每一個重要過程考慮放量的時候都需要前后照應,也要結合批量生產的因素,這個量,目前還沒有辦法定標準,與制作個體有極大關系,經(jīng)驗至關重要作者: 海邊聽濤 時間: 2009-1-30 14:32
Chapter I Introduction
第一章 介紹
Fiber reinforced plastic (FRP) parts are molded to the design shape using a cure tool (commonly called a mold) and a molding protocol. At its minimum, a mold consists of a mold skin.
纖維加強塑料件(FRP)成型需使用固化工具(通常叫做模具)和壓模程序。模具至少應包括模具外殼。
The molding protocol has a large impact on the cure tool design. When a molding process involves high pressures, or whenever any mold deflection must be limited, bracing is used to reinforce the mold skin. This can be accomplished with any combination of increased thickness, the use of cores, and/or shaped stiffener elements like hat-section or c-section laminates. Each case of bracing can be unique in its design. When a mold skin is larger than a few square feet, a framing system is also used to provide a means of handling the mold skin without causing it to be deformed or fractured. A framing system can be one of two types. The simplest framing system supports the dead weight of the mold and concentrates it on a few load points. The more complex type also provides structural support to react molding forces and restrict mold deformation. Both systems provide a means of grabbing the mold for lifting and transport operations.
壓模程序對固化工具設計有很大影響。當成型過程中需要較大壓力時,或者需要限制模具變型時,補強件用來加強模具外殼??梢酝ㄟ^結合以下方法實現(xiàn):增加厚度,使用芯材和/或加強筋,例如帽形薄板或c形薄板。每個補強件在其設計中可以是唯一的。當模具外殼大于幾平方英尺時,也可以使用支架以防止模具外殼變形或斷裂。支架系統(tǒng)有兩種類型。最簡單的支架系統(tǒng)將承受模具的靜載荷,且將這些載荷集中在一些載荷點上。更復雜的結構支架會抵消成型力,限制模具變型。這兩種系統(tǒng)都可應用于舉起和運輸模具。
Most mold skins used to produce FRP parts are fashioned from FRP type materials. For high production runs, a metal mold skin can be most economical, but at a higher up-front cost. An FRP type mold skin is produced using a master model, also known as a pattern or plug. This master model is a full-scale representation of a part design that incorporates all of the geometry for one of the part surfaces. A model may be geometrically equivalent to the part image or it can be a mirror image about the part’s external surface.
大多數(shù)用于生產FRP件的模具外殼都是使用FRP材料制成。若進行大規(guī)模生產,使用金屬模具外殼可能是最經(jīng)濟的,但是初始投入成本較高。制作FRP模具外殼需使用原模,也可叫做基?;蜿柲!T酝瑯颖壤笮≌宫F(xiàn)部件表面的形狀設計。原模應和部件有一樣的外形,或者是此部件外表面的鏡像。
There is no quick or easy way to produce quality FRP tooling. Good tooling is a precise, painstaking craft. It begins with careful preparation of the master model and continues through the final building of the production mold. Any defects on the master model will translate onto each subsequent piece of tooling and require extra effort to remove. The highest quality production mold begins with an even-higher quality master model.
生產優(yōu)質的FRP模具是沒有捷徑的。好模具是精細艱辛工作的結晶。必須精心準備原模和生產模具。原模的任何缺陷都會被轉化到模具上,進而需要更多努力去改正。高質的生產模具源于優(yōu)質原模。
The terms master model, pattern and plug are sometimes used interchangeably. Due to recent advancements in computer numerically controlled (CNC) routers, the term pattern generally describes a master model that is machined from a blank constructed of a single material or material type. In contrast, the term plug generally describes a master model that is constructed from a variety of materials and shaped manually. Neither a pattern nor a plug is particularly durable and is suitable for producing only one, or a small number of moldings. When two or more molds are required to meet production requirements, a master mold is used to produce the production molds. This master mold is a durable, robust, full-scale representation of a part image design and is constructed in the same manner as a production mold.
術語“原模,基模,陽?!庇袝r是可互換的。由于近來科技進步,CNC數(shù)控鏤銑機中,基模通??梢杂脕砻枋鲇脝我徊牧匣蛲愋筒牧现瞥傻脑!O鄬Χ?,陽模用以描述各種材料手工制作的原模?;:完柲6疾皇翘貏e耐用,且僅適合生產一個或者少量模具。當要求生產兩個或更多模具來滿足生產要求時,需用一個原模來生產這些生產模具。
Chapter II POLYESTER TOOLING: The Master Model
第二章 聚酯模具:原模
1.Introduction概述
2.Number of Moldings模具數(shù)量
3.Surface Quality表面質量
4.Generator代數(shù)(第一代模具,第二代模具)
1. INTRODUCTION—A wide variety of materials can be used to construct the master model. Some examples are plaster, polyester resin, epoxy resin, urethane foam, polyvinyl chloride (PVC) foam, body filler, FRP materials, wood coated with epoxy or polyester resin, medium density fiberboard (MDF) and certain laminated Melamine®-faced sheet materials like Formica® or bathroom wallboard.
概述—生產原??梢允褂酶鞣N各樣的材料。例如:塑料,聚酯樹脂,環(huán)氧樹脂,聚氨酯發(fā)泡,PVC發(fā)泡,填料,F(xiàn)RP,外表涂有環(huán)氧樹脂或聚酯樹脂的木頭,中纖板(MDF)和某些三聚氰胺面薄板,例如Formica®或浴室墻板。
2. NUMBER OF MOLDINGS—The number of moldings expected from the master model will influence the choice of materials and construction methodology. Plaster or foam-board type patterns, or plugs constructed from numerous materials will seldom survive one pull without incurring some damage. If several molds are needed, it is best to build a master mold using FRP materials.
