JP2004277875A

JP2004277875A - Tool for extrusion application of resin to wire rod

Info

Publication number: JP2004277875A
Application number: JP2003115071A
Authority: JP
Inventors: Takahiro Saito; 貴広斉藤; Hideki Ishikawa; 英樹石川; Osamu Terada; 修寺田
Original assignee: Fuji Die Co Ltd
Current assignee: Fuji Die Co Ltd
Priority date: 2003-03-14
Filing date: 2003-03-14
Publication date: 2004-10-07

Abstract

<P>PROBLEM TO BE SOLVED: To improve the deposition resistance to a resin and wear resistance and corrosion resistance in a nipple and a die used to a device for the extrusion application of the resin to the surface of a wire rod. <P>SOLUTION: The tool is composed in such a manner that the surface of the nipple and the inside surface of the die are coated with an amorphous hard carbon film. In the tool, the space between the amorphous hard carbon film and the base material is provided with an intermediate layer, further, the micro-Vickers hardness of the amorphous hard carbon film is controlled to HV 2,000 to 5,000, or ≤30 mass% fluorine is incorporated into the film. More preferably, a superalloy having a Rockwell A hardness of ≥88.0 is used as the base material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、線材に樹脂を押出し被覆するための装置に用いられるニップル及びダイスに関するものである。
【０００２】
【従来の技術】
各種通信用や電線用ケーブル等の線材には、芯線の保護及び外部との導通防止のため、樹脂を一定の厚さとなるように押出し被覆される。このような工程に使用される樹脂押出し被覆装置の概略図を図１に示す。樹脂材料には、従来よりポリエチレン（ＰＥ）、架橋ポリエチレン（ＸＬＰＥ）、ポリ塩化ビニル（ＰＶＣ）、耐燃ポリエチレン（ＥＭ）等が用いられており、それらを図１に示した押出し機１内にて１００〜３００℃に加熱・混練して溶融樹脂Ａとし、クロスヘッド２に供給する。クロスヘッド２内で溶融樹脂Ａは、ニップル３とダイス４によって形成される間隙を経由して、芯線Ｂとともに押出されながら芯線上に被覆され、ダイスを出た後は直ちに冷却される。
【０００３】
ニップル３及びダイス４の材料としては、従来より工具鋼や超硬合金が知られている。特にＷＣ−Ｃｏ系超硬合金は硬さが高く、耐摩耗性や製品形状安定性に優れること、また１００〜３００℃における熱膨張率が低いこと等から、好適であるとされている（例えば、特許文献１参照）。
【０００４】
一方、超硬合金では耐食性に問題がある場合には、各種セラミックス製のニップルやダイスが提案されている（例えば、特許文献２参照）。
【特許文献１】特開２００２−１８９２６号公報
【特許文献２】特開平７−２５６７２８号公報
【０００５】
【発明が解決しようとする課題】
