation method, a conventionally well-known configuration such as using an existing application can be used, and the method is not limited.

As shown in FIG. 2, the gates of the mold of the extension member 10 in this embodiment include a first gate G1 located approximately in the center of the upper side 21 of the frame portion 20, and a second gate G2 located approximately in the center of the lower side 22. A total of two gates are provided. In addition to the first gate G1 and the second gate G2, additional gates can also be provided. When three or more gates are provided in the mold, the molding method described later deals with a pair of gates arranged with the pier 12 in between.

Figure 4 shows weld lines that occur in the extension member. FIG. 4(A) shows predicted positions of weld lines generated by simulation. FIG. 4(B) shows the position where a weld line actually occurs. The simulation in FIG. 4(A) and the actual molding in FIG. 4(B) are performed under the same conditions, and the gate opening start times of the two gates are the same. The thick line rectangle in the figure indicates the position of the degassing insert provided in the mold of the extension member 10. In FIG. 4, the extension member 10 is shown in light black, and the weld line is shown in dark light black.

As shown in FIG. 4(A), when the first gate G1 provided on the upper side 21 and the second gate G2 provided on the lower side 22 are opened simultaneously and the molten resin is injected at the same time, the weld line predicted by the simulation preWL1 to preWL3 occur on three sides: the left side 24 connecting the upper side 21 and the lower side 22, the right side 23, and the pier 12.

A first predicted weld line preWL1 occurring on the left side 24, a second predicted weld line preWL2 occurring on the pier 12, and a third predicted weld line preWL3 occurring on the right side 23 are generated near the connection between the side and the upper side 21, respectively. do.

However, depending on the form of the extension member, the weld line is not conspicuous, such as the connection between sides, the area where other parts are assembled, the area where a vehicle lamp is assembled and hidden, the step of the outer lens, etc. It is preferable to provide a gate so that the gate is generated at the narrowest point such as the inner side or a bridge pier.

The mold of the extension member 10 is provided with a degassing insert corresponding to the predicted position of the weld line. A first degassing insert 51 is placed at a position corresponding to the upper left side 24 where the first predicted weld line preWL1 occurs, and a second degassing insert 52 is placed at a position corresponding to above the pier 12 where the second predicted weld line preWL2 is generated. , a third degassing insert is provided in the mold at a position corresponding to the right side 23 where the third predicted weld line preWL3 occurs.

The gas venting insert is formed with multiple small gas venting grooves (vents) that communicate with the outside, and the gas that has accumulated in the cavity at the position where the gas venting insert is placed passes through the vents and is released into the mold. released outside. By providing a degassing nest in the mold, the melted resin joins at the location where the degassing nest is placed, and the gas that cannot flow and stays escapes out of the cavity, suppressing the occurrence of weld lines or preventing weld lines. You can make the lines thinner and less noticeable.

Based on the above simulation results, three weld lines that occurred in the extension member 10 that was actually injection molded using a mold equipped with degassing inserts 51, 52, and 53 at the predicted positions of weld line occurrence are shown in FIG. Shown in B).

As shown in FIG. 4(B), the first weld line WL1 is located approximately at the center of the left side 24, the second weld line WL2 is located below the pier 12, and the third weld line WL3 is located near the upper end of the right side. , respectively occurred.

The first weld line WL1 and the third weld line WL3 are close to the predicted occurrence positions and occur at the installation positions of the first degassing insert 51 and the third degassing insert 53. However, the second weld line WL2 that has occurred on the pier portion 12 is considerably shifted from the predicted position, and is out of the position where the second degassing insert 52 is arranged.

This is because the pier 12 is narrower and thinner than the left side 24 and the right side 23, has a smaller volume, and therefore the flow rate of the molten resin in the cavity is faster, so it is difficult to predict the position of the weld line on the pier 12. This is because it is more difficult to predict the position of weld line occurrence in the thicker and more voluminous frame portion 20, and a deviation between the actual weld line occurrence position and the simulation predicted occurrence position is likely to occur.

Generally, if there is a misalignment between the actually placed degassing insert and the position of the weld line, countermeasures are taken such as cutting the mold or changing the placement of the degassing insert. It will be done. However, this takes time and effort, and it is impossible to restore the mold once it has been cut.

For this reason, in this embodiment, by making the gate opening start times of the two gates G1 and G2 different (delay control), the generation position of the second weld line WL2 formed on the pier 12 is controlled by the second gas. Adjust so as to guide it to the location of the punching nest 52.

(delay control)
A detailed explanation will be given of delay control that makes the gate opening start times of the gates different, and in particular delays the gate opening start time of one of the pair of gates.

