【発明の詳細な説明】[Detailed description of the invention]
本発明は複合ラツプ工具に関するものである。
前加工された工作物の平面度を高め良好な仕上
げ面をつくる工作法としてラツピングがあり、従
来では加工物より軟質のラツプと加工物のあいだ
に遊離砥粒と油剤を混合したラツプ剤を介在さ
せ、あるいはラツプ表面に配した微小穴に砥粒を
押込み、この状態でラツプと工作物表面を相対摺
動させる方法がとられていた。しかし、前者の方
法は、砥粒の流出による無駄が多い点、砥粒の転
動により加工面の梨地状化が生じやすい点、およ
びラツプの摩耗量が多くラツプ表面平担度の耐久
性に乏しい点にそれぞれ欠点があつた。また、後
者の方法は細かい砥粒を装着する作業がきわめて
煩雑であると共に、砥粒の固定が不十分で使用中
に容易に砥粒離脱を起す点に欠点があつた。
このようなことから、本発明者らは昭和55年特
許願121025号において、鋳鉄を母材としこれに砥
粒を混合して成形焼結したラツプ工具を提案し
た。このラツプ工具は既存のこの種工具と違つて
砥粒が定盤と遊離しておらず、頭初から固定され
ているため前記した従来工具の欠点がなく、被加
工物が硬脆材料であつても塑性流動による良好な
加工面が形成され、従つて精密加工において遊離
砥粒によるラツピングより非常に有利であるとい
う利点があつた。
しかし、このラツプ工具は砥粒が大きくこれと
鋳鉄粉の粒度と同程度の場合には鋳鉄粒子間の結
合する部分が多いため砥粒保持力はかなり大きい
か、砥粒が＃1000以下のように微粉となつた場合
には焼結品としての機械的強度（圧縮強さ、引張
り強さ）が低下し、また、砥粒の保持力が弱く、
砥粒の離脱により仕上面に悪影響を与えるという
不具合があり、これを改善するため砥粒と鋳鉄粉
の粒度比を１：10以上（メツシユサイズ）にして
も＃2000以下になると砥粒保持効果が少ないとい
う問題があつた。
本発明は前記した従来のものの欠点を解消し、
砥粒粒度が＃2000以下のような微粒であつても優
良な砥粒保持力を発揮し、圧環強さや引張り強さ
も良好な研摩工具を提供しようとするものであ
る。
この目的のため本発明者らはさきに提案したラ
ツプ工具の不具合発生原因について詳細な検討を
加えた。その結果、鋳鉄粉に砥粒を混合して成形
焼結した当該工具は鋳鉄粒の境界にそつて砥粒を
配列分布した工具（セメント）組織になるのを特
徴としているが、砥粒が細粒であるときには鋳鉄
粒子の空間に砥粒が顆粒状にかたまり、これによ
る一種の壁現象により焼結の際に金属相互の接合
が妨げられ、また保持力が低下して使用中に砥粒
が離脱する傾向となることがわかつた。
そこで本発明は、単に鋳鉄粉と砥粒を用いるだ
けでなく、これに純鉄粉を添加して成形焼結した
複合体とするものであり、鋳鉄粉は鋳鉄粒子と完
全遊離の黒鉛粉の混合した状態にあるが、これに
微粉の砥粒と純鉄粉を混合すれば、混合過程で鋳
鉄粒子の間に砥粒、純鉄および鋳鉄粉から遊離し
た黒鉛の混合物が充填される。そして、これを成
形し焼結することにより、さきの工具組織におい
て問題となつていた鋳鉄粒子の空隙部分が前記混
合物により埋められると同時に母地と同じ一様な
鋳鉄組織が形成され、その鋳鉄組織に砥粒がしつ
かりと包埋され、砥粒保持力が著しく増強される
ものである。
以下本発明の実施例を添付図面に基いて説明す
る。
第１図ないし第３図は本発明に係る複合ラツプ
工具の一例を示すもので、円盤１の上に複数のセ
グメント２を配列接着しており、各セグメント間
には所定の間隔で溝３を形成している。前記各セ
グメント２は、鋳鉄粉と微粒の研摩剤（以下砥粒
と称す）および適量の純鉄粉を混合して成形しそ
れを焼結してなる焼結複合体から構成されてお
り、砥粒５は第３図のごとく一様な鋳鉄組織８，
８′に包埋され、表層の砥粒５はその先端を母地
表面８１に微少に突出している。
しかして、従来のように鋳鉄粉と砥粒を混合し
て成形焼結した場合には、第４図のごとく鋳鉄粉
（鋳鉄粒子）４，４の境界に空隙９が形成される
と共に、この空隙９に砥粒５が顆粒状にかたま
る。このかたまりとなつた砥粒５は鋳鉄粉４より
固定化されていないため、被加工材との相対摺動
により容易に離脱しやすい。
これに対し、本発明においては、鋳鉄粉４に対
し砥粒５だけでなく純鉄粉６を併せて添加するた
め、それらの混合により第２図のごとく各鋳鉄粒
子４，４の空隙部分９が砥粒５と純鉄粉６および
遊離黒鉛７の混合物により充填される。そして、
こうした鋳鉄粉４と砥粒５および純鉄粉６の配合
を成形したのち焼結することにより、第３図の如
く鋳鉄粉４，４の溶着により鋳鉄母地８が形成さ
れると共に、空隙部分に充填されていた純鉄粉６
と遊離炭素７が反応して前記鋳鉄母地８と同じパ
ーライト組織などの小さなボリユームの鋳鉄組織