しかし、これら工具鋼や超硬合金製のニップル及びダイスでは、工具表面に溶融樹脂が溶着しやすく、それにより被覆層に、いわゆる“目やに”と呼ばれる溶着樹脂塊が混入する問題がある。これはニップル及びダイスに溶着、固化した樹脂塊があるとき脱落し、被覆層内に混入して被覆強度を著しく低下させるという問題である。
【０００６】
また最近では線材の被覆樹脂の強さ及び硬さの向上のため、前記樹脂材料中に硬質のフィラーを添加することがあり、この場合にはニップル及びダイスが摩耗し易くなるという問題がある。
【０００７】
加えて、樹脂にＰＶＣを用いた場合や、線材の難燃化のため水酸化マグネシウムを添加した樹脂を用いる場合には、それらの熱分解により発生した腐食性ガスによる、ニップル及びダイスの腐食も問題となっている。
【０００８】
これらの問題に対してはアルミナセラミックスや窒化珪素セラミックス製ニップル及びダイスを用いることもあるが、金属製に比して材料強度や靭性に劣るため、工具に割れや欠損が生じ易いという問題がある。
【０００９】
本発明は、前記溶融樹脂のニップル及びダイスへの溶着を低減し、かつ耐摩耗性と耐食性を共に向上させたニップル及びダイスを提供することを目的とする。
【００１０】
【課題を解決するための手段】
そこで本発明者らは、樹脂に対する耐溶着性、耐摩耗性及び耐食性に優れた非晶質の硬質炭素被膜を、前記ニップル及びダイスに被覆することに着目した。
【００１１】
非晶質の硬質炭素は、主として炭素及び水素からなり、これらの結合状態が不規則な非晶質状態の物質であり、ダイヤモンドライクカーボン（ＤＬＣ）、ｉ−カーボン等とも呼ばれる。この物質は表面が非常に平滑で緻密な被膜をつくることや、化学的に安定であり、樹脂に対する耐溶着性や耐摩耗性、耐食性に優れるので、前記“目やに”発生防止に効果があると推測した。
【００１２】
非晶質の硬質炭素被膜を被覆する方法は、ＰＶＤ（物理的気相蒸着）法やプラズマＣＶＤ（化学的気相蒸着）法の他、最近ではイオン注入法がある。そのうちＰＶＤ法には、イオン化蒸着法、イオンビーム法、スパッタリング法や、イオンプレーティング法（高周波イオンプレーティング、陰極アークイオンプレーティング、ホローカソード法）が挙げられる。
【００１３】
また、母材と非晶質硬質炭素被膜との間に中間層として、周期律表の第ＩＶａ、Ｖａ、ＶＩａ族遷移金属及びＢ、Ｓｉ、Ｇｅまたはそれらの炭化物から選ばれる単層または複層の被膜を合計０．２〜１．０μｍの厚さで被覆することにより、非晶質硬質炭素被膜と母材との密着力を向上させることができる。中間層の被覆方法は非晶質硬質炭素被膜と同様で良い。しかし中間層の厚さが１．０μｍを超えると、中間層自体は硬さが低く、また脆いことから、被膜全体の強さが低下する。
【００１４】
非晶質硬質炭素被膜の厚さは、被覆時の原料ガス量や被覆時間により変化させることができるが、その厚さは０．５μｍ〜１０μｍが望ましい。厚さ０．５μｍ未満では耐摩耗性に乏しく、１０μｍを超えると被膜と母材との熱膨張係数差に起因する残留応力が高くなりすぎることや被膜の靭性が低いことから、被膜が剥離しやすくなる。
【００１５】
非晶質硬質炭素被膜の微小ビッカース硬さは、被覆時の母材に印加するバイアス電圧や母材温度により変化させることができる。またＰＶＤ法のうち、陰極アークイオンプレーティング法やスパッタリング法を用いると、他方法よりも硬質な非晶質炭素被膜を得ることが可能となる。被膜硬さはＨＶ２０００〜５０００が望ましい。ＨＶ２０００未満では、被膜は軟質であり、耐摩耗性に乏しい。一方ＨＶ５０００を超えると、被膜そのものの靭性に乏しく、被膜中クラックや被膜剥離を生じやすい。
【００１６】
また、ニップル及びダイス母材の仕上げ面粗さを調節して、非晶質硬質炭素被膜の表面粗さをＲｙ５μｍ以下とすることにより、樹脂溶着をより効果的に抑制することができる。これはＲｙ５μｍを超えると、被膜の凹凸により摩擦係数が大きくなり、樹脂の溶着が起こりやすくなるためである。
【００１７】
また、被覆処理ガス中にフッ素ガスや四フッ化炭素ガスを含有させることにより、フッ素を含む非晶質硬質炭素被膜を被覆することができる。被膜中にフッ素を含むと、非晶質硬質炭素被膜の樹脂に対する耐溶着性を更に向上させることができるが、被膜中のフッ素濃度が３０質量％を超えると、被膜強さが低下する。非晶質硬質炭素被膜に含まれるフッ素の量は、前記フッ素ガスあるいは四フッ化炭素ガスと、炭化水素ガスとの混合比によって調節することができる。
【００１８】
ニップル及びダイスの母材は、炭素鋼、工具鋼、超硬合金等の何れでも良いが、硬さが高いことや製品形状安定性に優れること等から超硬合金が望ましく、そのうちロックウェルＡ硬さが８８．０以上のものが特に望ましい。
【００１９】
【実施例】
以下、実施例により本発明を更に詳細に説明する。
超硬合金製ニップルの表面及びダイスの内面に、炭化珪素中間層及び非晶質硬質炭素被膜を順次被覆した。ニップル及びダイスの被覆処理面には、予め所定の表面粗さになるように研削、研磨仕上げを施した。被覆方法は前記の何れの方法でも良いが、本実施例では高周波イオンプレーティング法及び陰極アークイオンプレーティング法を用いた。これらの方法の被覆原理図をそれぞれ図２、３に示す。高周波イオンプレーティング法は、母材５を母材支持電極６に装着し、１〜１００Ｐａ程度の低圧の炭化水素ガス雰囲気中で高周波発振器及び高周波発生電極７によりガスプラズマを発生させ、炭化水素ガスを分解し、バイアス電圧を印加した母材表面に被膜を蒸着させる方法である。陰極アークイオンプレーティング法は、母材８を母材支持電極９に固定したのち、１０^−２〜１Ｐａ程度の低圧の炭化水素ガス雰囲気中で、被膜原料である炭素陰極１０表面にトリガー１１により真空アーク放電を発生させ、それにより陰極表面を蒸発させて、バイアス電圧を印加した母材８及び母材支持電極９に蒸発粒子１２を蒸着させ、被膜を形成させる方法である。本発明において、これらの方法を用いた理由は、高周波イオンプレーティング法にて被覆した非晶質硬質炭素被膜は、被膜表面の面粗さが優れていること、及び複雑形状品への被膜のつき回りが比較的優れるからである。しかしこの方法ではビッカース硬さ５０００以上の被膜の形成が困難である。よって高硬度被膜の形成には陰極アークイオンプレーティング法を用いた。また、被覆処理雰囲気をメタン／四フッ化炭素混合ガスとすることにより、種々量のフッ素を含む非晶質硬質炭素被膜も被覆した。さらに種々の硬さを有する母材超硬合金にてニップル及びダイスを作製し、前記と同様に炭化珪素中間層及び硬質炭素被膜を被覆した。
【００２０】
このようにして硬質炭素被膜を被覆したニップル及びダイスを図１の概略図に示すような線材被覆装置内に取り付け、樹脂被覆テストを行った。樹脂にはポリエチレンを用い、樹脂加熱温度は２００℃とした。溶融樹脂Ａは図１で示した押出し被覆装置内のクロスヘッド２に送り込まれ、ニップル３及びダイス４により芯線Ｂに被覆される。その際に、ニップル及びダイスに溶着し、固化した樹脂塊がいわゆる“目やに”となり蓄積、脱落し、被覆層内に混入したときまでの被覆線材長さを製品寿命とした。
【００２１】
（実施例１）従来品であるＷＣ−Ｃｏ系超硬合金製ニップル及びダイスに、高周波イオンプレーティング法により、有機珪素化合物ガス雰囲気中にて炭化珪素中間層を種々の被膜厚さとなるように所定時間被覆し、続けて雰囲気をメタンガスとして非晶質硬質炭素被膜を種々の被膜厚さとなるように所定時間被覆した。母材超硬合金のロックウエルＡ硬さは９０．０、被覆面の表面粗さはＲｙ２μｍ、母材温度は１００℃とした。このニップル及びダイスを、図１の概略図に示すような線材被覆装置内に取り付け、樹脂被覆テストを行った。樹脂にはポリエチレンを用い、樹脂加熱温度は２００℃とした。得られた本発明品及び従来品の炭化珪素中間層及び非晶質硬質炭素被膜の被覆時間、被膜厚さと製品寿命を表１に示した。これより炭化珪素中間層の被膜厚さが０．２〜１．０μｍの範囲内にあり、かつ非晶質硬質炭素被膜の被膜厚さが０．５〜１０．０μｍの範囲内にある本発明品は、ニップル及びダイスへの樹脂溶着速度が小さく、製品寿命が３０ｋｍを超え、長寿命を示した。一方、比較品の炭化珪素中間層無しまたはその厚さが０．２μｍ未満あるいは１．０μｍを超えるニップル及びダイス、または非晶質硬質炭素被膜の被膜厚さが０．５μｍ未満または１０．０μｍを超えるニップル及びダイス、あるいは何れの被覆処理も無しのニップル及びダイスは、樹脂溶着速度が大きいか、または被膜の剥離が発生し、短寿命であった。
【００２２】
【表１】

【００２３】
（実施例２）次に実施例１と同様の超硬合金製ニップル及びダイス（ロックウエルＡ硬さ９０．０）に、高周波イオンプレーティング法及びアークイオンプレーティング法により、炭化珪素中間層を厚さ０．５μｍ及びその上に被膜厚さ１．０μｍの非晶質硬質炭素被膜を被覆した。この時、母材温度は１００℃一定として、母材に印加するバイアス電圧を変化させ、種々の被膜微小硬さが得られるように調節した。得られた本発明品と比較品の被膜微小硬さ、及び実施例１と同様の線材樹脂被覆テストを行った際の寿命を表２に示した。被膜微小ビッカース硬さが２０００〜５０００の範囲内にある本発明品は“目やに”の付着が抑えられ長寿命となったが、比較品では、被膜硬さが２０００未満のものは、被膜が摩耗、消失し、短寿命であった。また被膜硬さが５０００を超えるものは、被膜強さに乏しく、テスト初期に被膜が剥離し、短寿命であった。
【００２４】
【表２】

【００２５】
（実施例３）次に超硬合金製ニップル及びダイス（ロックウエルＡ硬さ９０．０）の被覆面を種々の表面粗さに仕上加工し、その後、実施例１と同様の高周波イオンプレーティング法により、炭化珪素中間層を厚さ０．５μｍ及びその上に被膜厚さ１．０μｍの非晶質硬質炭素被膜を被覆し、種々の被膜表面粗さを有するニップル及びダイスを得た。得られた本発明品と比較品の被膜表面粗さ、及び実施例１と同様の線材樹脂被覆テストを行った際の寿命を表３に示した。被膜表面粗さがＲｙ＝５μｍ以下である本発明品は“目やに”の付着が抑えられ長寿命となり、一方、Ｒｙが５μｍを超える比較品では、表面凹部への樹脂の溶着が顕著となり、短寿命であった。
【００２６】
【表３】

【００２７】
（実施例４）次に超硬合金製ニップル及びダイス（ロックウエルＡ硬さ９０．０）に、実施例１と同様の高周波イオンプレーティング法により炭化珪素中間層を厚さ０．５μｍ被覆した後、続けて被覆処理雰囲気を種々の混合比のメタン／四フッ化炭素混合ガスとし、被膜厚さ１．０μｍのフッ素含有非晶質硬質炭素被膜を被覆した。得られた本発明品及び比較品の非晶質硬質炭素被膜の被膜中フッ素量及び実施例１と同様の線材樹脂被覆テストにおける寿命を表４に示した。被膜中フッ素量が３０質量％以下である本発明品は“目やに”の付着が抑えられ長寿命となったが、３０％を超えた比較品では被膜強度が乏しく、テスト初期に剥離し、短寿命であった。
【００２８】
【表４】

【００２９】
（実施例５）次に、超硬合金中のＣｏの添加量を変化させることにより、硬さが種々異なるニップル及びダイスを作製し、実施例１と同様の高周波イオンプレーティング法により、炭化珪素中間層を厚さ０．５μｍ、その上に被膜厚さ１．０μｍの非晶質硬質炭素被膜を被覆した。得られた本発明品と比較品の母材ロックウエルＡ硬さ、及び実施例１と同様の線材樹脂被覆テストを行った際の寿命を表５に示した。母材硬さが８８．０以上である本発明品は、“目やに”の付着が抑えられ、長寿命であった。一方、８８．０未満である比較品はテスト初期に母材硬さ不足による工具変形が発生し、製品寸法が変化したため短寿命であった。
【００３０】
【表５】

【００３１】
【発明の効果】
以上に説明したように、本発明に係る線材用樹脂押出し被覆装置のニップル及びダイスは、超硬合金に非晶質の硬質炭素被膜を被覆して作製しているため、優れた樹脂耐溶着性、耐摩耗性及び耐食性を有することにより、被加工材の品質が向上すると共にニップル及びダイスの寿命が長くなり、工業上極めて有益である。
【図面の簡単な説明】
【図１】線材樹脂被覆装置の概略図である。
【図２】高周波イオンプレーティング法の概略図である。
【図３】陰極アークイオンプレーティング法の概略図である。
【符号の説明】
１押出機
２クロスヘッド
３ニップル
４ダイス
５母材
６母材支持電極
７高周波発生電極
８母材
９母材支持電極
１０炭素陰極
１１トリガー
１２蒸発粒子
Ａ溶融樹脂
Ｂ芯線
Ｃ樹脂通路[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a nipple and a die used for an apparatus for extruding and coating a resin on a wire.
[0002]
[Prior art]
A wire material such as a cable for various communications or electric wires is extruded and coated with a resin to a certain thickness in order to protect a core wire and prevent conduction with the outside. FIG. 1 is a schematic diagram of a resin extrusion coating apparatus used in such a process. Conventionally, polyethylene (PE), cross-linked polyethylene (XLPE), polyvinyl chloride (PVC), flame-resistant polyethylene (EM), and the like have been used as the resin material, and these have been used in the extruder 1 shown in FIG. The resin is heated and kneaded at 100 to 300 ° C. to form a molten resin A, which is supplied to the crosshead 2. In the crosshead 2, the molten resin A is coated on the core while being extruded together with the core B through a gap formed by the nipple 3 and the die 4, and is cooled immediately after exiting the die.
[0003]
As a material for the nipple 3 and the die 4, tool steel and cemented carbide are conventionally known. In particular, WC-Co cemented carbides are considered to be suitable because they have high hardness, are excellent in wear resistance and product shape stability, and have a low coefficient of thermal expansion at 100 to 300 ° C. (for example, And Patent Document 1).
[0004]
On the other hand, when a cemented carbide has a problem in corrosion resistance, various ceramic nipples and dies have been proposed (for example, see Patent Document 2).
[Patent Document 1] JP-A-2002-18926 [Patent Document 2] JP-A-7-256728
[Problems to be solved by the invention]
However, in such nipples and dies made of tool steel or cemented carbide, there is a problem that the molten resin easily adheres to the tool surface, thereby causing a so-called "eye-saw" to adhere to the resin layer. This is a problem that when there is a resin lump that has been welded and solidified on the nipple and the die, the resin lump drops off and is mixed into the coating layer, thereby significantly reducing the coating strength.
[0006]
Also, recently, a hard filler is sometimes added to the resin material in order to improve the strength and hardness of the coating resin of the wire. In this case, there is a problem that the nipple and the die are easily worn.
[0007]
In addition, when PVC is used for the resin or when magnesium hydroxide is added to make the wire flame-retardant, corrosion of the nipple and die due to the corrosive gas generated by their thermal decomposition also occurs. Has become a problem.
[0008]
For these problems, nipples and dies made of alumina ceramics or silicon nitride ceramics may be used. However, since the material strength and toughness are inferior to those made of metal, there is a problem that cracks and chips are easily generated in tools. .
[0009]
An object of the present invention is to provide a nipple and a die in which the fusion of the molten resin to the nipple and the die is reduced, and the wear resistance and the corrosion resistance are both improved.
[0010]
[Means for Solving the Problems]
Therefore, the present inventors have paid attention to covering the nipple and the die with an amorphous hard carbon coating having excellent welding resistance, abrasion resistance, and corrosion resistance to a resin.
[0011]
Amorphous hard carbon is mainly composed of carbon and hydrogen, and is a substance in an amorphous state in which the bonding state thereof is irregular, and is also called diamond-like carbon (DLC), i-carbon, or the like. This material has a very smooth surface and forms a dense coating, is chemically stable, and has excellent welding resistance, abrasion resistance, and corrosion resistance to resin. I guessed.
[0012]
As a method of coating the amorphous hard carbon film, there are recently an ion implantation method in addition to a PVD (physical vapor deposition) method and a plasma CVD (chemical vapor deposition) method. Among them, the PVD method includes an ionization vapor deposition method, an ion beam method, a sputtering method, and an ion plating method (high-frequency ion plating, cathodic arc ion plating, hollow cathode method).
[0013]
Further, as an intermediate layer between the base material and the amorphous hard carbon coating, a single layer or a multiple layer selected from transition metals of Groups IVa, Va, VIa of the periodic table and B, Si, Ge or their carbides. By coating the film with a thickness of 0.2 to 1.0 μm in total, the adhesion between the amorphous hard carbon film and the base material can be improved. The coating method of the intermediate layer may be the same as that of the amorphous hard carbon coating. However, when the thickness of the intermediate layer exceeds 1.0 μm, the intermediate layer itself has low hardness and is brittle, so that the strength of the entire coating film decreases.
[0014]
The thickness of the amorphous hard carbon coating can be changed depending on the amount of the raw material gas at the time of coating and the coating time, and the thickness is desirably 0.5 μm to 10 μm. When the thickness is less than 0.5 μm, the abrasion resistance is poor. When the thickness exceeds 10 μm, the coating is peeled off because the residual stress due to the difference in thermal expansion coefficient between the coating and the base material is too high or the toughness of the coating is low. It will be easier.
[0015]
The fine Vickers hardness of the amorphous hard carbon film can be changed by a bias voltage applied to the base material at the time of coating and a base material temperature. When the cathode arc ion plating method or the sputtering method is used among the PVD methods, it is possible to obtain an amorphous carbon film harder than other methods. The coating hardness is desirably HV2000 to 5000. Below HV 2,000, the coating is soft and poor in abrasion resistance. On the other hand, when it exceeds HV5000, the toughness of the film itself is poor, and cracks and film peeling in the film tend to occur.
[0016]
Further, by adjusting the finished surface roughness of the nipple and the die base material so that the surface hardness of the amorphous hard carbon coating is Ry 5 μm or less, resin welding can be more effectively suppressed. This is because, when Ry exceeds 5 μm, the friction coefficient increases due to the unevenness of the coating, and the resin is easily welded.
[0017]
Further, by including a fluorine gas or a carbon tetrafluoride gas in the coating gas, an amorphous hard carbon film containing fluorine can be coated. When fluorine is contained in the coating, the adhesion resistance of the amorphous hard carbon coating to the resin can be further improved. However, when the fluorine concentration in the coating exceeds 30% by mass, the coating strength decreases. The amount of fluorine contained in the amorphous hard carbon coating can be adjusted by the mixing ratio of the fluorine gas or carbon tetrafluoride gas and the hydrocarbon gas.
[0018]
The base material of the nipple and die may be any of carbon steel, tool steel, cemented carbide, etc., but cemented carbide is desirable because of its high hardness and excellent product shape stability. It is particularly desirable that the particle size be 88.0 or more.
[0019]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
The surface of the cemented carbide nipple and the inner surface of the die were sequentially coated with a silicon carbide intermediate layer and an amorphous hard carbon coating. The coated surface of the nipple and the die was previously ground and polished to a predetermined surface roughness. The coating method may be any of the above-mentioned methods, but in this embodiment, a high-frequency ion plating method and a cathodic arc ion plating method were used. The coating principle diagrams of these methods are shown in FIGS. In the high-frequency ion plating method, a base material 5 is mounted on a base material support electrode 6, and a gas plasma is generated by a high-frequency oscillator and a high-frequency generation electrode 7 in a low-pressure hydrocarbon gas atmosphere of about 1 to 100 Pa. Is decomposed and a film is deposited on the surface of the base material to which a bias voltage has been applied. In the cathodic arc ion plating method, after a base material 8 is fixed to a base material support electrode 9, a trigger 11 is applied to the surface of a carbon cathode 10 as a coating material in a low-pressure hydrocarbon gas atmosphere of about 10 ^{−2 to 1} Pa. This is a method in which a vacuum arc discharge is generated, the cathode surface is evaporated, and evaporated particles 12 are deposited on the base material 8 and the base material supporting electrode 9 to which a bias voltage is applied, thereby forming a coating. In the present invention, the reason for using these methods is that the amorphous hard carbon film coated by the high-frequency ion plating method has an excellent surface roughness of the film surface, and that the film is formed on a complex-shaped product. This is because the throwing power is relatively excellent. However, with this method, it is difficult to form a coating having a Vickers hardness of 5000 or more. Therefore, a cathodic arc ion plating method was used to form the high hardness coating. In addition, an amorphous hard carbon film containing various amounts of fluorine was also coated by using a methane / carbon tetrafluoride mixed gas as a coating treatment atmosphere. Further, nipples and dies were prepared from base metal cemented carbides having various hardnesses, and covered with a silicon carbide intermediate layer and a hard carbon coating in the same manner as described above.
[0020]
The nipple and the die coated with the hard carbon coating in this manner were mounted in a wire coating apparatus as shown in the schematic diagram of FIG. 1, and a resin coating test was performed. Polyethylene was used as the resin, and the resin heating temperature was 200 ° C. The molten resin A is fed into the crosshead 2 in the extrusion coating apparatus shown in FIG. 1 and is coated on the core wire B by the nipple 3 and the die 4. At this time, the length of the coated wire rod until the solidified resin mass welded to the nipple and the die became a so-called "blind", accumulated, dropped off, and mixed into the coating layer was defined as the product life.
[0021]
(Example 1) A WC-Co cemented carbide nipple and a die, which are conventional products, were subjected to a high frequency ion plating method so that a silicon carbide intermediate layer having various thicknesses was formed in an organic silicon compound gas atmosphere. Coating was performed for a predetermined time, and subsequently, an amorphous hard carbon coating was coated for various times using an atmosphere of methane gas so as to have various coating thicknesses. The Rockwell A hardness of the base metal cemented carbide was 90.0, the surface roughness of the coated surface was 2 μm Ry, and the base metal temperature was 100 ° C. The nipple and the die were mounted in a wire coating apparatus as shown in the schematic diagram of FIG. 1 and a resin coating test was performed. Polyethylene was used as the resin, and the resin heating temperature was 200 ° C. Table 1 shows the coating time, coating thickness, and product life of the obtained silicon carbide intermediate layer and amorphous hard carbon coating of the present invention product and the conventional product. According to the present invention, the coating thickness of the silicon carbide intermediate layer is in the range of 0.2 to 1.0 μm, and the coating thickness of the amorphous hard carbon coating is in the range of 0.5 to 10.0 μm. The product had a low resin welding speed to the nipple and the die, had a product life exceeding 30 km, and exhibited a long life. On the other hand, the nipples and dies having no silicon carbide intermediate layer or having a thickness of less than 0.2 μm or more than 1.0 μm, or an amorphous hard carbon coating having a thickness of less than 0.5 μm or 10.0 μm are used as comparative products. Exceeding nipples and dies, or nipples and dies without any coating treatment, had a high resin welding speed or peeling of the coating, resulting in a short life.
[0022]
[Table 1]

[0023]
(Example 2) Next, a silicon carbide intermediate layer was formed on a nipple and a die (Rockwell A hardness 90.0) made of cemented carbide similar to those in Example 1 by a high-frequency ion plating method and an arc ion plating method. An amorphous hard carbon film having a thickness of 0.5 μm and a coating thickness of 1.0 μm was coated thereon. At this time, the base material temperature was kept constant at 100 ° C., and the bias voltage applied to the base material was changed so that various coating microhardnesses were obtained. Table 2 shows the microhardness of the film of the obtained product of the present invention and the comparative product, and the life when the same wire resin coating test as in Example 1 was performed. The product of the present invention, in which the coating has a micro Vickers hardness in the range of 2,000 to 5,000, has a long life because the adhesion of "eyes" is suppressed. Disappeared and had a short life. When the coating hardness was more than 5000, the coating strength was poor, the coating peeled off at the beginning of the test, and the life was short.
[0024]
[Table 2]

[0025]
(Example 3) Next, the coated surface of a nipple and a die (Rockwell A hardness 90.0) made of cemented carbide is finished to various surface roughnesses, and then the same high-frequency ion plating method as in Example 1 Thus, a silicon carbide intermediate layer was coated with an amorphous hard carbon coating having a thickness of 0.5 μm and a coating thickness of 1.0 μm on the silicon carbide intermediate layer to obtain nipples and dies having various coating surface roughnesses. Table 3 shows the surface roughness of the coating film of the obtained product of the present invention and the comparative product, and the life when the same wire resin coating test as in Example 1 was performed. The product of the present invention having a coating surface roughness of Ry = 5 μm or less has a longer life because the adhesion of “eyes” is suppressed, while the comparative product having a Ry of more than 5 μm has a remarkable adhesion of the resin to the surface recesses, resulting in a shorter life. Life was over.
[0026]
[Table 3]

[0027]
(Example 4) Next, a silicon carbide intermediate layer was coated on a cemented carbide nipple and a die (Rockwell A hardness 90.0) with a thickness of 0.5 µm by the same high-frequency ion plating method as in Example 1. Subsequently, the coating treatment atmosphere was changed to a mixed gas of methane / carbon tetrafluoride with various mixing ratios, and a 1.0 μm-thick fluorine-containing amorphous hard carbon coating was coated. Table 4 shows the fluorine content in the amorphous hard carbon coatings of the obtained product of the present invention and the comparative product and the life in the same wire resin coating test as in Example 1. The product of the present invention, in which the amount of fluorine in the coating is 30% by mass or less, has a long life because the adhesion of "eyes" is suppressed. Life was over.
[0028]
[Table 4]

[0029]
(Example 5) Next, nipples and dies having various hardnesses were produced by changing the amount of Co in the cemented carbide, and silicon carbide was produced by the same high-frequency ion plating method as in Example 1. The intermediate layer was coated with an amorphous hard carbon film having a thickness of 0.5 μm and a coating thickness of 1.0 μm. Table 5 shows the base material Rockwell A hardness of the obtained product of the present invention and the comparative product, and the life when the same wire resin coating test as in Example 1 was performed. The product of the present invention having a base material hardness of 88.0 or more has a long life because the adhesion of “eyes” is suppressed. On the other hand, the comparative product having a viscosity of less than 88.0 had a short life because tool deformation occurred due to insufficient base metal hardness in the initial stage of the test and the product dimensions changed.
[0030]
[Table 5]

[0031]
【The invention's effect】
As described above, the nipples and dies of the resin extrusion coating apparatus for wires according to the present invention are manufactured by coating an amorphous hard carbon coating on a cemented carbide, and thus have excellent resin welding resistance. By having abrasion resistance and corrosion resistance, the quality of the workpiece is improved, and the life of the nipple and the die is prolonged, which is extremely useful in industry.
[Brief description of the drawings]
FIG. 1 is a schematic view of a wire rod resin coating apparatus.
FIG. 2 is a schematic diagram of a high-frequency ion plating method.
FIG. 3 is a schematic diagram of a cathodic arc ion plating method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Extruder 2 Cross head 3 Nipple 4 Dice 5 Base material 6 Base material support electrode 7 High frequency generation electrode 8 Base material 9 Base material support electrode 10 Carbon cathode 11 Trigger 12 Evaporated particles A Molten resin B Core wire C Resin passage

Claims

A nipple and a die used in an apparatus for extruding and coating a resin on a wire, wherein the surface of the nipple and the inner surface of the die are coated with an amorphous hard carbon film.

The nipple and the die of the wire coating apparatus according to claim 1, wherein an intermediate layer between the base material and the amorphous hard carbon coating, a transition metal belonging to Group IVa, Va, or VIa of the periodic table and B, A nipple and a die, wherein a single-layer or multiple-layer coating selected from Si, Ge or a carbide thereof is coated with a total thickness of 0.2 to 1.0 [mu] m.

The nipple and the die of the wire coating apparatus according to claim 1, wherein the thickness of the amorphous hard carbon coating is 0.5 to 10 μm.

4. The nipple and the die of the wire coating apparatus according to claim 1, wherein the amorphous hard carbon film has a Vickers hardness in the range of HV2000 to 5000.

The nipple and die of the wire coating apparatus according to claim 1, wherein the surface hardness of the amorphous hard carbon coating is 5 μm or less Ry.

The nipple and the die of the wire coating apparatus according to claim 1, wherein the amorphous hard carbon coating contains 30% by mass or less of fluorine.

The nipple and the die of the wire coating apparatus according to claim 1, wherein the base material is a cemented carbide and the Rockwell A hardness is 88.0 or more.