FIG. 5 shows a change in the position of the weld line that occurs in the extension member 10 when delay control is performed to delay the opening start time of one of the gates G1 and G2 by a predetermined period of time during injection molding. . In FIG. 5, as an example, when delay control is performed to delay the gate opening start time of the first gate G1 by 1 second, compared to when a pair of gates G1 and G2 are opened at the same time (no delay control), The amount of movement and the direction of movement are shown as the weld line movement, which is how much the weld line has moved.

As shown in FIG. 5, by delaying the gate opening start time of the first gate G1 arranged above by one second than the gate opening start time of the second gate G2, the left side 24 and the right side 23 of the frame portion 20 are The first weld line WL1 and the third weld line WL3, which are generated in , are moved upward by 2 mm. On the other hand, the second weld line WL2 generated on the pier 12 moves upward by 10 mm under the same conditions.

When delay control is performed to delay the gate opening start time of the first gate G1, all the weld lines move upward. Weld lines occur at the point where the melted resin joins in the cavity, so if delay control is performed to delay the opening start time of one of the pair of gates, the weld line will occur at the same position as the weld line without delay control. It will be closer to the gate delayed than the position.

Furthermore, the amount of movement of the weld line generated on the pier portion 12 is much larger than the amount of movement of the weld line generated on the frame portion 20. Weld lines that occur on the narrow and thin pier portion 12 respond more sensitively to delay control of the gate opening start time, and the delay control is more effective than weld lines that occur on the frame portion 20.

Because the piers are narrower, thinner, and smaller in volume than other parts (frames), it is difficult to predict where weld lines will occur, and the weld lines that occur are susceptible to delay control. Weld lines that occur when the degassing nest 52 is out of place can also be guided to the position of the degassing nest 52 by delay control. Thereby, the weld line generation position can be guided to a desired location without machining the mold.

FIG. 6 shows the position of the weld line that occurs in the extension member 10 between the pair of gates G1 and G2. Both the weld line without delay control and the weld line with delay control in which the opening start time of one gate is delayed by a suitable time are shown. The thick line rectangle in the figure indicates the position of the degassing insert provided in the mold of the extension member.

As shown in FIG. 6, the generation position of the first weld line WL1' with delay control is slightly higher than the generation position of the first weld line WL1 without delay control. Similarly, the position of the third weld line WL3' after the delay control is slightly above the left side 24 compared to the position of the third weld line WL3 before the delay control. All weld lines occur within the placement range of the degassing inserts 51 and 53, and the degassing inserts 51 and 53 suppress the retention of gas in the cavity during the injection molding process, so the weld lines The effect is that the occurrence itself is suppressed, or the weld line becomes thinner and less noticeable.

The generation position of the second weld line WL2' with delay control is significantly higher than the generation position of the second weld line WL2 without delay control, and is near the joint with the upper side 21 of the pier 12. Therefore, the second weld line WL2' with delay control is generated within the installation range of the second degassing insert 52, and like the other weld lines WL1' and WL3', the second weld line WL2' with delay control is generated in the cavity in the injection molding process. By suppressing the retention of gas inside the weld line, the generation of the weld line itself is suppressed, or the weld line becomes thinner and less noticeable.

By performing delay control that makes the gate opening start times of the pair of gates different, the weld line generation position of the pier 12, which is difficult to predict in simulation, is adjusted to be guided to the desired position, that is, the degassing nest arrangement position. be able to.

In this embodiment, the pair of gates G1 and G2 are provided corresponding to the upper side 21 and the lower side 22, which are two opposing sides connected to the end of the pier 12. A pair of gates G1 and G2 are arranged separately in the extending direction (vertical direction) of the pier 12, and the gate opening start time of the gate arranged in the direction (upward or downward) in which the weld generation position is desired to be moved is determined. Since it only needs to be delayed, adjustment by delay control is easy. In this way, by arranging the pair of gates at opposing positions with the pier in between, it is easy to guide the weld line of the pier. By delay control that delays the gate opening start time of either gate, the position of the weld line generated on the pier 12 can be adjusted to a desired position without machining the mold of the extension member 10.

(Mold for extension part)
7 and 8 show a mold 90 for the extension member 10. FIG. FIG. 7 is a cross-sectional view of the mold 90 taken at a position corresponding to line VII-VII in FIG. The cutting line passes through the first gate G1 and the second gate G2. FIG. 8 is a cross-sectional view of the mold 90 taken at a position corresponding to line VIII--VIII in FIG. The cutting line passes through the first degassing insert 51, the second degassing insert 52, and the third degassing insert 53.