８′となる鋳鉄母地８と一体不可分に結合される。
これにより砥粒５は鋳鉄母地８と同等の均一な鋳
鉄組織で包埋固定され、図示のように空隙部分が
生じないため、きわめて強固な保持力が達成され
るものである。
ここで、前記砥粒５は天然又は人造ダイヤモン
ド（ND、SD）、ホワイトアランダム（WA）、球
状窒化ほう素（CBN）など任意の材質のものを
用いることができる。また、鋳鉄粉４は鋳鉄材料
や鋳鉄製品の切削や研削加工で生じた屑を粉砕ふ
るい分けしたもの、あるいはさらにこれを脱炭処
理した鋳鉄粉などを用いることができる。さら
に、純鉄粉６は、カーボニル鉄粉、電解鉄粉、環
元鉄粉などを用いることができる。この純鉄粉６
はいずれにしても鋳鉄粉４よりも粒度の小さいこ
とが必要であり、添加量は鋳鉄粉４の材質や砥粒
５の材質、粒度および焼結条件などに応じて適当
に設定すればよく、一例としては鋳鉄粉に対し、
砥粒を５〜15wt％添加した場合、純鉄粉を砥粒
重量に対し２〜３倍添加するごとくである。な
お、砥粒５と鋳鉄粉４は砥粒が細粒の場合はそれ
らの粒度比が１：10程度が適当である。例えば
＃2000砥粒に対し鋳鉄粉は＃150〜＃250のものを
選定することが望ましい。
次いで本発明によるラツプ工具の製造を説明す
ると、第５図のように母地となる鋳鉄粉４に対し
砥粒５と純鉄粉６を所要割合で添加し、それらを
ボールミルなどにより均一に混合する。この混合
により第２図のごとく鋳鉄粉粒子４，４の間に砥
粒５と純鉄粉６および鋳鉄粉から遊離した黒鉛７
が充填される。次いでこのような混合粉をダイス
に充填し、ポンチにより加圧成形する。このとき
混合粉の下に予め所要厚さに鋳鉄粉を充填してポ
ンチにより加圧成形することにより、鋳鉄ベース
で裏打された成形体が得られる。
次いで前工程で得られた鋳鉄粉４と砥粒５と純
鉄粉６および遊離黒鉛７からなる圧粒成形体を炉
中に装入し、アンモニア分解ガスや水素窒素混合
ガスなどの還元性雰囲気中で無加圧ままあるいは
加圧しながら焼結する。なお、焼結後に予熱ダイ
ス中で加圧するなどして鍛造してもよく、さらに
焼純工程を付加してもよい。このときの焼結条件
としては、1100〜1150℃のごときで行えばよく、
予熱−加熱−冷却のサイクルは種々の選定が可能
である。とくに冷却速度により母地の組織が変化
し、一般には40−40−40（分）のサイクルのごと
きを採用することで能率的に好結果が得られる。
上記のような工程でラツプセグメント２が得ら
れ、これを研削して定寸仕上げし、円盤に整列接
着することで第１図のような工具となる。この工
具の初表面を整えるには表面研削仕上げの後、修
正リングなどによる湿式ラツピングやポリシング
を行えばよい。これにより母地のわずかな減耗に
より目立が行われ、亀裂のない一様かつ平坦な鋳
鉄母地上に微少で一様な粗さの切刃（砥粒先端）
が分散状に配されたラツプ工具となる。なお本発
明はセグメント化せずに全体を一度に作つてもよ
いのは勿論である。
本発明による複合ラツプ工具は上記のような構
成からなるので、第１図の状態のものをラツプ盤
に取付け、これを回転させながら表面に軽油など
の砥粒を含まない油剤を付着させ、被加工物を押
付ければよい。この場合、本発明においては単に
鋳鉄粉と砥粒だけでなく純鉄粉を添加した焼結複
合体でラツプが構成されており、第３図のように
鋳鉄粉粒子のあいだの空隙が純鉄粉と遊離黒鉛の
反応組織８′すなわち鋳鉄組織で満たされると同
時にこれと一体化しており、砥粒５は突出部分以
外をさきの反応組織８′で完全に包埋されており、
各砥粒５，５が顆粒状に密集する形態とならな
い。そのため砥粒５が微粒であつてもきわめて確
実強固に保持され、砥粒離脱やこれの転動による
破さい面を生じさせない。そのため、被加工材が
硬脆材料が鋳鉄製品、シリコンなどの難加工材で
あつてもこれを短時間のうちに美麗な光沢面に研
摩することができる。さらにさきのように砥粒が
離脱しないため工具としての耐摩耗性が非常に良
好となり経済効果も大きい。
次に本発明の具体的な実施例を示す。
実施例
鋳鉄粉に砥粒を添加すると共に純鉄粉を加え
て混合焼結し、複合ラツプを作つた。このとき
母地となる鋳鉄粉の粒度分布と化学成分は下記
第１表のとおりである。
The present invention relates to a composite lap tool. Lapping is a processing method that increases the flatness of a pre-machined workpiece and creates a good finished surface. Conventionally, a lapping agent made of a mixture of free abrasive grains and an oil agent is interposed between the lap, which is softer than the workpiece, and the workpiece. Alternatively, a method was used in which abrasive grains were forced into minute holes arranged on the surface of the lap, and in this state the lap and the surface of the workpiece were allowed to slide relative to each other. However, with the former method, there is a lot of waste due to the flow of abrasive grains, the rolling of abrasive grains tends to cause the machined surface to become matte, and the amount of wear on the lap is large, resulting in poor durability of the lap surface flatness. Each of them had their own shortcomings. Furthermore, the latter method has disadvantages in that the work of attaching fine abrasive grains is extremely complicated, and the abrasive grains are insufficiently fixed and easily come off during use. For this reason, the present inventors proposed in Patent Application No. 121025 filed in 1980 a lap tool in which cast iron is used as a base material, abrasive grains are mixed therein, and the mixture is molded and sintered. Unlike existing tools of this type, this lap tool does not have the abrasive grains separated from the surface plate and is fixed from the beginning, so it does not have the drawbacks of the conventional tools mentioned above, and it can be used even when the workpiece is made of hard and brittle materials. However, a good machined surface can be formed due to plastic flow, and therefore it has the advantage that it is much more advantageous than lapping with loose abrasive grains in precision machining. However, with this lap tool, if the abrasive grains are large and the particle size is similar to that of the cast iron powder, the abrasive retention force is quite large because there are many bonding parts between the cast iron particles, or if the abrasive grains are less than #1000. If it becomes a fine powder, the mechanical strength (compressive strength, tensile strength) of the sintered product will decrease, and the holding power of the abrasive grains will be weak.
There is a problem that the detachment of abrasive grains has a negative effect on the finished surface, and even if the particle size ratio of abrasive grains and cast iron powder is set to 1:10 or more (mesh size) to improve this problem, if it is less than #2000, the abrasive grain retention effect will be reduced. There was a problem with the lack of it. The present invention eliminates the drawbacks of the conventional ones described above,
The objective is to provide an abrasive tool that exhibits excellent abrasive retention even when the abrasive grain size is as fine as #2000 or less, and has good radial crushing strength and tensile strength. For this purpose, the inventors conducted a detailed study on the causes of failures in the lap tool proposed above. As a result, the tool, which is formed and sintered by mixing abrasive grains with cast iron powder, has a tool (cement) structure in which abrasive grains are arranged and distributed along the boundaries of cast iron grains, but the abrasive grains are fine. When the abrasive grains are in the form of granules, they aggregate in the spaces between the cast iron particles, and this causes a kind of wall phenomenon that prevents the metals from joining together during sintering, and also reduces the holding power, causing the abrasive grains to clump during use. It was found that there was a tendency to leave. Therefore, the present invention not only uses cast iron powder and abrasive grains, but also adds pure iron powder to form a composite that is formed and sintered.The cast iron powder is a composite of cast iron particles and completely free graphite powder. If fine abrasive grains and pure iron powder are mixed together, a mixture of the abrasive grains, pure iron, and graphite released from the cast iron powder will be filled between the cast iron particles during the mixing process. Then, by forming and sintering this, the voids in the cast iron particles that were a problem in the previous tool structure are filled with the mixture, and at the same time, a uniform cast iron structure similar to that of the base material is formed, and the cast iron The abrasive grains are firmly embedded in the structure, and the abrasive grain retention is significantly enhanced. Embodiments of the present invention will be described below with reference to the accompanying drawings. Figures 1 to 3 show an example of a composite wrap tool according to the present invention, in which a plurality of segments 2 are arranged and bonded on a disk 1, and grooves 3 are formed at predetermined intervals between each segment. is forming. Each segment 2 is composed of a sintered composite obtained by mixing cast iron powder, fine abrasive particles (hereinafter referred to as abrasive grains), and an appropriate amount of pure iron powder, molding the mixture, and sintering the mixture. The grains 5 have a uniform cast iron structure 8 as shown in Fig. 3,
The abrasive grains 5 in the surface layer are embedded in the abrasive grains 8' with their tips slightly protruding from the base surface 81. However, when cast iron powder and abrasive grains are mixed and molded and sintered as in the past, voids 9 are formed at the boundary between cast iron powder (cast iron particles) 4 and 4, as shown in FIG. The abrasive grains 5 agglomerate into granules in the voids 9. Since the abrasive grains 5 that have become agglomerated are not fixed as much as the cast iron powder 4, they are easily separated by sliding relative to the workpiece. On the other hand, in the present invention, not only the abrasive grains 5 but also the pure iron powder 6 are added to the cast iron powder 4, so that by mixing them, the void portions of the cast iron particles 4, 4 are is filled with a mixture of abrasive grains 5, pure iron powder 6 and free graphite 7. and,
By molding and sintering the mixture of cast iron powder 4, abrasive grains 5, and pure iron powder 6, a cast iron matrix 8 is formed by welding the cast iron powders 4, 4 as shown in FIG. Pure iron powder filled in 6
and free carbon 7 react and are inseparably bonded to the cast iron base 8 to form a small volume cast iron structure 8' such as pearlite structure similar to the cast iron base 8.
As a result, the abrasive grains 5 are embedded and fixed in a uniform cast iron structure equivalent to that of the cast iron matrix 8, and as there are no voids as shown in the figure, an extremely strong holding force is achieved. Here, the abrasive grains 5 may be made of any material such as natural or artificial diamond (ND, SD), white alundum (WA), spherical boron nitride (CBN), etc. Further, the cast iron powder 4 may be obtained by crushing and sifting scraps generated during cutting or grinding of cast iron materials or cast iron products, or cast iron powder obtained by further decarburizing the waste. Further, as the pure iron powder 6, carbonyl iron powder, electrolytic iron powder, ring iron powder, etc. can be used. This pure iron powder 6
In any case, it is necessary that the particle size is smaller than that of the cast iron powder 4, and the amount added may be appropriately set according to the material of the cast iron powder 4, the material of the abrasive grains 5, the particle size, the sintering conditions, etc. For example, for cast iron powder,
When 5 to 15 wt% of abrasive grains are added, it is as if pure iron powder is added 2 to 3 times the weight of the abrasive grains. In addition, when the abrasive grains 5 and cast iron powder 4 are fine grains, it is appropriate that their particle size ratio is about 1:10. For example, it is desirable to select #150 to #250 cast iron powder for #2000 abrasive grains. Next, to explain the manufacturing of the lap tool according to the present invention, as shown in Fig. 5, abrasive grains 5 and pure iron powder 6 are added in the required ratio to cast iron powder 4, which is the base material, and they are mixed uniformly using a ball mill or the like. do. As a result of this mixing, as shown in Fig. 2, abrasive grains 5, pure iron powder 6, and graphite 7 liberated from the cast iron powder are present between the cast iron powder particles 4, 4.
is filled. Next, such a mixed powder is filled into a die and press-molded using a punch. At this time, a cast iron powder lined with a cast iron base is obtained by filling cast iron powder to a required thickness under the mixed powder and press-forming it with a punch. Next, the compacted compact consisting of the cast iron powder 4, abrasive grains 5, pure iron powder 6, and free graphite 7 obtained in the previous step is charged into a furnace, and is heated in a reducing atmosphere such as ammonia decomposition gas or hydrogen/nitrogen mixed gas. The material is sintered inside without pressure or with pressure applied. Note that after sintering, it may be forged by applying pressure in a preheated die, or a sintering process may be added. The sintering conditions at this time may be 1100 to 1150℃.
Various preheating-heating-cooling cycles can be selected. In particular, the structure of the matrix changes depending on the cooling rate, and generally good results can be obtained efficiently by adopting a cycle of 40-40-40 (minutes). The lap segment 2 is obtained through the process described above, which is then ground to a specified size and aligned and adhered to a disc to form a tool as shown in Figure 1. To prepare the initial surface of this tool, wet lapping or polishing using a correction ring or the like may be performed after surface grinding. As a result, sharpening is performed by slight wear of the base material, and a cutting edge (abrasive grain tip) with a minute and uniform roughness is created on a uniform and flat cast iron base surface with no cracks.
are arranged in a dispersed manner to form a lap tool. Note that, of course, in the present invention, the entire structure may be produced at one time without segmentation. Since the composite lapping tool according to the present invention has the above-mentioned configuration, the lapping tool in the state shown in Fig. 1 is attached to a lapping board, and while it is being rotated, a non-abrasive oil such as light oil is applied to the surface of the lapping tool. All you have to do is press the workpiece. In this case, in the present invention, the lap is composed of a sintered composite in which not only cast iron powder and abrasive grains but also pure iron powder is added, and as shown in Fig. 3, the voids between the cast iron powder particles are filled with pure iron powder. It is filled with and integrated with the reaction structure 8' of powder and free graphite, that is, the cast iron structure, and the abrasive grains 5 are completely embedded in the reaction structure 8' except for the protruding portions.
The abrasive grains 5, 5 do not form a dense granular form. Therefore, even if the abrasive grains 5 are fine, they are held extremely reliably and firmly, and the abrasive grains do not come off or break up due to their rolling. Therefore, even if the workpiece is a hard and brittle material such as cast iron or silicone, it can be polished to a beautiful glossy surface in a short time. Furthermore, since the abrasive grains do not separate as mentioned above, the wear resistance as a tool is very good, and the economic effect is also large. Next, specific examples of the present invention will be shown. Example A composite lap was made by adding abrasive grains and pure iron powder to cast iron powder, mixing and sintering the mixture. At this time, the particle size distribution and chemical composition of the cast iron powder serving as the base material are shown in Table 1 below.
【表】
砥粒は圧環テスト用としてWA砥粒＃2000を
用い、それ以外はSD＃2000とND＃2000を用
い、その含有量は５、7.5、10％の３種とした。
純鉄粉としてはカーボニル鉄粉（粒径10μｍ）
と電解鉄粉（粒度40μｍ）を用い、それらの含
有量は砥粒重量の２倍および３倍の２種とし
た。カーボニル鉄粉はFe：99.69％、Ｃ：0.01
％残部下可避的不純物からなる組成のものを用
い、電解鉄粉はFe：99.5％以上のものを用い
た。
上記の粉をボールミルで混合し、ラツプ工具
の要素である30×30×10（mm）のセグメントを
製作した。このとき砥粒の消費を最小限にし同
時に機械的性質を保持するため表面積１〜1.5
mmのみに砥粒を含有させ残部を普通鋳鉄組織と
なるよう成形ダイスに充填した。成形圧力は
8ton／cm2とし、焼結はアンモニア分解ガス雰囲
気中で1100〜1140℃で行い、予熱−加熱−冷却
のサイクルは40−40−40（mm）で行つた。得ら
れたセグメントを円盤上に並べて接着し、
φ210mmの機械ラツプを構成し、表面研削仕上
げ後砥粒のWA遊離砥粒によるラツピングを行
いラツプ定盤とした。
得られた工具についてまず圧環テストを行い
焼結性の良否を確めた。試験片は15×30φ、
WA＃2000、５、7.5、10wt％、カーボニル鉄
粉WA×２、WA×３を用いた。比較のため純
鉄粉を無添加としそれ以外を上記と同じ条件と
したセグメント（従来品）を作り同条件で試験
を行つた。この結果を示すと第６図のとおりで
ある。
第６図から明らかなように、本発明品は従来
品よりも圧環強さが大きい。これは鉄粉が砥粒
周辺を包埋し、焼結の際に鋳鉄粒子間の媒介と
して寄与し、従つて鋳鉄粒子間に空隙がなく一
様な鋳鉄組織になつたためであると考えられ
る。砥粒含有量が大きくなると従来品は著しい
強度の低下をきたすが、本発明の場合にはその
傾向が少なく、とくに純鉄粉を砥粒重量に対し
３倍添加したものは、砥粒含有量7.5wt％にお
いて従来品の1.5倍、10wt％において２倍もの
高い強度を得ている。
次にラツプセグメントの摩耗試験を行つた。
試験片形状はφ20mm、厚さ６mmであり、FC15
鋳鉄粉にSD＃2000を7.5wt％含有し、純鉄粉は
カーボニル鉄粉（SD×30wt％）、電解粉（SD
×3wt％）の２種とした。対向の摩擦板はWA
＃800、10wt％を含有した鋳鉄ラツプ定盤を使
用し、軽油を注入し、摩擦速度29ｍ／min、圧
力0.7Kg／cm2とした。
この試験結果を示すと第７図のとおりであ
り、純鉄粉無添加の従来品は４時間（６，96
Km）の走行でかなり摩耗するが、本発明の場合
はほとんど摩耗せず、きわめて良好であつた。
このとこは、＃2000又はそれ以下の微細な砥粒
を使用する場合に、純鉄粉添加が砥粒保持力の
強化に著しい効果のあることを示すものであ
る。
次に本発明品（ND＃2000、7.5wt％、カー
ボニル22.5wt％）により４種の材料をラツピン
グしてみた。
被加工材料は、サフアイア（前加工：研削、
前加工粗さ4.0μｍ）、GGG（前加工：スライシ
ング、前加工粗さ3.0μｍ）、水晶（多刃式切断、
3.1μｍ）、およびシリコンウエハ（スライシン
グ、1.7μｍ）であり、実験条件はラツプ液：軽
油、ラツプ圧力：0.25、0.5、1.0、1.5Kg／cm2、
ラツピング速度：平均16ｍ／min、ラツピング
時間：１〜60minとした。
まずラツプ量とラツプ距離の関係を示すと第
８図であり、本発明は長時間にわたりラツプ量
が減少せず、良好な耐久性を得ていることがわ
かる。またラツプ能率もサフアイア以外はかな
り高いことがわかる。
第９図は被加工材料をGGGにとつてND
＃1000と＃2000の効果を比較したもので、従来
加工し難かつたGGGに対し＃2000で有効に加
工できることが示されている。さらに、第１０
図はラツプ圧力とラツプ量の関係を示し、第１
１図はこのときの表面粗さとラツプ圧力の関係
（ラツプ時間３分）を示すものである。これら
の図から、本発明の場合には実用的な圧力範囲
でラツプ量が増しても表面粗さの変化が少いこ
とがわかる。すなわち、ラツプ量はラツプ圧力
に比例して増大するが、表面粗さはほとんど変
化しない。GGGもラツプ圧力を低くすれば問
題ない。サフアイヤの場合、ラツプ量は低いが
加工表面形成は迅速に行われる。
なお、本発明により炭化けい素（Hv2400）
をラツピングしたときのラツプ圧力とラツプ量
および表面粗さの関係を示すと第１２図のごと
きであり、表面粗さも良好でしかもラツプ量が
大きく、優れた性能が得られている。このよう
な精度を遊離砥粒方式で得るには＃4000という
ような粒度としなければならず、従つてこの意
味からも本発明は実用的である。
以上説明した本発明によるときには、鋳鉄粉と
研摩剤および純鉄粉を所要割合で混合して成形焼
結し、鋳鉄組織に研摩剤を包埋保持した形態の複
合ラツプとしたので、研摩剤の粒度を微細にした
場合に問題となつていた鋳鉄粒子の空隙への砥粒
のかたまり現象が防止され、空隙の発生がなく砥
粒保持力のきわめて増強された工具とすることが
でき、これにより工具として必要な圧環強さなど
の機械的強度が優れると共に耐摩耗性のきわめて
良好な美麗な仕上面を形成することのできる実用
的な工具を提供できる。なお、本発明はサフアイ
ア、GGGなどの電子材料のラツピングに好適で
あるほか、超仕上げやホーニングなどの工具とし
て適用され、また超硬合金の金型研摩具や鋳鉄製
品の研摩工具などあらゆる難加工材の加工に利用
できるものである。[Table] WA abrasive grains #2000 were used for the radial crushing test, and SD #2000 and ND #2000 were used for other abrasives, with three types of abrasive grains: 5, 7.5, and 10%.
Carbonyl iron powder (particle size 10μm) is used as pure iron powder.
and electrolytic iron powder (particle size 40 μm) were used, and their contents were two types, twice and three times the weight of the abrasive grains. Carbonyl iron powder has Fe: 99.69%, C: 0.01
The electrolytic iron powder used had a composition consisting of % balance of inevitable impurities, and the electrolytic iron powder had a Fe content of 99.5% or more. The above powder was mixed in a ball mill to produce 30 x 30 x 10 (mm) segments, which are the elements of a lap tool. At this time, in order to minimize consumption of abrasive grains and maintain mechanical properties at the same time, the surface area is 1 to 1.5.
A molding die was filled so that only the abrasive grains were contained in mm and the remaining part had a normal cast iron structure. The molding pressure is
8 ton/cm 2 , sintering was performed at 1100 to 1140° C. in an ammonia decomposition gas atmosphere, and the preheating-heating-cooling cycle was performed at 40-40-40 (mm). The obtained segments are arranged on a disk and glued.
A mechanical lap with a diameter of 210 mm was constructed, and after surface grinding, lapping was performed using WA free abrasive grains to create a lap surface plate. First, a ring crushing test was performed on the obtained tool to confirm its sinterability. The test piece is 15×30φ,
WA#2000, 5, 7.5, 10wt%, carbonyl iron powder WA x 2, WA x 3 were used. For comparison, a segment (conventional product) was made with no added pure iron powder and the other conditions were the same as above and tested under the same conditions. The results are shown in FIG. 6. As is clear from FIG. 6, the product of the present invention has greater radial crushing strength than the conventional product. This is thought to be because the iron powder embeds around the abrasive grains and serves as an intermediary between the cast iron particles during sintering, resulting in a uniform cast iron structure with no voids between the cast iron particles. When the abrasive grain content increases, the strength of conventional products decreases significantly, but in the case of the present invention, this tendency is less; At 7.5wt%, the strength is 1.5 times higher than that of conventional products, and at 10wt%, it is twice as strong. Next, a wear test was conducted on the lap segment.
The specimen shape is φ20mm and thickness 6mm, and is FC15.
Cast iron powder contains 7.5wt% SD#2000, pure iron powder contains carbonyl iron powder (SD x 30wt%), electrolytic powder (SD
×3wt%). The opposing friction plate is WA
A cast iron lap surface plate containing #800 and 10 wt% was used, and light oil was injected to set the friction speed to 29 m/min and the pressure to 0.7 Kg/cm 2 . The test results are shown in Figure 7, and the conventional product without pure iron powder was tested for 4 hours (6,96 hours).
However, in the case of the present invention, there was almost no wear and the performance was extremely good.
This shows that when using fine abrasive grains of #2000 or smaller, the addition of pure iron powder has a remarkable effect on strengthening the abrasive grain retention. Next, four types of materials were wrapped using the product of the present invention (ND#2000, 7.5wt%, carbonyl 22.5wt%). The material to be processed is sapphire (pre-processing: grinding,
Pre-processing roughness 4.0μm), GGG (pre-processing: slicing, pre-processing roughness 3.0μm), crystal (multi-blade cutting,
3.1 μm) and silicon wafer (sliced, 1.7 μm), and the experimental conditions were lapping liquid: light oil, lapping pressure: 0.25, 0.5, 1.0, 1.5 Kg/cm 2 ,
Wrapping speed: average 16 m/min, wrapping time: 1 to 60 min. First, the relationship between the amount of wrap and the distance of the wrap is shown in FIG. 8, and it can be seen that the amount of wrap does not decrease over a long period of time in the present invention, and good durability is obtained. It can also be seen that the wrap efficiency is quite high except for Saffire. Figure 9 shows ND when the workpiece material is GGG.
A comparison of the effects of #1000 and #2000 shows that #2000 can effectively process GGG, which was previously difficult to process. Furthermore, the 10th
The figure shows the relationship between wrap pressure and wrap amount.
Figure 1 shows the relationship between surface roughness and lapping pressure (lapping time: 3 minutes). From these figures, it can be seen that in the case of the present invention, even if the amount of lapping increases, the change in surface roughness is small within a practical pressure range. That is, the amount of lapping increases in proportion to the lapping pressure, but the surface roughness hardly changes. GGG is also fine if the wrap pressure is lowered. In the case of sapphire, the amount of lapping is low, but the processed surface is formed quickly. In addition, according to the present invention, silicon carbide (Hv2400)
The relationship between the lapping pressure, lapping amount, and surface roughness when lapping is shown in FIG. 12, and the surface roughness is good, the lapping amount is large, and excellent performance is obtained. In order to obtain such precision using the free abrasive method, the grain size must be #4000, and therefore, the present invention is practical in this sense as well. According to the present invention as described above, cast iron powder, abrasive agent, and pure iron powder are mixed in the required proportions and molded and sintered to form a composite lap in which the abrasive agent is embedded in the cast iron structure. This prevents the phenomenon of abrasive grains clumping into the voids of cast iron particles, which was a problem when the grain size was made fine, and it is possible to create a tool with no voids and extremely enhanced abrasive grain retention. It is possible to provide a practical tool that has excellent mechanical strength such as radial crushing strength necessary for a tool, and can form a beautiful finished surface with extremely good wear resistance. The present invention is suitable for wrapping electronic materials such as sapphire and GGG, and is also applicable as a tool for superfinishing and honing, as well as for all kinds of difficult-to-process tools such as mold polishing tools for cemented carbide and polishing tools for cast iron products. It can be used for processing materials.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は本発明に係る複合ラツプ工具の一実施
例を示す斜視図、第２図と第３図はそれぞれ混合
時および焼結時の組織を模式的に示す断面図、第
４図は従来品の模式的な断面図、第５図は本発明
工具の製造工程を示す説明図、第６図は本発明工
具の圧環強さを従来品と比較して示すグラフ、第
７図は同じく本発明品と従来品の耐摩耗性を比較
したグラフ、第８図は本発明品により各種材料を
ラツピングしたときのラツプ量とラツプ距離の関
係を示すグラフ、第９図は本発明において砥粒粒
度を変えた場合のラツプ効果を比較して示すグラ
フ、第１０図は本発明におけるラツプ量とラツプ
圧力の関係を示すグラフ、第１１図は同じく表面
粗さとラツプ圧力の関係を示すグラフ、第１２図
は本発明により炭化けい素材料をラツピングした
ときの性能を示すグラフである。
２……セグメント、４……鋳鉄粉、５……研摩
剤（砥粒）、６……純鉄粉、８，８′……鋳鉄組
織。
Fig. 1 is a perspective view showing an embodiment of a composite lap tool according to the present invention, Figs. 2 and 3 are cross-sectional views schematically showing the structure during mixing and sintering, respectively, and Fig. 4 is a conventional FIG. 5 is an explanatory diagram showing the manufacturing process of the tool of the present invention, FIG. 6 is a graph showing the radial crushing strength of the tool of the present invention in comparison with conventional products, and FIG. A graph comparing the wear resistance of the invention product and the conventional product. Figure 8 is a graph showing the relationship between the amount of lapping and the lapping distance when various materials are wrapped with the product of the invention. FIG. 10 is a graph showing the relationship between the amount of lapping and lapping pressure in the present invention. FIG. 11 is a graph similarly showing the relationship between surface roughness and lapping pressure. The figure is a graph showing the performance when wrapping silicon carbide material according to the present invention. 2... Segment, 4... Cast iron powder, 5... Abrasive (abrasive grain), 6... Pure iron powder, 8, 8'... Cast iron structure.