模具的數(shù)量—從原模制得的模具數(shù)量決定于材料的選擇和其結構方法。塑料或發(fā)泡板制成的基?;蚋鞣N材料制成的陽模在脫模時或多或少都會有些損壞。
A master mold is robust and can be used to produce a large number of production molds.
如果原模堅固,就可以用來生產較多的生產模具。
3. SURFACE QUALITY—The surface quality of the master model is its most important feature. It should be hard, glossy and free of defects. The molding process will reproduce and worsen any defects on the master model. CCP tooling gel coat makes an excellent final coating for the master model. When properly applied, tooling gel coat provides the most fool-proof surface (see DS-45 Tooling Gel Coat Data Sheets for specific information).
表面質量——原模的表面質量非常重要。原模表面應堅硬、有光澤、無缺陷。成型過程將會復制和惡化原模上的任何缺陷。CCP模具膠衣可為原模提供很好的涂層。如果合理使用,模具膠衣將提供最佳防錯誤的表面。(參見DS-45模具膠衣參數(shù)單上的特殊信息)。
Resin shrinkage during the molding process will result in a part that is smaller than the master model. For some parts, the master model may be made slightly larger to offset this. The exact amount will depend on the type of resin and its inherent shrinkage, the glass content, process temperatures and the number of generations between the master model and the production part. A general rule of thumb for conventional room-temperature cured polyesters is 1/32 inch of shrinkage per linear foot when reinforced with 25 weight percent glass content. Gel coat shrinks more than fiber reinforced resin, resulting in parts that are more concave on the gel coat side. For this reason, any large, flat areas should be crowned convex to prevent dishing in the reverse direction. A crown of 1/4 inch per linear foot is typical for small panels.
成型過程中,樹脂收縮將會導致部件比原模稍小。對某些部件,應將原模制做得稍大以抵消收縮。具體數(shù)值決定于樹脂類型和其固有收縮量、玻纖含量、過程溫度和原模翻新生產模具的次數(shù)。常規(guī)室溫下固化聚酯的經(jīng)驗法則是:直線每一英尺的收縮量為1/32英寸(當加強玻纖重量比為25%時)。若膠衣收縮比加強樹脂收縮量大,將導致部件的膠衣面上將有更多凹面。同樣原因,較大的平坦表面應稍拱起以避免在相反方向凹下。對小板來說,直線每一英尺的長度通常會有1/4英寸的凸起。
4. GENERATOR—The term ‘generation’ refers to the number of successive moldings between the master model and the production part. If a production mold is made on the master model, it is a first generation production mold. If a production mold is made from a master mold that is made from the master model, it is a second generation production mold. A second generation mold requires a master model geometry that is a mirror image about the part design surface as described in the schematic below. Each subsequent generation can be slightly smaller than its predecessor. The exact amount will depend upon the materials and processes involved.
代數(shù)(第一代模具,第二代模具)—術語“代”是指原模翻成生產模具的代數(shù)。舉例說就是:若原模僅制作了一個生產模具,那么這個生產模具是第一代;若生產模具來自原模制成的原模,那么這個生產模具就是第二代生產模具。第二代模具要求原模的幾何形狀是部件形狀的鏡像。每下一代可比上一代稍小。具體縮小數(shù)值決定于使用的材料和工藝方法。
Producing a master mold from the geometry of a master model that is identical to the part design surface requires an intermediate piece of tooling. This intermediate piece is made from the master model and is called a zero mold. The zero mold is used to manufacture the master mold. The master mold yields the production molds one, two, etc. Here, the zero mold is a first generation mold, the master mold is from the second generation, and all of the production molds (one, two, etc) are from the third generation.
從原模翻新原模時,如果要求翻新的原模和設計部件形狀相同,就需要使用一個中間工具。這個中間工具可以從原模制得,叫做零模(過渡模)。零模是用來制作原模的。
When the master model is constructed from certain materials and/or certain combinations of materials, the boundaries between materials may become visible as witness lines in the subsequently molded FRP part. This cosmetic defect, known as mark-off, happens due to a combination of molding exotherm, substrate heat capacity, substrate thermal expansion, cure shrinkage and softening in the gel coat, both on the model and molding. The zero mold presents an opportunity to remove these witness lines by wet sanding, buffing and polishing. This is particularly true for outside edges and corners on the zero mold (convex, or ‘male’ type features). Outside features are more easily sanded than inside edges and corners (concave, or ‘female’ type features). Defects at these inside edges and corners are more easily corrected on the next piece of tooling, the master mold, when they become outside edges and corners.
當原模是由某種材料和/或某種材料的組合制成,那么這兩種材料的分界線是可見的,同樣在隨后成型的FRP件上,此分界線也可見。外觀缺陷(分界線)產生的原因為原模和模具的成型放熱曲線、底材熱容量、底材熱膨脹、,膠衣的固化收縮和軟化。零模為除去這些可見分界線提供了機會,可使用濕磨、拋光的方法。零模上的外邊緣和角落是其典型特征(凸起,或公模特征)。外凸比內部邊緣和角落(凹面,或母模典型特征)更容易處理。內部邊緣和角落缺陷更容易在下一個工具,也就是原模上修改。在原模上,這些內凹邊緣和角落就會變成凸面。