As shown in FIGS. 7 and 8, the mold 90 includes a fixed mold 91 and a movable mold 92. The fixed side mold 91 and the movable side mold 92 are arranged facing each other and fastened together, and are configured to form a cavity C corresponding to the extension member 10 therebetween.

The movable mold 92 is provided with a first gate G1 and a second gate G2. The stationary mold 91 is provided with a first degassing insert 51, a second degassing insert 52, and a third degassing insert 53.

The cavities C include a first cavity C1 corresponding to the upper side 21, a second cavity C2 corresponding to the lower side 22, a third cavity C3 corresponding to the right side 23, a fourth cavity corresponding to the left side, and a fifth cavity corresponding to the pier 12. Includes cavity C5.

In order to stably arrange the gate during injection molding, the first cavity C1 includes an additional part CC1, and the first gate G1 is arranged with its injection port open to the additional part CC1. Similarly, the second cavity C2 includes an additional part CC2, and the second gate G2 is disposed with its injection port opening into the additional part CC2.

The parts formed by the additional parts CC1 and CC2 are parts to be removed in a subsequent process, are not included in the extension member 10, and are provided only for the molding process. The molten resin is injected into the cavity C through the gates G1 and G2, fills the cavity C, and solidifies when cooled. When the mold 90 is removed, the resin formed in the additional parts CC1 and CC2 is cut off.

The arrangement of the gate is not limited to this, and the additional parts CC1 and CC2 may not be provided, and the gate may be provided at a position corresponding to the back side of the upper side 21 and the lower side 22 or the attachment part of the extension member 10 (not shown).

The first degassing insert 51 forms a part of the fourth cavity C4 forming the left side 24 and is provided in the stationary mold 91. The first gas venting insert 51 has a ventilation portion 51a and a ventilation hole 51b. The ventilation part 51a, which is arranged facing the fourth cavity C4 of the first gas venting insert 51, is made of a dense layer having fine pores that prevent the melted resin from penetrating, and communicates with the outside air through the ventilation hole 51b. Therefore, even if the melted resin flowing inside the cavity C merges in the cavity portion facing the first degassing insert 51, the gas inside is released from the vent hole 51b to the outside of the mold 90, so it is difficult to remain. , the occurrence of gas burns (weld lines) is suppressed.

Similarly, the second degassing insert 52 forms part of the fifth cavity C5 that forms the bridge pier 12 and is provided in the stationary mold 91. The second degassing insert 52 has a ventilation section 52a and a ventilation hole 52b. Further, the third degassing insert 53 is provided in the stationary mold 91 and constitutes a part of the third cavity C3 forming the right side 23. The third gas venting insert 53 has a ventilation portion 53a and a ventilation hole 53b. The

ventilation parts

52a and 53a have the same configuration as the ventilation part 51a. The ventilation holes 52b and 53b have the same configuration as the ventilation hole 51b. Therefore, even if the melted resin flowing inside the cavity C merges at the portion facing the second degassing insert 52 and the third degassing insert 53, the internal gas flows through the vent holes 52b and 53b to the mold 90. released outside.

The first gate G1 is a direct gate and includes a first gate portion 71, a first resin flow path 72, and a first gate pin 73. The first gate portion 71 opens to the additional portion CC1 in the first cavity C1.

The first gate pin 73 is a rod-shaped member and is configured to be movable toward and away from the first gate portion 71 by a drive device (not shown), thereby opening and closing the gate portion 71.

The first resin flow path 72 is a flow path for supplying a molten resin member to the cavity C. The first resin flow path 72 is heated by a heating device (not shown) and maintained at a high temperature. This prevents the molten resin member from solidifying in the resin flow path.

In the mold clamping state, the first gate portion 71 is closed by the first gate pin 73.

The second gate G2 has the same configuration as the first gate G1, and includes a second gate portion 81, a second resin flow path 82, and a second gate pin 83. The second gate portion 81 opens to the additional portion CC2 in the second cavity C2. The configuration of the second gate G2 is the same as that of the first gate, and detailed explanation will be omitted.

When the gate pins 73, 83 are separated from the

gate parts

71, 81 and the

gate parts

71, 81 are opened, the melted resin heated to a predetermined melting temperature is injected into the cavity C, and the cavity C is filled.

At this time, by making the start times at which the first gate pin 73 and the second gate pin 83 are driven different by a driving device (not shown), delay control can be performed to make the gate opening start times different.

Further, at this time, by making different the first speed V1 at which the first gate pin 73 is driven by the driving device and the second speed V2 at which the second gate pin 83 is driven by the driving device, the movement of the weld line is guided. Further adjustment is also preferable.

