JP4262385B2

JP4262385B2 - Injection molding method for speaker diaphragm

Info

Publication number: JP4262385B2
Application number: JP2000054996A
Authority: JP
Inventors: 武弘榎本; 正志徳森; 信也溝根; 良幸高橋
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2000-02-29
Filing date: 2000-02-29
Publication date: 2009-05-13
Anticipated expiration: 2020-02-29
Also published as: JP2001245385A

Description

【０００１】
【発明の属する技術分野】
本発明は、スピーカ用振動板の射出成形方法に関するものである。
【０００２】
【従来の技術】
スピーカ振動板の材料として、従来より内部損失が高く、成形性、耐水性、耐湿性に優れている特性を有するポリプロピレン等の樹脂材料が使用され、射出成形機により図２に示すような、ドーム形状中央部にゲート７を有し、中央に一定肉厚の振動部６と外周部に剛性を高める厚肉のエッジ部５から構成される振動板に成形される。
【０００３】
【発明が解決しようとする課題】
上記図２に示す従来のスピーカ用振動板の構造では、射出成形時に射出成形金型入れ子が僅かに偏り、金型キャビティが僅か偏肉すると、ゲート７から充填された樹脂が圧力損失の低い偏肉した振動部６の厚肉部分に偏って流れるため、偏肉した振動部６の薄肉部分が充填される前にエッジ部５が充填される。エッジ部５の充填時には樹脂温が低下し樹脂が固化するため、薄肉部分が完全に充填されず、成形品にショート、ウェルドが発生する。本発明は、このショート、ウェルドの発生の防止を目的とする。
【０００４】
【課題を解決するための手段】
この課題を解決するために本発明は、ドーム形状中央部にゲートを有し、中央に一定肉厚の振動部と外周部に厚肉のエッジ部を有するスピーカ用樹脂振動板において、振動部とエッジ部の連結位置に振動部の肉厚より薄い薄肉部を設けたものである。
【０００５】
これによりキャビティが僅かに偏肉した場合であっても、ゲートから充填される樹脂は、偏肉した振動部の厚肉の部分に偏って流れた後、振動部とエッジ部の間に設けられた薄肉部に到達すると、この部分は圧力損失が高いため、樹脂はエッジ部に流れず偏肉した振動部の薄肉部分が充填され、薄肉部分の充填後、エッジ部が充填される。振動部が充填される時は樹脂温は高温で樹脂の流動性が高く固化していないので、振動部にショート、ウェルドのないスピーカ用振動板が得られる。
【０００６】
【発明の実施の形態】
本発明の請求項１に記載の発明は、ドーム形状の一定肉厚の振動部と、ドーム形状の周囲の肉厚のエッジ部と、エッジ部と振動部の連結位置に設けた薄肉部と、で構成したスピーカ用振動板を射出成形するに際し、
前記ドーム形状中央部に設けたゲートより樹脂の充填が開始され、前記樹脂が前記振動部から圧力損失の高い前記薄肉部に到達すると、前記振動部の前記樹脂の圧力が高まり前記振動部全体に前記樹脂が充填され、その後前記エッジ部に前記樹脂が充填されることを特徴とするものであり、成形時にキャビティが僅かに偏肉した場合であっても、ゲートから充填される樹脂は、偏肉した振動部の厚肉の部分に偏って流れた後、振動部とエッジ部の間に設けられた薄肉部に到達すると、この部分は圧力損失が高いため、樹脂はエッジ部に流れず偏肉した振動部の薄肉部分が充填され、薄肉部分の充填後、エッジ部が充填されるため、振動部にショート、ウェルドのないスピーカ用振動板が得られる作用を有する。
【０００７】
請求項２に記載の発明は、薄肉部は振動部肉厚の２０％〜８０％であることを特徴とするものであり、請求項１記載の発明と同じ作用を有する。
【０００８】
以下、本発明の実施の形態について、図１を用いて説明する。
（実施の形態）
図１は本発明のスピーカ用振動板を示し、図において、１は厚肉のエッジ部、２は一定肉厚の振動部、３はドーム形状中央部に設けたゲート、４はエッジ部１と振動部２の連結位置に設けた薄肉部である。
【０００９】
各部の厚さの一例を示すと、振動部２の肉厚が０．０５ｍｍの場合、エッジ部１は０．４ｍｍ、薄肉部４は０．０３ｍｍ、ゲートは０．３ｍｍであり、この例の場合は薄肉部４の肉厚は振動部２の肉厚の３／５である。
【００１０】
この形状のキャビティを備えた金型で成形すると、樹脂はまず直径０．３ｍｍのゲート３より充填が開始され、肉厚０．０５ｍｍの振動部２から圧力損失の高い肉厚０．０３ｍｍに絞られた薄肉部４に到達すると、振動部２の圧力が高まり振動部２全体に樹脂が充填され、その後肉厚０．４ｍｍのエッジ部が充填される。振動部２が充填される時は樹脂温は高温で流動性が高いため、振動部２にはショート、、ウェルドが発生しない。
【００１１】
なお、振動部肉厚に対する薄肉部肉厚の割合は、樹脂材料の温度特性、樹脂充填時の温度、金型の加熱温度等の諸条件により適宜設定されるが、一般には２０％から８０％の範囲が最も好ましい。
【００１２】
【発明の効果】
本発明によれば、成形時にキャビティが僅かに偏肉した場合であっても、ゲートから充填される樹脂は、偏肉した振動部の厚肉の部分に偏って流れた後、振動部とエッジ部の間に設けられた薄肉部に到達すると、樹脂はエッジ部に流れず偏肉した振動部の薄肉部分が充填された後、エッジ部が充填されるため、振動部に薄肉部分が存在する場合であっても、薄肉部分を完全に充填するので、ショート、ウェルドのないスピーカ用振動板が得られる。
【図面の簡単な説明】
【図１】本発明のスピーカ用振動板の形状を示す図。
【図２】従来のスピーカ用振動板の形状を示す図。
【符号の説明】
１エッジ部
２振動部
３ゲート
４薄肉部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for injection molding a speaker diaphragm.
[0002]
[Prior art]
As a material for the speaker diaphragm, a resin material such as polypropylene having higher internal loss and excellent moldability, water resistance and moisture resistance is used, and a dome as shown in FIG. 2 by an injection molding machine. A diaphragm 7 having a gate 7 at the center of the shape and comprising a vibrating portion 6 having a constant thickness at the center and a thick edge portion 5 for increasing rigidity at the outer periphery is formed.
[0003]
[Problems to be solved by the invention]
In the structure of the conventional speaker diaphragm shown in FIG. 2, when the injection mold insert is slightly biased during injection molding and the mold cavity is slightly thickened, the resin filled from the gate 7 is biased with low pressure loss. Since the flow is biased toward the thick portion of the vibrating portion 6 that has been fleshed, the edge portion 5 is filled before the thin portion of the vibrating portion 6 that has been thickened is filled. When the edge portion 5 is filled, the resin temperature is lowered and the resin is solidified. Therefore, the thin portion is not completely filled, and a short and a weld are generated in the molded product. An object of the present invention is to prevent the occurrence of shorts and welds.
[0004]
[Means for Solving the Problems]
In order to solve this problem, the present invention provides a resin diaphragm for a speaker having a gate at the center of the dome shape and having a constant thickness vibration part at the center and a thick edge part at the outer periphery. A thin part thinner than the thickness of the vibration part is provided at the connection position of the edge part.
[0005]
As a result, even if the cavity is slightly uneven, the resin filled from the gate flows between the thick wall portion of the uneven vibration portion and flows between the vibration portion and the edge portion. When reaching the thin part, the pressure loss is high in this part, so that the resin does not flow to the edge part, and the thin part of the vibration part that is unevenly thick is filled, and after filling the thin part, the edge part is filled. When the vibration part is filled, since the resin temperature is high and the fluidity of the resin is high and the resin is not solidified, a diaphragm for a speaker without a short and weld in the vibration part can be obtained.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention includes a dome-shaped constant-thickness vibration portion, a dome-shaped peripheral edge portion, and a thin-wall portion provided at a connection position between the edge portion and the vibration portion, When the speaker diaphragm configured with
Resin filling is started from the gate provided at the center of the dome shape, and when the resin reaches the thin-walled portion having a high pressure loss from the vibrating portion, the pressure of the resin in the vibrating portion increases, and the entire vibrating portion increases. The resin is filled, and then the edge is filled with the resin. Even when the cavity is slightly uneven during molding, the resin filled from the gate is uneven. After flowing biased to the thick part of the vibrating part and then reaching the thin part provided between the vibrating part and the edge part, this part has high pressure loss, so the resin does not flow to the edge part. Since the thin portion of the vibrating portion is filled and the edge portion is filled after the thin portion is filled, there is an effect that a diaphragm for a speaker having no short and weld in the vibrating portion can be obtained.
[0007]
The invention described in claim 2 is characterized in that the thin portion is 20% to 80% of the thickness of the vibrating portion, and has the same effect as that of the invention described in claim 1.
[0008]
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
(Embodiment)
FIG. 1 shows a diaphragm for a speaker according to the present invention, in which 1 is a thick edge portion, 2 is a constant thickness vibration portion, 3 is a gate provided at the center of the dome shape, 4 is an edge portion 1 It is a thin part provided at the connecting position of the vibration part 2.
[0009]
As an example of the thickness of each part, when the thickness of the vibration part 2 is 0.05 mm, the edge part 1 is 0.4 mm, the thin part 4 is 0.03 mm, and the gate is 0.3 mm. In this case, the thickness of the thin part 4 is 3/5 of the thickness of the vibration part 2.
[0010]
When molding with a mold having a cavity of this shape, the resin is first filled from the gate 3 having a diameter of 0.3 mm, and the vibration part 2 having a thickness of 0.05 mm is narrowed to a thickness of 0.03 mm with high pressure loss. When the thin part 4 is reached, the pressure of the vibration part 2 increases and the whole vibration part 2 is filled with resin, and then the edge part with a thickness of 0.4 mm is filled. When the vibration part 2 is filled, since the resin temperature is high and the fluidity is high, no short circuit or weld occurs in the vibration part 2.
[0011]
The ratio of the thickness of the thin portion to the thickness of the vibrating portion is appropriately set according to various conditions such as the temperature characteristics of the resin material, the temperature at the time of resin filling, and the heating temperature of the mold, but generally 20% to 80%. The range of is most preferable.
[0012]
【The invention's effect】
According to the present invention, even when the cavity is slightly uneven during molding, the resin filled from the gate flows unevenly to the thick part of the uneven vibration part, and then the vibration part and the edge When the resin reaches the thin part provided between the parts, the resin does not flow to the edge part, and after filling the thin part of the vibrating part that is unevenly thick, the edge part is filled, so there is a thin part in the vibrating part. Even in this case, since the thin-walled portion is completely filled, a speaker diaphragm without short circuit or weld can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing the shape of a speaker diaphragm of the present invention.
FIG. 2 is a view showing the shape of a conventional speaker diaphragm.
[Explanation of symbols]
1 Edge part 2 Vibrating part 3 Gate 4 Thin part

Claims

When injection-molding a loudspeaker diaphragm composed of a dome-shaped vibration part with a constant thickness, a thick edge part around the dome shape, and a thin part provided at the connection position of the edge part and the vibration part. ,
Resin filling starts from the gate provided at the center of the dome shape, and when the resin reaches the thin-walled portion with high pressure loss from the vibrating portion, the pressure of the resin in the vibrating portion increases, and the entire vibrating portion increases. An injection molding method for a resin diaphragm for a speaker, wherein the resin is filled, and then the edge is filled with the resin.

2. The method for injection molding of a resin diaphragm for a speaker according to claim 1, wherein the thin part is 20% to 80% of the thickness of the vibration part.