As the speed at which the gate pin is driven becomes slower, the flow of the melted resin into the cavity C becomes slower, and the speed at which the resin is filled into the cavity C becomes slower. If the gate opening start times of the two gates, that is, the movement start times of a pair of gate pins are the same, and the speed of movement of one gate pin is controlled to be slow, the position of the weld line will be determined by the movement of the gate pin. The weld line generation position is closer to the gate where the gate pin movement speed is slower than the weld line generation position when the speeds are the same.

For this reason, first, delay control is performed to delay the opening start time of one of the gates G1 and G2, and the speeds of the driving speeds V1 and V2 of the gate pins 73 and 83 are made different, thereby further fine-tuning the weld line generation position. Adjustments can be made.

In this embodiment, the gate pin driving device (not shown) is assumed to be an air cylinder, and by increasing/decreasing the air pressure that sends air to the air cylinder, the speed at which the gate pin is driven can be increased or decreased. Can be done. The opening speed of the gate is not limited to this, and the opening speed of the gate can be adjusted using a known drive device or method.

In this way, the generation of weld lines can be prevented by guiding the weld line generation position of the gate pin to the location where the degassing nest is placed by adjusting the gate pin drive start time and the gate pin drive speed. suppressed.

(Flow of molding method)
FIG. 9 shows a flow of a method for molding the extension member 10.

First, in step S101, the weld line occurrence position of the extension member 10 is predicted. Before creating the mold 90 of the extension member 10, the gate arrangement is determined and the position of the weld line that will occur in the extension member 10 is predicted by simulation. At this time, a plurality of gates are arranged, and at least one pair of gates are arranged at opposing positions across the pier 12 so that the expected position of at least one weld line becomes the pier.

Next, in step S102, a mold 90 for the extension member 10 is created. Based on the results of step 101, at least one pair of gates is provided, and a gas venting nest is provided at the position where weld lines are predicted to occur.

Next, in step S103, a prototype is produced using the mold 90. Resin molding is actually performed using the mold 90 without delay control, a prototype of the extension member 10 is molded, and the actual position of the weld line is confirmed.

Next, in step S104, the gate opening start time is adjusted. The position where the weld line occurs in the prototype molded in step S103 is ascertained, and based on this, the gate opening start time is adjusted to guide the position where the weld line is generated to the placement position of the degassing nest. Adjust the gate opening start time, perform actual molding, and check the position of the weld line on the molded product.

Next, in step S105, the opening speed of the gate is adjusted. Based on the molded product whose gate opening start time has been adjusted in step S104, if it is desired to further finely adjust the weld line generation position, the gate opening speed is changed. The opening speed of the gate may be increased as well as delayed. For example, by increasing or decreasing the driving speed of the gate pin by the driving device, the weld line generation position can be further finely adjusted. If the weld line generation position can be guided to a desired location in step S104, step S105 may not be performed. Additionally, steps S104 and S105 may be repeated multiple times to obtain acceptable results.

By the above molding method, it is possible to guide the position of the weld line that occurs in the molded product to a desired position. By guiding the weld line generation position to the degassing nest, it is possible to suppress the occurrence of molding defects and reduce the influence on the design of the vehicle lamp 1.

The preferred embodiments of the present invention have been described above, but the above embodiments are only examples of the present invention, and these can be combined based on the knowledge of those skilled in the art, and such embodiments are also included in the present invention. Included in the range.

This international application claims priority based on Japanese patent application No. 2022-137600, which is a Japanese patent application filed on August 31, 2022. The entire contents of No. 1 are incorporated by reference into this international application.

The above descriptions of specific embodiments of the invention have been presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the precise forms described. It will be obvious to those skilled in the art that many modifications and variations are possible in light of the above description.

1: Vehicle lamp 10: Extension member 12: Pier 90: Mold C: Cavities G1, G2: Gate LU: Optical units V1, V2: Speed WL1 to WL3: Weld line

Claims

Equipped with a vehicle lamp that houses multiple optical units that emit light,
A method for injection molding an extension member that has an opening formed inside, has a pier that divides the opening into a plurality of parts, and shields at least a part of the optical unit from the outside, the method comprising:
The mold for molding the extension member is provided with at least a pair of gates at opposing positions with respect to the cavity forming the pier,
Adjusting the position of the weld line formed on the pier by guiding the weld line to a desired location by making the gate opening start times of the pair of gates different;
An injection molding method characterized by:
adjusting the opening speeds of the pair of gates to be different so as to guide the weld line formed on the pier to a desired location;
The injection molding method according to claim 1, characterized in that: